Solving the Salinity Control Problem in a Potable Water System

Abstract. Salinity is the relative concentration of salts in water. In a city of southern China, the local water supply company pumps water from a nearby river for potable use. During the winter dry season, the intrusion of sea water raises the salinity of the river to a high level and affects approximately the daily life of 450,000 residents of the city. This paper reports the application of constraint programming (CP) to optimize the logistical operations of the raw water system so as to satisfy the daily water consumption requirement of the city and to keep the potable salinity below a desirable level for as many days as possible. CP is the key to the success of the project for its separation of concerns and powerful constraint language that allows for rapid construction of a functional prototype and production system. Flexibility and adaptiveness allow us to deal with our clients' many changes in the requirements. Deriving good variable and value ordering heuristics, and generating useful implied constraints, we demonstrate that branch-and-bound search with constraint propagation can cope with an optimization problem of large size and great difficulty

The aquatic biota of the now extinct lacustrine complex of the Mexico basin

The commonest organisms of the original Mexico lake complex are listed, including those that exist today in the Lago Viejo. In addition, a brief hydraulic history of this endorheic basin is given

Alternative Water Supplies for Arid Areas

Water is an essential component of growth and life; unfortunately, many countries face growing challenges in providing safe water. This has created a need for alternatives in the ways water can be treated, saved, or reused. In this paper, four alternative water supplies are reviewed: desalination, grey water reuse, harvesting of rainwater, and harvesting of stormwater. These alternatives are examined in terms of their advantages and disadvantages, the waste by-products, other pollution that can be produced by them, and how to handle each one. To accomplish this, brief information about each alternative, what technologies are used for water treatment, and the advantages and disadvantages for each technology are provided

Use of Reclaimed Water in China: management issues and strategies

As one of the fastest economic growing country in the world, China faces many water challenges. While there is no magic bullet to solving those challenges, a diversified selection of alternative water resources to help stretch traditional freshwater supplies is one of the optimal solutions. For this reason, the view of managing wastewater is moving from safe disposal of the treated product to incorporating it into the water supply. Since reclaimed water is increasingly consider being a valuable resource, the management of reclaimed water is also going to play a significant role in China’s future water management. This paper aims to give an overview of reclaimed water used activities in China and outline some issues arise from the management defect. And the innovative management strategies relevant to the management that put forward in this paper may become a part of the journey towards sustainable management of water resources in China. Key words: Reclaimed water; Historic and modern applications; Issues; Strategie

Study of Potential Integrated Management of Water Resources in Las Vegas Valley

Water resource management under short term system perturbations such as storms and longer-term systemic changes caused by climate change such as droughts is a challenge when multiple agencies are involved. To address this challenge this research focuses on water management under changing climate conditions and population growth through understanding the agency water jurisdictions, management strategies, and modes of operation in Las Vegas Valley. A framework for integrated management through sharing data and models is presented that combines drinking water supply, flood control, and waste water treatment. This framework can be adopted to improve coordination among different water management agencies

SLIDES: Last in Line: Environmental Impacts of Increased Colorado River Stress and Shortages

Presenter: Michael Cohen, Pacific Institute. 35 slides and 34 pages (includes color illustrations and map)

SLIDES: Last in Line: Environmental Impacts of Increased Colorado River Stress and Shortages

Presenter: Michael Cohen, Pacific Institute. 35 slides and 34 pages (includes color illustrations and map)

Risk Assessment for National Natural Resource Conservation Programs

This paper reviews the risk assessments prepared by the U.S. Department of Agriculture (USDA) in support of regulations implementing the Conservation Reserve Program (CRP) and Environmental Quality Incentives Program (EQIP). These two natural resource conservation programs were authorized as part of the 1996 Farm Bill. The risk assessments were required under the Federal Crop Insurance Reform and Department of Agriculture Reorganization Act of 1994. The framework used for the assessments was appropriate, but the assessments could be improved in the areas of assessments endpoint selection, definition, and estimation. Many of the assessment endpoints were too diffuse or ill-defined to provide an adequate characterization of the program benefits. Two reasons for this lack of clarity were apparent: 1) the large, unprioritized set of natural resource conservation objectives for the two programs and 2) there is little agreement about what changes in environmental attributes caused by agriculture should be considered adverse and which may be considered negligible. There is also some "double counting" of program benefits. Although the CRP and EQIP are, in part, intended to assist agricultural producers with regulatory compliance, the resultant environmental benefits would occur absent the programs. The paper concludes with a set of recommendations for continuing efforts to conduct regulatory analyses of these major conservation programs. The central recommendation is that future risk assessments go beyond efforts to identify the natural resources at greatest risk due to agricultural production activities and instead provide scientific input for analyses of the cost-effectiveness of the conservation programs.

Water Scarcity, Marketing, and Privatization

Most Americans take water for granted. Turn on the tap and a limitless quantity of high quality water flows for less money than it costs for cable television or a cell phone. The current drought has raised awareness of water scarcity, but most proposals for dealing with drought involve quick fixes-short-term palliatives, such as bans on washing cars or watering lawns except on alternate days. It is assumed that things will return to normal, and we will be able to wash our cars whenever we wish. But the nation's water supply is not inexhaustible. A just-released report of a White House subcommittee ominously begins: "Does the United States have enough water? We do not know." In a survey of states conducted by the U.S. General Accounting Office, only 14 states reported that they did not expect to suffer water shortages in the next 10 years. Is the sky falling? Not yet, but the United States is heading toward a water scarcity crisis: our current water use practices are unsustainable, and environmental factors threaten a water supply heavily burdened by increased demand. As the demand for water outstrips the supply, the stage is set for what Jared Diamond would call a collapse. How will we respond? When we needed more water in the past, we built a dam, dug a canal, or drilled a well. With some exceptions, these options are no longer viable due to a paucity of sites, dwindling supplies, escalating costs, and environmental objections. Instead, we are entering an era in which demand for new water will be satisfied by reallocating and conserving existing sources. The current water rights structure is the outcome of historical forces that conferred great wealth and power along with the water. The solution to tomorrow's water shortages will require creative answers to challenging issues of equity, community, and economics