Incorporating geological effects in modeling of revegetation strategies for salt-affected landscapes

This paper synthesizes results of research into the impact that major faults have on dryland salinity and the development of revegetation treatments in the wheatbelt of Western Australia. Currently, landscape planning does not routinely incorporate geology, but this research shows that faults can have a dramatic impact on land and stream salinization and on the effectiveness of revegetation treatments, and evidence exists that other geological features can have a similar influence. This research shows that faults can be identified from airborne magnetic data, they can be assigned a characteristic hydraulic conductivity based on simple borehole tests, and four other geological features that are expected to affect land and stream salinity could be identified in airborne geophysical data. A geological theme map could then be created to which characteristic hydraulic conductivities could be assigned for use in computer groundwater models to improve prediction of the effectiveness of revegetation treatments and thus enhance the landscape planning process. The work highlights the difficulties of using standard sampling and statistical techniques to investigate regional phenomena and presents an integrated approach combining small-scale sampling with broad-scale observations to provide input into a modeling exercise. It is suggested that such approaches are vital if landscape- and regional-scale processes are to be understood and managed. The way in which the problem is perceived (holistically or piecemeal) affects the way treatments are designed and their effectiveness: past approaches have failed to integrate the various scales and processes involved. Effective solutions require an integrated holistic response.