Water Demand Simulation Using WEAP 21: A Case Study of the Mara River Basin, Kenya

Osoro George Marcellus Metobwa

doi:10.11648/j.ijnrem.20180301.12

Osoro George Marcellus Metobwa

Open Access

https://doi.org/10.11648/j.ijnrem.20180301.12

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Abstract

The competing water uses within the Mara River Basin MRB has increased water demand, which has affected the Mara river. In this paper, water resources and demands were modelled using Water Evaluation and Planning system (WEAP), by which different methods and strategies were assessed to mitigate the overuse practices from the Mara river. For this, water uses and resources in the basin were quantified and mapped in regard to their current and future statuses taking 2010 as a reference year for the simulation’ scenarios up to 2045. The Parameter Estimation Tool (PEST) was used to calibrate the model. The results showed that the total water demand within the basin under the reference scenario was 4.91 BCM, the demand dropped to 4.1 BCM under the ¨Demand Management Strategy DMS scenario and to 3.5 BCM under the Enhanced Policy Implementation and DMS scenario. The results also showed that the proposed DMS could increase water sustainability by reducing water demands at the basin.

Highlights

The main goal of this paper is to assess and simulate water demands in the MRB to provide an in-depth knowledge on water demand, which will be the key for the implementation of water allocation policies by Water Resources Management Authority in Kenya (WRMA) and other governmental policies
According to the reference scenario, water demand projections at all nodes show a remarkable increase in the abstraction levels in all the abstraction points
The total demand on the Mara river is projected to rise from 0.03 BCM in the year 2013 to 2.65 BCM in the year 2045 (Figure 2)

Summary

Introduction

Kenya has five main water basins; the rift valley, Tana, the Lake Victoria, Athi, and the Ewaso Ngyiro basin (Figure 1). Mara River Basin MRB, within the Lake Victoria basin, runs through 13,750 km area of South Western Kenya and NorthWestern Tanzania before entering Lake Victoria at the Musoma bay. Water resources in the Lake Victoria South catchment area that includes MRB has recently decreased due to population growth and the increase of socioeconomic activities [1]. The basin experiences a bimodal rainfall pattern of wet and short rains. The mean annual precipitation ranges from 500 mm in the south to around 1750 mm at the northern and the western parts of the basin. The socioeconomic activities have converted some forest lands to agricultural and urban uses [3]

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