Prioritising landscape investment using a process-based catchment model

This paper reports on the application and enhancement of a catchment-wide biophysical modelling framework to support an evidence-based approach for the procurement of environmental goods. A biophysical modelling framework known as the Catchment Analysis Tool (CAT) is been used in this exercise to estimate on-site impacts of land management changes with off-site environmental outcomes. The framework comprises a suite of one-dimensional farming systems models capable of simulating a range of farming enterprises with modifications to account for lateral flow and groundwater recharge and is integrated into a fully distributed 3D-groundwater model. This paper reports on the application to the Upper Wimmera catchment (310 326 ha) in western Victoria, Australia. The model is used to assess likely environmental outcomes due to farm scale revegetation. Additional information derived included the mapping of aquifer response times to land use/management change. This information is then used to prioritise catchment investment. The objectives of this paper are to; (i) Describe the construct of the modelling framework, (ii) Detail the modifications to the 3D-groundwater model to account for landuse, evapotranspiration and surface water/groundwater interactions, and (iii) Present the application results. The paper concludes that spatially explicit, physically-based models can provide robust information to support evidence-based approaches to the procurement of environmental outcomes.