Forecasting the effect of climate change on soil erosion hazard in Navrood watershed

Climate Change and its consequence changes in precipitation patterns can affect soil erosion, as the most important global problem of land degradation. Therefore, it is essential to assess soil erosion risk under climate change condition. The aim of this study was to evaluate the impacts of future climate change on soil erosion risk in Navrood watershed, located in west of Guilan province, North of Iran.
In this study, the trend of climate change was evaluated through effective climatic parameters by XLSTAT software based on the data obtained from Rasht and Bandar Anzali stations. Also the soil erosion risk was predicted using RUSLE in combination with geographic information system and remote sensing, in Navrood watershed. The data of previous research were used to calculate the K, LS, C and P factors for the RUSLE model. The atmospheric general circulation model NCCCSM and three scenarios A1B, A2 and B1 were used to study climate change. The daily rainfall pattern were simulated for two 20-year periods of 2046-2065 and 2080-2099 for Kharajgil, Khalian and NAV stations located inside the watershed, based on the outputs of NCCCSM, daily rainfall values of the base period 2002-2007, and the LARS-WG model.
The results showed that a decrease will occur in rainfall at the Nav and Khalian stations; while there will be an increase for Kharajgil station. In contrast, the rainfall erosivity will increased for all scenarios and stations in future in compare with the base period due to increase of rainfall intensity. Based on the obtained results, soil erosion risk changes from zero to more than 77 tons per hectare per year, between zero and over 115 tons per hectare per year, and from zero to more than 98 ton per hectare per year across the watershed at the base period (2002-2007), and 2046-2065 and 2080-2099 periods, respectively.
The results showed that rainfall erosivity will increased due to increase of rainfall intensity. Most of the watershed area is faced with low erosion risk, but the south-western and middle north parts of the watershed are experiencing high erosion. Additionally, although rainfall erosivity is at its highest level at some stations, but the erosion rate is low because of the positive impact of plant coverage in reducing soil erosion. Higher the density of plant coverage, particularly forest type, reduces the negative impacts of rainfall erosivity, resulted in lower soil erosion risk.