GWAVA is a hydrological model which incorporates additional water resource components such as reservoirs, abstractions, and water transfers that modify water quantity and flow regime. It was developed with funding from DFID (UK Department for International Development).

The model typically operates on 0.5 or 0.1 degree latitude-longitude grid. The choice of grid size is a compromise between that needed to represent spatial variability and the availability of suitable data. The model outputs include simulated monthly flows and a cell-by-cell comparison of water availability. GWAVA can be used to examine scenarios of change, both for climate and water demands. The requirement to manage water resources in an integrated and sustainable manner has become a driving force behind the use of such models in understanding how basin water resources will be affected by change. GWAVA has been applied to Eastern and Southern Africa, West Africa, the Caspian Sea basin, South America, and the Ganges-Brahmaputra basin, and is currently being applied to Europe and globally.

GWAVA map for Southern and Eastern Africa

Fig 4.6 shows a Water Availability Index (WAI) plot for the "present" climate (1961 - 1990). Cell with yellows and browns are those currently experiencing water stress

Fig 4.18 shows the same WAI for a future scenario of climate change (2050) and increased demand for water

References

J R Meigh, A A McKenzie and K J Sene. (1999) A Grid-Based Approach to Water Scarcity. Estimates for Eastern and Southern Africa. Water Resources Management 13: 85 – 115, 1999.

Sonja Folwell and Frank Farquharson. (2006).The impacts of climate change on water resources in the Okavango Basin. Climate Variability and Change – Hydrological Impacts (Proceedings of the Fifth FRIEND World Conference held at Havana, Cuba, November 2006), IAHS Publ. 308, 2006.

Chak Fai Fung, Francis Farquharson and Jahir Chowdhury. (2006). Exploring the impacts of climate change on water resources – regional impacts at a regional scale: Bangladesh. Climate Variability and Change – Hydrological Impacts (Proceedings of the Fifth FRIEND World Conference held at Havana, Cuba, November 2006), IAHS Publ. 308, 2006.