JOURNAL OF WATER SCIENCES AND ENGINEERING
Year:2011 | Volume:1 | Issue:2|Papers Count:8

Deposition of sediment inside the conduit structures reduces the flow cross section area and increases the flow roughness which causes reduction of flow discharge passing through the conduit. Among the methods which can prevent sediment deposition is non sedimentation condition in the structure, since the critical section of the inverted siphon in sedimentation is the outlet. In the beginning of this research, a general relationship for conditions of incipient motion that is minimum of non sedimentation in the outlet of Karkhe inverted siphon was developed by applying the dimensional analysis. Then experimental tests were conducted by using physical model and 5 non-cohesive sediment with dimensions of 0.5, 0.7, 1, 2 and 3.2 mm and one graphs was drown that can be used for determining non-sedimentation in outlet conduit of Karkhe inverted siphon. Then, by using this graph and suspended load particle size distribution curves of the Karkheh River in Hamidiyeh diversion dam, minimum non sedimentation velocity was extracted for prevent sediment particle diameter of 1.5 mm that is the largest particle size input to upstream channel of Karkhe inverted siphon from Hamidiyeh diversion dam, were determined. The results show there is a non-sedimentation condition in the Karkheh inverted siphon in designed discharge and velocity.

Today, remote sensing technology is used in all scientific and informing fields around the world, and it has achieved to very satisfying results. In the present study, by using remote sensing technology and application of satellite photographs the coefficient of curve number was estimated with high accuracy and pick discharge of the flood was calculated with a good accuracy. In this study, in terms of land use changes effect on data of a historical event for decision making and evaluating long term variations of land use, basin area is also used. The results show that remote sensing and GIS technology are proper for analyzing runoff depth distribution beneath the studying basins. Daily rainfall and flow measurements showed that the land use changes on the precipitation - runoff in the basin has an effect However, because satellite images (except for the two periods 1990 and 2002) were available in different time periods, the results of land use change and its effect on the results of rainfall - runoff is not shown. This technology can be used for predicting runoff in watershed management and water recourses.

Earth dams have been used widely recently in flood and sedimentation control projects and feeding ground waters in country's watersheds and correct locating for such structures is necessary for increasing their efficiency. In this work, it is attempted to determine the correct locations for constricting earth dams in Yoosef-abad watershed in Tabas using v and incorporating information layers.Thus maps for local limitation (boundary out of 10m to river), natural local factors (slope percentage, boundary to river, geomorphologic units and geological features), economical factors (Resource materials, boundary to road, boundary to aqueduct and boundary to residential area) were entered into GIS environment and heterogeneous local layers were incorporated and made homogenous and all took phase values between 0 and 1. Due to heterogeneity of layers' values, layers were weighed. Finally, layers were incorporated and combined index map was obtained, where optimal locations for constructing earth dam were given priority, and the best location for construction in the area was determined. Comparing results with field studies showed that the selected locations are acceptable in terms of engineering and meeting needs of residents and proposed method can be generalized to other watersheds.

Control of sedimentation in reservoirs of dams is considered to be one of the most important issues in exploitation of dams and increasing their useful life.Reservoirs act as traps for sediments and prevent transport of sediments to the river. The deposited sediments will decrease the capacity of the reservoirs so that they cannot be in use any more. Various methods are discussed in this study to remove a part of the deposited sediments, but Flushing is the method, which has been used extensively in many projects all over the world due to the fact that the flow energy is utilized and there is no need to employ an external source of energy. In this study a one-dimensional model is developed in which continuity equation of sediment is solved by the finite difference method using the Cranck-Nickolson method. The developed model is capable to compute the variation of the reservoir bed with time. Also, the accumulated flushed sediment volume and reservoir water volume are calculated at different time steps. The Fotran language used for programming of the model was based on the results obtained from physical models employed by several investigators.And comparison was done with HEC-6 Model. The verification of the model was done using data from the natural reservoir of Dashidaira dam in Japan. The results were compared with the actual measurements. A good agrement was observed between them but the Hec-6 doesn’t show a good verification.

Application of gepraphic information system and image processing in evaluation of surface runoff of a watershed in recent years has increased greatly. In the study, the runoff curve number map was prepared using geographic information system (GIS) and Landsat Satellite Images (ETM+) for two watersheds of Mansourabad in southern Khorasan province and Navroud in Gilan province based on the factors of hydrologic soil group, land use, land cover and hydrologic conditions. The land cover map was perpared by NDVI index and watersheds were classified by three classes of good, fair and weak situation vegetation in Mansourabad watershed but for Navrood watershed, Vegetation had three classes of excellent, good and moderate. Land use map of this watersheds was prepared from Landsat Sattelite Images and Soil Hydrologic Group addition to soil, slope and Land use, geology maps plus filed investigations. From Coalition of GIS shape files and SCS tables, runoff curve number map was extracted for both watersheds. In evaluation of accuracy of Curve Number, maximum flood discharge in both two watersheds was simulated by HEC-HMS model and compared with observed data.Low error discrepancy between simulated and observed dischrge showed that curve number for both basins was calculated with high accuracy. So results showed that weithing runoff curve number in MansoorAbad basin is highly greater than Navrood basin, that this parameter can cause destructive floods during hight intensity events.

Due to territorial condition and available land in Iran cities, Stabilization Ponds are one of the best choices for wastewater treatment. Studies whole the world indicates that treated water from a well design pond is more reliable than other systems. The other point for accepting this system is related to low cost of installation and operation. The present study is about Khomein city of stabilization ponds by investigating an interference study of any analysis- ….. Samples are taken from row wastewater and effluent of ponds and wastewater treatment system by random. Tests of numbering of Colifourms and Nematods which are include PH, BOD5, COD, TSS, TDS, TS, DO have done. Correlation and Variance medium is used for analyzing of data. Results designed by Matlab and Excel graph. For chemical-physics and Coliform and Nematods tests 366 samples are taken. This study shows that there is a meaningful relation between temperature and surface load and retention time in removal of BOD, COD, COLIFORMS. (pvalu>0.05). Speed wind, evaporation, sunny days and rainy days in statistic analysis shows that stabilization pond in Khomein which are used in cold weather extremely impressed of natural parameters. Comparison of effluent result with standards shows that effluent water is usable for irrigation of parks

In regions like south of “ khouzestan” that water table are high, under the effect of water rise moving through capillary fringe and its vaporize, the salts move to soil surface and cause salin or salin and sodic soils. Leaching assign as one of those adjustment soils methods. In order to investigate the leaching process and draw the curves of desalinization and dealkalization in region of Darkhovin Shadegan, The research was conducted in a randomized complete block design that included four treatments using 40, 60, 80 and 100 cm of water for leaching was repeated three. In present work, we investigate leaching experiment by continuous ponding in experimental plates as a metal plat model in square meter based on plane of experiment and associated treatment. After using 100 centimeter of leaching water the results show the desalinization for continuous ponding with 74 percent, and cause a decrease in exchange sodiom percent (ESP) with 50 percent respectively. The comparison between dealkalization and desalinization in field tests, and experimental models of leaching showed that, new inverse model respect to other experimental models has a better coordination by the field data.After this model “Reeve”, “Hoffman”, “Pazira”and “Kawachi”, “Leffelaar” and “Sharma” models take position. Finally by usage of new inverse equation, we plot a curve of desalinization and dealkalization.

Analysis of low flow is one of the important considerations in any water resource project. Meanwhile, as a general idea it seems that flow control is more important than drought mitigation but it is necessary to pay more attention to drought problem in future projects. In this paper, available data for 28 selected watersheds were analyzed and then Flow Duration Curve was drew, and discharge of parameters includes Q75%, Q90%, Q92%, Q95% and  Q99% were calculated. Also, hydro climatic and geomorphologic parameters were considered to obtain the most effective factors on low flow. With using Principal Component Analysis from between 21 effective parameter on low flow, factors that showed lowest correlation was selected. The most effective factors were: average slop of the watershed, area, average altitude of the watershed, compactness coefficient and slop of main channel which illustrate 80.1 percent of variation of data. Meanwhile, obtain relation between low flow and watershed characteristics, regional analysis with multivariate regression was carried out. Results were compared with data of 9 control watersheds to evaluate accuracy of the model which showed these models were significant (at 99% level).