History of land-use reconstructed for hydrologic modelling of the Tarcutta Creek catchment Aleksandra Rančić a,b,c, David Readc,d, Brendan Christyc,e,f, Terry McLeanc,e, Iain Humec,g aOffice of Environment and Heritage, Wagga Wagga, NSW 2650 bSchool of Civil and Environmental Engineering, University of New South Wales cFuture Farm Industries CRC, University of Western Australia, WA 6009 dPO Box 105, Lockhart NSW 2656 eLandscape and Water Sciences Future Farming Systems Research Division, Department of Environment and Primary Industries, Rutherglen, Vic 3685 f e-Water CRC, University of Canberra, ACT 2601 gWater in Primary Industries, Division of Science and Research, NSW Department of Primary Industries Australia
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Paper: Abstract: This paper describes the history of dynamic changes in land-use in the Tarcutta Creek catchment in New South Wales. The reconstruction of land-use since 1950 was undertaken for the entire catchment of 170,000 ha, on a decadal basis to enable the exploration of land-use change on stream flow. Reconstruction was based on aerial photography, satellite imagery and sequence of spatial layers that provided information on advancement of pine plantation. Based on this reconstruction, and the intensive literature review it was evident that most of the catchment was cleared during the nineteenth century, while twentieth century saw the extensive development of the tree plantation industries, especially Pinus species. Clearing extent reached the maximum of 67% of the catchment in the 1970s. After that, Pine conquest reversed the trend, reducing cleared area to 58%. The effect of pine plantations on the catchment stream flow marginally changed it towards its original state, prior to European settlement. However, land clearing for agriculture caused native forest habitat fragmentation with an overall reduction from 33% of the catchment to 22%, decreasing it by one third since 1950. The current study represents the largest areal landuse reconstruction in Australia at 1ha resolution. Introduction: A modelling study (Rančić et al., 2014) was done using CATplus software (Christy et al., 2011) to test the influence of increasing perennial vegetation on water cycle and provide advice for management of water resources of the Tarcutta Catchment (Figure 1). It considered changes in perennial vegetation: plantation forestry (mainly Pinus radiata) and pasture renovation. Changes in land-use needed to be incorporated into the calibration process, on the spatial-temporal scale adequate for hydrologic modelling. Methods: Table 1 summarises the imagery used in the study. The catchment was photographed from the air and satellites on approximately decadal bases: in 1959/61, 1969/72, 1980, 1989, 2000, 2004 and 2010. Where mosaics were available we used them instead of individual photographs. The imagery was imported into the GIS, rectified and overlayed with the 1ha grid cells corresponding to raster elements of the CATplus model. We used Australian Collaborative Land-use Mapping Programme guidelines map to distinguish between: (1) vineyards/orchards, (2) irrigated pasture, (3) water bodies, (4) paved surfaces (urban/roads) and (5) various land-uses lumped together as “other”. These five categories we kept unchanged over time. The reminder of the cells we identified based on the imagery as (A) Pines, (B) native trees, for tree cover >50%, C) Cleared land, for tree cover
