The quantity of runoff in a basin is of the main components influenced by various factors, including the basin climate as well as the type of the land use. Any changes in each will cause transformation in the runoff basin. Making changes in the types of natural lands is a problem that has long plagued developing countries such as Iran. Altering the lands use, destruction of pastures and forests as well as the urban and rural areas development are among the factors affecting the runoff of the area. As a result, it is highly important to explore and recognize the effects of changes in lands use on the runoff conditions. Concerning the climate changes, it is important to note that over the recent decades, due to the greenhouse gases extension within the Earth atmosphere, the level of precipitation and temperature have experienced alterations in different basins. Therefore, this trend is expected to be continuing in the coming years, affecting the basinsʹ runoff. Being conducted for the purpose to investigate the effects of changes both in the land use as well as the climate of the upstream runoff of the Zayandehrood Dam, the present study has utilized images by satellite and remote sensing technology, drawing the map of the land applications in 1996, 2008 and 2018. Reaching this goal, we used the Tm5 and OLI8 image sensors of Landsat satellite, applying nonparametric support vector machine technique afterwards to classify the images received. Then, applying Kapa coefficient method and thorough authenticity, the classification accuracy was eva‎luated, in which all the relevant validation coefficients indicate values of more than 80%. In fact, this reveals the acceptability of the classification performed. Having prepared the land use map of the region, applying the transformation scheme upon both the land use and the climate change, the watershed runoff was predicted for the subsequent periods. Hence, the land use layout for the next period of 2033 were firstly extracted, using the Markov-automatic cell model. Subsequently, through creating the HEC-HMS hydrological model as well as performing calibration and validation of the basin runoff for the upcoming 15 years, the period under the RCP2.6 and RCP8.5 climate change scheme was simulated from the fifth IPCC report. According to that, the effects of the stated climatic schemes render a reduction of 16.7 and 21.2 for the Eskandari Basin along with a decrease of 25.8 and 32.9 for the Ghale Shahrokh Basin, respectively. Finally, in order to determine the effects of land applications changes in the coming times on the basin runoff, both climate and land applications plots were applied simultaneously. The results demonstrated that in terms of the land applications layout, in the Eskandari basin these effects experience a shift of nearly 16% and in the Ghale Shahrokh basin a trend of approximately 5.3% decline compared to the runoff in the climate change scheme.

آزاده احمدي

محمد حسين گلمحمدي، حامد يزديان