Water Supply Constraints Research Articles

Reservoir operating rules to sustain environmental flows in regulated rivers

Sustainable water resource developments require reservoir operations that provide environmental flows (e‐flows) to support the downstream riverine ecosystem by minimizing the degree of hydrologic alteration under given water supply constraints. The effective management of e‐flows below dams was explored by combining three e‐flow management strategies for “normal,” wet, and dry year situations, delivering a range of e‐flow regimes for different reservoir storage levels and different natural flow (reservoir inflow) conditions. We combined these into a single combined e‐flow strategy and coupled this with reservoir operating rule curves to form a reservoir operating approach that optimized e‐flow provision under given water supply constraints. We also explored constraints imposed by the dam's valve release capacity. To investigate the capability of the approach to minimize the degree of hydrologic alteration downstream from a reservoir, we presented a case study of the Tanghe Reservoir in China's Tang river basin. The approach triggered a preferred e‐flow strategy when the reservoir water level was high to better maintain the ecological functions within downstream riverine ecosystems, a basic e‐flow strategy when the water level was low to reduce the water supply risk, and an acceptable strategy under intermediate conditions. The approach effectively balanced human and ecosystem needs and demonstrated the minimum levels of flow regime alteration achievable within the regulated river.

Closing the South Saskatchewan River Basin to New Water Licences: Effects on Municipal Water Supplies

The Alberta provincial government approved the Water Management Plan for the South Saskatchewan River Basin (SSRB) in August 2006. As a result of this plan, the Province stopped accepting applications for new allocations of water in the Oldman, Bow, and South Saskatchewan sub-basins in southern Alberta. This licence closure has had a significant effect on water supply strategies available to municipal water users, as many communities currently hold water licences that are not adequate for their projected growth. To meet additional water demands, these communities must reduce their water use, arrange water licence transfers, or purchase water from another licence holder. This paper describes how closing the SSRB to new water allocations has affected water supply planning for municipalities in the Calgary region in southern Alberta. It also discusses water supply and licence constraints and potential mitigation strategies, and examines the effects of the basin closure on water supply and land-use planning, and utility governance.

Thinking globally, acting locally — institutionalizing climate change at the local government level in Durban, South Africa

Durban is unusual among cities worldwide in having a municipal government that has developed a locally rooted climate change adaptation strategy. This paper considers how climate change came to be considered by local government against four institutional markers: the emergence of climate change advocates among local politicians and civil servants; climate change as a significant issue in municipal plans; staff and funds allocated to climate change issues; and a serious consideration of climate change issues within local government decision making. Considerable progress has been achieved on the second and third of these — but less so on the first and fourth. The paper highlights how climate change issues need to be rooted in local realities that centre on avoiding or limiting impacts from, for instance, heat waves, heavy rainfall and storm surges and sea-level rise, and also the ecological changes and water supply constraints brought about by climate change. To date, international agencies have paid little attention to adaptation, as the reduction of greenhouse gas emissions (mitigation) has been prioritized. This paper also stresses the importance of building local knowledge and capacity about climate change risks and adaptive responses. Without this, decision makers will continue seeing environmental issues as constraints on development rather than as essential underpinnings of and contributors to development.

The economic impact of restricted water supply: A computable general equilibrium analysis

Water problems are typically studied at the level of the river catchment. About 70% of all water is used for agriculture, and agricultural products are traded internationally. A full understanding of water use is impossible without understanding the international market for food and related products, such as textiles. The water embedded in commodities is called virtual water. Based on a general equilibrium model, we offer a method for investigating the role of water resources and water scarcity in the context of international trade. We run five alternative scenarios, analyzing the effects of water scarcity due to reduced availability of groundwater. This can be a consequence of physical constraints, and of policies curbing water demand. Four scenarios are based on a “market solution”, where water owners can capitalize their water rent or taxes are recycled. In the fifth “non-market” scenario, this is not the case; supply restrictions imply productivity losses. Restrictions in water supply would shift trade patterns of agriculture and virtual water. These shifts are larger if the restriction is larger, and if the use of water in production is more rigid. Welfare losses are substantially larger in the non-market situation. Water-constrained agricultural producers lose, but unconstrained agricultural produces gain; industry gains as well. As a result, there are regional winners and losers from water supply constraints. Because of the current distortions of agricultural markets, water supply constraints could improve allocative efficiency; this welfare gain may more than offset the welfare losses due to the resource constraint.

Development Of A Storm Runoff Simulator: Part 1 – Design Considerations

Evaluation of conservation buffers has relied primarily on small-scale plot (30 to 50 m2) studies with a limited range of buffer widths and field to buffer area ratios (BARs). Most studies used simulated runoff at steady flow rates. There is a need to evaluate conservation buffers installed at NRCS design widths and BARs to assess how well in-field buffers reduce nonpoint source pollution, especially for unsteady flow. The goal of this project is to develop a storm runoff simulator to distribute variable flow rates and contaminant concentrations across the upslope end of a buffer in a reproducible fashion. The simulator design should allow for easy transportation and adaptability to terrain and resource constraints found in the field. The SCS CN Method and the MUSLE were used to evaluate eight alternative combinations of BAR and buffer size. Buffer size ranged from 30 to 67.5 m2. Given the design constraints of less than 1 metric ton of soil per simulation, only a 1- 9-m plot size met the design criteria. Based on realistic constraints of a 7580-L available water supply, the final design constraints included a 7.3-L s-1 peak flow rate and 0.71 tons of soil, for a 1- 9-m plot, which allowed for BARs up to 49:1.

Short-Term Water Consumption Patterns in Ciudad Juárez, Mexico

Water utility planning efforts are becoming increasingly difficult throughout the world. Located in a semi-arid region, Ciudad Juarez, Mexico is a fast growing municipality that faces both physical infrastructure and water supply constraints. This paper examines monthly water consumption in Ciudad Juarez utilizing a linear transfer function procedure (LTF). Analysis is carried out for per customer usage and for the total number of municipal water system accounts. Models estimated for both series are subjected to a series of simulation benchmark tests. Findings suggest that water consumption in Ciudad Juarez reacts quickly to changes in economic and weather conditions. Out-of-sample simulation results are mixed. Per customer usage forecasts do not fare as well those for total customers relative to random walk benchmarks.

Water Market Characteristics: Results from a Survey of Southern Alberta Irrigators

In Alberta the passage of the Water Act of 1999 and the Irrigation Districts Act of 2000 enabled water license holders to transfer water rights on a permanent basis and water allocations on a temporary basis, establishing the foundation for water markets. This study explores water market activity in southern Alberta, focusing on the temporary transfer of water allocations by the region's dominant water consumer: irrigators. Irrigators in the region's largest irrigation district were surveyed. It was found that the characteristics of the water market conform to characteristics of water markets elsewhere. Most notable is that the market provided flexibility to producers to manage water during times of water supply constraints and in so doing, enhanced water productivity and efficiency. However, water market activity in southern Alberta is very limited and will likely remain so under the current water management regime.

Simulation and optimization model for irrigation planning and management

AbstractA simulation and optimization model was developed and applied to an irrigated area in Delta, Utah to optimize the economic benefit, simulate the water demand, and search the related crop area percentages with specified water supply and planted area constraints. The user interface model begins with the weather generation submodel, which produces daily weather data, which is based on long‐term monthly average and standard deviation data from Delta, Utah. To simulate the daily crop water demand and relative crop yield for seven crops in two command areas, the information provided by this submodel was applied to the on‐farm irrigation scheduling submodel. Furthermore, to optimize the project benefit by searching for the best allocation of planted crop areas given the constraints of projected water supply, the results were employed in the genetic algorithm submodel. Optimal planning for the 394·6‐ha area of the Delta irrigation project is projected to produce the maximum economic benefit. That is, projected profit equals US$113 826 and projected water demand equals 3·03 × 106 m3. Also, area percentages of crops within UCA#2 command area are 70·1%, 19% and 10·9% for alfalfa, barley and corn, respectively, and within UCA#4 command area are 41·5%, 38·9%, 14·4% and 5·2% for alfalfa, barley, corn and wheat, respectively. As this model can plan irrigation application depths and allocate crop areas for optimal economic benefit, it can thus be applied to many irrigation projects. Copyright © 2003 John Wiley & Sons, Ltd.

Minimum performance standards for showerheads in Australia: the benefits and the barriers

This paper discusses the potential merits and opportunities of introducing national minimum performance standards (MPS) for water efficient appliances, in particular showerheads. At a national level the introduction of MPS for showerheads by 2005 is expected to result in a reduction in the demand for water by over 79 GL/annum by 2015. The reduction in energy consumption associated with reduced water heating needs by water efficient showerheads is 7.7 million GJ/annum, while greenhouse gas emissions will be reduced by 1.3 million tonnes CO2/annum, by 2015. This initiative will generate benefits to an array of stakeholders. These benefits include: increased allocation of water for environmental flows, reduced demand on groundwater sources, reduced wastewater flows and associated pollution, and financial benefits to water utilities, particularly if the utility is experiencing water supply or wastewater treatment constraints. Regulation will also protect the investment (estimated to be of the order of $16 million) that a number of water utilities are making in incentive and retrofit programs. The most effective form of regulation to achieve the greatest outcomes in terms of reducing water and energy consumption and greenhouse gas emissions is a regulation that controls the supply of showerheads on the basis of flow rate. The MPS being proposed is 9 L/minute, and regulation would involve mandatory labelling of showerheads and compliance with the AAA-rating. The legislative options and challenge of introducing such a requirement within the current regulatory environment are discussed.

COMPARATIVE STUDY OF OPTIMIZATION TECHNIQUES FOR IRRIGATION PROJECT PLANNING1

ABSTRACT: This study presents three optimization techniques for on‐farm irrigation scheduling in irrigation project planning: namely the genetic algorithm, simulated annealing and iterative improvement methods. The three techniques are applied to planning a 394.6 ha irrigation project in the town of Delta, Utah, for optimizing economic profits, simulating water demand, and estimating the crop area percentages with specific water supply and planted area constraints. The comparative optimization results for the 394.6 ha irrigated project from the genetic algorithm, simulated annealing, and iterative improvement methods are as follows: (1) the seasonal maximum net benefits are $113,826, $111,494, and $105,444 per season, respectively; and (2) the seasonal water demands are 3.03*103 m3, 3.0*103 m3, and 2.92*103 m3 per season, respectively. This study also determined the most suitable four parameters of the genetic algorithm method for the Delta irrigated project to be: (1) the number of generations equals 800, (2) population size equals 50, (3) probability of crossover equals 0.6, and (4) probability of mutation equals 0.02. Meanwhile, the most suitable three parameters of simulated annealing method for the Delta irrigated project are: (1) initial temperature equals 1,000, (2) number of moves equal 90, and (3) cooling rate equals 0.95.

Guidelines for the design and control of intermittent water distribution systems

Water supply in many towns and cities is intermittent, with low and uneven pressures around the system. The guidelines described here help engineers design systems with a more equitable distribution of available water within the constraints of intermittent water supply.

Decision support for irrigation project planning using a genetic algorithm

This work presents a model based on on-farm irrigation scheduling and the simple genetic algorithm optimization (GA) method for decision support in irrigation project planning. The proposed model is applied to an irrigation project located in Delta, Utah of 394.6 ha in area, for optimizing economic profits, simulating the water demand, crop yields, and estimating the related crop area percentages with specified water supply and planted area constraints. The user-interface model generates daily weather data based on long-term monthly average and standard deviation data. The generated daily weather data are then applied to simulate the daily crop water demand and relative crop yield for seven crops within two command areas. Information on relative crop yield and water demand allows the genetic algorithm to optimize the objective function for maximizing the projected benefits. Optimal planning for the 394.6 ha irrigation project can be summarized as follows: (1) projected profit equals US$ 114,000, (2) projected water demand equals 3.03×10 6 M 3, (3) area percentages of crops within UCA#2 command area are 70.1, 19, and 10.9% for alfalfa, barley, and corn, respectively, and (4) area percentages of crops within UCA#4 command area are 41.5, 38.9, 14.4, and 5.2% for alfalfa, barley, corn, and wheat, respectively. Simulation results also demonstrate that the most appropriate parameters of GA for this study are as follows: (1) number of generations equals 800, (2) population sizes equal 50, (3) probability of crossover equals 0.6, and (4) probability of mutation equals 0.02.

Reduced growth and yield of wheat with conservation cropping. II. Soil biological factors limit growth under direct drilling

Wheat was grown in intact cores of soil removed from a field experiment in which seedlings had grown more slowly in direct-drilled soil than in cultivated soil. Experiments were conducted in controlled environments to resolve (1) whether shallower sowing of direct-drilled crops caused slower growth, (2) whether the soil factors causing the slower growth were physical or biological and (3) if biological, whether Rhizoctonia solani was the major pathogen. The conditions of the experiments removed possible constraints of water and nutrient supply but otherwise simulated the environment of wheat seedlings in southern Australia. Shallower sowing led to faster emergence and increased seedling growth, but irrespective of sowing depth, direct-drilled plants grew more slowly than plants in cultivated soil. Shoot growth of direct-drilled plants was 25-65% less than that of cultivated plants. These growth reductions were largely overcome by sterilizing the soil with y radiation or by fumigation with methyl bromide, indicating that biological factors were primarily responsible. Rhizoctonia was implicated as the cause of the reduced shoot growth when infection was severe (>3 on a 0-5 scale). There was no correlation between infection severity and shoot growth at moderate levels (<3) and significant reductions in shoot growth occurred in the absence of Rhizoctonia. These reductions were evident on the first leaf suggesting a direct influence on shoot growth rather than one mediated through inadequate uptake of water or nutrients. Infection of the germinating seed by Pythium spp. or the effects of phytohormones produced by inhibitory bacteria on the roots are possible causes of reduced shoot growth of direct-drilled seedlings. The dominant role of biological factors in determining plant response to soil management indicates the need for further studies to identify the organisms responsible, to determine the mechanism by which they influence shoot growth, and the effect of management on their populations and activity.

Land-based limitations and threats to world food production

The decreasing availability of new productive lands for agricultural use combines with many threats of degradation to lands now In productive use to pose serious challenges to scientists, planners and policy makers who aim to meet the ever expanding demand for food, fodder, fuel, and fibre around the globe. Constraints to productive land use may be physical or biological, natural or man-made. All prevent the realization of high and sustainable production goals, pdrticularly in the developing and less developed countries. Climate, topographic and water supply constraints are, in general, less manageable than are soil-based constraints; these can be alleviated by an abundance of available technologies. The current emphasis towards agricultural sustainability is very timely for countering the threats of degradation to the availability and productivity of land resources as well as the quality of the environment.

Water Analysis: A Systems Approach Incorporating Linear Programming

ABSTRACTThis paper reviews an interactive, policy‐oriented simulation model and introduces the addition of a water module. This module enables policymakers to estimate and analyze those direct and indirect socioeconomic effects on a regional economy, occurring over time, which are attributable to regional water supply constraints and water allocation decisions. In addition, this paper presents a hear‐programming‐based approach which can guide the user in making water parameter adjustments for a chosen objective. An empirical demonstration of the procedure based on the Minnesota state economy illustrates its usefulness.

Water Supply Constraints on Nigeria's Economic Development: The Example of Anambra State

Water Supply Constraints on Nigeria's Economic Development: The Example of Anambra State

Energy and Water

The geographic and temporal variability of freshwater supply in the United States constrains the choice and level of use of future energy sources. Ecological criteria for acceptable freshwater consumption, together with hydrological data on stream flow, provide a framework for estimating these constraints. The water consumption requirements for a variety of energy options are presented, and comparative judgments drawn. Attention is focused on problems resulting from synthetic, gaseous, and liquid fuel production. Scenarios describing possible future levels of coal and electricity use are analyzed. They point to the importance of water supply constraints in both the eastern and western United States.

Experiments on the Heaving Force of Freezing Soil

AbstractFrost heaving of soil is accompanied by a force which often causes severe damage to structures. It was suggested by Everett that this so-called “heaving force" can be attributed to the coexistence of ice and water in micropores among soil particles which characterize the soil type and can be computed thermodynamically. However, the actual heaving force changes in a complicated manner depending on various factors including freezing speed, constraining condition for a soil block, and, of course, soil type.Measurements of heaving force were carried out on various soil samples (sand, sandy loam, sandy clay loam, and two kinds of clays) under various freezing conditions: freezing speed in a range from 0.10 cm/h to 0.35 cm/h, presence or absence of water supply, complete or loose axial constraint applied to a soil block. In each experiment, soil was packed in a cylindrical container with a diameter of 11 cm and a height of 10 cm. A disk was placed on top of the soil contained in the container to constrain the sample either rigidly (a complete axial constraint) or less rigidly through a spring (a loose axial constraint). Main results of the measurements were as follows: (1)Under complete axial constraint, the heaving force decreased with decrease in the freezing speed and with the increase in the size of soil particles (from 6 bars to 1 bar for clay; from 4 bars to 1 bar for sandy clay loam; from 4 bars to 0.8 bar for sandy loam; from 1.5 bars to 0.6 bar for sand).(2)Without the constraint, the heave amount was almost independent of the freezing speed when there was no water supply (8 mm for clay; 6.5 mm for sandy clay loam; 3.5 mm for sandy loam; 1 mm for sand).(3)The heaving force decreased very rapidly with the loosening of the axial constraint by weakening the spring.The results indicate that it is practical to treat the heaving force phenomenologically as a kind of resistive force exerted by freezing soil on a container holding the soil. Because of a volumetric increase due to the transformation of water into ice at the freezing front, both unfrozen and frozen parts of the soil suffer some strain if the soil is somehow constrained by the container. The strains cause stresses which appear as the heaving force. A formula for the heaving force is given in which both the frozen and the unfrozen soil are treated as viscoelastic bodies.

Experiments on the Heaving Force of Freezing Soil

Abstract Frost heaving of soil is accompanied by a force which often causes severe damage to structures. It was suggested by Everett that this so-called “heaving force" can be attributed to the coexistence of ice and water in micropores among soil particles which characterize the soil type and can be computed thermodynamically. However, the actual heaving force changes in a complicated manner depending on various factors including freezing speed, constraining condition for a soil block, and, of course, soil type. Measurements of heaving force were carried out on various soil samples (sand, sandy loam, sandy clay loam, and two kinds of clays) under various freezing conditions: freezing speed in a range from 0.10 cm/h to 0.35 cm/h, presence or absence of water supply, complete or loose axial constraint applied to a soil block. In each experiment, soil was packed in a cylindrical container with a diameter of 11 cm and a height of 10 cm. A disk was placed on top of the soil contained in the container to constrain the sample either rigidly (a complete axial constraint) or less rigidly through a spring (a loose axial constraint). Main results of the measurements were as follows: (1) Under complete axial constraint, the heaving force decreased with decrease in the freezing speed and with the increase in the size of soil particles (from 6 bars to 1 bar for clay; from 4 bars to 1 bar for sandy clay loam; from 4 bars to 0.8 bar for sandy loam; from 1.5 bars to 0.6 bar for sand). (2) Without the constraint, the heave amount was almost independent of the freezing speed when there was no water supply (8 mm for clay; 6.5 mm for sandy clay loam; 3.5 mm for sandy loam; 1 mm for sand). (3) The heaving force decreased very rapidly with the loosening of the axial constraint by weakening the spring. The results indicate that it is practical to treat the heaving force phenomenologically as a kind of resistive force exerted by freezing soil on a container holding the soil. Because of a volumetric increase due to the transformation of water into ice at the freezing front, both unfrozen and frozen parts of the soil suffer some strain if the soil is somehow constrained by the container. The strains cause stresses which appear as the heaving force. A formula for the heaving force is given in which both the frozen and the unfrozen soil are treated as viscoelastic bodies.