Climate Change Impacts On The Hydrology Of The Dominican Republic

Climate Change Impacts on the Hydrology of the Dominican Republic: Projections and Policy Options

Carlos Rymer, Emmanuelle Humblet, and Nosisa Ndaba

MPA-ESP Program School of International and Public Affairs Columbia University

August 13, 2008

Please correspond to the authors at [email protected], [email protected], or [email protected].

Climate Change Impacts on the Hydrology of the Dominican Republic

Executive Summary The Dominican Republic presently enjoys satisfactory freshwater availability that can adequately sustain its economic development. The country’s mean annual precipitation is approximately 1,400mm, with the range spanning from 700mm to 2,400mm depending on the region. The variable terrain, ranging from large valleys to mountain ranges, also contributes to the lack of freshwater in some areas and its abundance in other areas. Total annual precipitation averages 69 cubic kilometers, while annual

evapotranspiration

averages

58

cubic

kilometers,

leaving

approximately 21 cubic kilometers as runoff that supplies surface and groundwater. While the country has a rapidly growing economy, it faces many socioeconomic and environmental challenges, one of them being freshwater availability, particularly in relation to future climate change and population growth. In this assessment, we analyze the current water balance and project future changes in freshwater availability using existing climate change and population projections. We conclude that currently, freshwater availability is approximately 2,200 cubic meters per capita per year, but that this will fall by nearly 85% to 360 cubic meters per capita per year by 2100. We also conclude that freshwater availability will reach the water scarcity threshold of 1,000 cubic meters per capita around mid-century. These projections are due to a predicted 20% drop in annual rainfall in the region and an expected increase in evapotranspiration of approximately 0.1 mm per day by 2,100. Groundwater availability will also be impacted by saltwater intrusion due to sea level rise. These predictions require a policy framework in which all stakeholders are involved in collaborative, sustainable freshwater management and where adaptation to lower natural freshwater availability is prioritized. 2

Climate Change Impacts on the Hydrology of the Dominican Republic

Contents Introduction……………………………………………………….

4

Climate Change Projections for the Caribbean………………

6

Methodology and The Water Balance…………………………

7

The Hydrological Cycle…………………………………….

7

Calculating The Water Balance…………………………….

8

Hydrological Climate Change Impacts………………………...

10

Surface Water………………………………………………..

10

Groundwater………………………………………………...

11

Primary Stakeholders…………………………………………….

12

Adaptation Options………………………………………………

13

Policy Recommendations………………………………………..

14

Conclusion…………………………………………………………

15

References…………………………………………………………

16

Appendix…………………………………………………………..

18

3

Climate Change Impacts on the Hydrology of the Dominican Republic

Introduction

Dominican Republic

Figure 1. Map of the Caribbean, with the Dominican Republic highlighted. Source: US Geological Survey The Dominican Republic is situated on the Caribbean island of Hispaniola at north latitude 19˚00 and west longitude 17˚40. It occupies two-thirds of the island on the east, with Haiti as its neighbor on the west. Its total surface area is 48,671 square kilometers and its perimeter is approximately 1,963 kilometers, of which 388 kilometers borders with Haiti. The climate is predominantly tropical with annual rainfall varying by region from 700 to 2,400 mm per year (see Figure A in Appendix). The annual mean temperature also varies by region from 25˚C to 30˚C (Secretariat on Environment and Natural Resources, 2006). The country enjoys one of the most abundant per capita water availability endowments in Latin America, approximately 2,350 cubic meters of water runoff per year per capita (Secretariat on Environment and Natural Resources, 2006). With a broad set of watersheds due to the mountainous nature of the island (see Figure E in Appendix), surface waters and groundwater storage can be found in every region of the 4

Climate Change Impacts on the Hydrology of the Dominican Republic country (see Figures B and D in Appendix). However, the climate is highly variable by region, creating a situation where some areas have an abundance of water availability and others have water scarcity (Roebuck, Fong, and Harlan, 2002). The mountainous areas of the country can be found in the Cordilleras Central, Oriental, and Septentrional, in addition to the Bahoruco and Neiba Sierras. The four most important sources of surface water come from the Cordillera Central; these include, by order of economic importance, the rivers Yaque del Norte, Yaque del Sur, Yuna, and Artibonito (Secretariat on Environment and Natural Resources, 2006). The country’s land use is also variable (see Figure C in Appendix). Approximately 30% of the country’s land area is protected under the National System of Protected Areas. The east’s vegetation is largely characterized by subtropical humid forests, with mangroves in certain coastal areas; the north’s vegetation is characterized with pine and montane cloud forests at high elevations; and the south’s vegetation is largely grasslands, scrublands, and deserts. The principal economically important urban areas are Santo Domingo (south; 3 million people), Santiago (north; 1 million people), and La Romana (east; 300,000 people). Other important urban areas include Higuey (east), La Vega (north), Puerto Plata (north), Samana (east), San Cristobal (south), San Juan de la Maguana (north), and San Pedro de Macoris (east). In terms of agriculture, which covers 10% of the land surface, the most important commodities are sugar cane, cocoa, coffee, and tobacco (CIA, 2008). Other less economically important commodities include bananas, plantains, rice, coconut, cassava, tomatoes, pulses, dry beans, eggplants, peanuts, and meat and dairy products. The country’s total population is approximately 9.5 million, with an annual growth rate of 1.5%. In 2007, its gross domestic product (at purchasing power parity) was approximately $62 billion, with a mean annual growth rate of 9.5% over the last three years (CIA, 2008). The most important productive sectors are tourism, agriculture, textiles, and mining. While the country has experienced significant growth over the last two decades, unemployment is still approximately 14% and 36% of the population is still considered to earn income that is below the poverty line (President’s Information, Press, and Publicity Office, 2008). In addition, income inequality is significant, with 10% of the population earning 40% of national income (CIA, 2008).

5

Climate Change Impacts on the Hydrology of the Dominican Republic The country suffers from various socioeconomic and environmental problems. Political corruption, while becoming less of an issue, has traditionally been a significant problem, especially in relation to projects that benefit the public. Some of the most prominent problems, in addition to corruption and income inequality, include a lack of good education, poor infrastructure in many areas, regular electricity blackouts, heavy reliance on foreign oil, deforestation, drug trafficking, and a low access to potable drinking water in some areas (CIA, 2008). In this assessment, we focus on the hydrology of the country and the impacts climate change will have on water availability in the future. Specifically, we analyze the current water situation and project climate change impacts on precipitation, runoff, and storage. Finally, we provide a policy framework under which potential solutions could be identified, assessed, and implemented accordingly to cope with projected impacts.

Climate Change Projections for the Caribbean Climate change poses a significant threat to regions across the world. Some of these global impacts that are anticipated to affect the Dominican Republic include an increase in temperature anywhere from 1.1°C to 4.5°C, as predicted by the Intergovernmental Panel on Climate Change (IPCC, 2007). This increase in temperature will result in a warming of the oceans, which will likely lead to increased intensity of hurricanes that could result in devastating physical, economic, and human losses. The coastal areas of the Dominican Republic are also vulnerable to sea level rise, for which the IPCC anticipates 18 to 59 cm by 2100 is likely. As we will show in this report, midlatitudes and semi-arid low latitudes are expected to experience decreased water availability and increased drought (IPCC, 2007). These climate predictions are likely to result in a wide range of impacts that will impact the physical, economic, and environmental systems of the island. In a recent study, Bueno et al. (2008) reported that without implementation of adaptation strategies, climate change impacts will result in the loss of 19.6% of current GDP in the Dominican Republic by 2050, and 40.3% loss of by 2100. In addition to these economic impacts, climate change presents a real threat to human life, due to an anticipated increase in stronger hurricanes, limitations in available freshwater, and decreased in sanitary conditions. Bueno et al. (2008) provide a detailed breakdown of the breadth of climate change impacts that the Dominican Republic is likely to experience this century: 6

Climate Change Impacts on the Hydrology of the Dominican Republic • • • • •

•

Salt water intrusion that will threaten freshwater supply. Frequent and longer droughts, which will affect freshwater supply. Increased heat stress that will affect the health of vulnerable populations such as the elderly. Water contamination from flooding that would further limit available freshwater supply and worsen sanitary conditions. Increased temperature, resulting in agricultural and ecosystem losses, especially of coral reefs and fisheries. In addition to the economic implications of losing important fisheries, loss of coral reef habitat will also result in economic impacts due to reduced tourism attraction. Tourism losses due to temperature changes, health risks, and degradation of coastal environmental features such as beaches from storms and coastal erosion.

Methodology and The Water Balance The projected increase in the regional mean annual temperature will have significant effects on water availability. In order to fully assess the impact climate change will have on the water resources available, it is necessary to understand the hydrology of the country and identify a methodology. In this section, we describe the country’s hydrologic dynamics and project climate change impacts on them. The Hydrological Cycle The Dominican Republic relies on surface water for most of its domestic uses, as that is its largest storage of freshwater. The mean annual precipitation for the entire country is approximately 1,400mm or 69 cubic kilometers, with most of it falling from April to October, particularly during periods of heavy rainfalls, tropical storms, and hurricanes. From the total precipitation, about 48 cubic kilometers of water are lost to evapotranspiration, making only 21 cubic kilometers of water runoff available for consumption annually (FAO, 2008). This water is stored in 14 watersheds, with some having above necessary supplies and others having below necessary supplies (Roebuck, Fong, and Harlan, 2002). There are 20 dams that store approximately 2 cubic kilometers of freshwater annually. In addition, the country’s groundwater systems naturally recharge approximately 2.2 cubic kilometers annually, with about 7.3 cubic kilometers being stored (INDRHI, 2003, 2004). The rest of the water is either discharged to the ocean or consumed (Roebuck, Fong, and Harlan, 2002; see Table A in Appendix). The 7

Climate Change Impacts on the Hydrology of the Dominican Republic table below summarizes the annual mean data that describes the hydrological cycle in the Dominican Republic.

Table 1. Hydrological Data for the Dominican Republic (km3/yr) Precipitation

69

Annual rainfall on the land surface.

Evapotranspiration

48

Freshwater conversion from liquid to gas due to sunlight or plant transpiration.

Runoff

21

Freshwater that flows from the land surface to water bodies, including the ocean.

Discharge

11

Freshwater that leaves the land surface into the ocean.

Storage

9.3

Freshwater that is annually renewed and kept in manmade or natural systems.

Consumption

10

Freshwater that is consumed environmental purposes.

for

human

and

Source: Roebuck, Fang, and Harlan; INDRHI; FAO Calculating the Water Balance The water balance of any region or watershed can be calculated using a set of simple equations that describe the inflow, outflow, and total storage of freshwater. In general, the first simple equation that can help describe a hydrological system is the conservation equation, which is written as follows (Dingman, 2002): I – O = ΔS, Where I is the incoming water quantity, O is the outgoing water quantity, and ΔS is the change in storage. In general, the conservation equation, as well as all other hydrological equations, applies to watersheds, which are regions characterized by spatial elevation changes where all water that falls drains into one basin. Figure E in the Appendix shows the relevant watersheds in the Dominican Republic. In

order

to

incorporate

hydrological

data,

such

as

precipitation,

evapotranspiration, and runoff, the conservation equation is expanded to include more 8

Climate Change Impacts on the Hydrology of the Dominican Republic details and to allow analysis of the water balance with higher resolution. The timeaveraged water balance equation is used for this purpose and is written as follows: P – ET = Q + Gout + ΔS, Where P is precipitation, ET is evapotranspiration, Q is surface water outflow, and Gout is groundwater outflow. Finally, to ensure sustainable water resource management of a watershed, the sustainable time-averaged water balance equation is used. It is written, for our specific purposes, as follows: ΔS = P – ET – Q – Gout – C – D, Where C is human consumption and D is water requirements for ecosystems. In addition, other relevant equations generally used include the runoff ratio and its integration with other hydrological parameters, and the water balance where the change in storage is equal to zero, as follow: W = Q/P ET = (1 – W) x P, where w is the runoff ratio. 0 = P – ET – Q – Gout – C – D For the purposes of this assessment, the following data is used:

Table 2. Hydrological Data for Water Balance Equation Volume (km3/yr)

P

ET

Q

Gout

C

D

69

48

8.5

2.5

9.5

0.5

Source: Roebuck, Fang, and Harlan; INDRHI; FAO Using the sustainable time-averaged water balance equation, assuming no changes in storage, we find the following, in cubic kilometers per year: 69 (P) – 48 (ET) = 8.5 (Q) + 2.5 (Gout) + 9.5 (C) + 0.5 (D) The left side of the equation represents total runoff (precipitation minus evapotranspiration), which is the total water availability. With a population of 9.5 9

Climate Change Impacts on the Hydrology of the Dominican Republic million (excluding tourists), the total water availability per capita from runoff alone is approximately 2,210 cubic meters, of which part must be left for ecosystem needs under sustainable water resource management. This quantity does not include storage such as groundwater and lakes, which are renewed over a period of time longer than one year. While the country has abundant water supplies today, it is important to assess what the impacts of future growth in consumption and climate change will have on water availability. We now turn to assess the impacts that population growth and climate change will have on total water availability.

Hydrological Climate Change Impacts Climate change will impact the hydrology of the Dominican Republic by reducing precipitation, increasing evapotranspiration, and causing saltwater intrusion into groundwater systems (IPCC, 2007). The IPCC, the world’s leading authority on climate change science, estimates that annual rainfall in the region will decrease by approximately 20%, that evapotranspiration will increase by 0.1mm per day by the end of the century, and that sea level will rise between 18 and 59cm. These estimates leave out uncertainties about positive feedback effects in the carbon cycle, such as greenhouse gas emissions from melting tundra. Surface Water As a result of a decrease of 20% in annual precipitation by 2100, an increase in evapotranspiration of two cubic kilometers per year, and an increase in the population to 14 million, there will be a sharp drop in the total runoff, impacting water availability significantly. Population is expected to stabilize by mid-century to 14 million, according United Nations projections. The table below summarizes the changes in these parameters.

10

Climate Change Impacts on the Hydrology of the Dominican Republic

Table 3. Water Availability Projection for 2100 Precipitation Evapotranspiration Volume (km3/yr)

55

Runoff

Per Capita Availability

5

3601

50 Data Source: IPCC, 2007

This significant drop in freshwater availability (84%) will be largely due to a drop in total precipitation from 69 cubic kilometers per year to 55 cubic kilometers per year by 2100 and a total increase in population size to 14 million. The figure below shows how the drop in water availability will proceed this century assuming constant slope.

Figure 2. Water Availability Projection With Climate Change Scenario 6,000

km³/capita-yr

5,000

4,700

4,000 3,000 2,000 1,000 0

360

Water Scarcity Threshold

Year

Groundwater In addition to surface water, groundwater will also be affected significantly. In part, groundwater depends on rainfall that percolates into the ground. This effect has already been accounted for in the assessment of surface water. According to the IPCC,

1

Over 75% of the IPCC models used to predict precipitation in the area agree.

11

Climate Change Impacts on the Hydrology of the Dominican Republic sea level will rise 18 to 59 cm this century, excluding uncertainties in positive feedback effects.2 It is also important to note that increasing reliance on groundwater will deplete available resources and make it more difficult to extract remaining resources. As of 2000, groundwater withdrawal was up to 2.7 cubic kilometers per year when the natural recharge rate was 2.2 cubic kilometers per year (INDRHI, 2004). With decreasing surface water availability and increasing groundwater withdrawals (assuming no changes in efficiencies), this alone will have a significant impact by lowering water levels and facilitating saltwater intrusion. Modeling saltwater intrusion as a result of sea-level rise and groundwater depletion will be necessary to understand how much groundwater will actually be available in the future.

Primary Stakeholders The reduced freshwater availability in the Dominican Republic this century will have a significant impact on the entire population. In effect, this makes every sector in the Dominican Republic a stakeholder because they all depend on freshwater. However, there are key, identifiable stakeholders that are critical to the nation’s economy and will be particularly impacted because of increasing water stress. We identify these stakeholders in the following table.

Table 4. Key Stakeholders of Reduced Water Availability Impact Agriculture

Reduced rainfall and storage will reduce the amount of land under agriculture and the amount of food produced.

Urban Areas

Potentially reduced drinking water purposes, leading to higher prices.

Power Production

2

availability

for

domestic

Reduced power generation from hydroelectric plants and regulation of thermal power plants, leading to higher electricity prices.

ote: Recent studies project sea-level rise to be on the order of one meter or more this century.

12

Climate Change Impacts on the Hydrology of the Dominican Republic

Tourism

Saltwater intrusion and prioritization of freshwater will make freshwater access in tourism clusters difficult.

Industry

Significant impacts on manufacturing and other industrial sectors, particularly textiles and mining.

Ecosystems

Lower ecosystem quality and the loss of biodiversity.

Adaptation Options The projected reductions in freshwater availability in the Dominican Republic will require the largest water users to significantly reduce water consumption. In effect, a strategy to adapt to lower freshwater availability inside the island will be necessary. Planning and acting now for these future impacts would lessen the impacts reduced freshwater availability may have and will save financial resources in the long-term. The table below shows the potential adaptation options for various sectors.

Table 5. Adaptation Options in the Dominican Republic Adaptation Options

Agriculture

Increased conservation agriculture; drip-water irrigation; droughtresistant crop varieties; water desalinization; treated sewage application; tax incentives; and collaborative water management.

Urban Areas

Increased conservation and efficiency; tax incentives; greywater recycling; water desalinization; and treatment and injection.

Power Production

Alternative renewable energy production; increased efficiency; and collaborative water management.

Tourism

Increased conservation and efficiency; tax incentives; greywater recycling; water desalinization; and treatment and injection.

Industry

Increased efficiency; tax incentives; greywater recycling; water desalinization; and collaborative water management.

Ecosystems

Increased freshwater allocation; reforestation; and increased protection. 13

Climate Change Impacts on the Hydrology of the Dominican Republic

Policy Recommendations The Dominican Republic faces a particularly challenging future in terms of freshwater availability. According to United Nations Development Programme (2007), the threshold for freshwater scarcity is approximately 1,000 cubic meters per capita per year. We project that freshwater availability will reach this level around 2050 given no adaptation measures. This projection comes at a time when the Dominican Republic’s government and the United Nations’ Secretary-General, Ban Ki-moon (as of 2008), are counting on making the Dominican Republic the Caribbean’s “breadbasket” (Campo, 2008). In order to achieve such a goal, there will need to be substantial improvements in the efficiency of the agricultural sector to ensure it can grow without reaching an unsustainable threshold that will render further growth or stability impractical. In order to address this challenge, a policy framework that is inclusive of all stakeholders is necessary. The figure below depicts an adequate policy framework in which appropriate government action could be made (Palma, 2008). Figure 3. Policy Framework for Public-Private Sector Action Concerns

Stakeholders Agriculture, Urban Populations, Power Producers, Tourism, Industry, Ecosystems

Assistance and Requirements

ational Institute of Hydraulic Resources

Legal Framework That Includes: -

State Secretariat on Environment and atural Resources

Adaptation Measures

-

State Secretariat on Agriculture

Mandate for Freshwater Assessment

-

Agency Authority to Implement Law

ational Institute on Potable Water and Sewer

This policy framework should be based on the understanding that water availability will be stressed in the future and that institutions have to work much more collaboratively than in the past. It is important to consider policy options that will 14

Climate Change Impacts on the Hydrology of the Dominican Republic address the challenge effectively and involve all stakeholders. Recently, the country’s National Institute for Hydraulic Resources has advocated for the adoption of a Water Code to replace old legislation and authorize the Institute to regulate effective and rational water management nationally (INDRHI, 2008). Given the projections of this assessment, passage of new legislation is necessary. This new legislation must consider the following policy recommendations to effectively address upcoming water shortages: •

Provide the authority to a government institution to fully regulate freshwater resources, which would include the power to implement price incentives and act as a mediator in controlling freshwater rights in conflicting situations;

•

Assess freshwater resources across the country and ensure that all necessary information is existing and readily available to the public;

•

Fully assess all available technologies and methodologies for every sector, particularly agriculture, and the access to these in domestic and foreign markets;

•

Provide fiscal incentives to large freshwater users to increase conservation and protect or restore ecosystems, such as forested mountain regions, valuable to the nation’s hydrology; and

•

Fund a national freshwater conservation campaign to raise awareness of freshwater conservation and promote public-private freshwater stewardship.

Conclusion The Dominican Republic faces a serious challenge this century. While there is enough freshwater today to fulfill the nation’s needs, freshwater availability is projected to decline by approximately 85% by the end of the century due to climate change and population growth. With a fast-growing economy, the nation will have to consider adaptation strategies that will allow livelihoods to continue to improve this century, particularly given that water demand is set to rise. Nevertheless, the country has the opportunity to begin planning now, within the broader framework of climate change adaptation, for the medium to long term to avoid having freshwater availability become a crisis that will significantly compromise the well-being of its citizens. This will require new policy to enable collaborative, sustainable freshwater management and incentivize dramatic improvements in conservation across the country. 15

Climate Change Impacts on the Hydrology of the Dominican Republic

References Bueno, Ramon et al. 2008. “The Caribbean and Climate Change: The Costs of Inaction.” Global Development and Environment Institute, Tufts University. Campo, Iban. 2008. “Queremos convertirnos en el granero del Caribe.” El País. http://www.elpais.com/articulo/internacional/Queremos/convertirnos/granero/Caribe/el pepuint/20080527elpepuint_1/Tes. Central Intelligence Agency. 2008. “Dominican Republic.” The World Factbook. https://www.cia.gov/library/publications/the-world-factbook/geos/dr.html. Dingman, S. Lawrence. 2002. “Physical Hydrology.” 2nd Edition, Prentice Hall. Food and Agriculture Organization. 2008. “Summary Fact Sheet: Dominican Republic.” AquaStat: Global Information System on Water and Agriculture. Instituto Nacional de Recursos Hidráulicos de la República Dominicana. 2003. “Recursos Hídricos y Ley de Aguas.” Estadísticas Ambientales de América Latina y el Caribe. Instituto Nacional de Recursos Hidráulicos de la República Dominicana. 2004. “Boletín Hidrogeológico.” Estadísticas Ambientales de América Latina y el Caribe. Instituto Nacional de Recursos Hidráulicos de la República Dominicana. 2004. “Resumen Hidrológico Ejecutivo.” Estadísticas Ambientales de América Latina y el Caribe. Instituto Nacional de Recursos Hidráulicos de la Republica Dominicana. 2008. “Codigo del Agua es meta del INDRHI.” Intergovernmental Panel on Climate Change. 2007. “Climate Change 2007: The Synthesis Report.” United Nations Framework Convention on Climate Change. Oficina de Información, Prensa, y Publicidad. 2008. “Mandatario destaca avances logrados en la reducción de desempleo.” Presidencia de la Republica Dominicana. http://www.presidencia.gob.do/app/article.aspx?id=9200.

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Climate Change Impacts on the Hydrology of the Dominican Republic Oficina de Información, Prensa, y Publicidad. 2008. “Gobierno hace esfuerzo por reducir la pobreza y la desigualdad social.” Presidencia de la Republica Dominicana. http://www.presidencia.gob.do/app/article.aspx?id=9577. Oficina Sectorial de Planificación y Programación. 2006. “Indicadores de Sostenibilidad del Recurso Hídrico en la República Dominicana.” Secretaria de Estado de Medio Ambiente y Recursos Naturales de la República Dominicana. Palma, Alejandro Gomez. 2008. “La Política Publica como enfoque estratégico y metodología.” Instituto de Políticas Públicas Para America Latina. Population Division. 2007. “World Population Prospects: The 2006 Revision.” Department of Economic and Social Welfare of the United Nations. Roebuck, Laura W.; Fong, Alan W.; and Harlan, Amy E. 2002. “Water Resources Assessment of the Dominican Republic.” U.S. Army Corps of Engineers. United Nations Development Program. 2007. “Human Development Report 2007/2008: Fighting Climate Change, Human Solidarity in a Divided World.” United Nations.

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Climate Change Impacts on the Hydrology of the Dominican Republic

Appendix3 Table A. Total Water Consumption by Sector, 2001 Volume (km3/yr)

Percentage of Total (%)

Irrigation

7,500

76

Domestic Uses

1,450

15

Ecosystems

500

5

Industrial

305

3

Cattle Farming

45

0.5

Tourism

40

0.5

Figure A. Mean Annual Rainfall Variation in the Dominican Republic

3

Sources: U.S. Army Corps of Engineers and the Secretariat on Environment and Natural Resources.

18

Climate Change Impacts on the Hydrology of the Dominican Republic Figure B. Groundwater Systems in the Dominican Republic.

Figure C. Land Use in the Dominican Republic. Orange, yellow, and light green are agricultural areas.

19

Climate Change Impacts on the Hydrology of the Dominican Republic

Figure D. Main Freshwater Zones in the Dominican Republic (highlighted).

Figure E. Watersheds in the Dominican Republic.

20