Civil-GIS incorporated approach for water resource management in a developed catchment for urban-geomorphic sustainability: Tallowa Dam, southeastern Australia
Damming rivers causes two main problems affecting a river's geomorphic ecosystem and its water quality. The Tallowa Dam on the Shoalhaven River in southeastern NSW, Australia, provides a case study to find the best sustainable solutions to avoid these problems. The project uses a civil-infrastructure idea to design a grid of collector pipes from the reservoir bottom surface. Spatial data analysis using ArcGIS 10.2 is used to determine the best grid location for the pipes in the reservoir. Water and sediment samples have been analysed for grain size, heavy metal and organic matter contents. The dam has led to a significant decline in sediment transport and water discharge to the lower reaches of the river which has resulted in greater erosion of sediment and higher salinity rates within the lower river and coastal streams. Water quality in the reservoir has been affected by increased sediment accumulation, particularly mud, which has increased the amount of heavy metal and nutrient pollution that could eventually affect the water users. A proposed solution is to use over-storage water to remove accumulated sediment from the base of the dam through a net of collector pipes controlled by auto-mechanical gates, instead of flowing over the top of the dam. This would maximize the volume of upstream sediment and contained pollutants that can be released from the reservoir into the downstream river ecosystems as well as providing better water quality and a longer water storage time.