Journal of Water Resources Planning and Management

Rapid economic development in the countries of the Arabian Peninsula has resulted in a substantial imbalance between the available water resources and demand. Demand has increased from 5.95 billion to 22.6 billion m ³ in the ten year period 1980–1990. Ambitious agricultural programs and the absence of conservation measures have lead to significant overdraft of the existing water resources. If current practices continue, water demand may reach 35.4 billion m ³ by the year 2010. Considerable volumes will have to be mined from nonrenewable ground-water reserves. In this paper, water supply and demand problems for each country of the Arabian Peninsula are examined. Projections for water supply and future demands are made. Suggestions for comprehensive water planning are made that emphasize conservation measures and optimum allocation both within and between countries.

This paper illustrates a methodology for the simplification of complicated hydraulic networks. The aim is to create a small hydraulic network that will in certain ways mimic the behavior of a larger network. The approach used is based on nonlinear programming to minimize a measure of the difference between the original and the simplified networks. As an illustration of this technique, a particular example drawn from part of the London distribution network is investigated. We discuss the accuracy that can be obtained by using different numbers of nodes in the simplified network.

The validation of a water-quality model for the Seneca River, a deep, stratifying, slow-moving river located in central New York, is documented. Model validation is supported by comprehensive field monitoring and kinetic experiment programs, and a mass-transport model. The river is severely impacted by the inflow from ionically polluted hypereutrophic Onondaga Lake. Chemical-based density stratification is induced in the river, and attended by violations of dissolved oxygen (DO) and free ammonia standards in the lower layer of the river. The model performed well in matching DO depletions in the lower layer of the river, and diurnal variations in DO. Model projections demonstrate DO standards can only be met by eliminating chemical stratification in the river. The water-quality model is to be used to support regional planning of domestic waste treatment and disposal, including diversion of a major discharge to the river.

Mathematical models are developed for determining optimum reservoir releases in order to minimize the aggradation and degradation in downstream river reaches. The physical system is composed of a reservoir-river interaction in which the releases from the reservoir comprise the inflows for the downstream river reach. A finite-difference scheme of sediment routing is adopted to determine the changes of bed profile along the river. The nonlinear programming problem is solved using a nonlinear programming solver, a dynamic programming (DP) procedure, and a differential dynamic programming (DDP) procedure. Four sediment transport functions have been used in order to evaluate and test the validity of the formulation. Chance-constrained formulations are also presented to consider the uncertainties of sediment transport parameters used in the modeling. A rectangular channel is used for the purpose of illustrating the procedure, which is a preliminary step toward the application of the methodology to a large existing system.

A water-supply-distribution-system planning model has been developed using a directed graph algorithm as its pre- and postprocessors and a linear programming (LP) procedure as an “intelligent” system operator at its core. The directed graph, as a preprocessor, is used to produce a mathematical representation of the distribution system in question, to check the consistency and correctness of the network topology before an input file is created for the LP procedure. In the postprocessing mode, the directed graph generates files for graphical displays of model results and performs graph analyses such as depth- and breadth-first traversals, cut-set and connectivity for evaluating water-quality blending, tracking of source-to-demand contributions, system reliability, and lifeline objectives. Unlike the conventional formulation of a resource-allocation problem, the demand requirements, storage capacities, and other system constraints are removed from the constraint set and translated into a composite objective function. This methodology was successfully applied to the Metropolitan Water District of Southern California's (MWD's) distribution system. The results indicate that the combination of using an LP procedure and graph algorithm is a very versatile tool for solving large-scale water-distribution problems. This paper documents the concept used in developing the system-planning model and the results of its application to a simplified example as well as application to four case studies involving the entire MWD's distribution system.

Most states have adopted some form of instream-flow–protection program. These programs are of three types: instream-flow water rights; reservations of water for instream purposes; and conditions on consumptive water rights. No matter which type of protection program is adapted, the same question remains: How can we tell if it works? Several authors have attempted to answer this question. The works of these analysts are reviewed and criteria are suggested to evaluate the success of an instream-flow–protection program. The criteria are public confidence, certainty, proper administration, expense, and outcome in-stream.

Seasonal waste discharge (SWD) programs allow different waste-discharge rates during different seasons of the year and reduce the cost of waste treatment. The efficiency of such programs for managing biochemical oxygen demand (BOD) and dissolved oxygen (DO) may be affected by reduced reaeration and slowed BOD decomposition on river systems that have ice-cover conditions. This paper presents a modified SWD program for managing BOD and DO in river systems that have ice cover during certain periods of the year. The program designs a set of seasonal uniform treatment removal levels such that the average percent removal over the year is minimized and the risk of water-quality violation is equal to that which would occur under a nonseasonal waste-discharge program. The uniform treatment levels during the ice-covered period are evaluated by simulating water quality based on reaeration coefficients that are nearly zero. Application of this program to a section of the St. John River indicates that the treatment levels for the ice-covered season are not the highest treatment levels required during the year. This suggests that the water-quality responses resulting during the ice-cover period are not the most critical conditions for the St. John River. A sensitivity analysis shows that such results occur even when the BOD decay rate is increased to a high value during the ice-covered period. Evaluation of two- and four-season SWD programs for the St. John River indicate that in the two-season case there is no advantage to separating the ice-covered period from other times of the year and that only marginal savings can be achieved by using a four-season program instead of a two-season program.