STUDY ON SOIL EROSION IN THE UPPER MUREŞ BASIN Zs. Magyari-Sáska 1 , I. Haidu 1 ABSTRACT The soil erosion process produces harmful effect in a relative short time and the repairing time is much longer. One of the most frequent used method in soil erosion evaluation is USLE. In our study we developed a methodology to calculate and estimate soil loss in the Upper Mureş Basin. Part of this methodology was implemented as a software based on IDRISI Andes Edition, R System and Borland Delphi. Based on this software several studies were made. As a result we could appreciate that the North part and the eastern downhill of the Giurgeu basin are the most vulnerable areas, and the surroundings of several establishments in the Mureş Defile (Stânceni, Lunca Bradului). We also found that orchards are more exposed to soil loss, and after than the mixed agricultural zone, with a much higher standard deviation for the last category. Keywords: soil erosion, application, RUSLE, Mures Basin * 1. INTRODUCTION Soil is an important resource especially for nutrition and woodland husbandry but also for maintaining biological and ecological equilibrium. The soil erosion process produces harmful effect in a relative short time and the repairing time is much longer. Thus it’s important to identify the vulnerable areas and take protective measures. Different meteorological phenomena (wind, rain, freeze-melting processes) have their importance in soil erosion. In this study we present soil erosion due to rainfalls. There are several methods for estimating soil erosion due to rainfalls (WEPP, PISA, SHETRAN, USLE, etc.). Some of them studies erosion in flow channels while others on the entire surface. One of the most frequent used method is USLE or its’ variants. The original equation for determining soil loss quantity is based on the initiative of Hugh Hammond Bennett in 1929, asking founding from the USA Congress to start researches on soil erosion. The database developed by Bennett was completed and used by Wischmeier, to develop the USLE (Universal Soil Loss Equation) model. Latter models were developed on this equation: RUSLE, MUSLE and USLE-M. RUSLE is a revised variant of the initial model, correcting some data values in the database, but also changing some methodological aspects. In MUSLE model, the raindrops energy was replaced with de flow energy, permitting the soil erosion study in hydrological basins. USLE-M is a recent development based on USLE, permitting short range time scale study of erosion (ex. for a single heavy rainfall). In our study we want to develop a methodology to calculate and estimate soil loss in the Upper Mureş Basin, which is the hydrological basin of Mureş form its’ rise to Deda. 1 “Babes-Bolyai” University of Cluj-Napoca, Romania