Investigation of the effect of slope on the intensity of water erosion rate (Case study: Latian watershed)

Due to its economic and environmental impacts، soil erosion has been a major concern to farmers، engineers and policy makers in recent years. So for fighting and subsequent to that success in controlling soil erosion action is necessary to knowledge and awareness of the effective factors on erosion، and the intensity of its impact on specifics and finally in the areas of soil erosion and yield sediment. But due to the complexity of soil erosion، number of indices and criteria involved in it and also lack of and efficient model in the country makes it a very difficult، complex، cost and time-consuming task. So introducing relevant indicates with higher accuracy and time saving to apply for water erosion prone areas are very important. Slope is one of the main factors responsible for this phenomenon and considerable efforts have been made to model it in the previous works. The relationship between percent of erosion and slope was studied in the study region. In other words different classes of the slope erosion risk evaluating a danger to the slopes of the erosion are clear. GIS & RS were used to facilitate the research. Also statistical tests such as Chi-square were considered for the final conclusion. Finally it was resulted that slopes between 20 to 40 percent have been mostly affected by the erosion. Meanwhile، in the gentle slopes، light erosion and in the upper slope existence of rock and lack of soil caused to the lower erosion rate. In this way، it was denoted that as the slope increase، soil erosion increases primarily and then will decrease. Also the slope and the weights assigned to each erosion rate classes based on quantitative geomorphologic approach، specific sediment discharge، erosional facies in 1% is significant. Therefore it can be classified in the preliminary zone erosion in areas of southern Alborz without sufficient data for complementary studies