Groundwater recharge from rainfall and irrigation in the campaspe river basin

Abstract

Reliable estimates of groundwater recharge are required for effective evaluation of management options for salinity control and high water-tables in the Riverine Plain of south-eastern Australia. This paper provides a brief description of the integrated surface and groundwater modelling approach used to estimate regional recharge rates and presents the recharge rates estimated for the Campaspe River Basin. The integrated model is a powerful management tool as it can predict the relationship between rainfall, irrigation, recharge and rises in the water-table levels. The model predicted that approximately 15% of irrigation water recharges the shallow aquifer. Approximately 6% of rainfall contributes to recharge in the irrigated areas while 4 to 5% of rainfall becomes recharge in the dryland areas. Rainfall makes a greater contribution in the irrigation areas compared to the dryland areas because irrigation predisposes the soil to recharge from rainfall. The water-table levels in the irrigation areas are currently rising at approximately 0.14 m yr-1. This rate of rise will increase faster than the increase in irrigation applications.