A Water Use Permit Analysis Tool assists Tanzania’s Ministry of Water with science-based water allocation decisions

Abstract

The Ministry of Water (MoW) in the United Republic of Tanzania runs an Operational Decision Support System (ODSS) developed with DHI that provides enhanced hydro-meteorological services through a framework comprising an information system with hydro-met-linkage, prediction tools for flood forecasting early warning, tools for reservoir operations, and the Water Use Permit Analysis Tool (WUPA) for water allocation. Risk of water shortages may vary according to monthly variation in water availability and permits. New permits may influence the area in which a permit is given and other areas in the basin (e.g., downstream abstractions in a river). The WUPA is an innovative tool that applies water accounting and allocation models and data analytics to address this complexity. WUPA represents all relevant water use permits in a basin, keeps track of water availability based on statistics of water flows or water storages in the basin, and allows for scenario analysis. Embedded in the ODSS, the WUPA’s web-based user interface is used by MoW officers to analyse and visualize the effects of changing water use allocations on water availability for defined hydrological scenarios (normal, dry or drought conditions) in the Pangani and Rufiji river basins. MoW officers are able to test the effects of selected water use applications and find the vulnerabilities of water use permits due to variations (e.g. extreme low flows). Hence, officers can assess the following situations: a water use application against existing water use permits, a variation of an existing permit against existing permits, and testing water availability constraints under water shortage conditions. Existing water use permits as well as new applications are added to a water accounting and allocation model based on their location in the basin and water demand. Priority between concurrent users is considered and follows the agreed priorities for water allocation in Tanzania. Surface and groundwater resources are considered. Dashboards show tabular and mapping outputs with elements such as, amongst several others: abstraction source, villages around the source, catchments and sub catchments, water availability at the source, water demand and supply, and deficit if any and at which location. Ultimately, the WUPA is a “plug-in” tool that facilitates the work of the MoW officers, who conduct assessments and inspections based on the WUPA results and recommend decisions on water use permit applications.