Abstract Spillways are structures used for releasing the surplus floodwater in necessary conditions from storage dams. Ogee spillway is one of the most common and simplest structures. . In this research, a three dimensional flow field over the spillway was simulated with Flow-3D, using two turbulence models, namely RNG and. First, for precise prediction of hydraulic specifications of over spillway flow, the mentioned turbulence models were validated using data gathered from a laboratory flume (Sivakumaran et al., 1983). Data collected from software validation showed that the RNG turbulence model produced better results than. In the next stage, this model was used for simulating the physical prototype of the Nimrod Reservoir Dam. The measurement factors included pressure and water surface profile. The obtained values were compared to the existing laboratory measurements. Results from the simulation were well consistent with experimental measurements. Keywords: Flow Pattern, Nimrod Reservoir Dam, Spillway, Flow-3D, Turbulence Model.

Background and Objectives: The most distinguished effect of dams is change in the hydrologic regime of its downstream areas, which can be attributed to permanent supply flow and changes in the level of groundwater. The assessment of groundwater level changes is an important issue in analyzing hydrogeological time series of aquifers. Considering the different performance of effective factors in budget and hydrology in the catchment area of ShahreChay plain, it is necessary to review the trend analysis, which is complicated. Investigating temporal and spatial variations of groundwater levels in planning and managing sustainable water resources in arid and semi-arid regions is very importance. The purpose of this study was to evaluate the changes in trend of groundwater level of the aquifer piezometers in the ShahrChahi before and after the construction of the reservoir with the use of nonparametric methods of Mann-Kendal, the Sen's slope, Pattit, Boishand and comparind with the result of the MODFLOW software. Materials and Methods: The methodology of this research was based on library, field, and statistical methods. In this study, 10 stations in ShahreChay aquifer were used to study the groundwater level changes from 15 years (1381-1396). Ground water level trend at all stations were evaluated annually and at minimum and maximum water levels of the aquifer. The groundwater model is provided using the Modflow code in the GMS software. In order to investigate the longitudinal groundwater slope changes, the Kriging method was used in GIS 10. 5 software. Results: The researches show that the trend of ground water level changes in the 80% of piezometers was negative and a failure occurred in the time series in 2007-2008. At the stations closer to ShahrChay Dam, it is usually the year of jumping from 2007 to 2008. It is usually the year of jumping after 2007, 2008, or 2009 at far and near the riverside and far off the rivers. In Modflow software, with using piezometric wells and other studies to predict the level of groundwater level in the stable state of the dam calibration and prediction was performed. Data from June 2002 were used to prepare the model in a steady state Modflow software was used to predict the level of groundwater level in the steady state of the dam calibration and prediction. For the years 2003 to 2005, groundwater level was predicted with less error. Continuing calculations, the groundwater level of observation by 2017 is less than predicted. Also, the study of changes in 15 years isopotential lines indicates a decrease in the slope of the basin due to the lack of nutrition due to the construction of the dam. Conclusion: The results show the effect of reducing the surface water level caused by the dam construction. One of the reasons is the water storage in the dam at flood time. How to use the stored water in the crop season conditions that are directly used before construction the dam the flood distributed in area and causes an increase in the level of ground water that construction dam haven't been caused the recharge in the groundwater.

In order to identify, density and distribution of zooplankton and its changes over from winter 2009 to summer 2010 in the 3-stage sampling was performed. A sample stuck with huge plankton net 55 microns (Judy Net) was performed, than 4% formalin fixed samples of an inverted microscope in a laboratory study. Investigation totally distinguished 31 Genus in 6 Phylums among of genus. In this regard, the following series of Protozoa and branches Rhizopoda 5 genus, Ciliophora 2 genus, branch of Gastrotricha 1 genus, Nematoda phylum 20 genera Rotatoria branch and the branch Arthropoda and the order Cladocera 2 genus with embryonic stage and the category Copepoda 1 genus with them nauplius and were Chironomidae family respectively. The combined population of the lake zooplanktons Arasbaran most diverse branches of the genera Rotatoria Polyarthra, Synchaeta, Brachionus, Keratella, and Trichocerca the greatest diversity and abundance of this category is in the spring. In total, an average of 1, 179 per liter Rotatoria 69 percent in the lake had the largest population. Between zooplankton abundance at different stations and months there was a statistically significant difference (P<0. 05). In the summer season with another two seasons showed significant differences (P<0. 05). Biological studies showed that plankton production potential Rotatoria branch in the lake at almost a high.

Introduction: The quality of the stored water behind the dam is extremely influenced by the environment and the flowing water in the pool. Chamgerdalan storing dam in Ilam province as a store, that due to the continuous in-flow of waste water from the upper villages, animal wastes, agricultural drain water and the liquidated extract of solid waste is facing a complicated ecological problem.The overall aim of this research was to determine the qualitative assessment and diagnosis of quantitative and qualitative pollutant sources in different sites and times in order to determine the capcity of the dam water for urban and agricultural usages.Materials & Methods: The present study was carried out based on collecting the data of the water quality from the dam running water, identifying the pollutants after operations and measuring parameters like temperature, DO, TDS, EC, BOD, COD, nitrogen, phosphor, PH and in seven intervals (from May to November months.Results: The results showed an increase in the density of all variables among the water flow pool particularly nitrate, sulfate, BOD and COD. Conclusion: It is concluded that the analysis and comparison of the results with some indicators of water quality, control and reduction of negative effects in water stores may finally lead to a management program for improving the water quality.

Juneghan-Farsan, a north-Karun sub-basin, is located in Chaharmahal and Bakhtiyari province-Iran, in which various storage dams are either built, under construction, or are subject of ongoing studies. In this research, the influence of storage dam construction on downstream flood reduction is investigated using flow routing modeling. The results indicated that complete construction of all considered dams in Juneghan-Farsan basin will reduce maximum flood discharge in downstream up to 34%. That was higher for floods with lower return periods (Two years). The results also showed that the off-stream storage dams would be less effective in reducing peak flood discharge. The study showed that 20% increase in the spillway length had no significant effect on the maximum output rate and cause on average only a 6% increase in it.