Statistical Justification of Hillside Farm Dam Distribution in Eastern Australia

Understanding farm dams, including their distribution and reasoning, is important in Australia. While most researches have aimed at the impact of farm dams, quantifying their spatial distribution is highly desired from management perspective. However, it is a difficult task due to the large uncertainty in farm dam construction and its variation in size and usage. In this paper statistical relationships were established to estimate the number of farm dams and volumes from climate factors and geophysical characteristics. As the large farm dams are easy to be mapped and difficult to be modelled by statistics, the current research is concentrated on the small and medium farm dams. The following results are found: (1) The area with more precipitation tends to have more farm dams; (2) Winter precipitation tends to result in more farm dams; (3) the volumes of farm dams are small in flat areas and tend to increase as the slope increases till around 3° and then decrease; (4) higher fraction of absorbed Photosynthetically Active Radiation (fPAR), which is used to represent vegetation cover, tends to result in more farm dams with a linear relationship with recurrent fPAR and nonlinear relationship with persistent fPAR. Our models can also be used to predict the volumes of small and medium farm dams by these climate factors and catchment characteristics for mapping purposes.