IRAN-WATER RESOURCES RESEARCH
Year:2009 | Volume:4 | Issue:3 (12)|Papers Count:7

Water resources limitations, increasing water demands. And occurrence of frequent droughts in our country calls for saving water programs and efficient use of available water suppl y. In this regard the optimization approaches can be an efficient tool. The main objective of this study is the comparison of three optimization approaches including Non-Linear Programming (NLP), Genetic Algorithm (GA), and Particle Swarm Optimization (PSO) when applied to the water allocation management during droughts. These are used to maximize the income in Zayandeh rud irrigation system in Esfahan, Iran during the 1999 -2001 drought. Each model considered the four layers; Chadagan dam operation, irrigation networks, crops, and growth stages. Comparison of the results showed that the highest income is obtained by NLP. Furthermore, this optimization method can increase the irrigation network income by about a 36% compared to the traditional managements.

Surface and ground water interaction modeling has always been one of the basic concerns in water resources management. Such interaction is usually considered as an u1ternal boundary condition in modeling and exact state of the components would be determined throughout the simulation process. This will need sets of accurate data which confirms the use of assistant tools such as the satellite images and the Geographical Information System (GIS). In this research, the interaction of the Najafabad aquifer and the Zayandchrud river passing through has been modeled. A conjunctive model have been developed by modifying the watershed and aquifer limits using geological maps and DEM Sheets of the region as well as statistical analysis of related data. By using satellite images and GIS technique, in addition to the improvement of the model capabilities a data base for further studies has been established. Model outcomes in both steady and unsteady states proved the basic and important role of the river, recharging the neighboring area. River bed thickness was determined as an average for the 36 km river branch as one of the basic elements of the process. Mass exchanges were also defined separately at the end of each calculation steps as well as in average during each stress period.

In Iran, the reservoir operation during floods is mostly carried out based on engineering judgments. There is no operation policy for the majority of the reservoirs especially those with no flood prediction and warning system. In this research, operation policies during flood are developed for Shahid Abbaspour Reservoir on Karun river southwestern Iran. A Genetic Algorithm (GA) model is developed to determine the reservoir releases. The parametric objective function of the GA model is to minimize the flood losses associated with releases exceeding the safe carrying capacity of the downstream river. The GA model performance is evaluated using historical flood data as well as simulated floods with.-50-ycar return period. The GA model output has been used along with a K-Nearest Neighbor (K-NN) model to develop the reservoir operation policies for controlling floods. Comparison between the results of K-NN and linear regression model shows the accuracy of the GA and K-NN models to develop the operation policies for reservoir operation during floods.

The Instantaneous Unit Hydrograph {IUH) concept is widely applied in the simulation of the rainfall-runof process. in this paper a new geomorphologic unit hydrograph, based on the concept of cascade linear reservoirs has been developed and analyzed. This method represents the watershed as a cascade of reservoirs across the watershed main channel.The two most important characteristics of the model are: (a) it explicitly includes the watershed morphology in its formulat ion and (b) it depends on only one uncertain parameter which must be estimated. The result of the model. has been compared with Nash’s black box model with one more parameter. The study area was the Ammameh watershed southern of central Alborz mountain chain in Iran. The results showed the efficiency of this model to simulate the rainfall-runoff process using the watershed geomorphologic properties. GIS tools in the current modeling allow the accurate and easy determination of the geomorphologic characteristics of the model.

Soil erosion and sediment yield from watersheds arc among the key limitations to achieve sustainable use of land and to maintain the water quality in water bodies. Studying the soil erosion process and evaluation of dominant factors on erosion is therefore considered fundamental in watershed management. The accurate measurement of sediment yield using sediment graph data is accordingly of major importance. The present research was conducted to analyze sediment graphs in Chehelgazi Watershed upstream Gheshlagh Dam basin in the Kurdistan province in Iran with an area of 27233 hectare. The hydrographs and sediment graphs of 11 storms from winter 2006 to spnng 2007 were investigated. The results revealed that the sediment graphs with average sediment yield of 79.56±47.93 tones followed the general trends in corresponding hydrographs. All hydrographs preceed the sediment graphs with an average lag of 2.94±1.04 hours.

In the past few decades, the use of spur dikes for stability of the outer banks of rivers and in the bend has attracted the attention of hydraulic engineers. These structures affect the stability of river banks. Setting spur dikes in the flow direction leads to local scour around the spur dike and changes the topography of the stream bed. This paper examines the geometry of the scour bole, the maximum depth of scour, and the bed topography around the T­ Shaped spur dike located in a 90 degree bend. The experiments were carried out in an experimental channel with a smooth bend of 90 degrees (having the ratio of the bend radius to the channel width equal to four) under the clear water condition and with sediments having an average diameter of 1.28 mm. The effects of parameters like the length of the spur dike and its wing, the location of the spur dike in the bend, and the approach Froude number were studied on the amount of scour. The results showed that by increasing the length of the spur dike, decreasing the wing length of the spur dike, increasing the Froude number, and changing the location of spur dike towards downstream, the dimension of the scour hole increases. New equations for scour parameters at a T­ Shaped spur dike are obtained.

Population growth and socio-economic development have caused increasing demand for water amongst different consumers. Severe loss of storage and critical conditions in some aquifers within the last two decades are the consequences of such phenomenon. The optimum use of water from aquifer and subsequently in basin levels therefore requires an optimum management on ground water resources considering the qualitative measures. The development potential for the aquifer should accordingly be set to prevent the irrecoverable damages. Following the field studies and relevant research activities, this paper presents the results of irregular water exploitation in Rafsanjan plain as a case study.