|
Spatial Query Tool to estimate water use for key land use types
 M.G.S.M. Zaffar Sadiq and Katherine J Williams Sinclair Knight Merz 590, Orrong Road, Armadale, Victoria - 3144, Australia zsadiq@skm.com.au Abstract The spatial query tool (SQT), estimates the differences in water use for key land use types across the entire state of Victoria, Australia. The tool was developed in the ARCGIS 9.2, VBA environment. SQT enables the user to query results of extensive SoilFlux (developed at SKM) modelling to determine the local impact of changes in land use on water availability. The SoilFlux model represents a sub-catchment with a shallow ground water system that is connected to the stream or river network and, in some cases, an underlying deep groundwater system. SQT has two functionalities: 1) query plant water use difference mapping for a number of predefined land use changes at catchment level; and 2) report information generated on the fly for effective decision making. The major challenge was to query about 230,000 records and create information on the fly to report spatial and non-spatial results in the layout. Efficient query optimisation techniques were adopted in ArcObjects for faster information retrieval (results within 5 seconds for land use query and results within 4 seconds for query by rainfall zone). SQT has the potential to be a useful tool to support decision making for water resource management. 1.0 Introduction In the late 1990s, Zhang et al. (1999) reviewed literature on the relationship between mean annual rainfall and evapotranspiration, and found consistent differences in the relationships for forest and grassland. Since then, the recent Water and Land Use Change (WatLUC) study (SKM 2005, 2008a, 2008b) has attempted to address the challenges posed by land use and hydrologic change in south western Victoria. This considered a wider range of land uses than the work by Zhang et al., in an area that has seen large scale land use changes in the past few decades. One of the key outcomes of this project was the identification of areas where there have been or are expected to be significant impacts as a result of land use change. Through various means, the Victorian State Government is encouraging land use changes where these result in economic, environmental and/or regional development benefits for the State. Private forestry and the planting of indigenous species on agricultural land are examples of land use changes that are currently supported through the Victoria’s plantation and native vegetation strategies. While some regulations and policies are in place to control land use change, the Government acknowledges that further frameworks are required to enable decision makers to assess the likely impacts of the proposed land use change on catchment health and sustainability. In particular, the importance of understanding the impacts to water resources as a result of land use change has been acknowledged by the State Government in their White Paper, Our Water Our Future: Securing our Water Future Together, and by the Council of Australian Governments in their National Water Initiative. 2.0 Objectives The development of state wide estimates of water used for key land use types is the focus of this project. The overall objectives of this project are: Provide an estimate of water use for a range of key land use types as a function of catchment characteristics across the state of Victoria; and Link the outcomes with the Sustainable Diversion Limits study to provide a spatial interactive tool that allows users to derive an estimate of the impacts of various land use change scenarios on water availability at the catchment scale, relative to the SDLs.
Page 1 of 2 | Next | |