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Water from the alluvium of ephemeral rivers in Zimbabwe is increasingly being used. These alluvial aquifers are recharged annually from infiltrating floodwater. Nonetheless, the size of this water resource is not without limit and an understanding of the hydrological processes of an alluvial aquifer is required for its sustainable management. This paper presents the development of a water balance model, which estimates the water level in an alluvial aquifer recharged by surface flow and rainfall, while allowing for abstraction, evaporation and other losses. The model is coupled with a watershed model, which generates inflows from upland catchment areas and tributaries. Climate, hydrological, land cover and geomorphological data were collected as inputs to both models as well as observed flow and water levels for model calibration and validation. The sand river model was found to be good at simulating the observed water level and was most sensitive to porosity and seepage. [ABSTRACT FROM AUTHOR]

This paper compares the overall water balance of two contrasting cities. Glasgow and Beijing have different soil and climate characteristics and also different water resource policies. Glasgow uses remote rural surface water catchments while Beijing relies more on groundwater. Both cities are introducing sustainable water management policies in various forms. In the case of Glasgow the policies are more directed to flood alleviation while in Beijing one of the drivers is groundwater recharge. The overall water balance of the two cities is modelled using an integrated three-stage numerical tank model. This model represents the processes of infiltration, evaporation, runoff and storage for both paved and unpaved surfaces and indicates the overall water balance over a typical year. The results of the modelling highlight the importance of evaporation in the overall urban water balance and the potential for using stormwater runoff to reduce water demand or to recharge groundwater. [ABSTRACT FROM AUTHOR]