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Evaluation of Water
Scarcity in Africa
Todd J. Schram
CE 394K.2
Surface Water Hydrology
Term Project
Spring 1999
Dr. David Maidment
Nile River, Cairo
Overview
Concepts of Water Scarcity
Data Sources
Water Resources
Population Projections
Evaluation of Scarcity
Assessment of Climate Change
Future 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
 Benchmarks
Used by UN and
World Bank as tool to
evaluate water supply
abundance of country
Annual Renewable
Freshwater per
Capita (m3)
Effects on Country
>1,700
Limited Stress/Localized Problems
1,000 - 1,700
Water Stressed
<1,000
Water Scarce
<500
Absolute Scarcity
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
ArcView
Generate Fishnet
Table/Join Data with Attributes
Build Polygons
Create Feature Data Theme
Project Theme to Lambert
Azimuthal Equal Area
Convert to Grid
Population Count Grids
Year 2000
Population Count per Cell
Note: Cell size is 1o x 1o.
Year 2025
Year 2050
Evaluations of Scarcity Conditions
Immediate Factor
Effect of population growth on scarcity
Analyzed using Water Stress Index
benchmarks
Long Term Factor
Effect of climate change on scarcity
Methodology presented
Extent of Water Scarcity
Year 2000
Water Scarcity Designations
Year 2025
Year 2050
Annual Hydrologic Data
Precipitation (mm)
Temperature (oC)
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 evaporation
Net Radiation
Temperature
Saturated vapor pressure
Latent heat of vaporization
E = 1.3 * D/(D+g) * Er
D = 4098 * es/(237.3+T)2
g = Cp * p/(0.622 * lv) * (Kh/Kw)
Er = Rn/(r w* lv)
es = 611 * exp[17.27 * T/(237.3+T)]
lv = 2.5E+06 - 2370 * T
Conclusions
Water scarcity maps due to population
growth
Evaluate future water shortages of
countries within next 60 years
Effects 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