Assessment of soil erosion hazard of Victoria catchment area using GIS as a tool

Abstract

21for updated data and information relates to environment and to review the available information of land resource. The methodology used to collect data and information consisted of reference to the literature through recent publications, annual reports, periodicals and internet, visits to relevant institutions and personal communication with experts and officials. The results revealed that some of the authorities are able to maintaining their information regularly where as few are unable to maintain due to lack of their resources and man power. Few of them can be summarized as follows. Latest Soil Classification according to international methods and development of a soil data base and soil map for wet and intermediate zones has published in 2005 by the Soil Science Society of Sri Lanka.The existing map of24 agro ecological sub regions (1975) were updated into 46 sub regions in 2003. Preparations of hazardous maps for major areas in ten districts which are prone to landslide have been carried out by NBRO and few districts were already completed. At present the Department of Survey isplanning to publish the latest version of the National Atlas with up dated data and information and it includes distribution of almost all the natural resources and present land uses, further as a new chapter the tsunami information is also included. The Clean Air initiative, which releases regular ambient air quality monitoring reports, sets an important example in dissemination of public environmental information.Furthermore, the extent of coral reef in coastal area except North and East has been carried out by the NARA after the tsunami disaster. Survey of mineral resources of the country is been carried out by the Dept.of. Geological Survey and Mine Bureau as an ongoing project. Study emphasized the need for integration of the fragmented and sectoral information of the individual institutes and the need for timely reliable and systematic data base on environmental information that could aid in better decision making and management processes. 034Assessment of soil erosion hazard of Victoria catchment area using GIS as a tool Soil erosion occurs due to natural causes such as rain fall, rainfall runoff and wind, and due to human activities. Universal Soil Loss Equation (A = RKLSCP) introduced by Wischmeier and Smith in 1965 is a most widely used method for estimating soil erosion. This encounters detachment of soil particles and its transport by raindrops and surface runoff, which depends on the rainfall erosivity (R), erodibility of soil (K), slope length factor (LS), cover and management factor (C) and the support practice factor of the equation.The data on erosivity points were interpolated with SO rn resolution grid cells. The erodibility value relevant to each soil group was entered into the attribute table, which was converted into grid cells with 50 III resolution, containing soil erodibility values. The Triangulated Irregular Network (TIN) was created by contour interpolating with 20 m interval, and grid cell was 50 m. Usi...