Shapur Pilpayeh; Babak Aminnejad; Amirpouya Sarraf
Abstract
Sustainable use of fresh water resources and analysis of the hydrological behavior of the basin for water resources management requires knowledge of the state of water balance components. The main goal of the research is to estimate the water balance components of the Balkhlochai catchment area with ...
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Sustainable use of fresh water resources and analysis of the hydrological behavior of the basin for water resources management requires knowledge of the state of water balance components. The main goal of the research is to estimate the water balance components of the Balkhlochai catchment area with an area of 567 square kilometers. Therefore, necessary information such as meteorological parameters, monthly discharge, as well as required maps were prepared and introduced to the model. In order to test and validate the model, SUFI2 algorithm was used. The period of 2003 to 2013 was considered for the validation period and 2014 to 2018 for validation. The results showed that the Nash-Sutcliffe and explanation coefficients were 0.52 and 0.60 respectively for the validation period and 0.60 and 0.65 respectively for the validation period. Also, the balance components of the basin showed that 69% of precipitation enters the atmosphere through evaporation and transpiration. About 16% enters waterways as surface runoff, lateral flow, and return flow, and 15% of it also infiltrates. The results of the research show the good performance of the SWAT model in simulating the water balance of the Balkhlochai watershed. One of the most important reasons for the decrease in the efficiency of the model can be attributed to the incompleteness of the snow melting coefficients, the less compatible initial assumptions of the model, for the simulation of water flow at high altitudes and frozen layers, and the lack of necessary information regarding the simulation of underground water cited.
ayoub moradi; Ali Nakafinejad; Majid Ownagh; Choghi Bairam Komaki; mehrangiz foladi mansouri
Abstract
Indiscriminate land utilization methods, forest and rangeland degradation, land abandonment and development of residential areas contribute to the changes in flow intensity, erosion rate and sedimentation. Therefore, having knowledge on the effect of land use changes on discharge flow and sediment yield ...
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Indiscriminate land utilization methods, forest and rangeland degradation, land abandonment and development of residential areas contribute to the changes in flow intensity, erosion rate and sedimentation. Therefore, having knowledge on the effect of land use changes on discharge flow and sediment yield has been found necessary. The present research aims at investigating the effects of these factors by means of the semi-distributed Soil and Water Assessment Tool (SWAT) in Galikesh watershed, Golestan province (as a tributary of the River Gorganroud), in an area covering approximately 39000 hectares. This model was used in a 27-year period for simulation, calibration, validation and optimization of the parameters affecting flow and sediment yield. Land-use maps were prepared form the Landsat imageries dated 1987, 2000 and 2013. The SUFI2 model was used for model calibration and validation. Nash-Sutcliffe (NS) index was used as the objective function during model calibration (1990-2007) for the simulation of discharge and suspended load, which resulted in 0.63 and 0.61 that could be interpreted as satisfactory compared to the standards set in previous research. To evaluate the effect of land use changes on runoff and sediment yield, all model inputs, other than land use, were assumed constant. The results demonstrated that land use changes since 1987 to 2013 have led to an increase in annual runoff height by 1.40 mm and annual sediment concentration by 2 t.ha-1.
