Downstream Water Management Strategy in Murray–Darling Basin to Improve Adelaide’s Water Quality and Agricultural Output — Feasibility Analysis of a Dual-Purpose Coastal Reservoir

Abstract

Australia is the driest country in the world, and the lower Murray–Darling Basin and Adelaide have experienced extreme water scarcity crisis, especially during the Millennium Drought (2000–2010). Many counter measures have been proposed or implemented like desalination plants and water buyback, etc., some progress has been made, but far away from a complete solution. Different from existing measures, this research aims at using coastal reservoir technology to shift from upstream water development to downstream development, in order to solve a series of water supply and ecological environment problems by redesigning a coastal reservoir in the downstream area. It is suggested that high-quality water is stored in a “coastal reservoir” inside the Alexandrina Lake for Adelaide’s water supply. The lake water outside the “coastal reservoir” is used for agricultural development. A preliminary feasibility study was conducted in terms of water quantity and water quality, river’s environmental flow and agricultural output. The results show that if a small size (550–630[Formula: see text]GL) coastal reservoir was created inside the Lake Alexandrina in the mouth of Murray River, the Adelaide’s water supply could be secured and its water quality be improved even during droughts like the Millennium Drought. Besides, if the agricultural development is concentrated around the lake, its water demand can be fully met from the lake, rather than the river, thus the agricultural development has little negative impacts on the river’s ecosystem, it is a win-win solution for agricultural development and river ecosystem. It is suggested that Australian government should provide stimulus package for upstream farmers to relocate to areas around the lake.