An assessment of surface and groundwater withdrawals/harvests over Uganda

The demand for freshwater continues to grow globally, as population increases and water insecurity due to irregular rainfall distribution patterns rise. Water harvesting in its broadest sense can be defined as the process of collecting and concentrating precipitation through available runoff and storage for its productive use and now is being employed all over the world. Runoff may be harvested from roofs and ground surfaces as well as from alternating watercourses. Central to this is the desire by governments to achieve the sustainable development goals (specifically SDG6) by the stipulated time 2030, which in Uganda has partly contributed to the growth of the water supply/abstraction points network (the network stood at 40,233 boreholes, 21,567 shallow wells, 28,908 protected springs and 20,187 rainwater harvesting tanks in 2018). This has increased water use from both surface and groundwater over the country by 112% between 2002 (300 million cubic meters) and 2005 (637 million cubic meters) as reported in literature. However, knowledge about water use by individual source and the spatial temporal variations in water abstraction/harvesting across the country is still lacking, yet it is necessary to guide sustainable management of the resources. Such knowledge would be also useful for modelling efforts aimed at understanding the hydrologic impact of increased water withdrawals across the country. Therefore, this study is to present the first estimates of the amount of water abstracted/harvested across Uganda. Data on the different types of water supply technologies (rainwater harvesting, surface water and groundwater collection points), their year of commissioning and the number of users supplied, were sourced from the Ministry of Water and Environment, Uganda. Our analysis involves a simple method in which for each supply point (in case of groundwater collection points), the number of users is multiplied by the WHO recommended daily water demand per person (20 liters per day) to estimate the amount of water abstracted daily. Preliminary results show that the amount of groundwater withdrawn from each supply source in the country ranges between 300 - 4000 liters/day.