Challenges for Sustainable Water Resources Management in Botswana

Like many semi-arid areas of Africa, Botswana continues to experience inadequate water supply particularly in the southern part of the country. In the last ten years, water restrictions have become part of water demand strategy aimed at maintaining sustainable water supply throughout the year. This has affected many economic sectors particularly small scale enterprises which directly rely on water for their business operations such as car wash and landscaping businesses. The issue of inadequate water availability and supply is more pronounced in Gaborone, the capital city of Botswana which relies on Gaborone dam as the main source of water to drive the economy. The dam was last filled to capacity in 2006 and has not spilled since then. While there are several factors affecting the inflows to the dams, rainfall is the principal candidate limiting water availability in the area. Past studies have shown a decline in rainfall and an increase in temperature since 1982. However, there are uncertainties associated with rainfall data, mainly regarding the presence of missing values which affect many hydrological modelling tools. In this chapter, we focus specifically on the effects of missing rainfall data and data infilling strategies on hydrological applications using rainfall and hydrological modelling tools. We also demonstrate the implications of these on spatial rainfall interpolation methods based on Geographic Information Systems (GIS). Our discussion focuses on the value of data as a priority developmental issue which should receive utmost attention particularly in the wake of climate change.