Water Banking-conjunctive water use management Approach to Improve River Environmental Performance

Amgad ELMAHDI, CSIRO LAND AND WATER

Abstract

Water demand is driven by cropping activities which result in higher river flows in the reaches upstream of the irrigation areas. This situation led to alter flow regime in turn alters the seasonality of flows which significantly causing important ecological impacts. The combination of regulation, operation and water polices has also resulted in a significant reduction in flow variability. Maintaining irrigation supply flows and increasing river flows for environmental requirements downstream represent a critical challenge and requires innovative solution.

One promising option to achieve these two objectives is the conjunctive use management of surface and groundwater using water banking. The aim of this study is to present and investigate the use of water banking concept to the farmers and water mangers as it is critical and important as its design and operation to improve the environmental performance of the river. Water banking has been modeled and introduced to the integrated hydrological, economic and environmental river modelling framework (NSM) for the Murrumbidgee River catchment using system dynamics approach. The model has been tested water banking under different management scenarios under different climatic conditions and two recharging methods (infiltration and injection). Results indicate two strong messages; Firstly there is clear trade-off between agricultural income, environmental performances and water use; Secondly; water banking performed as a good mechanism that is can managing irrigation demand, and in turn improve the seasonal flows and enhance in-stream flows that are biologically and ecologically significant.