Can the GRACE satellite mission help in the Murray-Darling Basin?

Achieving a successful long-term strategy for sustainable water resource management of the Murray-Darling Basin (MDB) involves improving our understanding of the integrated hydrological system and assessing the impacts of land use and climate change upon this system. A methodology is currently being developed with the potential for addressing these issues by way of a new satellite technology system called GRACE (Gravity Recovery and Climate Experiment). The principle behind GRACE is that hydrological processes occurring throughout the earth’s surface lead to temporal changes in the distribution of mass, which subsequently cause subtle changes in the earth’s gravity field. By observing changes in the earth’s gravity field at unprecedented accuracy over the next several years, this mission has the potential to provide precise measurements of changes in terrestrial water storage over large regions at monthly to annual time scales. Thus GRACE promises to provide the first-ever observations of total water storage changes across the entire MDB; measurements by which we can assess the monthly, seasonal, and inter-annual trend in water storage and the effectiveness of recent revegetation efforts for reducing ground water recharge and the subsequent impacts of salinity. Moreover, GRACE will provide novel insight on the uncertainty of model-based prediction of hydrological processes at the catchment-to-basin scale. In this paper we present a methodology for assessing the overall utility of GRACE in the MDB which involves hydrological modelling, data assimilation, and ground-based monitoring within the Murrumbidgee catchment. Initial results from the monitoring network indicate that GRACE will likely provide a statistically significant measure of water storage change across the MDB. Results from a conceptual-based hydrological model of the Murrumbidgee catchment illustrate the potential for GRACE to improve model prediction by way of a data assimilation framework. Can the GRACE satellite mission help in the Murray-Darling Basin? Ellett