IRAN-WATER RESOURCES RESEARCH
Year:2010 | Volume:6 | Issue:2 (17)|Papers Count:11

Introduction In dam reservoirs whirlpools cause problems such as increased energy loss, decreased discharge coefficient, increased noise, and vibration at intakes (Knauss, 1987).Hecker (1981) divided vortices based on visual classification from weaker to stronger into 6 types. For a powerhouse tunnel intake it is assumed that in vortex type 5 debris and some air bubbles are entrained to the tunnel and in the strongest vortex (type 6) a stable air core from water surface is formed in the center of the vortex and air is entrained into the power tunnel steadily. By reducing the submergence depth in power intakes, the strength of vortices increase regarding to the unchanging discharge. However in orifice spillways, the discharge is a function of submergence depth and by decreasing it, the discharge will decrease.

Introduction: Water quality protection along rivers involves water quality monitoring and assessment, establishing water quality goals, and controlling pollutant discharges, so that an acceptable level of water quality is maintained.The control of water quality at various locations along a river requires determining the optimal pollutant removal levels at point and nonpoint pollution sources that would yield a satisfactory water quality response in a cost-effective, equitable, and efficient manner (Burn and McBean 1985; Burn and Yulianti 2001). This is known as the “Optimal Waste Load Allocation.” Typical multi objective optimal waste load allocation problems address minimization of the total treatment cost and minimization of the inequity among the pollutant dischargers, subject to constraints on satisfaction of a specified dissolved oxygen (DO) standard at all the check points along the river (Burn and Yulianti 2001). In this research, the capability of Multi objective Ant Colony Optimization algorithm is applied to a multi objective waste load allocation problem.

Introduction: Challenges and conflicts over limited water resources have come up due to the increase in water demands that cannot be resolved by the existing optimization models.In recent years a few discrete stochastic dynamic models have attempted to solve cases of water use (conflicts) so that more efficient water distribution management can be achieved (Ganji et al., 2007, 2008).These models have to some extent addressed the conflict issues of water resources. However, they still cease to accommodate certain needed constraints and they also involve complicated procedures and massive computational efforts. The discrete nature of these models seems to have been the limiting factor.

Introduction: The methods of system identification used to estimate the ordinates of Instantaneous Unit Hydrograph (IUH) encounter the presence of noise in the form of oscillation. Noise in the IUH originates from the errors in the rainfall- runoff data and the linear assumptions in unit hydrograph theory. Rao and Delleur (1971) used Fourier transform to estimate IUH. In their work noise is controlled by the moving average technique. The aperiodic and transient signals with short duration (like in an IUH) are signals for which wavelet transform are particularly useful. Chou and Wang (2002) controlled the noise using a Haar wavelet with a boxcar-like function. Soman and Ramachandran (2005) showed that for smoothly varying signals a smooth wavelet function such as Daubechies (1992) wavelets should be selected. In this paper, the fast Fourier transforms (FFT) are used to estimate the IUH in the presence of noise. Daubechies wavelets are also applied for noise reduction.

Introduction: Water resources management bodies are under increasing pressure to meet potable water demands.Population growth and socio-economic development have led to the increase in urban water consumption and costly development and improvement of the water wastewater systems. Therefore, there is a need to integrate the water resources supply and demand management measures (Baumann et al., 1998). The main part of the urban water demand is residential consumption. One of the most effective residential water conservation measures can be the use of water efficient fixtures and faucets. Retrofit of low-flow showerheads and ultra-low volume toilet fixtures could reduce household indoor water consumption up to 15.6 percent based on a research by Anderson and Nero (1993) in Tampa, Florida. Most projects and studies are based on the flow rate of low consumption sanitary fixtures reported by manufacturers, but it is important to measure the actual impacts of the fixtures on water consumption (Hwang, 2003).

Introduction: Shrimp farming is one of the high priority programs in the south coasts of Iran because of its potential to increase fishery production, to generate export earnings, and to affect employment in rural areas.Site selection is a key factor in Shrimp farming It affects both success and sustainability and also helps preventing conflicts between different activities and making rational use of the land. The Analytic Network Process (ANP) was applied to prioritize and select appropriate shrimp culture sites in the context of flood damage in southern coasts of Iran. ANP is the modified version based on the AHP method and its super matrix approach. This method is a flexible analytical program that enables decision makers to find the best possible solution to complex problems by breaking down a problem into a systematic network of interrelationship among the various levels and attributes. In this paper we used the interrelationships of the alternative and flood damage attributes that cannot be considered in other decision making methods like AHP. Therefore, the alternatives will prioritize based on a feedback interrelationship decision structure.

Introduction: Vortices resulted by fluids movement around cylinders were initially studied for gases. When a rigid cylinder is placed within a flow path (including gas or liquids), as the fluid particles reach the leading edge upstream of the cylinder, the velocity of fluid inclines to zero and the particle pressure decreases from the initial fluid pressure to a dynamic pressure at the stagnation point.Near the widest section of the cylinder, the boundary layers may detach from each side of the cylinder surface and form vortices and wake interfaces. Few researches has been done on the formation of vortices in water environment and related phenomena. In a recent research, Ghomeshi et al. (2007) studied the transverse surface waves in a laboratory flume, 1.2 m in width and using cylinders with a diameter of 0.024 m.

Introduction: Flood is one of the most destructive natural disasters that have historically done considerable harm to humans. Unfortunately nowadays despite great technological improvements, there is still no acceptable prevention method for this natural phenomenon. This is mainly due to lack of knowledge or the limited facility in this field. Knowing the causes and predicting the time and intensity of the flood is a necessary step in such practices.Iran is a dry and semi dry country with a small amount of rainfall that is unevenly distributed over time and space. Rainfalls are usually in the form of short and intensive showers as regards to the country's special climatic condition. According to the vegetation and topography, these showers would generally not get the chance to penetrate into the underlying layers and thus form disastrous floods. [Lashkari (1375)] Every year many people lose their lives because of floods. Records also show massive economical losses are a result of flood events.

Introduction: The optimal allocation of resources has always been a challenging issue for human life. It is important especially in allocating the factors of production in order to insert the choices that among other allocating options yield better living standards for humans.The best allocation is achieved if factors are used in an "efficient" methods Understanding the concept of "efficiency" is the starting point in this process.Objectives In this paper, the operational efficiencies of the Iranian provincial Water and Wastewater Enterprises are investigated. It is also examined whether the existing resources are allocated in an efficient manner.Economic development is simply formed over efficient allocation.Methodology Using non-parametric methods, which are mathematical programming, we will evaluate the efficiency of companies.