its estuary and mouth. Areas of other smaller catchments are represented in the south-east of the map; the Towns River and the Limmen Bight River. Little surface water information is available on these smaller catchments, which by the end of the dry season contain little if any flowing water. Within the map area, only the upper reaches of the Roper River are perennial whilst most of the adjoining tributaries cease to flow in most years. These tributaries include Maiwok Creek, Hodgson River, Flying Fox Creek, Jalboi River and Wilton River (Figure 7.4). Of these, the Flying Fox Creek and the Wilton River can continue to flow throughout the year in wet eras. Flow data for the site on the Wilton River G9030146 and Hodgson River G9030102 is presented in Appendix K. Perennial tributaries in the region, Tollgate Creek and Phelps River have limited flow measurements (Appendix K). These two rivers are perennial in their upper reaches buttheir flow does not always reach the Roper River. 7.3 Availability of river water 7.3.1 Mapping minimum baseflows To gain a perspective on water availability from a river, it is necessary to examine the variability in annual minimum flow at sites along a river over the years. This work has only been undertaken for the Roper River, in section 7.3.3, because of its perennial reaches and good data availability. Most of the adjoining tributaries within the mapped region cease to flow in most years. To provide an overview of water availability all rivers on the Water Resources map have been plotted according to their minimum flow, thereby reflecting the environment at its driest. It is intended to raise awareness of how supplies from these rivers can be limited. In cases where there was little recorded data, site visits, flow gaugings and local knowledge were used to determine minimum flows. Local knowledge proved vital to this task as this project was conducted during a period of above average rainfall and higher than minimum flows were observed in most rivers. The minimum flow categories of some rivers have been estimated from anecdotal evidence or scientific interpretation, as not all sites could be visited during the project duration. There are four categories of minimum flow shown on the water resource map: River with a minimum flow of 100 L/s at the end of the Dry season Only the upper Roper River is listed under this category. The river section shown on the Water Resource map is dominated by braiding. Plate 7.1 Roper River adjacent to Moroak Station. Rodney Metcalfe measuring the flow at site G9030123. 56.