Management of stressed groundwater basins for improved environmental sustainability
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NO FULL TEXT AVAILABLE. Access is restricted indefinitely. ----- Sustainable management of groundwater resources is of vital importance in relation to food security, health and the growing demands being placed on already stressed groundwater systems by the world's Mega cities. The development and calibration of the Lower Murray groundwater model was undertaken to estimate sustainable yield. The sustainable yield estimated from the water balance for the Shepparton aquifer is 61 GL/yr and for the Calivil/Remark is 82 GL/yr. These estimates together with the evaluation of sustained groundwater pumping scenarios were used to provide guidance for Resource Managers on improving the management of the groundwater resource. The development and application of simulation and optimisation techniques for management of shallow groundwater in the Wakool Irrigation District in the Murray Region of New South Wales is demonstrated, in particular the embedding approach. Management of high watertables in irrigated regions is one of the key factors in ensuring the sustainability of agricultural production and for minimising the adverse impacts of salinisation of our land and water resources. The development of PUMPMAN, a novel and elegant approach for managing shallow watertables is used to determine optimal pumping rates for maintaining piezometric levels at or below a critical depth below the soil surface. Optimisation of the scheme was shown to reduce the potential of water-logging and salinisation in the Wakool Irrigation District, reduce electricity costs for the pumping scheme, and reduce the volume of saline groundwater for disposal. The development of PUMPSITE builds on the optimisation approach to develop a methodology for siting pumps. PUMPSITE is applied to the Wakool Irrigation District to enhance the effectiveness of the scheme by determining where additional pumps need to be located to control rising watertables. Optimum pumping locations would allow better control of the shallow watertable and reduce the cost of operating the scheme by eliminating sites where pumps are not required with the added benefit of reducing the likelihood of excess volumes of saline groundwater for disposal. Both PUMPMAN and PUMPSITE are generic optimisation tools that can be applied to irrigation districts in Australia and also in many of the world's irrigated regions which are affected by high watertables and where tubewells need to be located to control shallow watertables such as in Pakistan, India, China and Egypt. A completely new concept is introduced for managing aquifers using Sustainability Bands which is based on the famous Bollinger Bands a widely used tool in the financial markets, and one that is well known by many traders and stock brokers. Also discussed is the emerging use of indexes and indicators to manage water resources, and the development of the Relative Stress Indicator (RSI) and the Aquifer Stress Index (ASI) to characterise the level of stress in an aquifer. The ASI allows the spatial distribution of stress at various locations in an aquifer to be evaluated during discreet planning periods.
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