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

2

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.


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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


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Introduction

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

Dominican Republic


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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).


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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, mid-

latitudes 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:


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• 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


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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 man-

made or natural systems.

Consumption 10 Freshwater that is consumed for human and

environmental purposes.

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


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details and to allow analysis of the water balance with higher resolution. The time-

averaged 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

P ET Q Gout C D

Volume

(km3/yr) 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


10

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.


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Table 3. Water Availability Projection for 2100

Precipitation Evapotranspiration Runoff

Per Capita

Availability

Volume (km3/yr) 55 50 5 3601

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.

0

1,000

2,000

3,000

4,000

5,000

6,000

km

³/ca

pit

a-y

r

Year

Figure 2. Water Availability Projection With Climate

Change Scenario

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.

4,700

Water Scarcity Threshold 360


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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 availability for domestic

purposes, leading to higher prices.

Power

Production

Reduced power generation from hydroelectric plants and regulation

of thermal power plants, leading to higher electricity prices.

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


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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; drought-

resistant 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.


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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

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

Stakeholders

Agriculture, Urban

Populations, Power Producers,

Tourism, Industry,

Ecosystems

�ational Institute of

Hydraulic Resources

State Secretariat on

Agriculture

�ational Institute on

Potable Water and Sewer

State Secretariat on

Environment and �atural

Resources

Concerns

Assistance and

Requirements

Legal Framework

That Includes:

- Adaptation

Measures

- Mandate for

Freshwater

Assessment

- Agency

Authority to

Implement Law


15

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.


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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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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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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.


19

Figure B. Groundwater Systems in the Dominican Republic.

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

areas.


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

Figure E. Watersheds in the Dominican Republic.

climate change impacts on the hydrology of the dominican republic

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