Evaluation of Water Scarcity in Africa

Todd J. Schram

CE 394K.2Surface Water HydrologyTerm ProjectSpring 1999Dr. David Maidment Nile River, Cairo

Overview

Concepts of Water ScarcityData SourcesWater ResourcesPopulation ProjectionsEvaluation of ScarcityAssessment of Climate ChangeFuture Work

Water Scarcity Concepts

Water Stress Index ‘approximate min. level of water required per capita to

maintain adequate quality of life in a moderately developed country in an arid zone’

developed by Swedish hydrologist M. Falkenmark

Annual Renewable

Freshwater per

Capita (m3) Eff ects on Country

>1,700 Limited Stress/ Localized Problems

1,000 - 1,700 Water Stressed

<1,000 Water Scarce

<500 Absolute Scarcity

Benchmarks Used by UN and

World Bank as tool to evaluate water supply abundance of country

Consequences of Water Scarcity

Why should we be concerned? Deterioration of water quality Costs of producing/delivering water increases

rapidly Constrains economic development

Statistics for Developing Countries 80% of diseases caused by contaminated water 1/3 of all deaths attributed to water-related

diseases

Changes in Water Scarcity

Water Demand Population growth Industrialization Water conservation initiatives

Water Supply Climate variability Climate change

Sources of Data

UNEP-GRID Population Data

World Resource Institute Water Resources Data

ESRI Political Boundaries

ERBE Net Radiation

Geography Dept. (University of Delaware) Precipitation & Temperature

Data Characterization

Population Count Raster Dataset Resolution: 1o cells Tabular data converted to grid of 5,986 cells

Freshwater Resources 1) Spatially distributed value based on

country 2) Annual runoff from gridded precipitation

and evaporation data

Annual Renewable Freshwater Resources

Total Volume (cubic kilometers)

Note: Based on water resources of the country.

Development of Population Count Grid

Arc/Info

Generate Fishnet

Build Polygons

ArcView

Table/Join Data with Attributes

Create Feature Data Theme

Project Theme to Lambert Azimuthal Equal Area

Convert to Grid

Population Count Grids

Year 2000 Year 2025 Year 2050

Population Count per Cell

Note: Cell size is 1o x 1o.

Evaluations of Scarcity Conditions

Immediate Factor Effect of population growth on scarcity Analyzed using Water Stress Index

benchmarksLong Term Factor

Effect of climate change on scarcity Methodology presented

Extent of Water Scarcity

Year 2000 Year 2025 Year 2050

Water Scarcity Designations

Annual Hydrologic Data

Temperature (oC)Precipitation (mm) Net Radiation (W/m2)

Assessment of Climate Change

National Level USGS Global Change Hydrology Program

Hydroclimatology

International Level US Country Studies Program

Assessment of Water Resources Vulnerability and Adaptation to Climate Change

• Recommends annual stochastic approach for areas with insufficient data

• Q = P - E– Q - Runoff P - Precipitation E - Evaporation

• Use of GCM or Incremental scenarios

Evaporation Calculation

Priestly-Taylor Evaporation Equation Applicable to continental

scale Parameters

Potential evaporationNet RadiationTemperatureSaturated vapor pressureLatent heat of vaporization

es = 611 * exp[17.27 * T/ (237.3+T)]

lv = 2.5E+06 - 2370 * T

E = 1.3 * D/ (D+g) * Er

Er = Rn/ (rw* lv)

D = 4098 * es/ (237.3+T)2

g = Cp * p/ (0.622 * lv) * (Kh/ Kw)

Conclusions

Water scarcity maps due to population growth Evaluate future water shortages of

countries within next 60 yearsEffects of future climate changes

Not easily determined Can determine temperature change

effects

Available Reports World Resource Institute (WRI)

World Resources 1998-1999

World Bank World Development 1999

World Water Organization The World’s Water: The Biennial Report on Freshwater Resources, 1998-1999

Population Action International Sustaining Water: Population and the Future of Renewable Water Supplies

UN - Commission on Sustainable Development Comprehensive Assessment of the Freshwater Resources of the World

U.S. Country Studies Program Assessment of Water Resources Vulnerability and Adaptation to Climate Change

UN Food and Agriculture Organization (FAO) Water and Social Resource Scarcity AQUASTAT

Future Work

Utilize annual hydrologic data to: conduct spatial evaluation to determine

local regions of water scarcity determine impact of climatic

temperature change on water scarcity

Questions?

Lake Victoria, Uganda