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A set of nested models was applied to provide useful strategy to evaluate the storage, water yield and the operational performance of the multipurpose Mula reservoir in India. Insufficient yield from the reservoir for the purpose of water supply and irrigation has led to the need for reevaluation. These nested models were applied in tandem using linear programming (LP), dynamic programming (DP), artificial neural networks (ANN), hedging rules (HRs), and simulation. An LP-based yield model (YM) has been used to reevaluate the annual yields available from the reservoir for water supply and irrigation. The yields obtained from the YM have been refined by two DP models, viz; the controlled output DP (CODP) and the controlled inventory DP (CIDP). The prespecified annual release reliabilities and the yield deficits were similar to that used in the YM. In this approach, the ANN models use a hybrid model in the stochastic generation of monthly inflows to the reservoir for studying its operational performance. With the ANN, both the sigmoidal (DPN) and the radial basis function network (RBN) evaluated reservoir performance using results of the DP model. Continuous HR (CHR) and discrete HR (DHR) were also used for modeling the reservoir performance. The results show that the YM estimates the annual multiyields accurately. The data generated by the hybrid models preserve the characteristics of the historical data. The RBN is better than the DPN models. In the CHR, the sets of hedging trigger obtained from the YM gave an acceptable performance. The DHR reduces the number of reservoir empty conditions and hazards of droughts. The study reveals that the project may fail to fulfill the irrigation demands. DOI: 10.1061/(ASCE)0733-9496(2009)135:6(414) CE Database subject headings: Reservoir operation; Optimization: India; Water storage.

A conceptual examination of the energy impact of leaks in systems with storage is undertaken. Consideration of how leakage is experienced at the pump is followed by an analysis of how different leakage levels alter energy costs for a rudimentary system with three topological configurations: two with a storage tank located at different points, and one without storage. Additionally, two friction regimes are subsumed in the analysis. EPANET 2 simulations are used to determine system pressures, storage tank levels, energy costs, power consumption, and leakage volumes for all scenarios at live levels of leakage. Leaks increase operating costs in terms of lost water and extra energy consumption for all systems, and when a price pattern is implemented, the financial cost of energy can sometimes be traded off with actual energy consumption. Storage in a system does not guarantee lower energy use relative to direct pumping, and in some cases it may promote higher leakage due to elevated system pressures. The results, though system specific, suggest that the importance of leaks in a system with storage depends on a number of factors, especially the relative locations of system components and the pumping strategy. Thoughtful consideration of the latter can be instrumental in achieving operation that balances financial and energy conservation objectives. To further test key relationships, a representative network is briefly considered. In all cases, the percentage increase in energy cost is greater than percentage leakage when the same pressure requirements are met. DOI: 10.1061/(ASCE)0733-9496(2005)131:2(146) CE Database subject headings: Leakage: Energy consumption: Water storage: Water distribution: Pumped storage.

Investigation of small SDHW systems based on smart solar tanks are presented. The domestic water in a smart solar tank can be heated both by solar collectors and by means of an auxiliary energy supply system. The auxiliary energy supply system in this study electric heating elements heats up the hot-water tank from the top and the water volume heated by the auxiliary energy supply system is fitted to the hot-water consumption and consumption pattern. In periods with a large hot-water demand, the volume is large; in periods with a small hot-water demand, the volume is small. Two small SDHW systems, based on differently designed smart solar tanks and a traditional SDHW system were investigated by means of laboratory experiments and theoretical calculations. The investigations showed that the yearly thermal performance of SDHW systems with smart solar tanks is 5-35% higher than the thermal performance of traditional SDHW systems. Estimates indicate that the performance/cost ratio can be improved by up to 25% by using a smart solar tank instead of a traditional tank when the backup energy system is electric heating elements. Further, smart solar tanks are suitable for unknown, variable, large or small hot-water consumption and the risk of oversized solar heating systems and oversized tank volumes is reduced by using smart solar tanks. Based on the investigations it is recommended to start development of smart solar tank units with an oil-fired boiler or a natural gas burner as auxiliary energy supply system. Keywords: SDHW systems; Smart solar tanks; Smart control strategy; Experiments; Calculations

The economic value of stockpiled milled peat for fuel energy is dependent on its wet-weight water content when sold. Research into milled peat stockpile rewetting has shown that, while there is surface rewetting (a wet layer), there is also significant through-flow water movement into the center of the stockpile with associated zones (termed fingers) of water storage. A method of quantifying the importance of finger storage was developed using serial digital images obtained in the field. Results showed that the wetted volume within a stockpile was similar regardless of milled peat type ([approximately equal to] 40%), and that the internal wetting contributed up to 28 times more to final water content than the surface wet layer. Thus surface wet layers have relatively little economic impact when compared with finger storage. Field observation of through-flow indicated that a rivulet flow mechanism in conjunction with stockpile geometry contributes to the development of fingers.

Soil and water conservation is essential to the sustainability of Great Plains dryland agriculture. We hypothesized that cropping intensification improves the efficient use of precipitation. We evaluated long-term observations of soil water at three locations in eastern Colorado for a range of pan evaporations (1050-1900 mm), soils, and cropping systems. Soils at various locations were mostly of the Argiustoll subgroup except for one Ustochrept and one Haplargid, both at the higher evaporation location. Normal precipitation at the three locations ranges from 400 to 425 mm [yr.sup.-1]. Systems included a 2-yr winter wheat (Triticum aestivum L.)-fallow (WF) and more intense 3-yr winter wheat-corn (Zea mays L.)-fallow and winter wheat-sorghum [Sorghum bicolor (L.) Moench]-fallow and 4-yr rotations. To quantify the effectiveness of the intensified systems at utilizing precipitation, we introduce the System-Precipitation-Storage Index (SPSI) and System-Precipitation-Use Index (SPUI). Mean SPSI values were 0.19 and 0.28 for 2- and 3-yr systems, respectively, meaning that the fallow periods in the 3-yr rotation were collectively 47% more efficient at storing precipitation than fallow in WF. Inclusion of a summer crop, such as corn or sorghum, increased the fraction of precipitation allocated to growing-season crop production (i.e., SPUI) from 0.43 in WF to 0.56 (i.e., an increase of 30%) in 3-yr systems. The gains in efficient use of precipitation with intensification resulted from (i) reducing the frequency of the inefficient fallow preceding wheat, and (ii) using water for transpiration that would otherwise be lost during fallow through soil evaporation, runoff, and deep percolation.

Additional keywords: riparian zone, hydrology, infiltration, storage capacity, land management. Introduction Riparian zones are zones of vegetation adjacent to streams that serve to moderate environmental processes occurring between the catchment [...]

Nutrients such as nitrogen and phosphorus are distributed throughout the hydrologic environment in various forms. Whether in the atmosphere, as precipitation, or as surface and groundwater, the amounts and concentrations [...]

Explicit analytical mathematical models for use in water-quality simulation studies and management of distribution-system storage are developed. The proposed models can be used effectively for investigating the mixing characteristics of tanks and subsequent effects on water quality, and can directly supplement any of the existing distribution-system water-quality simulators. These models are formulated analytically from mass-balance principles, where specific hydrodynamic processes are modeled conceptually. The resulting models are simple to understand and implement and are well suited to the needs of those practicing engineers who wish to write and run their own programs. The performance of the models is illustrated by application to actualtank data taken from a previous paper. Enhancement of distribution-system water-quality management is a principal benefit of the developed models.

A procedure to calculate vertical hydraulic conductivities and inelastic and elastic specific storage in aquitards in compressible aquifers has been formulated. Deformation and effective stress graphs, which are plotted from ground water hydrographs and borehole extensometer data, are used to determine elastic and inelastic specific storage. Vertical hydraulic conductivity is calculated from the elapsed loading time, as obtained from the graphs, on the basis of Terzaghi's consolidation theory.

When utilized with a stochastic source of surface water for irrigation, groundwater may serve to mitigate fluctuations in the supply of water. The benefit corresponding to this service is the buffer value of groundwater. We show that the buffer value is positive. Numerical studies reveal that its magnitude can be significant. The paper also offers a characterization of groundwater extraction in such a setting.

Abstract: An approach for incorporating large-diameter wells into MODFLOW is presented. A transformation of transmissivity in the flow field is devised to simulate the well function for a large-diameter wells. Transformations for accounting for the well radius and well storage are also developed. Using these transformations, MODFLOW is used to obtain the drawdowns. It is observed that the flow to a large diameter well can be accurately modeled using the proposed transformations and MODFLOW. DOI: 10.1061/(ASCE)0733-9437(2008)134:3(414) CE Database subject headings: Aquifers; Wells; Numerical models; Transient flow; Drawdown; Water storage.

Yields from a proposed ground-water storage facility are evaluated using a nonlinear optimization model of the California State Water Project (SWP) and the Central Valley Project (CVP). Model constraints account for the major hydrologic, regulatory, and operational features of both projects, including mass continuity, facility capacities, regulatory standards, and delivery contracts. The model maximizes long-term SWP yields over a 70-year period, using a quarterly time step and assuming current facilities are in place. Maximum yields are recomputed for a second scenario that includes new ground-water storage in the North Las Posas Basin, located in Ventura County. Delivery increases associated with the new facility are computed as the difference in optimized project yields between the two model runs. Results indicate that the ground-water storage facility may increase the average annual yield of SWP by 6%.

Many authors have documented the minimal use of optimization in practical day-to-day multipurpose reservoir operations. The RiverWare decision support system is a flexible general river basin modeling tool that allows water resources engineers to both simulate and optimize the management of multipurpose reservoir systems for daily operations. This paper describes RiverWare's optimization capabilities and its use by Tennessee Valley Authority operations schedulers. Input data requirements include (1) physical and economic characteristics of the system; (2) prioritized policy goals; and (3) parameters for automatic linearization. RiverWare automatically generates and efficiently solves a multiobjective, preemptive linear goal programming formulation of a reservoir system. An advanced feature of RiverWare is that both the physical model of the river basin and the operating policy are defined and easily modified by the modeler through an interactive graphical user interface. Any modifications are automatically incorporated into the linear preemptive goal program. RiverWare's combination of detailed system representation, policy expression flexibility, and computational speed make it suitable for use in routine daily scheduling of large complex multiobjective reservoir systems.

There is a need for accurate and cost-effective methods to estimate the hydraulic properties of soils. Past work indicated measurements of a single hydraulic response will not necessarily result in unique and stable estimates of hydraulic parameters when the number of unknowns is more than two. Prior information regarding the parameters or additional measurements are needed for the estimation problem to be well posed. However, accurate prior information is seldom available due to variations of the hydraulic properties in space and time. This paper presents a method for estimating hydraulic properties from simultaneous measurements of soil water storage to a fixed depth as a function of time during constant flux infiltration, and steady-state pressure head readings using vertically installed multi-purpose time domain reflectometry probes (MTDR). Multi-purpose TDR probes have a porous steel cup at their ends allowing soil water storage and [Psi] to be simultaneously measured at the same location. Our parameter estimation is formulated by an inverse procedure which combines a weighted nonlinear least square method with analytical solutions for soil water content and pressure head as functions of depth and time during one dimensional infiltration. We analyze the possibility of using water storage data combined with the initial and steady-state pressure head readings for the purpose of estimating soil hydraulic properties. The uniqueness problem was analyzed by studying the behavior of response surfaces. The combination of water storage measurements during constant flux infiltration with an initial and a steady-state pressure head reading yielded unique and stable solutions of the inverse problem. The utility of the parameter estimation procedure is demonstrated using experimental and theoretical data.

(published in March-April 1998 issue, v. 36, no. 2: 198). The authors of the discussion raise three issues: 1. The uniqueness of the cylindrical source type curves with skin and [...]

Disease-causing microbes can effectively be eliminated from recycled water by storing it underground, says research scientists from the Commonwealth Scientific & Industrial Research Organization (CSIRO) in Australia. Researchers at CSIRO [...]