Afghanistan CHAPTER 5 GROUNDWATER DEVELOPMENT · 2012. 11. 16. · Afghanistan Dehsabz South...

Afghanistan Dehsabz South Groundwater Survey

JICA 5-1 DCDA

CHAPTER 5 GROUNDWATER DEVELOPMENT In the previous Chapters, all the field work results were described. In this Chapter, groundwater development potential is to be estimated roughly from a recharging potential based upon the existing hydrogeological data/information, field work results and examinations thereof. Given the basic purpose of this Sub-project, groundwater development potential in each site is to be estimated, and then the development potential will be examined in detail using MODFLOW simulation model only for the site(s) having promising high potential on the future development. Groundwater development scenarios are then examined, following which a conceptual development design will be formulated. A monitoring system on the groundwater table in the target sites will also be presented.

5.1 Estimation on Groundwater Development Potentials

Groundwater is one of the renewable natural resources, whereby we can develop it in a sustainable way if we keep exploiting groundwater within the volume it renews every year. Renewing groundwater volume in a certain groundwater basin takes place mostly by precipitation, which is called as “Perennial Yield” of the basin. Though renewing of the groundwater volume varies depending upon the annual precipitation, the sustainable groundwater development potential therefore settles almost same as the average perennial yield of the groundwater basin.

This Sub-project tries to estimate the average perennial yield of each target groundwater basin as a sustainable1 development potential roughly as the first step. The perennial yield of a groundwater basin shall be estimated through examinations on the direct groundwater recharge by precipitation in a certain groundwater basin and the indirect recharge by seepage from river-bed or canal bottom passing through the target basin. The precipitation data available in and around the survey area are only the observation records at the Kabul Airport. Based on the observation at the Airport, average annual precipitation for the current six years was found at around 303 mm/year (see Figure 5.1.1).

Exactly saying, groundwater development potential is not equal to the perennial yield since it must take existing groundwater usage in the groundwater basin into consideration. It follows that the groundwater development potential in a certain groundwater basin is “the perennial yield minus the existing level of groundwater exploitation”. The existing groundwater exploitation, current groundwater usage in other words, is difficult to exactly grasp on quantitative basis.

However, most of the existing groundwater usages are observed on domestic water use, periodical irrigation use for a period of roughly 3 months in a year, and also some industrial use especially for brick factories at the Bakhtyaran site and Daneshmand-Pymonar site. The current use of groundwater

1“Short-term Development Potential” may be referred to as the groundwater development volume we expect to be allowed to exploit, beyond the sustainable development volume, only for short period such as three or four years. However, there is no such allowable groundwater development volume which can be exploitable beyond the perennial yield, nor such term of Short-term Development Potential hydro-geologically. Continuous over exploitation beyond the perennial yield causes rapid groundwater depletion and finally dries up or destroys the aquifer. No one knows a certain aquifer once destroyed can recover or not. With this in mind, this Sub-project is to examine the sustainable amount of groundwater development.

193

292

386

279

165

504

0

100

200

300

400

500

600

2004 2005 2006 2007 2008 2009

Ann

ual P

reci

pita

tion,

mm

Figure 5.1.1 Annual Precipitation from 2004 - 2009

Average: 303 mm/year

Dehsabz South Groundwater Survey Afghanistan

DCDA 5-2 JICA

might be compensated from the groundwater development system to be constructed, except for the Tangi Kalay site which already has large scale production wells owned by an investor. Following discussion centers on the maximum perennial yield in each target site while current water usage is discussed in the following sub-chapter:

5.1.1 Development Potential in Site-1 (Tangi Kalay)

In Site-1 (Tangi Kalay area), there are large scale production wells already along with the north bank of the Kabul River. Therefore, it is unlikely that there is chance to develop groundwater furthermore. In the site, taking this condition into account, only groundwater quality analysis on the existing production well was conducted. No other hydrogeological investigation works such as geophysical prospecting and test well drilling have been conducted. The groundwater development potential is therefore roughly estimated based on the existing data and information.

1) Direct recharging

The north bank of the Kabul River has its own catchment area in its further north of around 19.5 km2

(see Figure 5.1.2). The infiltration ratio in this catchment area can be evaluated at 0.06 to 0.082 because the catchment area is composed of relatively course materials due to its rather high average inclination. Thus, the direct recharging through the own catchment area is calculated as:

19.5(km2) x 106 x 0.303(m) x 0.06 - 0.08 = 354,510 - 472,680 m3/year. ....................................(a)

2) Indirect recharging

In the Tangi Kalay area, Kabul River is passing through around 5km before it enters the steep and narrow gorge. The area is located at the low end of the Kabul Basin, and therefore results of a previous groundwater study on the Kabul basin; “Study on Groundwater Resources Potential in the Kabul Basin (2011)” conducted by JICA, can be applied. In accordance with the study, the low end of the Kabul River is recharging groundwater through seepage from the bottom by around 0.322 MCM/km/year. Based on the data, the groundwater recharge through the river is estimated as:

5.0 (km) x 0.322 (MCM/km/year) x 1,000,000 = 1,610,000 m3/year ........................................ (b)

3) Groundwater development potential

Groundwater development potential, thus calculated, shall be added together and resulted as (a) + (b);

354,510 + 1,610,000 ≒ 1,964,500 m3/year

2 Under the Study on Groundwater Resources Potential in the Kabul Basin, simulations were carried out dividing the target Kabul Basin into more than 130 sub-basins wherein infiltration ratio and coefficient of permeability were so evaluated as to meet the field observation results of groundwater tables. In so doing, 10%, 7% (or 0.06 – 0.08), 5% (or 0.04 – 0.06), and 3% (or 0.02 – 0.04) were identified as the infiltration ratios of area with high infiltration rate, e.g. fan or talus, area covered by coarse materials with rather high ground inclination, area of normal alluvial plain in the Kabul Basin, and area covered by fine materials e.g. silt or silty clay respectively.

Catchment Boundary

Tangi Kalay

Pol-e Charkhi Figure 5.1.2 Catchment area of Tangi Kalay Area


JICA 5-3 DCDA

≒ 5,380 m3/day ≒ 62 liter/sec

472,680 + 1,610,000 ≒ 2,082,680 m3/year ≒ 5,700 m3/day ≒ 66 liter/sec

Groundwater development potential in the site is roughly estimated as from 5,300 to around 5,700 m3/day. It is rather excellent potential but it may have more development potential because the area can be recharged from its southern bank too. As evidence, production wells for irrigation purpose existing in the north bank of the Kabul River can yield around 45 to 40 liter/sec with 6.0m drawdown.

5.1.2 Development Potential in Site-2 (Pol-e Charkhi)

At the site-2, Pol-e Charkhi area, one of the tributaries of the Kabul River, named “Buthkhak River” joins together. The Buthkhak River has a large catchment area of some hundreds sq.km but the catchment which can replenish the groundwater is confined at its lower middle stream (at the east of Atal Ghar) by a natural underground dam3. Direct recharging by precipitation can therefore be expected from only the downstream catchment area from the natural underground dam point. Even though it is less than 1/4 of the total catchment, the available Buthkhak catchment area comes to around 66.5 km2 (see Figure 5.1.3).


As explained in the previous section, a yearly average precipitation observed at Kabul Airport in current 6 years is 0.303 m/year. An infiltration ratio of precipitation in the Buthkhak River basin is, however, not so high as the northern catchment of Tangi Kalay because the catchment area is mostly flat and covered by fine materials such as silty soil. In this area, infiltration rate from 0.04 to 0.06, which is almost average infiltration ratio of Alluvial deposits in Kabul Basin, shall be adopted. Thus, direct recharge in this area is;

66.5 (km2) x 106 x 0.303 (m) x 0.04 - 0.06 = 805,980 - 1,208,970 m3/year ................................(c)

3 At this point of the Buthkhak River, hard foundation which has very low permeability comes up preventing the groundwater flow from upstream to downstream or simply saying such very low permeable foundation forms a natural underground storage in its upstream side, which is called underground dam. With this condition at the midpoint of Buthkhak River, only downstream area is counted as the catchment area which can replenish the groundwater of the Pol-e Charkhi area.

Figure 5.1.3 Catchment Area of Pol-e Charkhi Area


DCDA 5-4 JICA


In this area, the Kabul River runs through around 3.0km length. As mentioned above, the Kabul River recharges groundwater through seepage at around the rate of 0.322 MCM/km/year. With the rate, the site can be recharged through the Kabul River as:

3.0 (km) x 0.322 (MCM/km/year) x 1,000,000 = 966,000 m3/year.................................... (d)


Groundwater development potential in Pol-e Charkhi area is now estimated by adding (c) and (d);

805,980 + 966,000 ≒ 1,771,980 m3/year ≒ 4,850 m3/day ≒ 56.2 liter/sec

1,208,970 + 966,000 ≒ 2,174,970 m3/year ≒ 5,960 m3/day ≒ 69.0 liter/sec

Thus, groundwater development potential in this site is roughly estimated from 4,850 to 5,960 m3/day, nearly same as the potential of Tangi Kalay area. It shows also excellent development potential. In addition, the site may have an extra recharging through an old river route of the Logar River which was to join the Kabul River at Pol-e Charkhi area for some period in an ancient time. The effect of the old Logar is, however, not taken into consideration because AUWSSC and KfW are planning to develop groundwater in the lower Logar sub-basin, just upstream of the old river route.

5.1.3 Development Potential in Site-3 (Bakhtyaran)

Bakhtyaran site lies in the Dehsabz Basin and there is no major river. Only a Bakhtyaran canal is passing through along the western edge of the target site. Rather small but Bakhtyaran site also has a catchment area in it eastern side. The site can be recharged by precipitation and also by the Bakhtyaran canal, though the recharge from the canal may not be so noticeable.


Catchment area of Bakhtyaran site extends toward east to the Mount Gharib Ghar. The mountain is of the watershed at its eastern side and the catchment is enclosed by the Bakhtyaran canal at its western side. Catchment area of the site is estimated at only 16.0 km2 (see Figure 5.1.4). The area near the site where groundwater development is planned is widely covered by worked Loess, which is composed of very fine materials such as clay or silt, and the infiltration ratio of rain in this area is estimated at 0.02 to 0.04. Thus, the direct recharging by precipitation in this site is as small as:

Figure 5.1.4 Catchment Area of Bakhtyaran Area


JICA 5-5 DCDA

16.0 x 106 x 0.303 x 0.02 - 0.04 = 96,960 - 193,920 m3/year......................................................(e)


Bakhtyaran canal, passing through along the western edge of the site for around 3.0 km, is not perennial and the averaged flow rate is very small. The previous study on the Kabul Basin, Groundwater Resources Potential in the Kabul Basin, 2011, surveyed the flow sourced from Kabul River. The average yearly runoff of the canal was around 7.7 MCM/year, and this is only less than 2.0% the runoff of the Kabul River at Pol-e-Charkhi point. The condition of the canal bottom is also different from that of Kabul River, less permeable than that of Kabul River. Taking those into account, indirect recharging rate of the canal is set at only 1% of that of Kabul River:

3.0 (km) x 0.322 (MCM/km/year) x 1,000,000 x 0.01 = 9,660 m3/year ..................................... (f)


Groundwater development potential in Bakhtyaran area shall be estimated by adding (e) and (f);

96,960 + 9,660 ≒ 106,620 m3/year ≒ 292 m3/day ≒ 3.4 liter/sec

193,920 + 9,660 ≒ 203,580 m3/year ≒ 558 m3/day ≒ 6.5 liter/sec

There is an observation relating to the above potential. An observation well by AGS exists near the Bakhtyaran site. Yearly fluctuation of the groundwater table in the observation well is around 3.0m in average. When the area of target site is estimated at 1.8 km2 (3.0 km x 0.6 km) and effective porosity of the aquifer at 0.03, the volume of renewable groundwater can be estimated as follows, indicating quite similar calculation results:

1.8 (km2) x 1,000,000 x 3.0 (m) x 0.03 = 162,000 m3/year ≒ 434 m3/day ≒ 5.1 liter/sec

As aforementioned, estimated groundwater development potential in Bakhtyaran site is very low as only several hundreds cubic meter per day. When considering the water demand in the new Dehsabz city, it may be concluded that there seems little groundwater development potential in Bakhtyaran site.

5.1.4 Development Potential in Site-4 (Pymonar - Daneshmand)

Daneshmand site is located in a quite flat plain in between Pymonar village and Daneshmand village. Some small drainages are passing through the plain forming gullies from the west to the east. There is neither perennial river in this area nor canal. Therefore, resources of the groundwater here is only precipitation.


The area is widely covered by worked Loess on its ground surface, making difficult to infiltrate rain water into the ground. Infiltrate ratio in this area is set at less than 0.03 as the maximum estimation. The target site is confined at its western side by low mountain range separating the Dehsabz basin from the Parwan basin. Total catchment area of this site is estimated at 53.0 km2 (see Figure 5.1.5), and thus direct recharging by rainfall is calculated as:

53.0 (km2) x 106 x 0.303 (m/year) x 0.03 = 481,770 m3/year ............................................. (g)


DCDA 5-6 JICA


Indirect recharge through river or canal does not exist in this site.


Thus, the total groundwater recharging amount estimated for the area is 481,770 m3/year, which is converted into 1,320 m3/day and 15.3 liter/sec.

Though the estimated groundwater development potential in Pymonar - Daneshmand site is much better than Bakhtyaran site, there is still not enough recharging to develop at a certain scale. Farther, groundwater quality analysis also identified that the water quality was no good showing very high EC value and high Mn contents. Thus, groundwater development in this area located between Pymonar village and Daneshmand village will hardly be possible.

5.1.5 Summary of the Development Potential

As discussed so far, the averaged perennial yield in each target site varied from only 425 m3/day to more than 5,000 m3/day. Groundwater development potential in the two sites of Bakhtyaran and Pymonar - Daneshmand are very small while sites along the Kabul River show large potential thanks to the huge groundwater recharge through the seepage from the river bottom. Sustainable groundwater development potential in these target sites are summarized in Table 5.1.1:

Table 5.1.1 Summary of Groundwater Development Potential

Site Catchment Area, km2

Direct Recharge,

m3/Yr

Indirect Recharge,

m3/Yr

Development Potential, m3/day

Feasibility Remarks

Tangi Kalay 19.5 354,510 – 472,680 1,610,000 5,380 – 5,700(ave 5,500) Hard

Existing large yielding wells

Pol-e Charkhi 66.5 805,980 – 1,208,970 966,000 4,850 – 5,960(ave 5,400) High

High potential, not much current use

Bakhtyaran 16.0 96,960 – 193,920 9,660 292 – 558 (ave. 420) No

Very little water, poor water quality

Daneshmand 53.0 481,770 0 1,300 No Very small water resource available Source: JICA Sub-project Team Note: Average annual precipitation is 303 mm.

As shown in the above table, only the sites along the Kabul River have groundwater resources potential feasible to develop. However, Tangi Kalay site has already large scale production wells mainly for irrigation purpose owned by an investor. Therefore, the Tangi Kalay site may be said not to be much feasible in terms of development unless there is a water-trade agreement with the well owner. On the other hand, candidate sites of Bakhtyaran and Daneshmand-Pymonar, located in Dehsabz Basin, have a little groundwater resources and what is worse the water quality is not so good. It is therefore concluded that the groundwater development potential for the 2 sites is poor.

Figure 5.1.5 Catchment Area of Daneshmand-Pymonar Area


JICA 5-7 DCDA

5.2 MODFLOW Analysis on Potential Sites

As discussed so far, only Pol-e Charkhi site has high feasibility on further groundwater development, and Tangi Kalay site has the next feasibility depending upon the negotiation with the investor having large scale irrigation wells. In this section, groundwater development potential on these two sites are examined more detail through MODFLOW simulation, whether it is feasible to pump up the estimated development amount in these two sites.

5.2.1 MODFLOW Simulation on Pol-e Charkhi Site

(1) Concept of MODFLOW Model

Concept of MODFLOW model for Pol-e Charkhi site is shown in Figure 5.2.1. As shown in the figure, not all of the Buthkhak River basin was modeled but only the area underlain by Alluvial aquifer. The cross section model was simplified by two layers structure and the flat bottom from the northern end to the half of the total area.

The extent of area is around 30.1 km2, and depth of the aquifer is set from 12m to 30m below the ground surface. However, the upper 2m is already dry. Materials of aquifer are estimated as Sand and Gravels of river-bed deposits. Southern half of the model area (the Buthkhak river basin) is omitted

Figure 5.2.1 MODFLOW Model for Pol-e Charkhi Site


DCDA 5-8 JICA

from the analysis because there is no groundwater system in its area. Widths of the cells are set 20m at the minimum (near the New Production Wells) and 100m in the other areas. MODFLOW model, thus built up, is shown in ANNEX-VIII.1.

(2) Assumptions

For MODFLOW analysis, physical properties of layers consisting of the model, boundary conditions, and hydrogeological information on the site are required. Among them, some of hydrogeological information was obtained through the investigation and data collection under this Sub-project, but the other physical properties were assumed by general practices facing the little data availability.

Physical properties of the layers, assumed in the analysis, are summarized in Table 5.2.1. Permeability and Specific Storativity on the aquifer were estimated from the results of Pumping Test conducted in the existing well in the National Radio Station (T=3,400 m2/day, S=0.0036). The northern end of the model, which is the Kabul River was set as fixed head boundary, and the both sides of the Buthkhak River catchments area were set as no flow boundaries.

Precipitation on the area is 0.303 m/year from the 6-years average rainfall at Kabul Airport Station, and 0.05 of infiltration rate was applied. Those measured data or assumptions were given to the model, and four (4) wells of equivalent existing wells were assumed to evaluate the current groundwater balance through a “try and error trial”. The trial has changed the pumping rates from these assumed wells in order to adjust the groundwater table near the New Production Wells being around GL. -14m.

As a result, a current groundwater table was assumed as Figure 5.2.2. To adjust the groundwater table near the production wells, total 1,400 m3/day of pumping from those assumed equivalent wells were required.

Table 5.2.1 Assumed Physical Properties of Layers Particular Sandy Clay

(GL. 0 - -12m) Aquifer

(GL. -12 – 30 m) Permeability, K (m/sec) 1.0 x 10-6 2.46 x 10-3 Specific Storativity Ss (m-1) 1.0 x 10-4 2.25 x 10-4 Specific Yield Sy (%) 5 25 Source: JICA Sub-project Team

Figure 5.2.2 Current groundwater Balance of target Area


JICA 5-9 DCDA

(3) Case Study

Two new production wells were assumed in the Radio Station at Pol-e Charkhi site, and pumping simulations were carried out for several cases. The cases of Pumping Simulation are summarized in Table 5.2.2 (Results of MODFLOW simulation, estimated drawdown at each production well by the time-series and distance, and estimated groundwater contour maps in time series at every one year are attached in ANNEX-VIII.2).

(4) Results of MODFLOW analysis: Groundwater Level in the Well

Groundwater drawdown in the Buthkhak basin is relatively small (refer to ANNEX-VIII.2); drawdown only from a few centimeters to several tens of centimeters even near the production wells were simulated. These small scales of drawdown may be brought about by the influential interference of the Kabul River at the northern edge of the simulation area.

Then, the groundwater drawdown in the production wells during pumping was examined. The model was not dispersed enough to reproduce the water level in the pumping well (the minimum cell width was 20m). The water level at the just pumping well was calculated using the following empirical equation by Anderson and Woessner (1994):

hw = hij – Q (ln re – ln rw) / 2 πT Where hw: Water head in the well, hij: calculated water head at the node, Q: pumping rate, re: distance between the node and equal head point, (equal well radius) rw: radius of the well, and T: Transmissivity. Equal well radius was calculated as follows:

re = SQRT(⊿x⊿y/π)・E where, ⊿x, ⊿y: size of cell, E: Coefficient in the right table, and α= MAX(⊿x/⊿y, ⊿y/⊿x)

Groundwater drawdown in the production wells (No.1 well for eastern one, and No.2 for western one), thus calculated, are summarized in Table 5.2.3, and shown in Figure 5.2.3. Groundwater contour map of the site, in Case-4 (total 5,000 m3/day pumping) and at after 5 years from the time the pumping started, is shown in Figure 5.2.4.

Table 5.2.2 MODFLOW Case Study Case Pumping from No.1

well, m3/day Pumping from No.2

well, m3/day Total Pumping Rate, m3/day

Case-1 1,000 1,000 2,000 Case-2 1,500 1,500 3,000 Case-3 2,000 2,000 4,000 Case-4 2,500 2,500 5,000 Case-5 3,000 3,000 6,000 Source: JICA Sub-project Team

α E α E 1.1 1.002 1.5 1.041 1.2 1.008 1.6 1.077 1.3 1.017 1.7 1.118 1.4 1.028 1.8 1.204


DCDA 5-10 JICA

Table 5.2.3 Groundwater Table at Production Wells in Pol-e Charkhi Site Case.1 Case.2 Case.3 Case.4 Case.5

Q=1,000×2(m3/day) Q=1,500×2(m3/day) Q=2,000×2(m3/day) Q=2,500×2(m3/day) Q=3,000×2(m3/day)Time

(days) No.1 No.2 No.1 No.2 No.1 No.2 No.1 No.2 No.1 No.2

0 -13.965 -13.990 -13.965 -13.990 -13.965 -13.990 -13.965 -13.990 -13.965 -13.990 1 -14.706 -14.730 -15.096 -15.120 -15.485 -15.485 -15.906 -15.931 -16.269 -16.293 3 -14.733 -14.757 -15.136 -15.161 -15.539 -15.564 -15.974 -15.999 -16.352 -16.3765 -14.746 -14.770 -15.156 -15.180 -15.565 -15.590 -16.007 -16.032 -16.390 -16.415

10 -14.764 -14.788 -15.183 -15.207 -15.602 -15.626 -16.053 -16.077 -16.446 -16.471 20 -14.785 -14.808 -15.216 -15.238 -15.646 -15.668 -16.109 -16.130 -16.514 -16.534 50 -14.818 -14.840 -15.265 -15.285 -15.713 -15.731 -16.193 -16.210 -16.616 -16.631

100 -14.843 -14.864 -15.303 -15.322 -15.763 -15.781 -16.256 -16.273 -16.692 -16.707 200 -14.866 -14.885 -15.338 -15.355 -15.810 -15.825 -16.316 -16.328 -16.764 -16.774 365 -14.884 -14.900 -15.364 -15.377 -15.846 -15.855 -16.361 -16.366 -16.820 -16.820 730 -14.900 -14.912 -15.388 -15.396 -15.879 -15.880 -16.403 -16.398 -16.870 -16.859

1,095 -14.907 -14.918 -15.399 -15.404 -15.893 -15.891 -16.421 -16.411 -16.893 -16.876 1,460 -14.911 -14.921 -15.406 -15.409 -15.903 -15.898 -16.433 -16.420 -16.907 -16.886 1,825 -14.915 -14.924 -15.412 -15.413 -15.910 -15.903 -16.442 -16.427 -16.918 -16.894

Source: JICA Sub-project Team, MODFLOW Simulation Unit: GL -m

As shown in the table, groundwater drawdown caused by the pumping in the production wells, from each 1,000 to 3,000 m3/day are small, only from 81 cm to 2.45 m at the longest period (5 years) in Case-1 to Case-5.

Supposedly, they may be also due to the influence by constant recharge from the Kabul River. The maximum drawdown of 2.05 m from the original groundwater table in Case-4, which is the estimated groundwater potential in the site, is enough small comparing to the thickness of the aquifer which is around 16m (less than 13%), and it suggests that the pumping up of total 5,000 m3/day of groundwater through two production wells in this site shall be feasible.

Production Well No.1

-17.000

-16.500

-16.000

-15.500

-15.000

-14.500

-14.000

0 500 1000 1500 2000

Time after pumping started (day)

G.W

Tab

le G

L.(m

)

Case.1

Case.2Case.3Case.4Case.5

Figure 5.2.3 (1) Changing of Groundwater Table at the Production Well No.1

Production Well No.2

-17.000

-16.500

-16.000

-15.500

-15.000

-14.500

-14.000

0 500 1000 1500 2000

Time after Pumping started (day)

G.W

Tab

le G

L.(m

)

Case.1Case.2Case.3Case.4Case.5

Figure 5.2.3 (2) Changing of Groundwater Table at the Production Well No.2


JICA 5-11 DCDA

(5) Results of MODFLOW analysis: Groundwater Drawdown in the Village

Aforementioned section estimated the groundwater level in the well. MODFLOW simulation gives not only the groundwater level in the well but also all the groundwater levels at each nodal point of the model. Table 5.2.4 summarizes the groundwater drawdown with total 5,000 m3/day pumping (Case 4) by location such as 30 m away from the well, 100m, 200, etc. to 5 km away and by time such as 1 day, 10 days, 100 days, 200 days, 1 year, etc, to 5 years later. At a glance of the table is that the drawdown is not so much as exampled in the level at the time of 5 years after the pumping started, which is only 0.739 meter even at the 30 m from the well. If the location is 5 km far from the well, the drawdown becomes only 0.241 m.

Table 5.2.4 Groundwater Drawdown at Different Location by Time, Case 4: 2,500 m3/day x 2 wells Days 30m 100m 200m 300m 400m 500m 1km 2km 3km 5km

X-coord. (m) 2,090 2,130 2,170 2,220 2,300 2,380 2,700 2,900 3,500 4,300 Y-coordi.(m) 12,730 12,670 12,580 12,500 12,420 12,350 11,900 11,300 10,500 8,500

1 -0.208 -0.073 -0.021 -0.006 -0.001 -0.000 0.000 -0.000 -0.000 0.000 3 -0.274 -0.132 -0.062 -0.031 -0.013 -0.006 -0.000 -0.000 -0.000 0.000 5 -0.306 -0.162 -0.088 -0.051 -0.027 -0.014 -0.000 -0.000 -0.000 0.000

10 -0.351 -0.205 -0.127 -0.086 -0.055 -0.036 -0.003 -0.000 -0.000 0.000 20 -0.406 -0.258 -0.177 -0.132 -0.096 -0.071 -0.014 -0.002 -0.000 0.000 50 -0.489 -0.341 -0.259 -0.212 -0.172 -0.143 -0.057 -0.019 -0.002 0.000

100 -0.552 -0.406 -0.326 -0.280 -0.241 -0.212 -0.117 -0.059 -0.016 0.000 200 -0.612 -0.468 -0.392 -0.349 -0.313 -0.286 -0.195 -0.129 -0.060 -0.006

365 (1 yr) -0.658 -0.516 -0.444 -0.405 -0.372 -0.348 -0.268 -0.205 -0.125 -0.030730 (2 yrs) -0.699 -0.560 -0.492 -0.456 -0.427 -0.406 -0.341 -0.288 -0.212 -0.093

1,095 (3 yrs) -0.718 -0.580 -0.514 -0.480 -0.452 -0.434 -0.377 -0.332 -0.264 -0.1491,460 (4 yrs) -0.730 -0.593 -0.528 -0.495 -0.469 -0.451 -0.401 -0.361 -0.301 -0.1991,825 (5 yrs) -0.739 -0.603 -0.539 -0.507 -0.481 -0.465 -0.419 -0.384 -0.332 -0.241

Source: JICA Sub-project Team, by MODFLOW simulation Unit: m

Groundawter Contour Drawdown Contour

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

5 Years After

0 2000 4000 6000 8000 100000

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000

14000Kabul River : GL.-14m

Well Point : No.1

Well Point : No.2

Pol-e Charkhi Case.4: Q=5,000m3/s (No.1+No.2)

5 Years After

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Figure 5.2.4 Estimated Groundwater Contour at Pol-e Charkhi Site, Case-4, after 5 years


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5.2.2 MODFLOW Simulation on Tangi Kalay Site

(1) Concept of MODFLOW Model

Concept of MODFLOW model on Tangi Kalay site is shown in Figure 5.2.5. As shown in the figure, all of the northern catchments area of this site (19.5 km2) was fully modeled but its upstream zone was reduced to

the depth of aquifer, from the full depth of 42m to the upstream end, as shown in the cross section model. The cross section was built up from Lithological log of Mr. Omarzay’s Well No.1 shown as Figure 5.2.6. Southern edge of the model is the Kabul River as a fixed head boundary and the other sides are set as no flow boundary.

(2) Assumptions

Aquifer structure in this site was simply modeled as one layer structure. Physical properties on the aquifer, applied in the simulation, are the same as the ones for Pol-e Charkhi site (see Table 5.2.5). To estimate the current groundwater balance, current recharging and discharging were firstly evaluated.

For recharging, a yearly average precipitation was set at 0.303m same as that of Pol-e Charkhi site, but an infiltration ratio was assumed as 0.07 in this site. Then, the Kabul River was set as fixed head boundary. For discharge, two equivalent wells with each 1,014 m3/day of pumping rate were assumed at near around the Kabul River. Thus, the current groundwater balance (Groundwater Contour Map) was simulated as shown in Figure 5.2.7. As shown in the figure, the current groundwater table near the new production well was around 5.0m below the ground surface.

(3) Case Study

A new production well was assumed at near the Kabul River, in between the two equivalent assumed wells. MODFLOW simulation was conducted as case study changing the pumping rates of 1,500, 2,000, 2,500, and 3,000 m3/day, at an interval of 500 m3/day.

Table 5.2.5 Assumed Physical Properties Particular Aquifer

(GL. -5 – 42 m) Permeability, K (m/sec) 2.46 x 10-3 Specific Storativity Ss (m-1) 2.25 x 10-4 Specific Yield Sy (%) 25 Source: JICA Sub-project Team

Figure 5.2.5 MODFLOW Model on Tangi Kalay

Figure 5.2.6 Mr. Omarzay’s Well


JICA 5-13 DCDA

(4) Results of MODFLOW analysis

Results of MODFLOW analysis are attached in ANNEX-VIII.3. Only one results of the case on 3,000 m3/day of discharge rate, 5 years after the pumping had started, is shown in Figure 5.2.8. As easily readable from the figure, groundwater drawdown in the site, Tangi Kalay northern catchments area, is very small as only some centimeters in the nearest simulation cell to the production well.

In this site too, groundwater drawdown at the production well itself was estimated. As explained in previous section (Chapter 5.2.1 (3)), the model dispersion is not enough small to reproduce the water level in the pumping well (the minimum cell width was 20m). The water level at the pumping well was calculated using the equation by Anderson and Woessner (1994). Estimated groundwater drawdown in the new production well, in time sequence and discharge amounts, are shown in Table 5.2.6.

As shown in the table, the maximum drawdown in the production well is, even in the Case-4 (the maximum discharge of 3,000 m3/day), less than 1.4m which does not cause any problem for discharging groundwater in this site because the drawdown is only 3.5% of the aquifer thickness. Thus, the groundwater development potential in Tangi Kalay site shall be at least 3,000 m3/day on condition that the investor’s two wells are in operation as designed. Groundwater isobathic map on Tangi Kalay site at 5 years after the pumping started in Case-4 is shown in Figure 5.2.8.

Table 5.2.6 Groundwater Level in New Production Well in Tangi Kalay Case 1 Case 2 Case 3 Case 4 Days after

Pumping Q=1,500(m3/day) Q=2,000(m3/day) Q=2,500(m3/day) Q=3,000(m3/day) Remarks

0 -5.002 -5.002 -5.002 -5.002 1 -5.602 -5.814 -6.027 -6.239 3 -5.618 -5.835 -6.053 -6.271 5 -5.624 -5.843 -6.062 -6.282

10 -5.629 -5.849 -6.071 -6.292 20 -5.632 -5.853 -6.076 -6.298 50 -5.635 -5.858 -6.081 -6.305

100 -5.637 -5.861 -6.085 -6.309 200 -5.639 -5.863 -6.087 -6.312 365 -5.640 -5.864 -6.089 -6.314 730 -5.640 -5.864 -6.090 -6.315

1,095 -5.641 -5.865 -6.090 -6.316 1,460 -5.641 -5.865 -6.091 -6.316 1,825 -5.641 -5.865 -6.091 -6.317

Source: JICA Sub-project Team, MODFLOW simulation Unit: GL -m

Figure 5.2.7 Current Groundwater Contour Map


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(5) Results of MODFLOW analysis: Groundwater Drawdown in the Village

In addition to the groundwater level in the well, MODFLOW analysis estimated the groundwater levels at all the nodal point. Table 5.2.7 summarizes the groundwater drawdown with 3,000 m3/day pumping (Case 4) by location and by time up to 5 km away from the well. The table shows the drawdown is not so much as exampled in the water level at the time of 5 years after the pumping started, which is only 0.205 meter even at the 30 m from the well. If the location is 5 km far from the well, the drawdown becomes only 0.047 m.

Table 5.2.7 Groundwater Drawdown at Different Location by Time, Case 4: 2,500 m3/day x 2 wells Days 30m 100m 200m 300m 400m 500m 1km 2km 3km 5km

X-coord. (m) 1,530 1,475 1,475 1,550 1,550 1,550 1,675 2,450 3,350 5,250Y-coordi.(m) 670 725 825 950 1,050 1,150 1,650 2,450 3,050 4,050

1 -0.130 -0.056 -0.027 -0.010 -0.004 -0.002 -0.000 -0.000 -0.000 -0.0003 -0.161 -0.086 -0.054 -0.030 -0.019 -0.011 -0.001 -0.000 -0.000 -0.0005 -0.172 -0.097 -0.065 -0.041 -0.028 -0.019 -0.002 -0.000 -0.000 -0.000

10 -0.181 -0.107 -0.077 -0.053 -0.039 -0.030 -0.008 -0.000 -0.000 -0.00020 -0.187 -0.115 -0.085 -0.061 -0.048 -0.039 -0.015 -0.002 -0.000 -0.00050 -0.194 -0.122 -0.093 -0.070 -0.059 -0.050 -0.027 -0.008 -0.002 -0.000

100 -0.198 -0.127 -0.099 -0.077 -0.066 -0.058 -0.037 -0.017 -0.007 -0.001200 -0.201 -0.131 -0.103 -0.081 -0.071 -0.064 -0.044 -0.026 -0.016 -0.006

365 (1 yr) -0.202 -0.132 -0.105 -0.084 -0.074 -0.067 -0.049 -0.033 -0.024 -0.015730 (2 yrs) -0.203 -0.134 -0.107 -0.086 -0.076 -0.070 -0.053 -0.041 -0.035 -0.029

1,095 (3 yrs) -0.204 -0.135 -0.108 -0.087 -0.078 -0.071 -0.056 -0.045 -0.041 -0.0381,460 (4 yrs) -0.204 -0.135 -0.109 -0.088 -0.079 -0.072 -0.057 -0.048 -0.046 -0.043

0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 5500 6000 6500 70000

1000

2000

3000

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5000

6000

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Well Point : No.1

Figure 5.2.8 Groundwater Isobathic Map in Tangi Kalay (Case-4, 5 years after)


JICA 5-15 DCDA

Days 30m 100m 200m 300m 400m 500m 1km 2km 3km 5km 1,825 (5 yrs) -0.205 -0.136 -0.109 -0.089 -0.079 -0.073 -0.058 -0.050 -0.048 -0.047

Source: JICA Sub-project Team, by MODFLOW simulation unit: m

5.2.3 Summary on MODFLOW Analysis

MODFLOW Analysis was conducted for the two candidate sites of Pol-e Charkhi and Tangi Kalay. In both sites, physical properties were assumed in Table 5.2.8.

Table 5.2.8 Assumptions on Physical Properties Property Aquifer Surface Cover

Permeability k (m/sec) 2.46 x 10-3 1.0 x 10-6 Specific Storativity Ss (m-1) 2.25 x 10-4 1.0 x 10-4 Specific Yield Sy (%) 25 5 Catchments Area (km2) Pol-e Charkhi 0.08 Tangi Kalay: 19.5 Infiltration Ratio (%) Pol-e Charkhi: 0.05 Tangi Kalay: 0.07

Source: JICA Sub-project Team

Model was built up in 20 to 100m disperse, 20m cells near around the production wells (refer to Figure 5.2.9 for Pol-e Charkhi area). Two new production wells in Pol-e Charkhi and a new production well in Tangi Kalay sites were set near the Kabul River. The Kabul River in both sites was set as a fixed head boundary and the other sides were set as a no flow boundary. Current groundwater balance was estimated to adjust the groundwater table to the observed levels of around -14m in Pol-e Charkhi and -5m in Tangi Kalay site.

Simulation was carried out as Case Study; changing the discharge amount and estimating the groundwater drawdown in the target area, and the drawdown in the production wells (pumping wells) was estimated through the equation by Anderson and Woessner (1994) because the minimum cells are not enough fine to estimate the drawdown in the well.

As a result, the groundwater drawdown in the new production wells in Case-4 (discharge amount:

Figure 5.2.9 MODFLOW Model on Pol-e Charkhi Site


DCDA 5-16 JICA

2,500 m3/day/well totaling 5,000 m3/day in Pol-e Charkhi and 3,000 m3/day in Tangi Kalay) at the longest period (after 5 years since the pumping started) was estimated at only around 2.04m and only 1.3m in each site, respectively. The extent of drawdown is small comparing to the aquifer thickness4 in both sites: sharing 12.7% and 3.5% of the thickness of the aquifer in the respective sites of Pol-e Charkhi and Tangi Kalay. This means 2,500 - 3,000 m3/day/well of groundwater discharge is quite feasible. On top of this, the groundwater development at the maximum potential estimated by simple balance calculation on recharging, around 5,400 and 5,500 m3/day in the sites of Pol-e Charkhi and Tangi Kalay, are also feasible.

5.3 Development Scenarios of the Groundwater Potential

Discussions so far made have identified the groundwater potential by site based on simplified balance calculation referring to hydrogeological characteristics studied and the results of the pumping test. This sub-chapter explores development scenarios of the groundwater potentials; namely how the groundwater development should be explored in order to meet the population’s demand for the new city of Kabul. Discussions below start with how much water the new city will require based on the projected population and the water demand per capita, and then the scenarios or alternatives are to be presented in order to meet the urban water requirement by the groundwater.

5.3.1 Water Requirement

During the discussions on the Inception Report, DCDA clarified its stance in terms of the scale of the groundwater development as stipulated in the Minutes of the Meetings on the ICR:

DCDA stated that the groundwater to be surveyed under the Sub-project should target not only the Parcel-1 - Phase I area but also the Phase I development area of Dehsabz South, covering till the year 2015. DCDA further stressed that the Phase I development is planned to accommodate 400,000 population with stage-wise incremental unit water requirement, whereby the groundwater development should be targeted according to the scale of development.

Per-capita-water requirement has not been specified so far, but there may be an understanding that the requirement ranges from 25 liters per capita per day as the smallest case to as much as 150 liters per capita per day according to the development stage. Taking the per-capita requirement into account together with the step-wise population increase to the maximum 400,000, the total water requirement per day is resulted as shown in Table 5.3.1 and Figure 5.3.1.

Table 5.3.1 and Figure 5.3.1, as examples, simply indicate that population 400,000 will require a total 10,000 m3/day under the per-capita requirement of 25 liters per day per capita while the same population will require as much as 60,000 m3/day with the highest water requirement of 150 liters per 4 Usually it was said that the drawdown up to 1/4 (around 25%) of the aquifer thickness was allowable as a safe discharge not to harm the aquifer.

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Figure 5.3.1 Water Requirement by Different Per-capita Water Requirement and Population


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day per capita. On the other hand, if population of only 150,000 is projected by the time, the requirement will be 3,750 m3/day and 22,500 m3/day, respectively.

Table 5.3.1 Water Requirement by Different Per-capita Water Requirement and Population, m3/day Population 25 l/day/capita 50 l/day/capita 90 l/day/capita 120 l/day/capita 150 l/day/capita

50,000 1,250 2,500 4,500 6,000 7,500 100,000 2,500 5,000 9,000 12,000 15,000 150,000 3,750 7,500 13,500 18,000 22,500 200,000 5,000 10,000 18,000 24,000 30,000 250,000 6,250 12,500 22,500 30,000 37,500 300,000 7,500 15,000 27,000 36,000 45,000 350,000 8,750 17,500 31,500 42,000 52,500 400,000 10,000 20,000 36,000 48,000 60,000


5.3.2 Exploitable Groundwater Potential

“Chapter 5.1 Groundwater Development Potentials” explored the groundwater potential by site as once again summarized in Table 5.3.2. In addition, the table indicates the current use of the groundwater such as domestic use for the population, irrigation, and also brick making factories. To estimate the current use of the groundwater, following were assumed with reference to the inventory survey and also interview results:

1) To estimate newly exploitable amount of groundwater, current use of groundwater should be taken into account. These are; 1) domestic use mainly composed of drinking and laundry, 2) irrigation, and 3) brick factories’ use to mold bricks.

2) For the domestic use of water, mainly drinking and laundry water, per-capita requirement per day is set at 50 liters per capita per day while the population refers to the bigger number, either the estimated population based on number of households given by CSO or what was reported by the village representatives. Not all the residential areas are to be affected by the future groundwater development, e.g. almost half the Pol-e Charkhi area is segregated by different catchment, only small parts of Bakhtyaran site and Pymonar site are to be affected since the residential areas are far from the groundwater development area. Daneshmand area is replenished by a stream coming from upstream whereby no effect is foreseen.

3) Concerning irrigation by groundwater, irrigation wells are found in Pol-e Charkhi area, Pymonar area and Daneshmand area, numbers of which are 14, 22 and 30 respectively. These wells are operated during spring season mostly from May – July. According to the inventory survey, an average of 40 m3/day/well can be taken as the irrigation use for a well, converted in throughout the year pumping discharge as per day.

4) There are brick factories in Bakhtyaran area and the area between Pymonar village and Daneshmand village. To mold bricks, they use groundwater ranging mostly from 40 to as much as 150 m3/day for the period of half a year to throughout the year. Converting them into the throughout-year discharge, 48 m3/day/well and 52 m3/day/well are employed as the unit use by the brick factories in Bakhtyaran and Pymonar-Daneshmand area, respectively.

5) There are three large-discharge wells in Tangi Kalay owned by an investor. The discharges are reported at 45, 40 and 40 liters per day per well and one of the three wells is taken as emergency whereby two wells work in full operation during spring season, say 3 months, for irrigation purpose. Converting the 3 months discharge of the 2 wells, 45 liters plus 40 liters, into discharge throughout the year, an amount of 1,836 m3/day is estimated as the private investor’s water use.


DCDA 5-18 JICA

Following table shows, after subtracting current use of groundwater, that there are still exploitable potentials in Tangi Kalay and Pol-e Charkhi areas but not in Bakhtyaran and Pymonar-Daneshmand areas. For the latter 2 areas, the estimated total amount of current use indicates an already over-exploited situation, and therefore no further development would be foreseen.

Table 5.3.2 Groundwater Potential in Comparison with Current Use Site Tangi Kalay Pol-e Charkhi Bakhtyaran Pymonar Daneshmand Total

Gross Potential, m3/day 5,500 5,400 420 1,300 Average Current Use, m3/day 2,028 228 459 989 296 Max. Compensation % of to-be-affected area 100 50 30 40 0 Population 3,840 3,590 5,000 4,800 4,800

Assumed by MODFLOW

simulation results.

Domestic Use, m3/day 192 90 75 96 0 50 l/day/capita No. of Irrigation well 0 14 0 22 30 Irrigation Use, m3/day 0 138 0 217 296 40 m3/day/3months/well No. of brick factories 0 0 8 13 0 Brick Factory Use, m3/day 0 0 384 676 0 48-52 m3/d/fac. (thr. Yr) Private investor’s well, m3/day 1,836 - - - - (45+40) l/s/2 wells/3 m

Net Exploitable Pot’l, m3/day 3,472 Say 3,000 5,172

Say 5,000 -39 -15


In Tangi Kalay area, gross potential can be 5,500 m3/day while total amount of current use is estimated at 2,028 m3/day leaving net exploitable potential at about 3,000 m3/day. In fact, this exploitable amount is very much dependent on what extent the private investor is going to use his wells. In fact, should all the 3 wells owned by the investor be fully operational throughout the year, the total discharge would be 10,800 m3/day ((45+40+40) x 86,400/1,000), overweighing the gross potential by far. On the contrary, should the investor be willing to provide the water to the new City under a water trade-agreement, DCDA would be able to exploit as much as about 5,300 m3/day (5,500 – 192).

Therefore, in this Tangi Kalay site, negotiation between DCDA and the investor is recommend as the first stage towards concluding in an agreement whereby the water right owned by the investor can be traded to DCDA. Otherwise, the net exploitable potential of only about 3,000 m3/day may remain in the Tangi Kalay.

Pol-e Charkhi site shows the most promising exploitable potential amongst 4 sites. The net exploitable potential amounts at about 5,000 m3/day after subtracting domestic water (90 m3/day) and irrigation water (138 m3/day). Adding the exploitable potential at Tangi Kalay site, the total exploitable potential comes to about 8,000 m3/day, and should the agreement with the investor be made thereby DCDA could utilize his water right, the exploitable potential could

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25 l/day /capita 50 l/day /capita90 l/day /capita 120 l/day /capita150 l/day /capita 5,000 cum/day8,000 cum/day 10,000 cum/day

Figure 5.3.2 Water Requirements and Exploitable Potential


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be as much as about 10,000 m3/day.

Figure 5.3.2 superimposes development potentials on the water requirements, in which the potentials of 5,000 m3/day only from Pol-e Charkhi, 8,000 m3/day from combined use of Pol-e Charkhi and Tang Kalay, and 10,000 m3/day from the combined use of Pol-e Charkhi and total potential of Tangi Kalay including the one owned by the investor are assumed. From this figure, following are indicated:

In case of only Pol-e Charkhi being developed, population of approximately 200,000 could be served at the rate of 25 liters/day/capita, that of 100,000 at the rate of 50 liters/day/capita, and approximately 50,000 at 90 liters/day/capita.

In case of Pol-e Charkhi and Tang Kalay being developed excluding the investor’s water use, population of approximately 300,000 could be served 25 liters/day/capita, that of 150,000 at the rate of 50 liters/day/capita, that of approximately 75,000 at the rate of 90 liters/day/capita, and about 50,000 at the rate of 150 liters/day/capita.

In case of Pol-e Charkhi and Tang Kalay being developed including the investor’s water right, population of around 400,000 could be served with 25 liters/day/capita, that of 200,000 at the rate of 50 liters/day/capita, that of approximately 110,000 at the rate of 90 liters/day/capita, and about 70,000 with 150 liters/day/capita.


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5.4 Conceptual Development Designing

Based on the simple balance calculation by employing a concept of perennial yield carried out in the aforementioned sub-chapter 5.1 and 5.2, it was found that only Pol-e Charkhi can be the potential candidate site for the groundwater development amongst 4 sites. Though Tangi Kalay area has presented almost same potential as that of Pol-e Charkhi, there should be prior negotiation with the investor who owns large scale wells if DCDA wishes to exploit the groundwater therein. If the negotiation is settled with a success, it would be a better option to buy water from the existing wells rather than establishing new wells. Therefore, conceptual design is to be done for the Pol-e Charkhi area only.

5.4.1 Groundwater Development Potential and Production Wells

Groundwater development potential in the Pol-e Charkhi site was estimated from around 4,800 to 5,900 m3/day as a gross development potential, and around 230 m3/day5 shall be left from the development for the existing water use including both irrigation and domestic uses. Thus, a net groundwater development potential comes to a level of about 5,000 m3/day. Then, based on the results of pumping test in Pol-e Charkhi site, it was confirmed that the aquifer in this site was excellent as indicating 3,400 m2/day of Transmissivity (T), 0.0036 of Storativity (S) and 5.823 liter/sec/m of specific yield.

The specific yield suggests that a proper designed production well in this site can yield more than 29 liter/s inducing 5.0m of drawdown, and this yield in terms of liter per second is equivalent to 2,516 m3 per day. When considering the net groundwater development potential, only two production wells have enough capacity to exploit the potential as suggested by 2,516 m3/day x 2 wells = 5,031 m3/day, almost equal to the 5,000 m3/day of net potential.

5.4.2 Drawdown by the Production Well

Accordance to Theis theory, when a well penetrating an extensive confined aquifer is pumped at a constant rate, the influence of the discharge extends outward with time. The rate of decline of head times the storage coefficient summed over the area of influence equals the discharge. Because the discharged water must come from a reduction of storage within the aquifer, the head will continue to decline as long as the aquifer is effectively infinite; this is called as “Unsteady Radial Flow”. In a case of unsteady radial flow in a confined aquifer, the drawdown is shown as a following solution:

)(4

uWT

Qsπ

=

TtSru

4

2

=

where: s is drawdown (m), Q is discharge (pumping) rate (m3/day) T is Transmissivity (m2/day) W(u) is Well function, u is an indicator of W(u), r is distance from pumping well (m), S is Storativity, and t is time of pumping (day)

5 In Pol-e Charkhi area, 90 m3/day for domestic water and also 138 m3/day for irrigation water are estimated now in use, totaling 228 m3/day. With this rough estimation, rounded amount of 230 m3/day is left for the domestic use and irrigation use for the population.

……………………………………………………………(1)


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The equation was introduced for a confined aquifer but it can be applied to an unconfined aquifer as well if the drawdown is not so large as compared to the depth of aquifer, of course under the assumption that the aquifer is completely homogeneous and extending infinitely. As the equation indicates that the drawdown grows with the pumping rate and diminishes with the increase of the distance from the pumping well but it continues increasing steadily while pumping is continued.

Table 5.4.1 shows a drawdown of sample calculation in case of a production well in Pol-e Charkhi site under the conditions of 2,516 m3/day of pumping rate, 3,400 m2/day of Transmissivity, 0.0036 of Storativity. As shown in the table, drawdown after 1 day pumping at the point 30m far from the pumping well is only 46 cm, but it increases up to 90 cm at 5 years later. Whereas after 5 years continuous pumping, drawdown is 90 cm at the point 30 m apart from the pumping well, it is still less than 36 cm at a far point 3 km away from the well, if the actual aquifer condition is enough wide and homogeneous.

Table 5.4.1 Calculation of Drawdown by Theis, Pol-e Charkhi Site

5.4.3 Interference to the Existing Wells

Where a cone of depression between two nearby pumping wells appears, as the case of Pol-e Charkhi, one well interferes with the other because of its increased drawdown by pumping lift. For a group of wells forming a well field, the drawdown can be determined at any point if the well discharges are known, or vice versa. From the principle of superposition, the drawdown at any point in the area of influence caused by the discharge of several wells is equal to the sum of the values of draw-down caused by individual wells. Thus,

sT = sa + sb + sc + ・・・+ sn…………………………………………………………(2)

where T is the total drawdown at a given point and sa, sb, sc, ・・・ sn are the values of draw-down at the point caused by the discharge of wells a, b, c, ・・・, n, respectively. The situation is shown in

Time 4Tt S/4Tt u=r2S/4Tt r=30m r=100m r=200m r=300m r=400m r=500m r=1000m r=2000m r=3000m

1day 13600 2.64706E-07 u= 0.000238235 0.002647059 0.010588235 0.023823529 0.042352941 0.066176471 0.264705882 1.058823529 2.382352941W(u)= 7.758 5.3776 3.9463 3.176 2.634 2.206 1.014 0.186 0.028s= 0.457 0.317 0.232 0.187 0.155 0.130 0.060 0.011 0.002

10day 136000 2.64706E-08 u= 2.38235E-05 0.000264706 0.001058824 0.002382353 0.004235294 0.006617647 0.026470588 0.105882353 0.238235294W(u)= 10.06 7.678 6.236 5.458 4.9 4.45 3.098 1.737 1.076s= 0.592 0.452 0.367 0.321 0.289 0.262 0.182 0.102 0.063

1mon 408000 8.82353E-09 u= 7.94118E-06 8.82353E-05 0.000352941 0.000794118 0.001411765 0.002205882 0.008823529 0.035294118 0.079411765W(u)= 11.171 8.761 7.381 6.567 5.996 5.544 4.165 2.81 2.039s= 0.658 0.516 0.435 0.387 0.353 0.326 0.245 0.165 0.120

3mon 1224000 2.94118E-09 u= 2.64706E-06 2.94118E-05 0.000117647 0.000264706 0.000470588 0.000735294 0.002941176 0.011764706 0.026470588W(u)= 12.283 8.695 8.538 7.64 7.086 6.632 5.269 3.858 3.098s= 0.723 0.512 0.503 0.450 0.417 0.391 0.310 0.227 0.182

1year 4964000 7.25222E-10 u= 6.52699E-07 7.25222E-06 2.90089E-05 6.52699E-05 0.000116035 0.000181305 0.000725222 0.002900886 0.006526994W(u)= 13.669 11.25 9.871 9.064 8.451 8.046 6.646 5.269 4.465s= 0.805 0.662 0.581 0.534 0.498 0.474 0.391 0.310 0.263

2y 9928000 3.62611E-10 u= 3.2635E-07 3.62611E-06 1.45044E-05 3.2635E-05 5.80177E-05 9.06527E-05 0.000362611 0.001450443 0.003263497W(u)= 14.347 11.957 10.53 9.742 9.178 8.728 7.353 5.927 5.14s= 0.845 0.704 0.620 0.574 0.540 0.514 0.433 0.349 0.303

3y 14892000 2.41741E-10 u= 2.17566E-07 2.41741E-06 9.66962E-06 2.17566E-05 3.86785E-05 6.04351E-05 0.000241741 0.000966962 0.002175665W(u)= 14.752 12.363 10.966 10.147 9.575 9.144 7.758 6.362 5.544s= 0.869 0.728 0.646 0.598 0.564 0.538 0.457 0.375 0.326

4y 19856000 1.81305E-10 u= 1.63175E-07 1.81305E-06 7.25222E-06 1.63175E-05 2.90089E-05 4.53263E-05 0.000181305 0.000725222 0.001631749W(u)= 15.071 12.651 11.35 10.466 9.871 9.432 8.046 6.646 5.862s= 0.887 0.745 0.668 0.616 0.581 0.555 0.474 0.391 0.345

5y 24820000 1.45044E-10 u= 1.3054E-07 1.45044E-06 5.80177E-06 1.3054E-05 2.32071E-05 3.62611E-05 0.000145044 0.000580177 0.001305399W(u)= 15.289 12.833 11.48 10.673 10.103 9.655 8.228 6.876 6.07s= 0.900 0.756 0.676 0.629 0.595 0.569 0.485 0.405 0.357

Source: JICA Sub-project team

Figure 5.4.1 Interferences of Drawdown


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Figure 5.4.1.

Where a well is pumped near an aquifer boundary, the assumption that the aquifer infinitely extends is no longer valid. An example seen in the site is the situation of a well near a perennial stream. Because of the continuous recharging from a perennial flow, pumping water level (cone of depression) is modified as if there is an imaginary well system at the opposite side of the flow. Sectional view is exampled in Figure 5.4.2.

Taking these conditions; interference of production wells and recharging from perennial flow, into consideration, drawdown of groundwater taking place around the production wells was estimated through MODFLOW model simulation. Figure 5.4.3 shows a sample of drawdown contour map 5 years after two of the wells started pumping, shown in meter. In this simulation, the production wells have been operated at the rate of 2,500 m3/day each. In the figure, the contour lines are 0.1m interval, and water level of the Kabul River is GL. -14.0m.

5.4.4 Design of New Production Wells

As explained above, two newly drilled production wells are required, which must yield more than 2,500 m3/day under at least 30m of water-head ((S.W.L 14m + D.D 5m) x 1.5). However, one new large scale Test Well which can be converted to a production well later shall be drilled at first in order to confirm the well yield more precisely. Pumping rate of more than

Figure 5.4.2 Sectional View of Discharging Well near a Perennial Flow

5 Years After

0 2000 4000 6000 8000 100000

1000

2000

3000

4000

5000

6000

7000

8000

9000

10000

11000

12000

13000


Well Point : No.1

Well Point : No.2

Pol-e Charkhi Case.6 : Q=5,000m3/s (No.1+No.2)

Figure 5.4.3 Groundwater Contour under pumping


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2,500 m3/day means nearly 30 liter/sec, rather large amount of yielding, and to pump up such large amount of groundwater at least φ10” well must be required. To make up 10” well, drilling by 18-1/2” bit is needed. Thus, the structure of the production well shown in Figure 5.4.4 is recommended.

As shown in the figure, drilling diameter shall be 18-1/2” throughout the drilling, excepting an uppermost span of conductor pipe (6.0m), and the well depth shall be at least 40 m considering the geological condition of the site. Screen must be a wired type, so called “Johnson’s Screen” to obtain enough open ratio of more than 25%. Since the screen is set from the depth of 25m to 35m, the submersible motor pump shall be set at around 25m, just upper point from the screen pipes.

Two production wells will be drilled in the premises of Pol-e Charkhi Radio Station to avoid any land ownership conflict with the villagers, and shall be 1.0 km apart each other so as not to make a heavy interference. One of the two wells shall also work as a new test well, location of which can be at 531.500 / 3821.700 in UTM (1K unit) as recommended in Figure 5.4.5.

Compensation for the villagers may have to be considered. To identify such influence by the pumping at an earliest date, a monitoring system on groundwater level must be established before a full scale development is to commence. A monitoring system is therefore to be discussed in latter sub-chapter (Sub chapter 5.5).

5.4.5 Conceptual Design of Pipeline

If the proposed water resources site were selected in the Dehsabz sub-basin, it might have been much

Figure 5.4.5 Location of New Test Well

●Production well No.2 (New Test Well)

●Production well No.1

Figure 5.4.4 Structure of New Test Well


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easy to transport the water to the new city. However, possible groundwater resources development site is only Pol-e Charkhi site within the Kabul Basin. On top of this, the recommended production wells are to be installed inside of the Radio Station located at southern bank of the Kabul River. It means that the pipeline to carry the water shall pass across the river along with the newly constructed road and bridge joining the Jalalabad road.

Pipeline will pass across the road after crossing the bridge, then go west along with the northern side of the road. At a location around 3 km west from the joint with the road, the pipeline will turn to north along with the by-pass road to the Bagrum Road, just along with the district boundary between District 9 and District 19. After joining the Bagrum Road, the pipeline shall go further north along with the Bagrum Road approaching the new city. Total pipeline length is to be around 17 km. The rough route map of the pipeline is shown in Figure 5.4.6. As shown in the figure, the pipeline starts at the two production wells to be established in the Radio Station and the ends at a reservoir near the new city just beside the road.

5.5 Monitoring System for Groundwater Table

There are two categories of monitoring systems in this project; one is to monitor the natural ground water level of the three target sites for a basic hydrogeological data in Dehsabz Basin and another is to observe groundwater drawdown to be caused by the pumping inside the Radio Station influencing the outside.

5.5.1 Monitoring of Natural Groundwater Table

For the drilled three (3) wells under this Sub-project, after having placed concrete made basement (see photo as an example), they are to be so arranged that regular measurement of the groundwater level can be done. The frequency of groundwater level measurement can be as a rule once a month. This measurement may be carried out by DCDA supported by the Project on the Promotion of Kabul Metropolitan Area Development.

Figure 5.4.6 Outline of the Pipeline

Concrete made basement placed at the well for Bakhtyaran site


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This Sub-project is therefore to provide them with a manual showing procedures of the measurement and items to be taken. If the measurement is to be entrusted to a third party, the Sub-project Team is to prepare a standard contract form and the TOR.

5.5.2 Monitoring the Interference to be caused by Production Wells

In the previous section, draw-down to be caused by pumping at the production wells was explained. As shown in Figure 5.5.1, large parts of Pol-e Charkhi village will be affected by the pumping from the production wells but the influence is not anticipated serious judging from the result of the MODFLOW simulation. However, natural hydrological condition is not homogeneous, not infinitely equal. Therefore, it is quite important to monitor the values of actual groundwater draw-down in and around the production wells.

Major purpose of the monitoring is to evaluate an influence of the groundwater drawdown to be caused by operations of the production wells, so that the monitoring must be done to the directions most affective and must be commenced before the production wells start pumping. The proposed locations of the monitoring wells are shown in Figure 5.5.1. (Drawdown contours shown in the figure are only a reference). As shown in the figure, total three monitoring wells are required to observe the state of draw-down at the north, east, and south directions. The proposed locations are:

M1: 532000 E/ 3822200 N M2: 532850 E/ 3821800 N M3: 532000 E/ 3821500 N

Depths of the monitoring wells are to be the same as that of the production wells, 50m, but drilling diameter is to be 7” to 8” and completed by 4” screen and casing. Rough design of the monitoring well is shown in Figure 5.5.2. In case of observation wells, PVC casing and slotted screen can be applied. Screen depth shall be fixed from 25 to 35m in depth, the same as that of the new test well.

Figure 5.5.1 Location Map of Monitoring Wells

Figure 5.5.2 Structure of Monitoring Well


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5.6 Way-forward to the Population’s Consent for Groundwater Exploitation

The prime target is Pol-e Charkhi area for the groundwater development of the Dehsabz new city. Secondary target may be Tang Kalay area, however in this area there are already 3 large wells owned by an investor. Therefore, the development in this Tangi Kalay area will firstly depend on the result of the negotiation with the owner since there is no more potential to further exploit the groundwater other than those large wells. To this end, the way-forward to develop the groundwater including EIA clearance and the population’s consent should center on the Pol-e Charkhi area.

5.6.1 Groundwater Development in line with Legal Aspects

There is a law stipulating water related issues in Afghanistan, called Water Law6 issued at a Gazette No. 974 – 28, February 2009. In addition, there is environmental related law called Environmental Law, official Gazette No.912 dated 25 January 2007, and its relevant Environmental Impact Assessment Regulations (Gazette No.939, 10 March 2008). This session refers to these 2 laws to know the legal aspects to be required for the groundwater development:

1) Water Law

The Water Law has total 40 articles and governs not only surface water development but also groundwater development. The project for the groundwater development shall refer to the law especially for securing water right to develop and utilize the groundwater. Relevant articles in the law are cited and presented as below:

The water is defined as a public property and the government is responsible for its protection and management by Article 2 - Ownership and Management of Water. The Article 3 defines the definitions and terminologies used in the Law wherein groundwater is governed under this Law defining that groundwater is all waters beneath the ground surface at different depths (aquifer) including springs, Karezes, deep and ordinary wells.

Article 8 - Responsibilities of Governmental Institutions stipulates that the ownership of all waters in the country belongs to the people of Afghanistan and the government is responsible for their protection, control, management and effective use in accordance with the law. With this article, practical enforcement is stated as that MEW is responsible for planning, management and development of water resources in collaboration with concerned ministries and agencies, and for the groundwater the MoM shall be responsible in close collaboration with MoPH7 and also NEPA.

Aside from the line ministries, the Law stipulates under Article 13 ‘River Basin Council (RBC)’ that the MEW shall establish a River Basin Committee composed of members representing water users, relevant national and local agencies and other stakeholders in the river basin (as at July 2011, no RBC has been established, though). The article further says that the MEW may delegate, when appropriate, some of its powers to the RBC in accordance with the law, after improving the required working capacity and capability through technical trainings. To this end, the one who shall issue water permit is the RBC, if already established, as stipulated under No.5 provision of Article 14 – Functions of the RBC, i.e.; ‘Issue, register, change or cancel permits and maintain relevant documents’.

6 Referred to in an Unofficial English Translation by EIRP (Emergency Irrigation Rehabilitation Project) /FAO, Edited by UNEP and KRBP (Kunduz River Basin Programme) - July 6, 2009 7 Though the provision of Article 8 does not specify how to collaborate with MPH and NEPA, there is an understanding that the MPH should provide recommendations for the safe water quality in terms of chemical and bacteriological compositions. NEPA is the responsible agency for EIA clearance where required. In addition, NEPA is relevant with the protection of any water sources to be developed in Afghanistan.


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The Law states necessity of carrying out an environmental impact assessment in the Article No. 32 - Adverse Effects on the Environment. The article stipulates that the owners/proponents of any substantial water resources development projects shall be responsible for conducting Environmental Impact Assessment (EIA) at their own cost in accordance with Environmental Law and policy. Though the level of ‘substantial’ is not stated in the Law, the envisaged groundwater development for the new Dehsabz city will be categorized under this ‘substantial water resources development projects’ since the scale of the development goes beyond what the ordinary individual households require for their domestic purpose.

There is an article stipulating deep well drilling, namely, Article 38 - Deep Wells Drilling. This article states that the deep wells may be drilled only after obtaining an authorization from MoM for agriculture, commercial, industry and urban water supply purposes. Digging ordinary wells to meet the need for drinking water and livelihood purposes is exempted from this provision.

2) Environmental Law and its Regulations

The Environmental Law was enacted on January 25, 2008 by the National Assembly, and has total 78 provisions, following which Environmental Impact Assessment Regulations was gazetted on March 10, 2008. Relevant articles that shall refer to in developing groundwater are:

National Environmental Protection Agency (NEPA) is designated as an independent institutional entity responsible for coordinating and monitoring conservation and rehabilitation of the environment, and for implementation of the Environmental Law under Article 3. This NEPA is therefore the sole agency to authorize on the advice of the EIA Board of Experts the project submitted by a proponent, provided that any significant adverse impact on the environment takes place.

There is an article under the Law specifying public participation – Article 19 – Public Participation. The article states that the NEPA shall not reach a decision on any application for the permit until such time that the proponent has demonstrated to the satisfaction of the NEPA that the proponent has distributed copies of the document to affected persons, informed the public that the document is being made available for public review by advertising the document and display a copy of it for inspection, and convened and recorded the proceedings of a public hearing.

The Article 19 under the Law further says that after the NEPA has reviewed the conditions set in the aforementioned statement, the NEPA shall reach a decision and inform the pubic of that decision and make available any relevant documentation or information for public review.

In line with the Law excerpted above, the Regulations elaborates procedure of application in order to acquire permission for a project which may affect environment and its screening. Regulation 4 – Applications states that an applicant shall submit to the NEPA an application form in accordance with schedule specified in the Regulations. Regulation 5 – Screening8 points out that the proponent shall conduct a screening process and complete a screening report consistent with international best practice, which is to be submitted to NEPA for its decision for the permission.

Then, the NEPA may require the applicant to carry out environmental impact assessment process. If the applicant is instructed to do so by the NEPA, the applicant shall prepare environmental impact statement, which statement shall contain all the information required for the NEPA to

8 In relation to this, activities are categorized in 2; Category 1 and Category 2. No groundwater related activities are listed in the categories, however there is an activity of ‘water supply and treatment’. With reference to this category, a water supply scheme with a total cost of US$ 400,000 or more is categorized under Category 1 Activities while less than that water supply projects under Category 2 Activities.


DCDA 5-28 JICA

make a decision if it is permitted or not.

2) Procedure to EIA Clearance and Water Right to Secure

Taking account of above cited provisions of the Laws and Regulations relating to this groundwater development, DCDA is required to take following actions:

1) The production wells are to be constructed in the premises of Pol-e Charkhi Radio Station which is placed under the supervising authority of the National Radio and Television of Afghanistan (NRTA) of the Ministry of Communication and Culture. To construct the production wells within the premises, DCDA should start discussing with the Ministry of Communication and Culture for the permission of constructing the well(s), though this is not directly related to the requirement of the environmental law.

2) At the same time, DCDA to hold a public hearing meeting(s) inviting the population of the Pol-e Charkhi village (refer to Box). The size and contents of the development including the volume of the groundwater exploitation will be explained to the villagers. Expected drawdown of the groundwater table shall also be thoroughly explained with its monitoring system (For the procedure and the contents of the meeting are discussed in the following section).

3) In line with above 1) and 2) processes, DCDA to prepare for Screening of the groundwater development project required under the Environmental Law which is also a part of EIA. The contents of this Sub-project shall fully be utilized especially for the design of the works, scale of the groundwater development, level of expected negative impacts represented by drawdown of the groundwater table and mitigation measures including monitoring system. The EIA should incorporate the discussion results with and the consent from the villagers of the Pol-e Charkhi for the development of the groundwater.

4) Upon the consensus by the Pol-e Charkhi population and permission for the construction of the wells within the premises by the Ministry of Communication and Culture, DCDA will complete the EIA statement and submit to the concerned authority, NEPA, for authorization of the project. Upon approval, DCDA to prepare for and submit an application form of the water work, which here means the groundwater development works composed mainly of 2 deep wells construction, to the MEW. In fact, though the application is supposed to go to the River Basin Committee, the committee has yet to be established whereby to the supervising authority, namely, to the MEW. In addition, DCDA has to submit the plan/design for the deep well(s) to MoM for the authorization of the work.

5) Upon the granting of the permission, the DCDA may proceed with the construction of the deep well(s) in the premises of the radio station. The premises is a government property, and therefore no financial compensation for occupying a land, approximately 5m square each per well, for the construction of deep well(s) may be required on condition that the DCDA and the Ministry of Communication and Culture are in agreement.

People’s involvement/participation in EIA: In line with EIA procedure, the people who may be affected by the project should at least be given all the relevant project information (level-1), which is usually called ‘involvement of the population’. This also requires the implementing agency to discharge the responsibility of accountability to the people. On top of the involvement, there may be 2 levels in which the people participate. One is the participation to decide which alternative plans to be provided by the implementing agency shall be the best (level-2), and the other is that the people themselves participate in the design of the alternative plans and decide on them by themselves (level-3).


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5.6.2 Consensus on Groundwater Development from the Pol-e Charkhi Population

From the viewpoint of accepted customs and traditions, there are some statements given by some of the Shura members during the explanatory meetings arranged for the purpose of arriving at consensus on the conduct of the surveys under this Sub-project. The custom and tradition may suggest that the property right of the landowner does not govern that of the groundwater beneath his/her land.

It means that as far as the new development does not negatively affect the present use of groundwater, the villagers shall not claim any compensation for the groundwater exploitation according to costmary practices. This custom is also in accordance with the Water Law wherein water is specified as public property under Article 2 - Ownership and Management of Water.

According to the Water Law, DCDA is required to conduct EIA for this groundwater development project. The EIA procedure, according to the Environmental Law, requires DCDA to conduct public hearings from the Pol-e Charkhi population who may be affected by the project. Though the well(s) are to be constructed within the government premises, it is still necessary to hold the public hearing meetings with the Pol-e Charkhi villagers for the groundwater development as far as there is a possibility that they may be affected, otherwise the EIA procedure can not be completed.

Taking above conditions into consideration, following procedures are recommended to arrive at the consensus with the Pol-e Charkhi villagers for the development of the groundwater:

1) DCDA to invite village representatives such as CDC members and Shura members through Malik for the public hearing meeting(s). The meeting should also invite some villagers concerned who are heavily dependent on the groundwater, e.g. farmers with irrigation wells and nearby households who are dependent on the groundwater for their domestic uses. Villagers who reside outside the radius of 2 km may not be requested to attend the meeting since the impact will be negligible.

2) During the meeting, the DCDA will explain the plan/design of the groundwater development and also its relevant impact. DCDA will also request the village representatives who attended the meeting to hold small meetings in their areas to further discuss and explain the information provided by the DCDA. DCDA will inform the participants in the meeting of the following, and at the same time shall make all the relevant documents and information public/ available:

Rationale and the purpose of the groundwater development in the Pol-e Charkhi area,

Timeframe of the groundwater exploitation, which refers to the time when the water resources at the Panjishir fan is to be developed,

Development plan/design and the volume of the groundwater to be exploited by development stage (by year) in correspondence with the exploitable potential which exists in the Pol-e Charkhi area,

Expected impact especially in the form of drawdown of the groundwater table,

Monitoring system, and

Measures to cope with negative impact such as drawdown of the groundwater table which goes beyond allowable level.

3) DCDA and the village representatives will prepare record of discussions including issues and agreements made. The document should clarify the consensus with the villagers on the groundwater exploitation and also the measures to be taken in case that unallowable negative impact happens.


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DCDA should have in mind that as regards drawdown by more than 50cm from the present groundwater level it should notify the water users of what is happening on their groundwater through general communication practices. In case that groundwater level goes down by more than 50 cm from the original level, the users can feel that the pumping gets harder bit by bit due to the increased load and also the escalated time lag between starting the pumping and the moment the water starts pouring out. However, this situation does not instantly require the users to seek compensation since users still can avail of groundwater.

According to the well structure in the Pol-e Charkhi area, the level of drawdown which makes existing wells very hard to pump up groundwater would be from 2-3 meters or more. In fact, if the drawdown reaches as much as 5m, there will be many wells that will dry up. However this situation would hardly take place according to the simulation results by MODFLOW.

MODFLOW analysis has identified the drawdown of the groundwater under different pumping ratios of groundwater exploitation. Table 5.6.1 summarizes the drawdown of the groundwater table in case of total 5,000 m3/day pumping (2,500 m3/well x 2 wells) with time of lapse and by distance from the wells. From the table, it can be said that the present users would hardly be affected to a level at which they would have great difficulty of pumping up groundwater whereby needing compensation:

In detail, after a year since the pumping started, the groundwater drawdown will be only 66 cm even at a distance of 30m from the pumping well and only 27 cm at a place 1 km away from it. Likewise, 5 years later since the pumping started, the drawdown will be 74 cm and 42 cm at the place of 30 m away and at the place of 1 km away, respectively. From these results, though user villagers

would notify the drawdown of the groundwater to at least some extent, they would have very little difficulty in pumping up the water.

For the compensation should the case take place, the best way may be to install public taps sourced from the production well(s). The public taps, if needed, should be installed along existing village roads. Of course, the positioning of the taps should fully incorporate the users’ views. To provide the compensation water to about 50% of all the Pol-e Charkhi population as an example, there would be about 90 m3/day of domestic water based on a per-capita water requirement of 50 liter per day. Aside from this domestic use, there are 14 irrigation wells in Pol-e Charkhi area. One well usually provides about 40 m3/day during the irrigation period of 3 months. Though it is not likely for all the wells to be affected, the maximum compensation, if needed, would reach 560 m3/day for the 3 months from May to July.

Table 5.6.1 Drawdown of the Groundwater, 2,500m3/day x 2 WellsDistance from the Well

Day/Year 30 m 100 m 1.0 km

Day 1 -0.208 -0.073 0.000 Day 10 -0.351 -0.205 -0.003

Day 100 -0.552 -0.406 -0.117 Year 1 -0.658 -0.516 -0.268 Year 2 -0.699 -0.560 -0.341 Year 3 -0.718 -0.580 -0.377 Year 4 -0.730 -0.593 -0.401 Year 5 -0.739 -0.603 -0.419 Year 5 -0.739 -0.603 -0.419


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CHAPTER 6 GROUNDWATER DEVELOPMENT -2 (ADDITIONAL TEST WELL) 6.1 General

As explained in Chapter 4 and Chapter 5, the target site No.2, Pol-e-Charkhi area is the only site which has substantial groundwater development potential, on which present level of groundwater use is estimated below the annual rechargeable amount among total four candidate sites in this Sub-project. However, as described in Section 4.2.1 “Test Well Drilling General”, the test wells drilled in the study were finalized by 6” casing and screen, and also as shown in Section 4.2,3 “Pumping Test Results”, the size of test well drilled in Pol-e-Charkhi site was not enough to set a submersible pump with large discharge amount. On the other hand, total groundwater development potential in Pol-e-Charkhi site was estimated as 5,960 m3/day (Section 5.1.2), and exploitable groundwater potential was evaluated as around 5,000 m3/day (Section 5.3.2). The volume can be exploitable by only two production wells (2,500 m3/day/well, nearly 28.9 lit/sec/well) because of very excellent hydrogeological condition of the site.

However, actual pumping rate in the Constant Discharge Test in TW-Pol was only 3 lit/sec, and alternative pumping well (existing well in RTA compound) had rather enough discharge rate at around 24 lit/sec though no well design nor aquifer information were available. Thus, an additional test well was required to be drilled which had enough large casing diameter for setting submersible pump yielding around 30 lit/sec, and can be diverted to a Production Well after completing series of tests as a test well.

Based on such requirement, an additional test well with 10 inches casings and screens which were enough to yield around 30 lit/sec of groundwater was planned out, and implemented. The new test well (hereinafter called as TW-N) was sited by field reconnaissance around RTA compound (Radio S

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