Insar Coherence Over Regional Australia: Implications for Mapping Groundwater-Related Ground Deformation

In Australia, as in other regions, retrieving ground deformation due to groundwater extraction often requires InSAR processing over irrigated areas, with low and/or intermittent InSAR coherence. Hence an analysis of the temporal and spatial behavior of InSAR coherence is required so InSAR users can make informed choices while designing interferogram stacks and setting appropriate coherence threshold criterion. Here coherence time-series at different resolution and with different reference images are interpreted with a land cover map. While natural vegetation areas are mostly coherent in summer due to temporary dry conditions, irrigated areas show an inverse behavior and are mostly coherent in winter. By comparing coherence maps at different resolutions, it is shown that at high resolution, transportation corridors (tracks) between crops have higher coherence than crops. Decreasing the resolution decreases the coherence values over transportation corridors by diluting such highly coherent signal with surrounding low coherence areas.