IWRA Proceedings

AbstractTo manage or mitigate many of the hydrological issues threatening lakes, including increasing salinisation, frequent algae blooms, and the sensitivity of lakes to changes in land use and climate, information on the interaction between the surface water and groundwater systems is required. In southeastern Australia, many of the lakes are sustained by groundwater discharge or through flow. However, the interaction between groundwater and surface water in these areas is often poorly defined due to the limited hydro(geo)logical monitoring data, and the lakes are generally small and widely dispersed across large catchments. This study highlights remote sensing techniques using optical and lidar data that can be used to investigate lakes and groundwater interactions across regions where there is either limited historical hydrogeological data, or where the bore network is insufficient. Satellite remote sensing offers the ability to cover the surface of large areas with relatively fine spatial resolution. This is important to be able to (i) monitor numerous water bodies over large regions, and (ii) incorporate catchment-scale hydrological processes. Whereas hydrochemistry offers an accumulative record of dominant hydrological processes affecting lakes water with time. Where time series of physical hydro(geo)logical monitoring data is absent, both remote sensing and hydrochemistry can be used to ascertain dominant relationships between the surface water and groundwater systems. The study area is the Corangamite Catchment, located in the sub-humid region of southeast Australia. Much of the study region is a significant agricultural area and also contains wetlands with high cultural and ecological value (RAMSAR). The catchment covers an area of 1,334,000 ha, and contains over 1,500 wetlands and lakes many of which are ungauged and on private property. The optical and lidar remote sensing data were used in combination with the seasonal hydrochemistry to distinguish between lakes subject to groundwater discharge, through flow or recharge.