مجله آب و فاضلاب
پیاپی 38 (تابستان 1380)

In this article a computer model (LEVEEWRC) of underseepage analysis through levees on hree-layer foundations is presented. To test and verify this model, field data from the piezometer reading of the Mississippi River levees during flood events were used. This result showed that the model can be used to predict the potential of piping or sand boils.At the end of this article, applications of the proposed models were shown for the Sistan River levees. The results show the potential of sands boils and / or piping problems being present in the Sistan River at some cross – sections, however further field investigation is recommended.

Since Zayandehrood of Isfahan is an important source of water in central part of Iran, therefore an investigation was under taken for identification, enumeration and isolation of pathogenic bacteria, and their correlation with physicals and chemicals factors such as biochemical oxygen demand (BOD) and temperature. In this study two sites were chosen for sampling. They are as follows: 1) Shahrestan Bridge, 2) the distance between Sharestan Bridge and “Bozorgmehr “Bridge.Total bacteria, fecal coliform and fecal streptococci were counted using MPN standard methods. B.O.D and temperature were determined. The results showed that the gram positive cocci (Streptococcus faecalis) were is isolated in the all of seasons, while staphylococcus aureus isolated only in spring, summer and autumn. The gram negative bacilli isolated were Escherichia coli, Salmonella typhi, klebsiella pneumoniae, Shiglla sonnei, Proteus morganii, Serratia marcescens and pseudomonas aeruginosa. The measurement of B.O.D and temperature revealed the temperature have the direct correlation with increasing of number and type of pollutant bacteria, because these microorganismes were maximum during hot season and were found minimum in cold season. But increasing B.O.D had relative direct correlation with increasing number of bactria. In this study the M.P.N of coliform (Fc) and faecal streptococci (Fc) and their ratio (Fc/Fs) determined that the pollution of Zayandehrood river is human base origin.

Most regions of our country have an arid or semi-arid climate. However, available water is not efficiently used in agriculture. One of the major sources of water is that stored behind dams, which is used through modern irrigation networks downstream the reservoirs.Usually, this important source of water is not properly used. Therefore, by improving the management of an irrigation network, more water can be saved. Hence, the cultivated area can be extended which would result in higher amount of crop yield.In this study, due to far extension of the Isfahan modern irrigation network, only some branches of the network located in Mobarakeh and Falavarjan area (the Nekoabad network), were selected and the following objectives were investigated: study of the annual records of water intake from the river during various years, within-the-year water intake to the fields, measurement of conveyance and water application in integrated and non-integrated farms, ground water operation and shallow wells distribution, cropping pattern and intensity within the network district, changes in the network over the years of operation, network maintenance during operation and non-operation months, and, the reasons for malfunctioning of the water structures caused by some farmers and the situation of canal destruction.The results of this study showed that varition in inflow within the network during recent years are primarily due to disagreement between the beginning date of canal operation and water demand. Insufficient information about crop water requirements, low field application efficiency due to easy access to abundant water, low conveyance efficiency in traditional channel occasionally is due to various reasons, among them the abuse of ground water resources by operators and undesirable conditions in maintenance of channel. Some recommendations were made for the roles of Agricaltural Organizations and Regional Water Authority of Isfahan.

In the past years, environmental pollution brought about due to the disposal of different wastes such as municipal, industrial, and agricultural wastes in Iran has converted the treatment and control of these contaminants to an important priority in protection, management, and planning of the environment. In this regard, authorities in the country have imported a variety of technologies for wastewater treatment systems including activated sludge system. Although there exists many references for design of such systems and a good progress in this regard has been made, but lack of experience and / or knowledge in construction, operation, and maintenance of treatment systems in addition to their high cost is still a dilemma that makes it very difficult to select a suitable system. Therefore, in order to save time and capital, it is necessary and inevitable to optimize the common wastewater treatment systems in Iran, specially activated sludge from an economical perspective.In this paper, the activated sludge system for treatment of municipal wastewater has been optimized using a dynamic computer program such that the special intorrolation of different stages in the system can be properly modeled in this program construction, operation, maintenance, and repair costs of different units in an activated sludge treatment system have been evaluated using civil, mechanical, electrical, and construction plants for every structure and available standard charts and tables in the literature. Optimization has been performed with different combinations of the distinet units in the system. At the end, considering the increasing investment of the country in wastewater treatment plants and the need for economical considerations, complexities are investigated, explanations are presented, and some recommendations are made in that regard.

It is important that water and wastewaters should not corrode the structures, fitting or mechanical equipment with which they come in contact. In this investigation the corrosion and precipitation effect of Rasht’s water supply resources was ٍ‏studied. The qualitative and quantitative parameters such as; pH, Dissolved Oxegen, CO2, TDS, temperature, Alkalinity, etc. were measured done during two hydrological years (1997-1999). The name of resources and the results are summarized below. Shaghagi, Razi, Khachekins. Helal Ahmers, and Jandarmeri Shalko’s well water were not corrosive, Emamzadehhashem well water could be corrosive. The out going water of Rasht’s water treatment plant after operation and treatment can be classified as corrosive in cold water pipes.

The 15th of Khordad dam, with a height of 54.3m is constructed on the Qomrud river, 12km from city of Delijan. It is heterogeneous and has a clay core. Its main purpose is to provide water for downstream farms and drinking water of Qom city. The operation of the dam began in 1996 and two years later its water quality changed. The EC of water increased from 1ds/m in 1996 to 4ds/m in 1999. The possible causes for this variation include recent droughts, thermal stratification, intense evaporation from water surface, entrance of Shur and Darbande- Shur rivers, and chemical reaction of reservoir bed and water. To predict EC changes, Artifical neural network (ANN) is used. Based on weather forecasting, maximum EC in 1997-1998 would be 3.55 ds/m and is 1998-1999 would be 4.05ds/m other environmental effects of this dam include uprising of groundwater, downstream agriculture and social conditions. To improve water quality and reduction of negative effects on environment methods such as reservoir flushing, better management of water quality, diversion of Shur and Darband – Shur rivers from entering the reservoir, prevention of groundwater exploitation in the area, transfer of fresh water from Dez-watershed, and controlling wastewater entrance of Delijan city are proposed.

Sistan area, with an area of 8000 km2, is located in southeast of Iran in Sistan and Balouchestan province. The only source of water in the region is Hirmand river, which originates from Afghanistan. Drought and water deficit in the area is because of inadequate discharge of this river. There are two reasons for this water shortage: natural droughts, which have occurred 14 times in the last century (the last one was in 1999-2000). In that year, the river delivered 0.22 billion cubic meters, and its damages were more than 220 billion Rials in the agricultural sector. The second reason is water storage and use in Afghanistan.Drought can be defined as sensible and significant storage of water, and every process or program that increases fresh- water storage is a kind of alleviating drought and water shortage. To study different measures, some characteristics of the sistan area is reviewed. Based on the dependence of the area to Hirmand river, and high evaporation losses from water surfaces measures such as building more hydraulic structures to store water, change of agricultural practices, teaching courses like farming in dry regions, and substitution of risk management instead of water –crisis management are recommended.

Shahid kalantarie’s highway makes connection between two both side of west and east Azarbaijan centers possible, taking the shortest route on the width of the lake. It is the great project which has the significance effects on both province’s social and economical development. The highway’s soil loading operation’s has been done from the both eastern and western bank.The water course’s span has been opened for the length of 1200 Meter in the middle of the lake, in which the present connecting between two sides are being done by two floating vessels. For compeleting project and joining two sides to each other, there is a need for making bridge over the water course.For the construction of the bridge some studies on hydraulic and hydrological of the lake’s basin and also estimation on existing currents between two parts of the lake on the site of the water course was necessitated finally on hydrodynamic’s behaviour for connecting high way on Uromie’s lake must be carried out.This study has done and following results were achieved:1- Estimation of the proper length for highway’s water course’s span.2- Estimation on extreme difference of the probable water level elevation between two side’s of the highway.3- Necessary discharging estimation for the rate of flow of the flood inlet with one thousand year probability.4- Determining structure’s code on lake’s side for safeguarding of the water coverage due to lake’s flooding with one thousand year probability.