Soil erosion, surface runoff, watershed analysis studies have largely been neglected in the past. Only studies connected to specific developments, mainly mining and hydropower, have been carried out. Some of these studies show very high intensities of erosion, indicating that certain areas of Papua New Guinea are among the most geomorphologically dynamic areas on the earth. The advance application of Remote Sensing (RS) and Geographic Information System (GIS) techniques helps to estimate watershed characteristics, surface runoff and soil loss based on different parameters. Advanced Space-borne Thermal Emission and Reflection Radiometer (ASTER) Global DEM data and Landsat satellite image are used for morphometric analysis of the Busu watershed (1311.32 sq km). Different mandatory inputs parameters to the model, namely the land use/land cover, hydrological soil characteristics, rainfall data, Potential Maximum Retention, Weighted Curve Number for SCS model; and rainfall and runoff , soil erodibility, slope length and steepness, crop management and conservation practice factor for RUSLE, have been derived either from remote sensing data or from conventional data collection systems. Finally transport capacity of Busu watershed is derived using estimated storm runoff, cover and slope factor. ArcGIS v10.1 software is used to store, manipulate, analysis, and modeling of soil loss, runoff calculation and watershed analysis. The average drainage density of this watershed is computed as 0.6 km/sq km with the average slope measuring about 51.72%, maximum relative relief of 496 m and a maximum ruggedness index of 0.29. The result also estimates an average of 80 % of total rainfall flowing out as surface runoff. The average soil loss of Busu watershed is calculated as 0.79 tons/hectare/year. Model predict a transport of 162 tons in 3-days storm rainfall of 229 mm with an average slope of 51.72 % of the study area. Pixel-by-pixel spatial mapping for the entire watershed is carried out using these results. The study underscores that the integrated approach of SCS, RSLUE and transport capacity model with RS and GIS technologies have great potential for modeling of different hydrological parameters and producing risk maps in any watershed of Papua New Guinea after gathering geospatial data....
Authors: Sailesh Samanta.