Jamal Mosaffaie; Amin Salehpour Jam
Abstract
Evaluation of the impacts of past watershed projects provides useful insights for future projects. In this study, the hydrology and water resources status of Akujan Catchment of Qazvin Province has been the object of the study in which the effects of various measures of watershed managements were evaluated. ...
Read More
Evaluation of the impacts of past watershed projects provides useful insights for future projects. In this study, the hydrology and water resources status of Akujan Catchment of Qazvin Province has been the object of the study in which the effects of various measures of watershed managements were evaluated. For this purpose, the changes of water resources discharge, increased infiltration, water storage, peaks and volumes of catchment floods, were compared before and after the implementation of watershed management projects. Results showed that 114000 m3 more runoff storage has been carried out by watershed management operations that 20.1% of this volume was related to the structural operations and 79.9% of it was due to biological and biomechanical projects of the catchment. Results of the flood analysis indicated that the role of structural measures in the change of time of concentration is low and even negative. Therefore the reduction of the peak flow and flood volume at the outlet of the catchment is due to the implementation of biological and biomechanical measures which reduces the peak flows by 42.7, 25.4, 20.8, 17.1, 15.3 and 13.8% and flood volumes by 41.8, 24.8, 20.2, 16.5, 14.8 and 13.3% respectively for the return periods of two, five, 10, 25, 50 and 100 years. Another observation is that the effect of watershed management practices on the reduction of flood peak and volume decreases when the return period of flood is increased.
Mehdi Sepehri; Seyyed Abbas Atapourfard; Alireza Ildoromi; Hamid Nori; Saba Goodarz; Mohammadmehdi Artimani; Morteza Solgi
Abstract
Peak flow estimation is one of the major issues in water resources and flood management that have basic role in the design of hydraulic structures and biomechanics activities in basins. So that a proper assessment has a basic role in the success of administrative works. In this paper, using artificial ...
Read More
Peak flow estimation is one of the major issues in water resources and flood management that have basic role in the design of hydraulic structures and biomechanics activities in basins. So that a proper assessment has a basic role in the success of administrative works. In this paper, using artificial intelligence methods (MLP Neural Network, the mixture of SOFM with MLP, the mixture of FCM with ANFIS) to estimate Yalfan River’s peak discharge in hydrometer local station. For these models, eight variables have been considered as the inputs that includes rainfall amount in the occurrence time of flood, rainfall of five days ago from occurrence of flood, curve number of the basin (CN), basic discharge and finally peak discharge are considered as the output. In the artificial intelligences after preprocessing of the data, the optimal structure of the models are determined with input and output data, evaluation criteria and trial and error. At the end, the MLP model had better performance compared to ANFIS+FCM, MLP+SOFM, GRNN models.
Saeed Golian; Ahmad Ahmadi; Narjes Salarian
Abstract
A check dam is a small dam with a simple and low cost structure and because of its specific material and simple building technology, it has a wide range of applications in flood control projects. In this research, the effects of check dams on reducing the flood peak and increasing the time of flood flow ...
Read More
A check dam is a small dam with a simple and low cost structure and because of its specific material and simple building technology, it has a wide range of applications in flood control projects. In this research, the effects of check dams on reducing the flood peak and increasing the time of flood flow to reach to peak were investigated for Kan basin in north-west of Tehran.The hydraulic and hydrologic situation of the Kan basin was modeled using HEC-HMS software. Using hydrologic modeling the effect of building check dams on flood characteristics was studied in three scenarios of river slope change. The results showed that check dams reduced the flood peak to reduce between 0 and 0.9% in the first scenario (0.5 of the natural slope) and from 0.4% to 3.5% and 3.9% to 10.6% in the second (0.1 of the natural slope) and third (0.01 of the natural slope) scenarios, respectively. The time to peak also increased from 10 to 50 minutes. In hydraulic-hydrologic modeling, the effect of constructing check dams with no sediment in their reservoir was investigated for rainfalls of different return periods. The results revealed that with increase in rainfall return period, the effect of check dams on reducing flood characteristics will decrease. For instance, in the case of 100 check dams, the percentage reduction in peak outflow will decrease from 22.8 to 1.2 % for rainfalls of 2 and 20 years return period, respectively. In general, construction of check dams has no considerable influence on reducing constructive effects of floods. In other words, check dams should be used together with other structural and non-structural flood control methods.
