STUDY ON EFFECTS OF LAND USE CHANGE TA 7189-INO: INSTITUTIONAL STRENGTHENING FOR INTEGRATED WATER RESOURCES MANAGEMENT (IWRM) IN THE 6 CI'S RIVER BASIN TERRITORY - PACKAGE B NOVEMBER 2012 In association with: DEMIS B.V - EUROCONSULT MOTT MACDONALD -SIGNIFICANCE B.V - PT GEO ISSEC PT INDEC INTERNUSA - PT MULTI AREA CONINDO - PT PPA CONSULTANTS - PT SUPRAHARMONIA CONSULTINDO - PT TERA BUANA MANGGALA JAYA - PT TRANS INTRA ASIA - PT WASECO TIRTA - PT WIDYA GRAHA ASANA - PT WIRATMAN & ASSOCIATES ON HYDROLOGICAL CHARACTERISTIC OF WATERSHEDS Prepared by: Center for Water Resources Research and Development
Transcript
STUDY ON EFFECTSOF LAND USE CHANGE
TA 7189-INO: INSTITUTIONAL STRENGTHENINGFOR INTEGRATED WATER RESOURCES MANAGEMENT (IWRM)
2 CALIBRATION OF THE MODEL ............................................................................... 8 2.1 Sacramento Model .............................................................................................. 8 2.2 Data Availability for Callibration ......................................................................... 11 2.3 Ciujung River ..................................................................................................... 12 2.4 Ciliwung River ................................................................................................... 15
2.4.1 Calibration for Low Flow Time-Series ......................................................... 16 2.4.2 Calibration for Flood Event ......................................................................... 19
3.1 Ciujung River ..................................................................................................... 24 3.2 Ciliwung River ................................................................................................... 26 3.3 Citarum River .................................................................................................... 27
4 FLOOD ANALYSIS .................................................................................................. 28 4.1 Simulation for the year of 2002 and 2006 .......................................................... 28 4.2 Recalibrating the deforestation case.................................................................. 29
TABLE OF FIGURES Figure 1 Concept of Sacramento Model (Burnash, 1973) .................................................. 8 Figure 2 Model Component (Burnash, 1973) ..................................................................... 9 Figure 3 Availability of half-monthly river discharges data................................................ 11 Figure 4 Ciujung-Kragilan using BTA-155 Sacramento parameter................................... 12 Figure 5 Ciujung-Kragilan using modified Sacramento parameter ................................... 12 Figure 6 Sacramento parameter from BTA-155 study ...................................................... 13 Figure 7 Improved Sacramento parameter modified in this study .................................... 13 Figure 8 Ciujung-Rangkasbitung using Sacramento parameter from BTA-155 Study ...... 14 Figure 9 Ciujung-Rangkasbitung using improved Sacramento parameter ....................... 14 Figure 10 Land use change of forest and urban area in Ciliwung-Katulampa catchment area ................................................................................................................................. 15 Figure 11 Ciliwung-Katulampa using Sacramento parameter from BTA-155 ................... 16 Figure 12 Ciliwung-Katulampa using improved Sacramento parameter ........................... 16 Figure 13 Ciliwung Katulampa calibrated for around the year of 1992 ............................. 17 Figure 14 Ciliwung-Katulampa calibrated for around the year of 1997 ............................. 17 Figure 15 Ciliwung-Katulampa calibrated for around the year of 2003 ............................. 18 Figure 16 Hourly rainfall at Citeko and river discharge Ciliwung at Katulampa................. 19 Figure 17 Katulampa Calibration February 1996 ............................................................. 20 Figure 18 Sacramento Parameter for February 1996....................................................... 20 Figure 19 Land use change of forest and urban area in Citarum River Basin .................. 21 Figure 20 Cigulung-Maribaya using the BTA-155 parameter for the year of 1985-2000 ... 22 Figure 21 Cigulung-Maribaya calibrated for the year of 1985-2000.................................. 22 Figure 22 Sacramento parameter for Cigulung-Maribaya 1985-2000 .............................. 23 Figure 23 Ciujung-Kragilan using improved parameter for 1981-2005 ............................. 24 Figure 24 Ciujung –Rangkasbitung using improved parameters for 1981-2005 ............... 25 Figure 25 Simulation of Ciliwung-Katulampa using BTA-155 parameter for the year of 1999-2006 ....................................................................................................................... 26 Figure 26 Simulation of Ciliwung-Katulampa using improved parameter for the year of 1999-2006 ....................................................................................................................... 26 Figure 27 Cigulung Maribaya simulation for the year of 2001-2006 ................................. 27 Figure 28 Simulation of Ciliwung-Katulampa 19 January – 15 February 2002 using parameter of 1996 ........................................................................................................... 28 Figure 29 Simulation of Ciliwung-Katulampa 8 January – 26 February 2006 using parameter of 1996 ........................................................................................................... 29 Figure 30 Ciliwung-Katulampa 19 January – 15 February 2002 recalibrated ................... 29 Figure 31 Ciliwung-Katulampa 8 January – 26 February 2006 recalibrated ..................... 30
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TABLE OF TABLES Table 1 Sacramento Parameter ....................................................................................... 10 Table 2 List of Discharge Stations for Sacramento Calibration ........................................ 11
Balai PDAS Regional Board for management of River Basins (under Ministry of Forestry)
Balai PSDA Provincial River Basin Management Board
BBWS Greater River Basin Territory Board (Balai Besar Wilayah Sungai), at MPW level
BTA 155 Cisadane - Cimanuk Integrated Water Resources Development project Strategic WRM Planning project in Indonesia (1985 – 1991)
BWRMP 1) Basin Water Resources Management Plan (Rencana)
2) Project for formulation of BWRMP (2001 – 2004)
BWRP Basin Water Resources Planning (1996 – 2001, later changed to BWRMP)
DGWR Directorate General for Water Resources at MPW
DMI Domestic, Municipal and Industrial (water demand)
FEWS\HYMOS Hydrological data processing system based on Flood Early Warning System
FHM Flood Hazard Mapping, component under Jakarta Flood Management (2007 – 2010)
GIS Geographic Information System
GOI Government of Indonesia
IWRM Integrated Water Resources Management
JABOTABEK Area comprising Jakarta, Bogor, Tangerang, Bekasi. Later extended with Depok to become JABODETABEK and later also included Puncak and Cianjur in JABODETABEKPUNJUR
JWRMS JABOTABEK WRM Study
MIS Management Information System
MPW Ministry of Public Works
PSDA WRM
PTPA Present form of Water Resources Council at Provincial Level
PusAir Agency for Research and Development in Water Resources, under MPW
RBT River Basin Territory (Wilayah Sungai, WS)
RIBASIM River Basin Simulation Model, Decision Support System for WR planning /management
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1 INTRODUCTION
1.1 Background
The effect of changes in land use on hydrological characteristics of low and high discharges have been widely assumed to imply that decreasing vegetative cover would result in lower base flow during dry season and increasing flood discharges after storms. However, no quantitative data have been collected to confirm these assumptions, and information that correlates the land use change and the changing of hydrological properties is still based on hypotheses.
Adequate water resources management requires confirmation of this kind of relationships to assess the relative benefit of various conservation strategies. In component B.2 of the 6 Cis Project, various strategies for zoning will be assessed. Therefore it is considered necessary to verify the assumed effect of changing land use, especially the change from rural to urban area and its related decrease in vegetative cover, concerning low flows and flood discharges.
The RIBASIM model uses the Sacramento model for establishment of rainfall-runoff relationships. However, the model assumes values for several parameters based on experience from the past, and the effect of changes from a rural area to an urban area are not yet verified. Therefore one or two areas with sufficient data to simulate flows based on sufficient time series to re-calibrate the rainfall runoff relationship is needed. After assessment of the new values for the parameters to reflect the changes in land use, one can extrapolate this relationship with the specific factors for the other basins in 6 Cis. This is part of the standard practice when simulating with RIBASIM. This has also been discussed in the 6 Cis Inception Report on page 29, under point 2, and in the paragraph starting with " The Sacramento rainfall-run-off......".
There are two stations in the 6 Cis area with sufficient time series for hourly and daily discharges: Katulampa in the Ciliwung river just upstream Bogor and Nanjung in the Citarum river just upstream Saguling. The catchment of Katulampa (app 150 km2) represents a good example of changes in land use from rural to urban area. The catchment of Nanjung is much larger (app 1500 km2), and therefore it is not realistic to relate the changes to changes in land use, since also river normalization has taken place, and many other factors may have an influence. Therefore Nanjung is not proposed for this study.
In order to have a comparison from another basin it is necessary to look for in data base for other suitable areas, and there might be from hourly discharge data for Brantas and Bengawan Solo. Using a second site with sufficient data a more reliable estimation can be made of the land use - runoff relationship, which will improve the accuracy of extrapolation to other catchments. The extra costs for the extra site are not much, because the main problem is to develop the methodology.
Data collection and validation for rainfall data and discharges has been done, and they are ready for use. Data for land use changes are also available through available land use mapping (Geocover 1990, 2000, 2007). What has to be done now is to identify the land use changes for the Katulampa catchment, and relate this to various series of rainfall and discharge data, in order to assess the most likely changes for the applicable rainfall-runoff parameters. Only in this way we can get a better idea about the correlation between the land use and the runoff data, which can be extrapolated to other areas.
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1.2 Objectives
Determine quantitatively the effect of land use changes on low flow and flood discharge for some hydrological stations in the area of 6 Cis. This will be done by selecting two suitable river discharge gauging stations with adequate information concerning river discharges and simultaneous changes in land use for the catchment upstream of the river gauging station.
1.3 Expected Results (outputs/outcomes):
Correlation between the land use change and the change in low flow and flood discharge. Model parameter changes best reflecting the changes in condition of land use.
1.4 Methodology
The methodology is as follows:
- Rainfall-runoff analysis using Sacramento model and other methodologies applied
in HYMOS and RIBASIM,
- Comparing the measured discharges with the results of rainfall-runoff analysis
using the same parameter for the present condition, and examine the differences
of the low flow and the flood discharge before and after the land use change.
- Assess the parameters that better reflect the measured values
- Another approach is to calibrate the present condition and examine the
parameters that have to be changed to fit the present condition.
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2 CALIBRATION OF THE MODEL
2.1 Sacramento Model
In the simulation of the runoff process by the Sacramento model a distinction is made between the land phase and the channel phase. The land phase is represented by an explicit moisture accounting lumped parameter model. The catchment area is divided into one or more segments discharging to the main channels. Within every segment areal homogeneity with respect to rainfall and basin characteristics is assumed. The distance is not explicitly treated in the simulation process as is time. In this respect the lumped approach deviates from the distributed catchment models. The concept of the Sacramento model with the major storages and flow components is shown in Figure 1 (Burnash et al, 1973). The components of the model are shown in Figure 2. In this figure also the names of the components used in the menu are indicated. The components of the model, their working and their interaction are elaborated below. Note that for the storages a distinction is made between capacity (indicated with the letter M at the end of the name) and actual content (indicated with a C at the end).
Figure 1 Concept of Sacramento Model (Burnash, 1973)
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Figure 2 Model Component (Burnash, 1973)
There are 17 Sacramento parameters, which can be classified as direct runoff parameter, upper soil moisture parameter, percolation parameter, and lower zone parameter. Direct Runoff Parameter PCTIM: permanent impervious fraction ADIMP: additional impervious fraction SARVA: fraction covered by streams, lakes, etc. Upper Soil Moisture Zone Parameter
UZTWM: Upper Zone Tension Water reservoir capacity UZFWM: Upper Zone Free Water reservoir capacity UZK: Upper Zone lateral drainage rate Percolation Parameter ZPERC: proportional increase percolation from saturated to dry condition REXP: exponent in percolation demand equation Lower Zone Parameter LZTWM: Lower Zone Tension Water reservoir capacity LZFPM: Lower Zone Free Primary reservoir capacity LZFSM: Lower Zone Free Supplementary reservoir capacity LZPK: drainage rate of Lower Zone Primary reservoir LZSK: drainage rate of Lower Zone Supplementary reservoir PFREE: fraction percolation water directly to lower zone free RSERV: fraction of lower zone free not available for transpiration) SIDE: ratio of unobserved to observed base-flow SSOUT: fixed rate of flow lost from channel
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In the BTA-155 Project (Cisadane-Cimanuk Integrated Water Resources Development), Sacramento model has been calibrated, resulting one set of parameter for the all river basins in the Northern part of West Java. Using this parameter, half-monthly runoff is generated from rainfall time-series for all water districts. It should be noted that this parameter is recalibrated for Bengawan Solo River Basin in the study of BTA-155 Phase II. The lists of parameters are as follows. Table 1 Sacramento Parameter ───────────────────────────────────────────────────────────────────────────────────────────
In the 6 Cis River Basin Territory, effort has been made to collect catchment area having pairs of rainfall and runoff data, preferably small catchment area, and has been calibrated from the BTA-155 Project (Puslitbang Pengairan and Delft Hydraulics, 1989). Ciujung river at Rangkasbitung and Kragilan are river discharge stations that were used in the BTA-155 Project to calibrate the Sacramento parameter. Two additional stations having small catchments in this study: Ciliwung-Katulampa and Cigulung-Maribaya are listed in the following table, while the availability of the river discharge data is presented in the bar chart in Figure 3. Table 2 List of Discharge Stations for Sacramento Calibration Station Name Station Code CA (km2) BTA-155 Water Districts /
Figure 3 Availability of half-monthly river discharges data
Using the same river discharges and rainfall data in the BTA-155 Project (Delft Hydraulics and Puslitbang Pengairan, 1989), in this study, the parameter of Sacramento Model is recalibrated using the same rainfall and runoff data in the BTA-155 Project which half-monthly data is available from the year of 1951 until 1979. The parameter obtained in the calibration phase will be applied in the rainfall-runoff simulation of the recent rainfall and runoff data.
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2.3 Ciujung River
In Ciujung River, there are two river gauging stations calibrated in the BTA-155 project: Kragilan and Rangkasbitung (Figure 4 and Figure 8). This study recalibrated the parameter, and produces better results in Figure 5 and Figure 9. The Sacramento parameter has been modified from Figure 6 into Figure 7.
QS_Segment_1 QM_Segment_1
1969 Jan 01 00:00 - 1979 Dec 01 00:00 1977 Dec 11 00:00:001975 Dec 12 00:00:001973 Dec 12 00:00:001971 Dec 13 00:00:001969 Dec 13 00:00:00
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Figure 4 Ciujung-Kragilan using BTA-155 Sacramento parameter
QS_Segment_1 QM_Segment_1
1969 Jan 01 00:00 - 1979 Dec 01 00:00 1977 Dec 11 00:00:001975 Dec 12 00:00:001973 Dec 12 00:00:001971 Dec 13 00:00:001969 Dec 13 00:00:00
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Figure 5 Ciujung-Kragilan using modified Sacramento parameter
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Figure 6 Sacramento parameter from BTA-155 study
Figure 7 Improved Sacramento parameter modified in this study
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Figure 8 Ciujung-Rangkasbitung using Sacramento parameter from BTA-155 Study
Figure 9 Ciujung-Rangkasbitung using improved Sacramento parameter
From Figure 8 and Figure 9, indicate that there is no reason to change the parameters for the new situation. Both set of BTA-155 parameter and improved parameter produce the same good result for present condition.
QS_Segment_1 QM_Segment_1 1969 Jan 01 00:00 - 1979 Dec 01 00:00
1977 Dec 11 00:00:00 1975 Dec 12 00:00:00 1973 Dec 12 00:00:00 1971 Dec 13 00:00:00 1969 Dec 13 00:00:00
Ciliwung River is flowing through West Java Province and Jakarta Special Province. Katulampa river gauging station is situated at the upper part of Ciliwung River, having catchment area of 150 km2. An automatic rainfall station Citeko is situated in the catchment area of Katulampa River Gauging Station. Daily river discharges and daily rainfall data from the year of 1990 – 2006 are obtained from Research Center for Water Resources. Rating curve of the river discharges is based on the work of Ogink (2007) and Ogink (2008). The land use change of forest and urban area in the upper Katulampa river gauging station is obtained from satellite image interpretation by Institutional Strengthening for IWRM in the 6 Ci's River Basin Territory (package B) Project, for the year of 2000, 2003, 2007 and 2009 as shown in Figure 10. This figure present the percentage of forest that is decreasing from 58.8% in the year of 2000 to 18.2% in 2007, but little increase to 22.4% in the last two years of 2009. On the other hand the urban area is increasing from 0.2% in the year of 2000 to 7.2% in 2009
Figure 10 Land use change of forest and urban area in Ciliwung-Katulampa catchment area
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2.4.1 Calibration for Low Flow Time-Series
Calibration for Ciliwung-Katulampa is carried out from the year of 1990 to 1998. The calibration using the BTA-155 parameter and rainfall station Citeko is presented in Figure 11 shows good fit between the model and the observed data, especially around the year of 1995.
QS_Segment_1 QM_Segment_1
1990 Jan 01 00:00 - 1998 Dec 01 00:00 1997 Dec 06 00:00:001996 Dec 06 00:00:001995 Dec 07 00:00:001994 Dec 07 00:00:001993 Dec 07 00:00:001992 Dec 07 00:00:001991 Dec 08 00:00:001990 Dec 08 00:00:00
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Figure 11 Ciliwung-Katulampa using Sacramento parameter from BTA-155
Using the same set of Katulampa discharge and Citeko rainfall station, calibraton using improved Sacramento parameter, presented in Figure 12 is also give good fit, especially for around the year of 1997.
QS_Segment_1 QM_Segment_1
1990 Jan 01 00:00 - 1998 Dec 01 00:00 1997 Dec 06 00:00:001996 Dec 06 00:00:001995 Dec 07 00:00:001994 Dec 07 00:00:001993 Dec 07 00:00:001992 Dec 07 00:00:001991 Dec 08 00:00:001990 Dec 08 00:00:00
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Figure 12 Ciliwung-Katulampa using improved Sacramento parameter
This fact shows that the BTA-155 parameter is good for calibration in the period of BTA-155 (1951 – 1979) while the improved parameter is for more recent period.
Good fit of low flow
Good fit of
low flow
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Figure 13 show the result of calibration for the period of 1990-1996, give fit for this period as well as period of 2003-2006, and over estimate for the period of 1997-2002. This means that in the period of 1997-2002, parameter of the model related to land use and land cover has changed. This set of changed parameter that fit in this period can be used for the scenario of decreasing forest and increasing urban area. As a logical consequence this set of urban parameter would give under estimate for forest land cover condition.
Figure 15 Ciliwung-Katulampa calibrated for around the year of 2003
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2.4.2 Calibration for Flood Event
The hourly time step should be applied for analysing the effect of land use change to flood hydrograph. Until now it is found that only Ciliwung-Katulampa gauging station has relatively small catchment area, and sufficient hourly rainfall and corresponding discharge data. The hourly available discharge of Ciliwung River at Katulampa is from the year of 1996 to 2008, while the hourly rainfall is from Citeko from the year of 1995 – 2008. Both data was obtained from FHM Project, and verified by Ogink (2007) and Ogink (2008). There are also hourly discharge data from Tideda database Pusair from the year of 1996 until 2004.
CITEKO PH KATULAMPA1 QH
1996 Feb 02 00:00 - 1996 Feb 26 22:58 1996 Feb 26 00:00:001996 Feb 23 00:00:001996 Feb 20 00:00:001996 Feb 17 00:00:001996 Feb 14 00:00:001996 Feb 11 00:00:001996 Feb 08 00:00:001996 Feb 05 00:00:001996 Feb 02 00:00:00
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Figure 16 Hourly rainfall at Citeko and river discharge Ciliwung at Katulampa
The hourly rainfall at Citeko and river discharges of Ciliwung at Katulampa for February 1996 presented in Figure 16 shows timing error. The rainfall appear about 24 hours after the flooding happened. To overcome this problem, a backward shifting of 24 hours is applied for rainfall of Citeko in February 1996. The calibration results for Katulampa has been carried on for flood event on February 1996, and presented in the following figure. It shows relatively good fit between model and the observation data, especially in the peak flow. The next figure shows the Sacramento parameters for this calibration process,
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Figure 17 Katulampa Calibration February 1996
Figure 18 Sacramento Parameter for February 1996
QS_Segment_1 QM_Segment_1 1996 Feb 02 00:00 - 1996 Feb 25 22:58
1996 Feb 23 00:00:00 1996 Feb 20 00:00:00 1996 Feb 17 00:00:00 1996 Feb 14 00:00:00 1996 Feb 11 00:00:00 1996 Feb 08 00:00:00 1996 Feb 05 00:00:00 1996 Feb 02 00:00:00
85 80 75 70 65 60 55 50 45 40 35 30 25 20 15 10
5 0
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2.5 Citarum River
Cigulung River is a tributary of Citarum River, and river gauging station Cigulung-Maribaya is having small catchment area of 26 km2, situated near tourism object of Maribaya waterfall, which its upper catchment suffering land use changes into human settlement. There is no data available on the rate of change in this region, but data for the whole Citarum river basin might give impression on the land use change in this site. In Citarum basin, the land use change data from Bappeda Jawa Barat is presented in following figure. The forest cover is decreasing from 32.4 % in the year of 1994 to 9.3% in 2009, conversely the urban area increasing from 1.9% in 1994 to 26.1% in 2009. The decreasing forest is high during period in the year 1994 – 2000.
32.4%
12.1%11.3%
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Year
Forest Urban
Figure 19 Land use change of forest and urban area in Citarum River Basin
In Cigulung-Maribaya river gauging station, if the BTA-155 parameter is applied, the model gives underestimate low flow and over estimated peak flow (Figure 20). This means that the model expect the catchment area which is worse than in reality, drought in the dry season and flooding in the wet season. Therefore the Sacramento parameter can not be generalized for all catchment area in the 6 Cis. The calibrated model for the periode of during high decrease of forest in year of 1986-2000 is presented in Figure 21. It shows good fit, much better than BTA-155 parameter.
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QS_Segment_1 QM_Segment_1
1985 Jan 01 00:00 - 2000 Nov 01 00:00 1999 Dec 06 00:00:001997 Dec 06 00:00:001995 Dec 07 00:00:001993 Dec 07 00:00:001991 Dec 08 00:00:001989 Dec 08 00:00:001987 Dec 09 00:00:001985 Dec 09 00:00:00
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Figure 20 Cigulung-Maribaya using the BTA-155 parameter for the year of 1985-2000
QS_Segment_1 QM_Segment_1
1985 Jan 01 00:00 - 2000 Nov 01 00:00 1999 Dec 06 00:00:001997 Dec 06 00:00:001995 Dec 07 00:00:001993 Dec 07 00:00:001991 Dec 08 00:00:001989 Dec 08 00:00:001987 Dec 09 00:00:001985 Dec 09 00:00:00
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Figure 21 Cigulung-Maribaya calibrated for the year of 1985-2000
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Figure 22 Sacramento parameter for Cigulung-Maribaya 1985-2000
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3 LOW FLOW ANALYSIS
The main purpose of the low flow analysis in this study is to provide the rainfall-runoff parameter for input of simulation model Ribasim, and if necessary improve the parameter of the BTA-155 period from the year of 1951-1979, to accommodate the land use change effect. Based on the irrigation cycle, the time-step for simulation is half-monthly.
3.1 Ciujung River
The following two figures are showing the Sacramento simulation of Ciujung-Kragilan and Ciujung-Rangkasbitung for the year of 1981 – 2005. Kragilan station in Figure 23 shows that the past Sacramento parameter still gives good fit to the recent data. The same result also applied to Rangkasbitung station, although the model gives underestimate discharges for some years.
Figure 24 Ciujung –Rangkasbitung using improved parameters for 1981-2005
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3.2 Ciliwung River
The low flow simulation for Ciliwung-Katulampa is carried out for the year of 1999 to 2006, a period with low forest fraction. The result of simulation using BTA-155 parameter is presented in Figure 25. No general pattern exists. It shows over estimate of low flow for the year of 2000 but under estimate for the year of 2004 and 2005.
QS_Segment_1 QM_Segment_1
2005 Dec 04 00:00:002004 Dec 04 00:00:002003 Dec 05 00:00:002002 Dec 05 00:00:002001 Dec 05 00:00:002000 Dec 05 00:00:001999 Dec 06 00:00:00
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Figure 25 Simulation of Ciliwung-Katulampa using BTA-155 parameter for the year of 1999-2006
The simulation using improved parameter, presented in Figure 26 shows similar result with the simulation using BTA-155 parameter as in previous figure. The difference is so not clear, however the simulation result using improved parameter seems to be a little lower than using BTA-155 parameter.
QS_Segment_1 QM_Segment_1
1999 Jan 01 00:00 - 2006 Dec 01 00:00 2005 Dec 04 00:00:002004 Dec 04 00:00:002003 Dec 05 00:00:002002 Dec 05 00:00:002001 Dec 05 00:00:002000 Dec 05 00:00:001999 Dec 06 00:00:00
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Figure 26 Simulation of Ciliwung-Katulampa using improved parameter for the year of 1999-2006
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3.3 Citarum River
Simulation result of Cigulung River at Maribaya for the year of 2001-2006 using the calibrated parameter for the year of 1985-2000 is presented in Figure 27. It shows consistently that the low flow of the simulated model is always higher than the observed, in line with the high deforestation. In other word, the model expect the observed data to be higher than in reality. The magnitude of decreasing low flow is in between 0 (in 2004) to 75% (in 2003), with the average decreasing is around 25%.
QS_Segment_1 QM_Segment_1
2001 Jan 01 00:00 - 2006 Nov 01 00:00 2005 Dec 04 00:00:002004 Dec 04 00:00:002003 Dec 05 00:00:002002 Dec 05 00:00:002001 Dec 05 00:00:00
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Figure 27 Cigulung Maribaya simulation for the year of 2001-2006
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4 FLOOD ANALYSIS
Using the same Hymos Sacramento parameter calibrated in the Chapter 2, the model is run using the observed rainfall and discharge in the year 2002 and 2006. If the model and observed can be fitted using this parameter, it means that no change in catchment characteristic from 1996 to 2002 and 2006. If it doesn’t fit then it is caused by land use change.
4.1 Simulation for the year of 2002 and 2006
For the year of 2002, 19 January – 15 February, in Figure 28 the Sacramento model simulated using 1996 parameter only expecting flood of about 60 m3/s and 40 m3/s. However in reality the observed flood peaks are much higher, 170 m3/s and 240 m3/s, It is about 4 times higher.
QS_Segment_1 QM_Segment_1
2002 Jan 19 00:00 - 2002 Feb 14 22:58 2002 Feb 12 00:00:002002 Feb 09 00:00:002002 Feb 06 00:00:002002 Feb 03 00:00:002002 Jan 31 00:00:002002 Jan 28 00:00:002002 Jan 25 00:00:002002 Jan 22 00:00:002002 Jan 19 00:00:00
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Figure 28 Simulation of Ciliwung-Katulampa 19 January – 15 February 2002 using parameter of 1996
For the year of 2006, 8 January to 26 February, in Figure 29 the Sacramento model using 1996 parameter only expect flood of about 70 m3/s and 120 m3/s. However in reality the observed flood peaks are much higher than expected in the model, as high as 130 m3/s and 270 m3/s, or about twice higher. Both simulation cases for the year of 2002 and 2006 give consistent result, that the observed high flow is higher than expected, by a factor of around twice to 4 times. It is noted that the forest fraction in 1996 is 60%, and deforestation leaves remaining forest fraction of only 20% for the year of 2002 and 2006. At the same time the urban area is increasing from only 0.2% in the year of 1996 to about 5% in the year of 2002 and 2006.
Effects of Land Use Changes Final Report
Research Center for Water Resources
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2006 Jan 08 00:00 - 2006 Feb 26 22:58 2006 Feb 25 00:00:002006 Feb 18 00:00:002006 Feb 11 00:00:002006 Feb 04 00:00:002006 Jan 28 00:00:002006 Jan 21 00:00:002006 Jan 14 00:00:00
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Figure 29 Simulation of Ciliwung-Katulampa 8 January – 26 February 2006 using parameter of 1996
4.2 Recalibrating the deforestation case
Figure 30 and Figure 31 showing an attempt to fit the model with the observed flow for the year of 2002 and 2006 respectively. The Sacramento parameter to be changed is LZTW (Lower Zone Tension Water) from 300 to 30, which means lowering the capacity of soil to hold the water.
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2002 Jan 19 00:00 - 2002 Feb 15 22:58 2002 Feb 15 00:00:002002 Feb 12 00:00:002002 Feb 09 00:00:002002 Feb 06 00:00:002002 Feb 03 00:00:002002 Jan 31 00:00:002002 Jan 28 00:00:002002 Jan 25 00:00:002002 Jan 22 00:00:002002 Jan 19 00:00:00
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Figure 30 Ciliwung-Katulampa 19 January – 15 February 2002 recalibrated
Effects of Land Use Changes Final Report
Research Center for Water Resources
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2006 Jan 08 00:00 - 2006 Feb 26 22:58 2006 Feb 25 00:00:002006 Feb 18 00:00:002006 Feb 11 00:00:002006 Feb 04 00:00:002006 Jan 28 00:00:002006 Jan 21 00:00:002006 Jan 14 00:00:00
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Figure 31 Ciliwung-Katulampa 8 January – 26 February 2006 recalibrated
Effects of Land Use Changes Final Report
Research Center for Water Resources
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5 CONCLUDING REMARKS
1) This study has developed an improved parameter from BTA-155 parameter for
input of DSS-Ribasim. 2) No differences in low flow for Ciujung, and Ciliwung River. The parameter from the
BTA-155 from 1951-1979, can be used for the recent year in 2005. In other words, generally we can use old parameter resulting from BTA-155 study, or the improved parameter in this study for generating flows in the 6 Ci river basin territory.
3) For Citarum, in small catchment tributary Cigulung-Maribaya, the BTA-155 parameter cannot be applied, the possible cause is because the condition of the catchment is better than expected, or better than the average catchment area in the 6 Cis area. A new parameter for Cigulung-Maribaya for the year of 1985-2000, representing good catchment is developed. The application of this parameter for recent year in 2000-2008 gives over estimate low flow by 25%, to be suspected in line with the deforestation in its catchment area.
4) Concerning flood flow analysis, land use change in the upstream catchment of Katulampa, forest change from 58% in the year of 2000 into 22% in the year of 2009, and at the same time increasing urban area from 58% in the year of 2000 into 22% in the year of 2009, has made increase of peak flow in the year of 2002 and 2006, at about 4 times compared with peak flow in 1996.
5) Due to the limitation of the data availability, only Ciliwung-Katulampa for flood, and Ciliwung-Katulampa and Cigulung-Maribaya for low flow, we cannot yet generalize the predicted Sacramento parameter value for the deforestation catchment area.
6) To provide time-series of half-monthly runoff for all water district in 6 Cis area to DSS-Ribasim, it is recommended to make calibrations for some representative river gauging stations in each rivers, using the starting parameter value of BTA-155 or the improved parameter developed in this study.
REFERENCES
1. Burnash, R. J. C., Ferral, R. L., and R. A. McGuire, 1973. A Generalized
Streamflow Simulation System, Conceptual Modeling for Digital Computers,
United States Department of Commerce, National Weather Services. 2. Delft Hydraulics and Pusat Litbang Pengairan, 1989. BTA-155, Cisadane-Cimanuk
Integrated Water Resources Development Study, Ministry of Public Works. 3. Ogink, H.J.M. (2007), Discharge measuring stations, Jakarta Flood Hazard
Management, Delft Hydraulics. 4. Ogink, H.J.M. (2008), Hydrological data processing, floods of 2007 and 2008,
Partner for Water and Deltares. 5. Van der Weert, 1993. Hydrological Condition in Indonesia, Delft Hydraulics.
