Mitra Tanhapour; Mohammad Ebrahim Banihabib
Abstract
Debris flow is one of the natural hazards that threats people's lives in the mountainous populated areas. Thus, it is necessary to determine the rainfall thresholds for debris flow occurrence in order to develop an effective forecasting system. In this study, the empirical thresholds of rainfall for ...
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Debris flow is one of the natural hazards that threats people's lives in the mountainous populated areas. Thus, it is necessary to determine the rainfall thresholds for debris flow occurrence in order to develop an effective forecasting system. In this study, the empirical thresholds of rainfall for the occurrence of debris flow by Hirano method were assessed in a part of Alborz mountainous basins including Gorganrood, Navrood, Neka and Babolrood. For this purpose, the rainfall hyetographs of recording rain gauges were used from the period of 1983-2004. Then, the intensity-duration rainfall thresholds (I-D threshold) for selected basins were estimated and compared with previous studies from the local, regional and global scale. The examination of rainfall thresholds for the initiation of debris flow showed that the rainfall of more than 27.2 and 14.8 mm, respectively, in the Navrood and Gorganrood watersheds and rainfall more than 37.84 and 66.12 mm, respectively, in the Babolrood and Neka basins are able to trigger debris flow during their concentration time. Comparison of the I-D threshold of this study with the results of previous studies showed I-D threshold of the studied basins generally are lower than the thresholds of local and regional but higher than global thresholds. In other words, there are some areas in the world that need smaller rainfalls for initiation debris flow in comparison to the study area. The difference among threshold of debris flow occurrence in the world’s basins comes from their variety in climatic, geographical, physiographic and geological factors.
Mohammad Ebrahim Banihabib; Marina Ezzati amini; Mohammadhadi Shabestari
Abstract
Changing in urban life, climate change and successive droughts and floods have caused the issue of restoration of rivers to become one of the most important environmental issues and water resources problems. In recent years, the lack of attention to environmental issues, improper exploitation of water ...
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Changing in urban life, climate change and successive droughts and floods have caused the issue of restoration of rivers to become one of the most important environmental issues and water resources problems. In recent years, the lack of attention to environmental issues, improper exploitation of water resources, ignoring sustainable development, changes in natural structure and channelization of urban river have created undesirable conditions for urban rivers. This study tries to develop and select the best strategy to achieve river restoration by considering six sustainable development criteria and using the hybrid model of Analytical Hierarchy Process and Modified Technique for Order of Preference by Similarity to Ideal Solution (M-TOPSIS-AHP) and taking into account two goals of quantitative and qualitative restoration of base flow and securing against flood. The required data was collected through survey forms that have been filled by 38 experts in the field of water resources management. The inconsistency rates of surveys forms were investigated and inconsistent forms were removed. Then the pairwise comparison of AHP method was used to obtain the relative weights and finally the strategies were ranked by TOPSIS method and the best strategy was introduced.
Mohammad Ebrahim Banihabib; Bahman Vaziri
Abstract
Since most of water and soil researches require artificial rainfall simulation, thus rainfall simulators are applied instruments in this field of study. For this reason, various rain simulators have been designed, built and employed in researches till now. Even though all rainfall simulators provide ...
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Since most of water and soil researches require artificial rainfall simulation, thus rainfall simulators are applied instruments in this field of study. For this reason, various rain simulators have been designed, built and employed in researches till now. Even though all rainfall simulators provide good simulation for rainfall intensity, but simulation of varied rainfall by them are expensive and complicated, and field study cannot conducted easily by them. Thus, in this research, in order to simulate rainfall similar to natural rain and applicable for field tests, it is aimed to design and build a simple and affordable rainfall simulator using flow cascades reservoirs (tanks) routing. The result of calibration the simulator shows it has error less than 5%. Moreover simulation of observed hyetograph of Niyavaran station showed error of 6.1%. The simulator can simulate hyetographs with 3 hours duration and 30 millimeter per hour intensity. Consequently, the proposed instrument and its numerical model can be applied for simulating artificial rainfall hyetograph in rainfall erosion and infiltration field research tests.
Alireza Dehghani; Mohammadebrahim Banihabib; Saman Javadi
Abstract
Due to lack of surface water, the most important option for water supply in arid and semi-arid areas is from groundwater resources and one of the engineering measures to use the floods for improving groundwater resources is the implementation of artificial recharge systems. The purpose of the present ...
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Due to lack of surface water, the most important option for water supply in arid and semi-arid areas is from groundwater resources and one of the engineering measures to use the floods for improving groundwater resources is the implementation of artificial recharge systems. The purpose of the present study is to provide a model-based framework based on several quantitative indicators such as recharge efficiency and flood attenuation rate for assessing the performance of artificial recharge systems. Considering the capabilities of hydrological, hydraulic and seepage models, the combination of these models was used to estimate the parameters of the indicators. Finally, by determining the indices for floods with different return periods, their average values were determined using the expected value. The studied system (Emamzade Abdollah, Sorkheh) had a good performance based on recharge efficiency and flood attenuation rate indicators in events with frequency of more than 0.2, and the average value of these two indicators was 0.54 and 0.93, respectively. Due to the model based characteristic of the proposed framework, it has the potential to be used in similar cases.
Mitra Tanhapour; Mohammad Ebrahim Banihabib
Abstract
Prediction of the sediment load in water resources engineering projects such as flow diversion projects and dam construction is important factor for determining their service life. In this study, a model for estimation of daily sediment discharge was proposed using multilayer perceptron Artificial Neural ...
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Prediction of the sediment load in water resources engineering projects such as flow diversion projects and dam construction is important factor for determining their service life. In this study, a model for estimation of daily sediment discharge was proposed using multilayer perceptron Artificial Neural Network (ANN) model with back-propagation learning algorithm. For this purpose, current day’s discharge (Qt), precipitation, number of day in the year (DOY) and previous day’s discharge (Qt-1) data of Zoghal Bridge station (located on Chalus River) from 1990 to 2009 were used for training, verification and test. Results of testing different combinations of input data sets showed that effective parameters of the model performance are current discharge parameter, antecedent discharge, precipitation and DOY, respectively. This results has a relatively good agreement with standardized coefficients of regression model. Coefficient of determination (R2) and Root Mean Square Error (RMSE) were used to compare the different structures of ANN. Therefore, best network with 3-5-1 architecture and the amounts of R2=0.89 and RMSE=0.02 was obtained by elimination of DOY variable. The performance of ANN model in the prediction of sediment discharge was compared with Sediment Rating Curve (SRC) and Multiple Non-Linear Regression (MNLR) model. The results showed, in the training and test steps, SRC method and ANN model have the best performance, respectively. Furthermore, in the test step, the ANN model performed better results compared to two other methods by increasing R2 about 16%. Generally, the proposed ANN model can be estimated sediment discharge by less calculation time and cost and also with more accuracy.
