Journal of Water Resources Planning and Management

This paper presents a linear programming model for optimal water allocations in a large river basin system. The model is applied to the transboundary Subernarekha River in India, which has two main stream reservoirs, two barrages, and three small command area reservoirs. The Tripartite Agreement (TPA) among the cobasin riparian states for sharing of its waters is analyzed. The main objective is to find the maximum annual benefits from irrigation and hydropower subject to various constraints on the system. Design constraints as per the TPA relating to the water shares among riparian states (i.e., Bihar, Orissa, and West Bengal) at individual dams and barrages are also considered. Optimal water allocations are obtained based on the 75% water year dependable flow as specified in the TPA. Water shortage and water surplus years have also been considered to determine optical water allocations during the dry and wet years, respectively. The stream reservoirs Chandil and Icha would fail to meet the water demands during the low flow years, whereas the Kharkai and Galudih barrages would essentially satisfy water demands according to the TPA provisions. Results indicate that Bihar is likely to benefit most from the TPA.

A water availability modeling system was implemented during 1997–2004 by the Texas Commission on Environmental Quality and its contractors, in collaboration with the water management community, under a mandate provided by comprehensive water management legislation enacted by the Texas legislature in 1997. The availability and reliability of water resources are assessed based on simulating river/reservoir system management and water allocation practices using sets of historical naturalized monthly streamflow sequences to represent basin hydrology. The prior appropriation water rights permit system and other institutional mechanisms for allocating streamflow and reservoir storage resources among numerous water users are considered in detail in evaluating basinwide impacts of water management decisions. The generalized modeling system and lessons learned in its implementation in Texas are applicable to river basin management throughout the world.

Simulation-optimization methods, applied with adequate senstivitivity tests, can provide useful quantitative guidance for controlling seawater intrusion. This is demonstrated in an application to the West Coast Basin of coastal Los Angeles that considers two management options for improving hydraulic control of seawater intrusion: increased injection into barrier wells and in lieu delivery of surface water to replace current pumpage. For the base-case optimization analysis, assuming constant groundwater demand, in lieu delivery was determined to be most cost effective. Reduced-cost information from the optimization provided guidance for prioritizing locations for in lieu delivery. Model sensitivity to a suite of hydrologic, economic, and policy factors was tested. Raising the imposed average water-level constraint at the hydraulic-control locations resulted in nonlinear increases in cost. Systematic varying of the relative costs of injection and in lieu water yielded a trade-off curve between relative costs and injection/in lieu amounts. Changing the assumed future scenario to one of increasing pumpage in the adjacent Central Basin caused a small increase in the computed costs of seawater intrusion control. Changing the assumed boundary condition representing interaction with an adjacent basin did not affect the optimization results. Reducing the assumed hydraulic conductivity of the main productive aquifer resulted in a large increase in the model-computed cost.

A conventional proportional integral (PI) controller is modified with a nonlinear activation function (sigmoid function) applied directly to the controller output in order to improve the stability and target fidelity of the system response to large variational inputs in both state and internal controller gain variables. The controller is implemented in a simulated water management role applied to a major subregional pumping station between Lake Okeechobee, the Loxahatchee National Wildlife Refuge (WCA1), and the West Palm Beach supply canal (C51) in the South Florida geographic region. The simulation consists of an integrated hydrological numerical model implemented in the Regional Simulation Model (RSM), which is currently under development at the South Florida Water Management District. Analysis of the modified controller in the Laplace domain establishes the expected control behavior, and subsequent results of the simulation for the conventional PI and the sigmoid modified controller are presented and compared. The modified controller achieves significant improvement in stability while simultaneously reducing the control signal energy.

In maintenance of a water distribution network, the allocation of limited funds for maintenance among a network’s pipes and the decision to repair or replace a single pipe when failure occurs are the most important issues. Although some researchers in the past have addressed these issues, more work is needed to support water authorities in making maintenance decisions. In this research paper, a mathematical model is developed that aims to support the decision to allocate funds among pipes of the network as well as the decision to repair or replace the pipes in the state of failure. The objective function of the model is to maximize the total weighted long-run availability of the whole system. The concept of hydraulic reliability is employed to determine the weight of pipes in the maintenance program. The deterioration behavior of the pipe is depicted by a semi-Markov process, and the Dantzig–Wolfe decomposition algorithm is applied to deal with the large-scale characteristic of the resulting program.

An optimization method for urban wet-weather control (WWC) strategies is presented. The developed optimization model can be used to determine the most cost-effective strategies for the combination of centralized storage-release systems and distributed on-site WWC alternatives. The two major components of the model are an objective function that evaluates the cost of a given option and a process simulator that describes the production function. The data for developing the production function are generated by running process simulation models that provide estimates of performance for specified values of the inputs. In earlier research, a prespecified number of simulations were run and then an analytical function was fitted to the database. Typically, the fitted function did not approximate the data well, and manual graphical procedures or numerical analysis software had to be used to approximate the response surface. This paper presents a much improved version of this approach wherein an optimizer is used to direct the simulation process toward the optimal solution. Even more important, the results can be extended from three-dimensional problems to $n$ -dimensional problems.

Sudden pipe breaks occur in water transmission pipelines and distribution mains. The consequences of these breaks can be very expensive because of the service interruption, the cost of repair, and damage to surrounding property and infrastructure. The costs associated with the pipeline breaks can be reduced by minimizing the break detection and location time. This paper presents a new continuous monitoring approach for detecting and locating breaks in pipelines. A sudden pipe break creates a negative pressure wave that travels in both directions away from the break point and is reflected at the pipeline boundaries. Using the pressure data measured at one location along the pipeline, the timing of the initial and reflected transient waves induced by the break determines the location of the break. The magnitude of the transient wave provides an estimate of the break size. The continuous monitoring technique uses a modified two-sided cumulative sum (CUSUM) algorithm to detect abrupt break-induced changes in the pressure data. The adaptive tuning of CUSUM parameters is implemented to detect breaks of differing sizes and opening times. The continuous monitoring technique is verified by using results from both laboratory and field experiments and shows potential for detecting and locating sudden breaks in real pipelines.

Presented herein is an attempt to put into practice the multicriteria decision making technique of compromise programming for a real urban water management case study in the city of Zahidan in Iran. Zahidan, the capital of Sistan and Balouchistan Province, faces serious water problems in terms of both quality and quantity. To satisfy future water demands, a long-distance water transmission project is being implemented. Compromise programming is applied to aiding decision makers in selecting the best possible alternatives for distribution of both available and the transmitted water in the city. The results obtained reveal that the method is capable of being employed by decision-makers for comprehensive urban water management studies.