Memoire Online - Environmental impacts on lake Azuéà¯ in Haiti due to degradation of its watershed

Environmental impacts on Lake Azuéï in Haiti due to degradation of its watershed

Environmental impacts on Lake Azuéï in Haiti due to degradation of its watersheds

1 Introduction

Haiti is one of the most biologically significant but also one of the most environmentally degraded countries in the West Indies (Sergile and Woods, 2001). Deforestation systematically practiced in Haiti has a long history. In 1492, with the arrival of Christopher Columbus, the Island was covered with luxuriant vegetation over 80%. Many researchers agree that deforestation began in the late seventeenth century by the French colonists who destroyed thousands of hectares of virgin forest to plant sugar cane, cotton and coffee (Michel, 2005). However, according to agro-economist and geographer Michel (2005), "The most serious interference with the balance of the ecosystem was observed under U.S. occupation from 1915 to 1934 by the policy of concentration of land in violation of their occupants that had to be expelled or converted to a simple agricultural salaried''. Today, the Haitian environment is described as ecological disaster and we could not with this text address all the factors that increase the vulnerability of the Haitian people as they are many: deforestation, soil erosion, water scarcity, insalubrities urban, loss of biodiversity, unregulated exploitation of quarries, marine ecosystem degradation, unplanned urbanization, shantytowns, demographic pressures and poverty. One of the major problems confronted by government organs is the management of aquatic ecosystems. In Haiti, lake ecosystems are potential water resource forgotten. There is a periodic variation in the level of these ecosystems called sleeping waters (lakes, ponds). It is caused by the contribution of alluvium and sediment, or to the effects linked to rainfall regime, or even from human activities and finally to the hydrodynamics of continuous and discontinuous aquifers (Pierre et al., 2008). Lake Azuei that is the largest lake in Haiti and the second largest lake in the island of Hispaniola, after Lake Enriquillo, is affected due to extensive erosion and deforestation or degradation of its surrounding areas. The Watershed serving Lake Azuei has been significantly eroded or deforested. The concentration of salts and other deleterious substances in the lake and others water systems in the Plain of Cul-de-Sac have grown in excess of limits. This has resulted to a greater variability in the hydraulic regime, now much more irregular with heavy sedimentation and shallow zones in the Azuei Lake, (USAID, 1986). All quality parameters for surface waters are almost in red. These changes in the lake have impacts on the plants and animals of the lake. Thus, from 2007 there has been a dramatic increase in water level of Lake Azuei which worries not only area residents but also the Haitian authorities. In December 2010, there has been also the death of hundreds of fishes (Tilapia) in the lake. So it is clear that the lake's biodiversity is very threatened because of this problem. In this case, we must identify the causes of environmental impacts on this lentic ecosystem.

In fact, the objective of this research is to characterize the environmental impacts into Lake Azuei by the analysis of available data and suggest solutions to mitigate them. The search for information at the origin of the degradation of watersheds of the Lake, collecting information on the study area (soil, climate, topography, land use) and the physico-chemical parameters of Lake Azuei, will allow us to draw conclusions and make recommendations to mitigate the problem. Because of this point of view and in the perspective of sustainable development of communities, lakes and ponds need to be subjected to regular monitoring both in quality and quantity to make the right decisions for mitigation (Pierre et al., 2008).

The goal of this study is to evaluate the environmental impacts on Lake Azuei caused by erosion of its watersheds. To do this, it will be necessary to (i) identify, through the literature review, the causes of deterioration or erosion of the watershed of Lake Azuei; (ii) characterize the impacts generated by erosion of Lake Azuei; (iii) suggest viable solutions to mitigate the environmental impacts on the lake.

2 II. Study Site

2.1 Description

The Lake Azuei measures 170 km²in surface area. It runs along the axis Northwest - Southeast over a length of 24 km with 12 km wide. It has a depth of respectively 24 meters 60% of its area and 5 meters deep and 35% of its area with a strip of 500 meters wide deep from zero to five feet. The lake has approximately a volume of 2465 km³ or 2465 10⁹m^{3 1(*)}.

2.1.1 Geographical coordinates and location

Azuei Lake is located on the arid valley of Cul-de-Sac, East Port-au-Prince in the department of the West (Figure I). It is located at 30 km from Port-au-Prince 18 ° 35'31'' North Latitude and 72°00'53'' West Longitude (Pierre, 1980).

3 III. Methodology

The methodology of this research study consists in literature review focused the causes of the degradation of Lake Azuei watershed causing impacts on its ecological balance. To achieve this, we will be collecting information on the study area (soil, climate, topography, land use) and on the physico-chemical parameters of Lake Azuei.

3.1 Geology

Lake Azuei constitutes a closed depression, a remnant of inlets which occupied the plain of the Cul-de-Sac probably during the Pleistocene (Quaternary) between the mountain of in Trou d'eau and the Massif de la Selle. The explanation for the formation of the lake has been assigned by Woodring et al, 1924, a deposition of alluvial sediments from the surrounding mountains. This lake is located in an alluvial plain bordered by mountain ranges mostly carbonate, ground and karstified (landscapes lapiaz) coral limestone and basalt, with variable topography (Pierre, 2008). It is at a distance about 30 km from the Bay of Port-au-Prince. Its functioning is related to rainfall and its power by the torrential waters and karst springs emerging from the massive and very bottom of the lake. The original side of the bank of the lake is about 20 m, the highest point between the lakeshore and coastline of the Bay of Port-au-Prince reached 38m where a vertical drop of 18 m.

3.2 Prevailing Winds

The waters of Lake Azuei are constantly under the influence steady winds of about 18 to 36 km / h. The prevailing winds are from the Dominican Republic. During hurricanes, winds raise waves of up to two meters amplitude (Michel, 2011).

3.3 The rainfall in the study area

The operation of the Lake Azuei is related to rainfall (600 mm annual average) and its power by the torrential waters and springs emerging from the massive karst and the lake bottom. During 2007, rainfall measured at meteorological stations in the Ministère de l'agriculture, des ressources naturelles et du développement rural (MARNDR ) at Thomaseau gave 1900 mm against 499 to 800 mm traditional, three times the average rainfall in the area.

The abundant rainfall in the chain of Trou d'Eau (North side) is caused the appearance of many sources in the bottom of the Lake Azuei. According to some experts, the karst structure of Trou d'Eau mountains would have facilitated the infiltration of rainwater that accumulates in a layer of clay below and cause the emergence of several underground sources or underground rivers that would discharge into the Lake Azuei temporarily.

Graph I: Jimani Station Average Monthly Precipitation (Romero and Poteau, 2011)

3.4 The watersheds of Lake Azuei

The watersheds of Lake Azuei consists of two slopes karstic mountain ranges (Woodring et al, 1924): the chain of Trou d'eau and the Massif de la Selle. It is the eastern extension of the chain of Matheux and a branch of the Sierra de Neiba in Dominican Republic. The chain of Selle is a mountain range located at south of Haiti. It extends to the Dominican Republic under the name chain of Baoruco. The lake drains the southern slopes of the chain of Trou d'Eau from which originate the majority of its sources. It also drains some of the water that comes from the North Slope of the chain of Selle.

3.5 Hydrology

Lake Azuei is supplied in its periphery by 39 water sources of karstic origin. In the North, nine of these sources have a total average flow of 647 l / s. In the South there are sources that the average flow is between 94 l/ s and 140 l / s. It is reported that several sources are underwater. The water level of the lake varies with the rainy season and hurricane activity. In 1954, after Hurricane Hazel, the lake level rose and then returned to normal within the eight months that followed. The lake level has been exceeded on numerous occasions during the 1979-83 period with a storm rising water level of 2 meters above the current level (Thorbjarnason, 1984). But since 2007, there has been a dramatic increase in water level in Lake Azuei.

3.6 Surface Area and Lake Elevation Change

The surface area of the Lake Azuei fluctuates between 113 to 118 km² from 1985 to 2002. Surface area of Lake Azuei has increased about 15% from 1985 levels. After 2003, experienced a clear increasing trend of surface area increase with Lake Azuei, reaching an area of 132 km² in 2011 (Table I and Graph II). In Lake Azuei, the larger rate of surface area increase since 2007 may be related to water levels reaching lower sloping areas in the northwestern part in the lake.

Table I: Time Series of Lake Area Change for Lake Azuei : Romero and Poteau , 2011

3.7 Major threats to management of freshwater ecosystems in Haiti (Ministere de l'Environnement : MDE, 2001)

Threats to management of freshwater ecosystems in Haiti can be divided into two categories: Direct threats and indirect threats.

Over exploitation of the forest resources and erosion of drainage basins. Forests have been steadily exploited as wood for construction, as a source of energy ( 71% of the consumption) and as an expendable resource in the clearing of land for agriculture development. Deforestation is the major cause of erosion and the most crucial environmental concern of the nation. At present, of the thirty (30) major watersheds within the country, twenty five (25) are completely deforested (MDE, 1999). The forest cover was reduced from 60 % in 1960 to 6.7 % in 1978 (USAID, 1986). It has been estimated that the percent of the country remained forested represents less than 3% of the land surface today. The removal of vegetative cover negatively impacted freshwater ecosystems in Haiti by decreasing their capacities for sustained production. Non forested land use activities placed at risk the continued availability of reliable sources of domestic water, created general denudation of the landscape and increased erosional potential of upper water areas (MDE, 2001).

Ø The accelerated population growth coupled with increasing rate of poverty and uncontrolled urbanization process (shanty town): The Haitian population will reach 16 million by 2040 according to projections of the `'Secretairerie d'Etat à la Population''and as already stated the GNP per capita is $US 250, the lowest GNP in the western hemisphere (MDE, 2001).

Ø The lack of application of existing laws and land use control measures to fully protect upper water catchment against illegal squatting and land clearing;

Ø The lack of application, up to now, of existing policy in domestic water and its integration into a `'Schéma National d'Aménagement du Territoire'' and decision making;

Ø The lack, up to now, of official strategy and action plans for critical wetlands of the country.

3.8 Treats on Lake Azuei

Deforestation associated with heavy agricultural pressures on marginal farms, accelerating soil erosion, which increases the volume of sediment carried by streams into the lake (MDE, 2001) Lake Azuei receives water of watersheds of 110,000 ha. Deforestation and erosion has accelerated the formation of gullies, the flow capacity of the watershed has increased from 30 to 40% compared to traditional capacity which was 15 to 20% in the past. Some references give the watersheds of Haiti following characteristics: Evaporation 60-70%, 20-25% infiltration, runoff from 25 to 30%. If one assumes that the infiltration and runoff are very strong in the karst area, it will deduct about 20 to 25% of the watersheds finish their race in the Lake Azuei (Michel, 2011). According to Patrick Louis, a geologist, the bathymetric surveys conducted by his institution at the lake during the last thirty years, reports that the level of sedimentation, for the period from 1983 to 1990, more than 2 meters.

In December 2010, hundreds of fish were dead in the Lake Azuei. According to initial findings of the investigations, the death of fish was caused by oxygen deficiency and increasing the level of acidity (pH) in water following the use of calcareous materials in the work of raising the stretch of road (linking Haiti to the Dominican Republic) affected by the rising waters of Lake Azuei. Land use and land cover changes can affect the physical, chemical and biological characteristics of the soil. Changes in land use can specifically affect the infiltration capacity: changes from natural or seminatural vegetation to agriculture or pasture can decrease infiltration rates (Yimer et al., 2008).

3.9. Lake water Quality

Understanding a lake's physical, chemical, and biological properties is essential to determining the lake's condition and in making informed lake management decisions.

According to USEPA (1998), the water quality measurements or "parameters" most frequently tested in lakes are:

Ø Physical measurements such as water clarity,
dissolved oxygen, and temperature;

Ø Chemical measurements such as nutrients, suspended
solids, pH, and conductivity; and

a. Water clarity or Transparency: is commonly measured using a Secchi disk, an eight-inch diameter, weighted disk that is painted black and white in alternate quadrants and attached to a calibrated rope. The disk is lowered into the water and the depth at which it is no longer visible is recorded. Secchi disk measurements reveal how deep sunlight can reach into the water and thereby indicate general water quality conditions. Hence, Secchi transparency is considered an indirect measurement of how much algae and sediment is in the water.

b. Dissolved Oxygen measurements determine the amount of oxygen in the water available for fish and other aquatic life.

c. Temperature measurements are used to characterize the presence or absence of thermal stratification (the forming of "layers" of water with distinct temperature differences. Both dissolved oxygen and temperature measurements are an integral part of a basic lake assessment.

A lake's temperature variations are important in influencing what types and how many fish will live and reproduce in that lake. Low oxygen levels may restrict where fish can go within a lake and limit the types and numbers of fish in the lake's bottom waters. Generally, warm water fish (e.g., bass, bluegill, catfish) need at least 5 milligrams per liter (mg/L) of dissolved oxygen to survive, while coldwater fish (e.g., trout and salmon) require 6-7 mg/L.

3.9.2 Chemical Parameters

Nutrients in lakes serve the same basic function as nutrients in your garden: they help plants grow. In a garden, lush growth and high productivity are considered beneficial, but this is not necessarily so in a lake. While some algae and other aquatic plants are essential parts of a healthy lake ecosystem, elevated nutrient levels can stimulate nuisance plant growth and lead to an out-of-balance ecosystem and impaired recreation.

a. Phosphorus is usually the nutrient that regulates algae growth the most. For many lakes, additional phosphorus loadings will stimulate additional algae growth. Because phosphorus is so important to the growth of algae and aquatic plants, many lake and watershed management activities focus on reducing phosphorus availability in the lake water. Measuring phosphorus provides an indication of the fertility or "nutrient enrichment" of a lake. Lakes with low nutrient concentrations are termed "oligotrophic." Those with intermediate nutrient levels are called "mesotrophic." Lakes with high nutrient concentrations are termed "eutrophic." Lakes with extremely high nutrient levels are labeled "hyper-eutrophic." TP concentrations above 0.030 mg/L are enough to stimulate nuisance algae growth.

b. Nitrogen forms of greatest interest to lake studies are nitrate+nitrite nitrogen (NO₃⁼+ NO₂^-), total ammonia nitrogen, and total Kjeldahl nitrogen (total ammonia plus organic nitrogen). The inorganic nitrogen forms (nitrate and ammonia) are readily utilized by algae for growth. Researchers have found that inorganic nitrogen concentrations above 0.30 mg/L are able to stimulate algae growth. Additionally, high ammonia concentrations are toxic to fish and other aquatic organisms.

Suspended solids: Suspended materials influence a lake's transparency, color, habitat quality, recreational values, and overall ecosystem heath. Total suspended solids (TSS) and turbidity reveal the amount of solids suspended in the water, and include both inorganic forms (such as soil particles) and organic forms (such as algae). TSS measures the actual weight of material per volume of water. Turbidity measurements depend on how much light is scattered or absorbed by a water sample (more suspended particles cause greater scattering; tinted water absorbs more light). Turbidity is reported in nephelometric turbidity units (NTU).

Ions:The amount and types of ions (positively or negatively charged dissolved minerals) in the water provide general information on the lake's overall ionic chemistry. Parameters that describe the ionic makeup of lake water include alkalinity, conductivity, and pH. They also generally reflect the lake's watershed geology and soil characteristics.

1. Alkalinity is a measure of the acid-neutralizing or "buffering" capacity of water. The higher a lake's alkalinity, the greater its résistance to a decline in pH. Alkalinity is commonly influenced by bicarbonates and thus is reported as the concentration of calcium carbonate (CaCO₃) in the water. Natural alkalinities fall within a general range of 20 to 200 mg/L CaCO₃. Illinois lakes typically have high alkalinities and therefore are well-buffered from the effects of acid rain.

2. Conductivity (specific conductance) is a measure of the water's ability to conduct an electric current. It is useful for estimating the concentration of total dissolved solids (TDS) in the water (TDS equals about 60 percent of conductivity). Because the measurement is made using two electrodes placed one centimeter apart, conductivity is generally reported as micromhos per centimeter (umhos/cm). Lakes with high alkalinity often have high conductivity and vice versa.

The water's pH is a measure of its hydrogen ion (H⁺) concentration and reflects the water's acidity. The lower (more acidic) the pH, the more "free" or "unattached" hydrogen ions in the water. The pH scale ranges from 0 to 14. A pH of 7 is neutral, less than 7 is acidic, and greater than 7 is basic or alkaline.

A lake's pH will fluctuate somewhat each day and from season to season in response to photosynthesis by algae and other aquatic plants, watershed runoff, and other factors. Like dissolved oxygen concentrations, pH may change with depth, primarily due to various chemical reactions and a decrease in photosynthesis.

Chlorophyll is the pigment in plants that allows them to create energy from light (photosynthesis). There are several forms of chlorophyll and each absorbs a different wavelength of light. Chlorophyll a is found in all photosynthesizing plants. For this reason, the amount of planktonic (suspended) algae in a lake is commonly estimated using the chlorophyll a concentration. Chlorophyll a should be "corrected" for phaeophytin a, a common breakdown product of chlorophyll a that can interfere with its measurement. Analysis for chlorophyll b and c provides information on the various types of algae present (blue-greens, green algae, diatoms, etc.).

Analysis of bacteria levels at swimming areas is a good public health practice and it may be required by state, county, or local health department regulations. Analyses typically are made for fecal coliform bacteria, or for the particular fecal coliform Escherichia coli (E. coli). Fecal coliforms are microscopic organisms that live in the intestines of warm-blooded animals and are excreted in their waste. Coliform bacteria themselves usually are not disease-causing. However, they are good indicators for the presence of sewage and animal wastes that may contain disease-causing organisms and pathogens.

4 IV. Results

The results reported in the table below are coming from several different sources and some of them are old. However, they give an idea about the operating status of the lake in the past. But the exception is made for those produced by Christian, et al. (2011). They can provide information on current ecology of the lake.


A. Physical Parameters	Data available	References
1. Water Clarity or Transparency	Average Secchi^3(*) depth : 3.25 m	Christian, Dorval and Hannigan, 2011
2. Dissolved Oxygen	6.2-8.6 mg/L	US Army Corps of Engineers, 1999
3. Temperature	27-30.5 (28,75) ^OC	US Army Corps of Engineers, 1999
B. Chemical Parameters
1. Phosphorus	10.58 (#177; 13.82) ug/L	Christian, Dorval and Hannigan, 2011
2. Nitrogen	419.02 (#177;19.31 SD) ug/L	Christian, Dorval and Hannigan, 2011
4. Total Dissolved Solids (TSS)	7,500 to 10,650 mg/L	US Army Corps of Engineers, 1999
5. Hardness	525-2260 mg/L	Matthes, 1988
6. pH	7.5-8.1 (8.5)	Matthes, 1988
7. Alkalinity	195 - 490 mg/L	Matthes, 1988
8. Salinity	6.92 - 15.53 ( ppt)	Matthes, 1988
9. Conductivity	500-600 umhos/cm	Matthes, 1988
C. Biological Parameters
1. Chlorophyll a	2.39 (#177; 0.39 SD) ug/L	Christian, Dorval and Hannigan, 2011
Color of Water ( Code Forel)	greenish-40% (phytoplancton)	Matthes, 1988

The fish kill in Lake Azuei is the result of a series of biophysicochemical transformations in the lake environment (Table II). This transformation of natural or anthropogenic causes inevitably the death of the lake, due to inputs of sediments and nutrients. At first glance, this event is caused by the phenomenon of eutrophication of the lake. The mineral nutrients such as nitrogen, phosphorus, etc., depending on their concentration, operate in the equilibrium with the environment.

These elements are essential to plants, but a drastic increase in their concentration causes massive growth of algae and aquatic plants. An eutrophic aquatic environment is an environment rich in nutrients and with high productivity (Hade, 2002). These processes result in the change of the pH and the reduction of oxygen in the lake which is the origin of death of fishes into the lake.

Table III: Classification of Lakes concerning the trophic level based on OECD (1982)

Trophic Level	Phosphorus	ChlorophyllA	Transparence
Oligotrophic	< 10 mg/m3	< 2.5 mg/m3	6m-12m
Mesotrophic	10-35 mg/m3	2.5-8 mg/m3	3m-6m
Eutrotrophic	35-100 mg/m3	8-25 mg/m3	3m-1.5m
Hypertrophic	> 100 mg/m3	> 25 mg/m3	< 1.5m
Organisation for Economic Cooperation and Development (OECD, 1982)

These data were (Table III) collected by Christian et al. (2011 from some samples collected in the lake, we think they can help to understand what are happened in the ecological processes of the lake.

Euthrophic: Refers to a water body shallow and turbid where an excessive concentration of plant nutrients causes algal blooms.
Oligotrophic: refers to water clear, deep and low in nutrients. There is little organic matter and a high content of dissolved oxygen.
Mesotrophic: Refers to a lake enriched by nutrients, with an early accumulation of sediments and organic matter, which the water is slightly turbid with a reduction of the dissolved oxygen at depth. Biological productivity increases and is manifested by the installation of aquatic plants, an increased presence of algae. Changes in fish community appear.

Based on the OECD fixed boundary classification scheme, we classified Lake Azuei as mesotrophic. Secchi depth indicated euthrophic; chlorophyll indicated oligotrophic; and phosphorus and nitrogen indicated mesotrophic. But we can consider there is a tendency to an ecological disruption in Lake Azuei by providing nutrients to the process of erosion as the surrounding mountains of the lake are highly degraded. In this case, additional studies will be necessary to understand more on the biological functioning of Lake Azuei.

5 V. Conclusions and Recommendations:

Today, the available information we have shows clearly that the Azuei Lake is threatened by deforestation and degradation of its systematic watershed (the South side of the chain of Trou d'Eau and the North side of the chain of Selle). The case of eutrophication potential experienced by the lake Azuei is not unique. Because runoff carry along a lot of sediment which, by input of nutrients (P, N), change the ecological balance of the lake. We should also mention activities such as overfishing, uncontrolled hunting and agriculture in the immediate area as threats to the proper functioning of the Lake.

· Establish a system for collecting data on a regular basis on the physico-chemical parameters and pluviometric of the lake,

· Conduct research at the hydrogeological system supplied to the lake to better understanding the process of raising the level of the lake,

· Engage in political and technical discussions for the development of a sustainable development and rehabilitation the watershed of Lake Azuei.

Finally, efforts should also be made to classify Lake Azuei as a reserved area. In this sense, steps will be taken by the Haitian authorities to the Ramsar Convention^3(*) to make the lake an International Wetland Area.

6 References

1. Butterlin, J. (1960). Géologie Générale et Régionale de la République d'Haïti. Paris: Institut des Hautes Études de l'Amerique Latine, Université de Paris,

2. Christian, A. D., Dorval, E., Hannigan, R. E., (2011). Physical and chemical analysis and classification of lake Azuei, Haiti. University of Massachusetts Boston, Boston, USA

3. Eva Joelisa Romero Luna And Dina Poteau (2011). Water Level Fluctuations of Lake Enriquillo and Lake Saumatre in Response to Environmental Changes. Presented to the Faculty of the Graduate School of Cornell University In Partial Fulfillment of the Requirements for the Degree of Master of Engineering, August 2011.

4. Ehrlich, M. ( 1985). Haiti-Country Environmental Profile-A Field Study. Contract No. 521-0122-C-00- 4090-00, Washington, DC: U.S. Agency for International Development, June

5. Environmental Protection Agency (1998). Lake and Watershed Unit, DWPC-, PO. Box 19276, Springfield, Illmois. 62794-9276: 217/782-3362

6. Gonfiantini R. and. Simonot. M (1997). Isotope Techniques in Water Resources Development,«Isotopic Investigation of Groundwater in the Cul-de-Sac Plain, Haiti.» Proceeding of a symposium, International Atomic Energy Agency, Vienna, , p. 494

7. Hade André (2002). Nos lacs: les connaître pour mieux les protéger ; Québec: Éditions Fides,359p.

8. Ministere de l'Environnement : MDE (1999) . Haïti : Plan d'Action pour l'Environnement. MDE-Haiti.

9. MDE (2001). Haiti National Report: Integrating the Management of Watersheds and Costal Areas in Haiti» Haiti: MDE, Sep, 2001

10. Matthes, H. (1988). Evaluation de la situation de la peche sur les lacs en Haiti. Port-au-Prince (Haiti). 84 p. Data ownerFI /FIRA

11. Pierre M. G. , Emmanuel Molière , Helliot Amilcar, Simone D. Jn Baptiste et de l'ingénieur Gesner Robert (2008) . Point de vue de l'Université Quisqueya (UniQ) et de l'Ecole Nationale de Géologie Appliquée (ENGA) relatif à la remontée du lac Azuei ou étang saumâtre et de l'étang de Miragoâne. UniQ/ ENGA

12. Maurrasse, F.J., & C. Jean-Poix ( 1997). Transactions, «Hydrologeology of the Water-Supply Springs of Metropolitan Port-au-Prince, Haiti.» American Geophysical Union Spring Meeting, Baltimore, Maryland, 27-30 May.

13. Organisation for Economic Cooperation and Development : OECD (1982). Eutrophication on Waters: Monitoring, Assessment, and Control. OECD, Paris. 154 pp.

14. Michel R,( 2005). L'espace caféier en Haïti : déclin et espoir, pages 70 et 71, Éditions KARTHALA,.

15. Romero, E. J. L. & Poteau, D. (2011). Water Level Fluctuations of Lake Enriquillo and Lake Saumatre in Response to Environmental Changes. Presented to the Faculty of the Graduate School of Cornell University In Partial Fulfillment of the Requirements for the Degree of Master of Engineering, August 2011.

16. Vlaminck, B. (1989). La pecherie de l'etang saumatre: Recherche appliquee et activites periode octobre 88-septembre 89.No. HAI/88/003).United Nations Development Programme/Food and Agriculture Organization (PNUD/FAO). Retrieved October 31 2011 from http://www.fao.org/docrep/field/003/AC561F/AC561F00.htm#TOC

17. USAID (1986) .Haiti : Country and Environmental Profile a field study, 130p.

US Army Corps of Engineers (USACE).(1999). Water resources assessment of Haiti.

19. Thorbjarnanson, J.B. (1984): Status and ecology of the American Crocodile in Haiti. Master's thesis. University of Florida, Gainesville.

21. Woodring, W.P., J.S. Brown, and W.S. Burbank. (1924) : Geology of the Republic of

Haiti. Department of Public Works, Baltimore, Maryland: Lord Baltimore Press,.

22. Yimer, F., Messing, I., Ledin, S. and Abdelkadir, A. (2008) :, Effects of different land use types on infiltration capacity in a catchment in the highlands of Ethiopia. Soil Use and Management, 24: 344-349. doi: 10.1111/j.1475-2743.2008.00182.

* ¹ This volume is obtained by multiplying the average depth (24 m + 5 m / 2 = 14.5 m) by the surface area (170 km²) of the lake. Note, that these data can be changed if the shape of the bottom is poorly estimated.

* ² In this case the authors want to establish the relationship between the lake surface increase and the depth (24-25 m). It's like pours some water in a conic recipient, the depth increases by adding water that increases also surface.

* 1 N.B: A Secchi disk is a device for measuring the transparency of a body of water. It consists of a disc of about twenty centimeters, black and white (each quarter turn). The disc is attached to end of a cord and weighted, is left down to disappearance then there is the length of the rope. Then hauled the rope up there and then reappear the length of the rope. The depth of the Secchi disk is the midpoint between the two measures. Retrieved october 30, 2011 from www.wikipedia.com .

* ³The Ramsar Convention is the only global environmental treaty that deals with a particular ecosystem. The treaty was adopted in the Iranian city of Ramsar in 1971 and the Convention's member countries cover all geographic regions of the planet. It is an international cooperation for the conservation and wise use of wetlands and their resources.

Environmental impacts on lake Azuéà¯ in Haiti due to degradation of its watershed