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7/27/2019 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.
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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.
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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