A Semi-Detailed Technique for Soil Erosion Mapping Based on BLM and Satellite Image Applications

Abstract

An ever increasing population needs more energy and food to be provided from limited resources. Many different problems such as floods and droughts frequently occur and even happen at extreme values throughout the world, since the inherent capability of the resources is not evaluated properly. Soil erosion, as one of the major types of land degra- dation, is supposed to cause serious problems for future and even present generations. However, evaluation of the magnitude and sp atial distribution of fundamental types of soil erosion i.e. sheet, rill and gully erosion is an important task to be conducted in devel- oping countries where the necessary bases for development are required. An attempt has been made in the present paper to introduce a technique through which the condition of soil erosion is defined and mapped in the study area. All available and acceptably accu- rate information, such as the geologic sensitiv ity of the area to erosion, the land type and slope maps, are required for determination of homogeneous work units using overlying. The present character of soil er osion in the field is then eval uated by filling out the revised questionnaire forms adjusted on the basis of criteria mentioned by United States Bureau of Land Management (USBLM) and the final classi fication of each type of erosion is made according to the sum of scores obtained by each work unit. Finally, the overall situation is generalized in the fractional form. The presented technique has been implemented for more than 6 million hectares of the area of Iran and was able to reflect the governing conditions well and the results should be applied in the management of natural resources to achieve sustainable utilization. For the p resent study and for demonstrating the details of methodology, a small watershed located in the Markazi large watershed of Iran, known as Barahmoom, and comprising 4236.2 ha was sele cted as a case study. The presented soil erosion mapping technique can be applied for areas where only basic or very little data and information is available.