Celicourt Etienne Moknatian Report

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City College of New York GIS in Water Resources

CE G0801

Analysis of the Potential Impacts of the Water Level Increase

of the Azuei and Enriquillo Lakes Using GIS.

Paul Celicourt, Elius Etienne, Mahrokh Moknatian

December 11, 2012.



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Table of ContentsProject proposal ............................................................................................................................................ 4

1. Introduction .......................................................................................................................................... 6

2. Methodology ........................................................................................................................................ 6

3. Data requirements and description ...................................................................................................... 6

4. Geography of the Hispaniola Island ................................................................................................... 7

5. Digital Elevation Model Data Preparation......................................................................................... 7

6. Terrain Analysis and Results ................................................................................................................. 7

7. Comparison between previous watershed delineation ..................................................................... 15

8. Rivers in Azeui and Enriquillo.............................................................................................................. 15

9. Growth of the lakes ............................................................................................................................ 16

10. Land Cover and Land Use.................................................................................................................... 22

11. Potential Impacts of the Water Level Increase of the lakes ............................................................... 24

12. Soil types and geology analysis ........................................................................................................... 25

13. Conclusion ........................................................................................................................................... 29

14. References .......................................................................................................................................... 31





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Project proposal Analysis of the potential impacts of the Azeui and Enriquillo lakes using GIS .

Background

The Azuei and Enriquillo lakes, respectively located in Haiti and Dominican Republic (DR),are known as the two largest lakes of the Hispaniola Island extended on an immense valley

from Port-au-Prince town (Haiti) to the Neiba town (DR).

The Azuei wetland has raised great concerns due to its recent level rise which resulted in a

temporary suspension of transportation and trades between both countries, and flooding

of surrounding lands. It is also important to point out that people living close by are being

endangered.

“The Enriquillo wetland has also raised concerns due to an increase of its size which

doubles over the past eight years, swallowing thousands of acres of farms and more than a

dozen villages” (Associated Press, 2012)#. Using the estimation done by CATHALAC, an

international organization headquartered in Panama, in February 2009, the lake had

increased in size by more than 27 square miles when compared to its extent in 2000

(NASA, 2009).

While the cause of overflow of lakes still remains unknown, both countries now are dealing

with relocating many people and buildings in the affected areas (NASA, 2009).

The aim of this project is to feature the impacts of the lakes flooding on lands and peoples

living in surrounding by modeling the characteristics of watersheds and lakes using

Geographical Information System (GIS) techniques.

Objective

As it is said, the increase in water level of the lakes impacts the surrounding areas in terms

of ecosystems, the water cycle, people’s life, and thus causing many losses. In the project,

we will use the ArcInfo GIS software and its tools to produce data layer maps consisting of

ground elevation, land cover, population and others. Using the created maps and other

data, we will be able to calculate more properties of the watersheds which will finally helpus analyze the site and the impact of lakes flooding in the future.

Setting up the model and analyzing the data in the site, we can determine the increase of

the water level in the lakes, the expected inundation areas, the population in danger, and

the economic impacts.

Below are presented the steps that will be taken to achieve our goal.





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1. Introduction

This report documents the work that has been produced and presented as term

project in the context of the graduate course “GIS in Water Resources” at The City College of

New York. The focus of this work has been the twin lakes Azuei and Enriquillo respectively

in Haiti and Dominican Republic which constitute the Hispaniola Island located in the

Caribbean region. Recently, they have raised great concerns due to overflow and increase

in size over time. So, the aim of this project is to feature the impacts of these lakes flooding

on lands and peoples living in surrounding by modeling the characteristics of watersheds

and lakes using Geographical Information System (GIS) techniques.

2. Methodology

ArcMap, the central application of ESRI’s ArcGIS (version 10) suite of geospatial

processing programs, has been used as the platform to carry out the work . The Spatial

Analyst, Data Management, and Conversion tools of this platform have been used to

process the data. Moreover, the TauDEM tool (version 5.0) developed by David Taborton at

Utah State University has been partly used at some points in the hydrologic modeling of the

lakes watersheds.

3. Data requirements and description

The data were obtained from a plurality of sources. They include the following:

a. The 30-meter resolution ASTER Digital Elevation Model data, a product of METI

(Japan) and NASA has been downloaded from the LP DAAC website at

http://gdex.cr.usgs.gov/gdex/.

b.

The Surface Geology data of the island has been extracted from the USGS’ Map

Showing Geology, Oil and Gas Fields, and Geologic Provinces of the Caribbean

Region. It is available at http://pubs.usgs.gov/of/1997/ofr-97-470/OF97-

470K/graphic/data.html

c. Two Soil Types data were obtained from FAO et al (1998) and FAO (2003). The

last one is more detailed than the first one. But, we use them for comparison

purposes.

d. The Land Use and Land cover maps were obtained respectively from:

http://haitidata.org, and Luna and Poteau (2011).

e. Political boundaries and districts map has been downloaded from the GADM

website: http://www.gadm.org/version2.

http://gdex.cr.usgs.gov/gdex/


http://pubs.usgs.gov/of/1997/ofr-97-470/OF97-470K/graphic/data.html



http://haitidata.org/

http://www.gadm.org/version2




http://haitidata.org/








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We used the TauDEM toolbox developed by David Tarboton (Utah State University,

2011) to remove the pits in the DEM. This toolbox produced a better filling of the pits

compared to the Spatial Analyst tool of ArcGIS. Besides the bad filling of the pits, most of

the streams did not show up when using the latter tool to fill the pits and also the flow

direction did not match the potentially real flow directions in the area under consideration.

However, after filling the pits using the TauDEM, satisfactory results were obtained

for the flow direction using the Spatial Analyst tool of ArcGIS.

6.2. Flow accumulation

The Spatial Analyst tool of ArcGIS has been used to compute the flow accumulation.

We noticed that the flow accumulation is erroneous or does not match the reality in the

area close to the water bodies. A mask where all the water bodies have been taken out or

removed has been created in order to palliate the problem with flow accumulation. Finally,

we obtained much better results for the flow accumulation and streams as well.

6.3. Catchment Delineation and Stream Networks

We created stream raster with a threshold of 1000 to obtain the stream networks and

delineate the watersheds. The threshold of 1000 was chosen because it provided a

reasonable detailed of the stream networks.

A stream feature layer (the flow lines) was then created from the stream raster, and an

outlet point was placed at the end point of each stream line feature near the lakes borders.

The watershed raster associated with each of those outlet points could then be obtained,

and the next step is to convert the raster to a polygon. There were 42 stream lines ending

near the Azeui lake and 66 to Enriquillo lake which makes a total of 108 delineations. 108

watersheds were then delineated one by one for the two lakes. We tried to create thenusing a feature of all the outlets together, but the result was not satisfactory. Only parts of

some watersheds appeared in a mosaic squared pattern around the lakes. Maybe this is a

capability of ArcMap that needs to be improved.

To obtain a single basin for each lake, we merged all the watersheds for each one of the

lakes. A layout of the two basins with a table given some of their characteristics is

presented in figure 2.

6.4. Drainage Density

The drainage density was determined for the most of the watersheds. The ones that are

very small and/or are located near the lakes were excluded. Table 2 gives the results for

Azeui and Table 3 for Enriquillo. The highest values were recorded for the Azeui

watersheds, reflecting the irregular topography and the high slopes of those watersheds.



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Figure 2: Basins of Azeui and Enriquillo lakes

Table 1: Azeui and Enriquillo Basins Characteristics

Basin Area

(km2)

Total Stream Length

(km)

Lake Area

(km2)

Drainage

Density

Azeui 712.9 542.6 127.1 1.31

Enriquillo 3062.4 2538.6 249.3 1.21



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Figure 3: Watersheds and Streams Network of Azeui



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Figure 4: Watersheds and Streams Network of Enriquillo





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Table 2: Drainage Density for Azeui watersheds

Watershed

ID

Area

(km2)

Main Stream

length (km)

Total Length

(km)

Drainage

Density

3 294.4 51.0 225.5 0.77

14 103.6 22.3 74.1 0.72

18 21.3 7.7 17.6 0.82

21 15.0 8.0 10.9 0.73

23 4.0 1.4 2.1 0.53

24 1.5 1.0 1.0 0.65

26 34.8 14.0 19.8 0.57

29 48.2 20.8 34.3 0.71

31 13.7 8.8 10.5 0.77

33 2.3 4.3 7.1 3.06

35 7.9 4.3 7.1 0.89

36 3.3 2.5 2.5 0.75

37 2.7 3.0 3.0 1.11

38 5.2 4.7 4.7 0.90

39 5.5 4.3 4.8 0.87

41 34.8 13.6 25.8 0.74

42 40.7 14.5 37.0 0.91

Table 3: Drainage Density for Enriquillo lake

WatershedID

Area(km2)

Main Streamlength (km)

Total Streamlength (km)

Drainagedensity

11 1055.8 61.2 860.3 0.81

12 757.2 64.0 659.8 0.87

14 63.6 21.5 57.9 0.91

28 92.6 24.2 58.5 0.63

39 103.9 20.3 76.0 0.73

47 102.2 19.7 78.4 0.77

61 109.6 27.4 82.9 0.76

64 135.2 23.8 100.0 0.74

65 179.8 42.5 144.5 0.8074 204.8 31.3 196.5 0.96

37 21.8 11.8 19.5 0.89

72 27.6 15.6 20.7 0.75





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7. Comparison between previous watershed delineation

In the other documents concerning the growth of the lakes, the watersheds relating

each watershed are delineated base on DEM map, using GIS or other software such as

SWAT. Comparing the result of our watershed delineation with the results of other

documents reveals that watershed delineation for Enriquillo Lake is almost the same,

hence Azeui watershed from our work doesn’t match (is shown with red box in figure 7).

Figure 7: Comparison of Azeui watershed (Luna and Poteau, 2011)

Studying the area around Azeui Lake shows that in North-West of the lake there is

no dominant mountains and that area can be consider almost as a plain (flat area). This

means that the border of Azeui watershed cannot touch the lake (as shown in the figure **).

By looking into the procedure of our work, we found that we had the same problem

which was because of wrong results of pit filling using GIS tools.How does far the watershed border will extent? DEM map shows that there are

some hills in just several kilometers further away. We looked into our watershed to see

whether its border follow those hills. The results show consistency between DEM map and

the border of the watershed.

8. Rivers in Azeui and Enriquillo

Almost all the rivers and streams around both lakes are ephemeral. The only source

which shows streams clearly is Google map for Hispaniola Island. Nevertheless, even this

map is not quite reliable for our purpose. Using Georeference toolbar, we put the Google

map image on the DEM map in GIS and picked only the streams which were shown in it

(figure 8). The streams flow path completely matches the image and we found that not all

the streams eventually end up into the lakes.

Total length of streams in Azeui watershed is 216 km and in Enriquillo watershed is

141 km.





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Table 4: Statistics of Azeui lake water level change and surface area from 2003 to 2010

Azeui Lake, Haiti

Date Year Water Level (m) Area(km2)

12‐Feb‐03 2003 -0.72 116

01‐Jun‐04 2004 -0.43 11701‐Dec‐06 2006 2.87 118

11‐Aug‐07 2007 2.63 119

01‐Sep‐08 2008 3.04 124

01‐Mar‐09

2009 4.96 127

22‐Jan‐10 2010 4.63 129

Table 5: Statistics of Enriquillo lake water level change and surface area from 2003 to 2010

Enriquillo Lake, D.R.

Date year Water Level Area(km2)

12‐Feb‐03 2003 -3.42 194.9

30‐Jan‐04 2004 -3.10 198.6

03‐Jan‐06 2006 -1.40 236.4

22‐Jan‐07 2007 0.13 255.9

09‐Jan‐08 2008 1.48 303.2

11‐Jan‐09 2009 1.82 331.6

22‐Jan‐10 2010 2.26 332.3

Figure 9: Surface area changes from 1985 to 2010 for Azeui and Enriquillo lakes



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Using the data in the table 4 and 5, the water level changes, the volumes added to the lakes

and also the rate of water level changes per year and volume changes calculated as follows

(table 6):

Table 6: Water level changes and Volume changes in Azeui and Enriquillo lakes from 2003 to 2010

Azeui Lake, Haiti Enriquillo Lake, D.R.

Water level Change (m) 5.35 5.68

Volume Change (km3) 0.655 1.480

Rate of Water level changes (m/year) 0.764 0.811

Rate of volume changes (km3/year) 0.094 0.211

9.2. Lake growth in future

Great concern for the lakes is that how far they will grow in the future. Raster

calculator tool gave us the ability to change the water level of each lake and compute the

surface area and the volume changes. Having all data, we find the relationships between

water level change and surface area and volume change. Then base on the same yearly rate

of volume change from 2003 to 2010 and considering 2009 as the base year, which is the

reference year for the DEM map we used, we compute the shape and the parameters of

lakes growth using linear interpolation (table 7 and 8). (See Full tables 9 and 10 in

Appendix)

The figure 10 and 11 show the extent of lakes growth. As it can be seen, both lakes start to

expand toward the plain areas around them where the small towns and agricultural lands are

situated.

Table 7: Water level changes and Volume changes in Azeui lakes from 2009 to 2026

Year Volume (km3) Water level (m) Surface Area (km2)

2009 0 17 127.1

2010 0.094 17.7 127.9

2011 0.187 18.5 129.2

2013 0.374 19.9 133.3

2015 0.561 21.3 140.6

2016 0.655 21.9 144.8

2026 1.591 27.9 170.7



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Figure 10: Azeui Lake growth from 2009 to 2026

Figure 11: Enriquillo Lake growth from 2009 to 2115



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Table 8: Water level changes and Volume changes in Enriquillo lakes from 2009 to 2115

Year Volume (km3) Water level (m) Surface Area (km2)

2009 0 -42 249.4

2014 1.057 -38 287.3

2015 1.269 -37.3 295.92017 1.691 -35.9 312.8

2026 3.594 -28.4 403.8

2036 5.709 -25.2 435.9

2115 30.023 12 898.8

Lake growth continues for both lakes till they reach the border of their watersheds.

It shows that almost after 17 years (2026), Azeui Lake will grow to its biggest area of 170.7

km2 and by then it will reach its watershed border. While Enriquillo Lake need 142 years to

pass the border of its watershed which is because of the fact that Enriquillo watershed is bigger

than Azeui watershed and the Enriquillo Lake is located in the west corner of watershed which is

surrounded by high mountains.

The map of the Hispaniola island (figure 12) shows that there are two small lakes in the

neighbor of Azeui and Enriquillo lakes. One of them is Trou Caiman lake situated which is situated

on the west side of Azeui Lake and another one called Ricon Lake is on the east side of Enriquillo

Lake. The surface area of Trou Caiman Lake is 4.47 km2 and Ricon Lake is 36.38 km2.

Figure 12: Trou Caiman Lake and Ricon Lake

If both Azeui and Enriquillo lakes continue growing and pass their watershed border, they

might pour in to their neighbor lakes. Studying the growth path of Azeui Lake shows that after 17

Trou Caiman Lake

Ricon Lake







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Figure 15: Land Cover and land use map of the study area

Using produced land cover and land use map and Google satellite image, a new map

showing agricultural and urban areas along with the location and density of buildings

around the lakes and in the whole watershed encompassing them has been created (figure

16). For finding the place of buildings Google satellite image was overlaid on the DEM layer

using Georeference toolbar.



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Figure 16: Land Use map of the study area

11. Potential Impacts of the Water Level Increase of the lakes

Growth of the lakes poses a threat to the lands and areas around them. What will

really happen for the lakes is not unknown. Hence base on previous changes in the lakes,

they will continue growing in the following years. There are lots of small towns, villages

and farms in the path of lakes which are in danger.

Overlaying the land use map and the pattern of lakes growth shows that what will

happen in the future for the watershed. The total area of agricultural land in the watershed

is 134,100 hectares which 12,085 (20%) and 14,119 (17%) hectares of it will be flooded by

the lakes growth in almost 17 years. And by the year 2115, when Enriquillo Lake reaches its

watershed border 44,488 hectares of agricultural lands (33%) will be inundated (figure 17).While by this year Azeui Lake keeps pouring into Trou Caiman Lake on its west side and

inundated more lands and towns.





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Figure 18: Geological map of Azeui and Enriquillo Basins

12.2. Soil Types Maps

Two soil types datasets were found from FAO et al (1998) and FAO (2003). The later, as it

is more recent, shows some refinements with regards to the first one. However, they show

that the area under study is dominated by Vertisols and Cambisols.

Both of them have considerable agricultural potential; however, adapted management is a

precondition for sustained production (FAO, 2006). So, Agricultural lands can still be

relocated within these watersheds, but, under adapted management.







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Figure 21: Electrical Conductivity and Total Available Water Capacity of Azeui and Enriquillo Basins

The electrical conductivity of soils varies depending on the amount of moisture heldby soil particles (Grisso et al, 2009). This is perhaps, particularly demonstrated by the Total

Available Water Capacity of the Soil in the study area which shows the same trend as the

EC.

13. Conclusion

The watershed delineation results show that Azeui and Enriquillo lakes watersheds are

respectively 712.9 and 3062.4 km2 with the total stream flow length of 542.6 and 2538.6

km, using the threshold of 1000 cells.

Total ephemeral river length in Azeui watershed is 216 km and in Enriquillo watershed is

141 km, which not all of them end up to the lakes.

We found that from 2003 to 2010 the surface of Azeui lake grows 1.1 times and Enriquillo

grows 1.3 times of their size in 2003. Assuming a linear growth, we found that in 17 years

from 2009, the size of Azeui lake will be 1.3 times bigger and it will pass the border of its



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watershed inundating 20% of agricultural lands in its watershed. Along with that, in 17

years from 2009, the size of Enriquillo lake will be 1.7 times bigger and after 142 years will

grow 4 times of its original size in 2009 and inundate 80% of agricultural lands.

Soil types maps show that the study area is dominated by two major soil units: Cambisols

and Vertisols with good agricultural potential. This indicates that these agricultural landsmight well be relocated within the basins without undergoing any detrimental effects but

adapted management is key to sustained production after or before they have been

flooded.

Overall, this work is to be seen as a step toward the hydrologic modeling of the study area

and also a hint of what the overall impacts of the lakes will be in the future.







Table 10: Water level changes and Volume changes in Enriquillo lakes from 2009 to 2036

Year year Volume (km3) Water level (m) Surface Area (km2)

2009 0 0 -42 249.4

2010 1 0.211 -41.2 252.4

2011 2 0.423 -40.3 258.22012 3 0.634 -39.5 267.8

2013 4 0.846 -38.8 278.5

2014 5 1.057 -38 287.3

2015 6 1.269 -37.3 295.9

2016 7 1.480 -36.6 304.4

2017 8 1.691 -35.9 312.8

2018 9 1.903 -35.3 320.5

2019 10 2.114 -30.6 379.5

2020 11 2.326 -30.3 383.6

2021 12 2.537 -30.0 387.72022 13 2.749 -29.7 390.9

2023 14 2.960 -29.4 394.1

2024 15 3.171 -29.0 397.3

2025 16 3.383 -28.7 400.6

2026 17 3.594 -28.4 403.8

2027 18 3.806 -28.1 407.0

2028 19 4.017 -27.7 410.2

2029 20 4.229 -27.4 413.4

2030 21 4.440 -27.1 416.6

2031 22 4.651 -26.8 419.8

2032 23 4.863 -26.4 423.0

2033 24 5.074 -26.1 426.2

2034 25 5.286 -25.8 429.4

2035 26 5.497 -25.5 432.6

2036 27 5.709 -25.2 435.9

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