MICROCOMPUTER PROGRAMS FOR SUSTAINABLE PLNNING OF WATER RESOURCES DEVELOPMENT PROJECTS IN ETHIOPIA
(SPREADSHEED-BASED WRM COMPUTATIONAL MODELS)

ABSTRACT

In planning sustainable WRD projects, the framework for analysis has two components. These components are conceptual and computational framework for analysis. A simple WRM computational framework for analysis has been developed using MS-Windows95 compatible LOTUS 1-2-3 Release 5.0 spreadsheet macro programming for a hypothetical river basin (but it resembles in many ways the Incomati River Basin of Mozambique). The computational framework for analysis includes AWTIBCI, AWTIAGR, AWTIPWS, AWTIRRS, AWTIYLD, and AWTISTRAT. These models have been developed based on the algorithm developed by Koudstaal et. al (1995) to work under the classic MS-DOS based LOTUS 1-2-3 and symphony spreadsheet packages.

AWTIBCI supports a screening of alternative individual irrigation projects under the assumption that water is abundantly available. The indicators that can be used through this model are NPV, IFF, B/C ratio, N/K ratio, investments and maintenance costs, and agricultural production, employment and farmers income. Promising projects can be selected for further strategy formulation. AWTIAGR estimates monthly water demands for individual irrigation projects taking into account: (i) a specific cropping pattern and corresponding crop water use coefficients 9Kc coefficients); and (ii) specific precipitation and evaporation data. Resulting water demand data provide an input data into AWTIRRS model. AWTIPWS estimates monthly water demands for public water supply for individual urban areas for three different scenarios: average, low and high. These scenarios combine respective estimates of: (i) actual population; and (ii) population growth factors. AWTIRRS simulates water flows in monthly time steps in a river-reservoir system, matching demand and supply through the operation of reservoir. Through the application of reservoir operating rules, a reservoir release is determined as a function of the water available at the beginning of the month. Subsequently, water is allocated to the different use categories: irrigation, public water supply (PWS), hydropower and low flow requirements. AWTIYLD estimates consequences of water shortages in terms of : (i) the yield reductions for selected crops; (ii) expected financial and economic damages; and (iii) reductions in employment and farmer's income for four selected irrigated areas.

AWTISTART supports the formulation of strategies, enabling analysts to place the infrastructural components of a strategy in a proper time frame and calculating the impacts in terms of main indicators. The infrastructure components are the reservoir; four irrigation projects; a hydropower plant; the recharge facilities for the dunes; and the PWS connections.

The results of the above models will be used in preparing score cards for the various formulated strategies and decision support software like EXPERT CHOICE can be used for final decision. In fact, for each of the above programs, there are several commercial software. However, most commercial software does not exactly fit with one's specific problem. Therefore, the primary objective of this research project is to disseminate the use of spreadsheet macro programming in planning sustainable WRD projects in Ethiopia. Based on which, planners will be able to understand the physics of the analysis. However, if one uses commercial software, then one may not be able to fully understand the physics of the analysis.

Note: The final report is available at the Central Technical Library of the ESTC.

(Report July 2000)

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