JOURNAL OF WATERSHED MANAGEMENT RESEARCH
Year:2013 | Volume:3 | Issue:6|Papers Count:7

Flood routing computations in flooded rivers with floodplains (compound channels) are more complicated. In these conditions, using the Saint-Venant equations, that form the base of flood routing mathematical models, lead to some errors. For modifying these equations, many mathematical approaches have been presented. These methods, are often complicated and have long run-times. In this paper, based on Muskingum method, a simple and optimum idea has been presented for flood routing computations in flooded rivers. For increasing the speed of computations, the Muskingum coefficients have been calculated in an optimized manner, using Genetic Algorithm. For evaluating this method, some experimental flood routing data in homogenous and heterogonous compound channels have been used. The results show that the outflow discharge hydrographs have been simulated well throughout the channels, using Muskingum method. With run of HEC-RAS4, it was found that the results of this mathematical model have higher errors than Muskingum method.

Drought is a phenomenon that is usually quiet and creepy, which increases due to precipitation and relative humidity reductions and increases of temperature and wind. In the recent decades between various natural disasters frequency of drought was sensible than the other events. Therefore, understanding of the conditions through the prediction of drought and its intensities leads to decrease some unwanted costs considerably. The aim of this study is to evaluate the accuracy of ordinary and universal Kriging and inverse distance weights methods from the zone classification and mapping on the drought of Fars province in 1389 based on two indicators of abnormal rainfall and rainfall deciles. The survey results showed that the zone classification on the drought DPI and RAI indices ordinary Kriging and inverse distance weights methods of the results are better than the other interpolation methods respectively. Finally, according to the plans gained by two indices of RAI and DPI 60.91 and 51.05 percent of the study area was indicated under drought realm in 2010.

One of important methods for investigating the water condition of catchments is the direct runoff hydrograph driving. Regarding the quantitative and qualititative deficiency of water gages data, synthetic unit hydrograph models and especially instantaneous unit hydrographs is applied. Due to lack of enough studies on Performance of Laplace transforms and H2U models in Iran, this study analyses them in Khanmirza catchment of Chaharmahal and Bakhtiyari. In order to do this, 7 events of rainfall-runoff were selected for this catchment, then Laplace transform model was used by effective rainfall and lag time moreover H2U model was applied by order of catchment and mean of travel time. Furthermore, IUHs change to direct runoff hydrographs; for comparing with observed hydrographs. Statistical comparison of hydrographs indicated that Laplace transform and H2U models have mean absolute relative error 0.36 and 0.56 respectively; Therefore Laplace transform model simulated observe hydrographs more significant than H2U model. It should be noted that the Nash-Sutclif efficiency coefficient, BIAS and graphical method confirm this order.

Land use Change influences the components of the hydrological cycle which result in increasing or decreasing the amount of runoff. The purpose of this study is the evaluation of hydrological respond to land use change in Qhazaghli basin. After changing land use in GIS environment, four management scenarios in both positive and negative trends were introduced into the model and the model output of each model extraction and simulation results were compared with observed values. Simulations were done based on the monthly and semi-distributed using SWAT model and SUFI2 program. After running the model, Qhazaghli basin was divided in 37 sub basins and 278 hydrological response units (HRU). After model calibration, the runoff model simulated with a correlation coefficient (R2) of 0.85 and the Nash efficiency coefficient -Sutcliff (ENS) of 0.86 and the root mean square error (RMSE) of 7.67. The coefficients for the validation period, respectively were obtained 0.86, 0.82 and 9.05.The land use analysis showed that the basin land use improvement, reduces the amount of runoff by increasing infiltration, the deep and shallow aquifers percolation and by increasing evapotranspiration .in other hand the land degradation in the basin increased runoff but the infiltration values, the percolation of deep and shallow aquifers and the evapotranspiration significantly reduced. Protection and improvement of Current basin land use, is one of the basic strategies for managing surface runoff in the case study region.

Erosion and sediment transport in the rivers is one of the most important and complicated subjects in river engineering. These phenomena have specific effects on water quality, bed and bank scouring as well as considerable damages to water related structures and projects. Therefore, precise prediction of river sediment plays an important role in water resources management and planning as well as design and construction of hydraulic structures. In this research it has been tried to evaluate the efficiency of artificial neural networks in prediction of suspended sediment. Using multi-layer perceptron neural network suspended sediment of Heydarabad station on Jamishan river of Kermanshah has been predicted, and the results have been compared to those of sediment rating curve method. Then the strengths and limitations of these methods have been analysed. According to the results, ANN has presented acceptable predictions in Heydarabad station suspended sediment simulation in comparison to the sediment rating curve method. The values of R2 for the results of ANN and the sediment rating curve methods are respectively 0.92 and 0.83. However, it must be mentioned that ANN is also not able to predict the peak values with acceptable accuracy, which can be a weakness of this model.

Water pollution is one of the crucial issues which affect human and environmental ecosystems in the world. This necessitates investigation on water quality to do better management over water resources. To evaluate water quality some parameters should be measured in a specific temporal period. In this study focus is on prioritization of water quality parameters, finding relationship between them and also to explore their mineral or non-mineral origin. To do this study, period of 3 years (2003-2006) data were selected in Tadjan river. In this period, monthly data of 10 parameters including TDS, EC, K+, Na+, Cl-, SO42-, Ca2+, Mg2+, SAR and HCO3- were analyzed in 3 stations (Aliabad, Korcha and Soleiman tange) using principal component analysis (PCA) and cluster analysis (CA) techniques. The results of PCA technique show that all parameters play important role in river’s water quality except SAR and SO42- in Aliabad, HCO3- in Korcha and Mg2+, Ca2+ and HCO3- in Soleiman tange. CA technique represents that source of Mg2+, Ca2+ and HCO3- can be attributed to karstic formations in the region like Carbonate Rock (Lime stone and Dolomite). Source of K+ and Cl- can be related to Schists and SAR, Na+ and SO42- might be related to Clay, Marl, Diorite and green Tuff.

In the pastures, floods often happen due to surface runoff and violent storm. Initial soil water content has a direct influence on the infiltration capacity and as result on surface runoff. Hydrological models are strong instruments to investigate the main physical processes involved in the watershed. In the present study regression models, obtained from relationship between independent and dependent effective variables on runoff production. Through modeling used in this study, the daily precipitation and water discharge data for the period from 1974 to 2000 collected, refined and analyzed.Subsequently the pertinent models were recognized with using the concept of dynamic modeling statistical software's Excel 2003 & SPSS 11.5. The analysis of results showed that the effective time of antecedent precipitation and the most effective daily precipitation on daily discharge. The results indicated that the antecedent and daily precipitation were affected on the daily discharge of Tangrah pasture watershed in duration of different months significantly. It was also found out that the daily discharge was affected by the precipitation occurred respectively before three days while this is contrary to emphasizes of other common methods of estimate of runoff that was based on effect of precipitation of fifth previous days on daily discharge due to specific governing conditions on study watershed. The present study emphasizes determination of exact quantity of effective antecedent precipitation in different places attention to effective spatial & temporal changes on output discharge of watershed.