01 Nov Yi Lu
Senior remote sensing analyst in the NSW Department of Industry, Lands and Water Division. She was awarded a PhD degree of Remote Sensing and Photogrammetry in University of New South Wales, Australia
Competing water demands for agriculture and the environment is a challenge in semi-arid Australia. The Murray Darling Basin Plan (Basin Plan, 2012) and Water Sharing Plans (WSP) are two key pieces of legislation which assist in managing NSW’s limited water resources for long-term agriculture and environmental sustainability. For each WSP, the water extraction limit is adaptively managed based on the annual updated farm level development such as crop area, off river storage (ORS) and types of water used for irrigation. Reliable measure of irrigated crop area and ORS is essential for hydrological models to determine whether overall extraction has to be adjusted to satisfy the limitation of the plan. Regular and accurate information on irrigated areas is also critical to revise water access rules through the water planning process. Knowledge of the spatial location, extent of irrigated crops and change in water usage over time provides essential foundational knowledge to direct further scientific investigations.
The NSW Department of Industry has developed an innovative remote sensing method to determine the time series of irrigated crops and ORS utilising satellite imagery that both satisfies the needs of decision and water compliance protocols. This method employs Normalised Difference Vegetation Index, Normalised Difference Water Index, land use coverages, coincident spatial data and water license information to identify and categorise irrigated crops by water source (surface or ground) and summarise the cropping area by river reach amongst additional outputs.
Irrigated crop areas determined by this method have been found to provide comparable results with survey data in the respective water management valleys. Remote sensing approaches not only supply faster, more accurate and more efficient ways of mapping the irrigated crop areas and ORS than traditional field survey, but they demonstrate the spatial and temporal distribution of the irrigated crops, ORS and crop rotation patterns.