Water Demand Curves Research Articles

Dynamic Adaptive Environmental Flows (DAE‐Flows) to Reconcile Long‐Term Ecosystem Demands With Hydropower Objectives

AbstractThis study investigates how environmental flows (e‐flows) can be designed as dynamic operating policies to optimize long‐term economic and ecosystem performance in reservoir systems. The main goal is to provide e‐flow solutions that contribute to better preparedness and flexibility of hydro‐systems to face multiyear stress periods, reducing the impact of water crises. The methodology framework combines a fish‐flow model with a multi‐objective evolutionary algorithm to construct multiple environmental water demand curves and capture the opportunity cost of different levels of ecosystem preservation. The water demand curves applied to a stochastic dynamic hydro‐economic model then derive dynamic e‐flow policies that balance immediate and future water use tradeoffs. The approach, termed dynamically adaptive environmental flows (DAE‐flows), is demonstrated on the Paraná River Basin, Brazil, a large‐scale hydropower system. Results show that the approach can adjust e‐flows (coordinated with other hydro‐system releases) over the time horizon, sacrificing them at certain times at the expense of some ecosystem loss, but improving long‐term ecosystem functioning. A long‐term approach to adaptation also yields better results for the environment without imposing a hard constraint to hydropower during droughts. Even under a drier climate change scenario, this allowed maintenance and improvement of environmental performance in most years, so during severe droughts the water could still be reallocated to hydropower but at a lesser cost to the environment.

A Novel HydroEconomic - Econometric Approach for Integrated Transboundary Water Management Under Uncertainty

The optimal management of scarce transboundary water resources among competitive users is expected to be challenged by the effects of climate change on water availability. The multiple economic and social implications, including conflicts between neighbouring countries, as well as competitive sectors within each country are difficult to estimate and predict, to inform policy-making. In this paper, this problem is approached as a stochastic multistage dynamic game: we develop and apply a novel framework for assessing and evaluating different international strategies regarding transboundary water resources use, under conditions of hydrological uncertainty. The Omo-Turkana transboundary basin in Africa is used as a case study application, since it increasingly faces the above challenges, including the international tension between Kenya and Ethiopia and each individual country’s multi-sectoral competition for water use. The mathematical framework combines a hydro-economic model (water balance, water costs and benefits), and an econometric model (production functions and water demand curves) which are tested under cooperative and non-cooperative conditions (Stackelberg “leader–follower” game). The results show the cross-country and cross-sectoral water use—economic trade-offs, the future water availability for every game case, the sector-specific production function estimations (including residential, agriculture, energy, mining, tourism sectors), with nonparametric treatment, allowing for technical inefficiency in production and autocorrelated Total Factor Productivity, providing thus a more realistic simulation. Cooperation between the two countries is the most beneficial case for future water availability and economic growth. The study presents a replicable, sophisticated modelling framework, for holistic transboundary water management.

Current Conditions and Projected Changes in Crop Water Demand, Irrigation Requirement, and Water Availability over West Africa

Climate variability and change greatly affect agricultural and water resource management over West Africa. This paper presents the current characteristics and projected change in regional crop water demand (CWD), irrigation requirement (IR), and water availability (WA) over West Africa. Observed and simulated daily rainfall, minimum temperature, maximum temperature, and evapotranspiration are used to derive the above agro-meteorological and hydrological variables. For future periods, high-resolution climate data from three regional climate models under two different scenarios, i.e., representative concentration pathway (RCP) 4.5 and 8.5, are considered. Evaluation of the characteristics of present-day CWD, IR, and WA indicated that the ensemble mean of the model-derived outputs reproduced the prevailing spatial patterns of CWD and IR. Moreover, the wetter part of the domain, especially along the southern coast, was correctly delineated from the drier northern regions, despite having biases. The ensemble model also simulated the annual cycle of water supply and the bimodal pattern of the water demand curves correctly. In terms of future projections, the outcomes from the study suggest an average increase in the CWD by up to 0.808 mm/day and IR by 1.244 mm/day towards the end of the twenty-first century, compared to the baseline period. The hot-spot areas, where there is higher projected increment in CWD and IR, are over Senegal, Southern Mali, and Western Burkina Faso. In most cases, WA is projected to decrease towards the end of the twenty-first century by −0.418 mm/day. The largest decline in WA is found to be over Guinea and most of the eastern parts of West Africa. Despite the current under-utilization of the existing groundwater resources, the threat of global warming in reducing future WA and increasing CWD suggested caution on the scale of irrigation schemes and management strategies. The outcomes from the study could be a crucial input for the agricultural and water managers for introducing effective measures to ensure sustainability of irrigated farm lands.

Estimating Efficient Water Prices in the Sao Marcos River Basin: A Residual Imputation Approach

The conflicting demands for water used for irrigating crops, generating power, and supplying humans and livestock have placed many river basins around the world under stress. The competition for scarce water resources will be exacerbated by the impact of climate change. This article uses a residual imputation and net rents approach to obtain economic values and water demand curves of irrigators in Brazil’s Sao Marcos River Basin (SMRB). We estimate that current water prices must increase by over 230 times in the dry season to reduce the water consumption in the basin to the level that is required to accommodate its use to generate electricity as required by the water regulator. These estimated water prices are constrained efficient in the sense that they promote the efficient reduction in water consumption from the agricultural sector to satisfy the existing water permit granted for electricity generation.

Influence of crop-water production functions on the expected performance of water pricing policies in irrigated agriculture

Agricultural economics Water Programming Models (WPM) has found that irrigators in water scarce areas have a rather inelastic response to water prices, making water pricing cost-ineffective towards water saving. We hypothesize that the predicted water saving performance of pricing is significantly underestimated by issues of model structure, due to the exclusion of deficit irrigation from the set of decision variables available to agents in conventional WPM. To test our hypothesis, we develop a model that integrates a continuous crop-water production function into a positive multi-attribute WPM, which allows us to assess agents’ adaptive responses to pricing through deficit irrigation. The model is illustrated with an application to the El Salobral-Los Llanos irrigated area in Spain. Our results show that incorporating deficit irrigation as an adaptation option makes the water demand curve significantly more elastic as compared to an alternative model setting where deficit irrigation is precluded. We conclude that ignoring deficit irrigation can lead to a significant underestimation of the cost-effectiveness of water pricing towards water saving.

Modeling of a PV water supply system for different meteorological conditions

In this study, the behavior of a water supply system with PV technology was analyzed and modeled on different meteorological conditions. The photovoltaic water supply system, PVWSS, consists of a PV generator set, a frequency inverter, a motor pump and a storage system. This water supply system was thoroughly experimentally tested, on a test bench in real operating conditions (outdoor) in Recife, Brazil. The meteorological and geometric parameters of the system and its flow rates results were used to perform a modeling through ANN to estimate the pumped volume in function to meteorological conditions and the discharge heads. The ANN modeling predicted the flow rates with percentage deviation and normalized mean square error of − 0.6% and 6.85%, respectively. Using a residential water demand curve, the system was simulated for different meteorological conditions, resulting in a deficit of 0.2%, a unit cost of $0.29 per m3 pumped to a discharge head of 24 m with an optimum reservoir of 2 days of autonomy. This model can predict the flow rates for any location and weather conditions.

A METHOD FOR DEVELOPING IRRIGATION DECISION SUPPORT SYSTEMS de novo: EXAMPLE OF SESAME (Sesamum indicum L.) A KNOWN DROUGHT TOLERANT SPECIES

Irrigation decision support systems (DSS) are tools that can help achieve higher system level water use efficiency by more accurately targeting water application to crop need. They also have a role to play in preventing over-irrigation of drought tolerant crops that can be sensitive to flooded conditions. However, there are challenges in developing DSS for newly introduced crops in regions where they have not typically been produced. One such crop is sesame, a recently introduced drought tolerant crop in the southeastern United States where up to 50% of the agronomic crop production is irrigated. A first irrigation DSS, called SesameFARM1, was developed in 2013 by estimating a water demand curve using the Food and Agricultural Organization (FAO) crop coefficient (Kc) values, seasonal measures of the leaf area index (LAI) for the crop measured in 2012, and an estimated maximum rooting depth. On a daily time-step, SesameFARM1 estimated crop evapotranspiration using the product of the Kc and the ETo obtained from a local weather station, and an estimation of the maximum plant available water based on the available water capacity for the soil type and the maximum crop rooting depth. To improve SesameFARM1, LAI data from 6 years of field trials along with root data from a previous study were used to develop a breakpoint regression model for LAI and total functional root length. In SesameFARM2, the resulting curve for LAI was used to estimated continuous Kc values; and total measured functional root length replaced the estimation of maximum rooting depth in a new variable called root water access. SesameFARM2 performance was compared to SesameFARM1 using 6 years of weather data from Citra FL. SesameFARM2 consistently recommended less water be applied, and recommendations of water application during the senescence phase of the crop were reduced. Because of sesame’s inherent drought tolerance, a more conservative irrigation recommendation is likely more appropriate. Therefore, SesameFARM2 is likely a better model than SesameFARM1 and may help growers unfamiliar with sesame achieve irrigation higher irrigation crop water productivity.

Simulation of chlorine decay by waterhammer in water distribution system based on hypothetical water demand curve

Simulation of chlorine decay by waterhammer in water distribution system based on hypothetical water demand curve

Evaluation of water harvesting and managed aquifer recharge potential in Upper Fara' basin in Palestine: comparing MYWAS and water productivity approaches

The Upper Wadi Fara' basin, located at the West Bank, Palestine, has an average annual rainfall of 500 mm, which occurs only during winter. Agriculture uses stored soil water and complimentary irrigation from groundwater. Water harvesting (WH) and managed aquifer recharge (MAR) therefore is essential for sustainable water resources management in the basin. This study focuses on the comparison between two methods to determine best practices for WH/MAR. The first method uses the change in water productivity and can be considered a one parameter cost benefit analysis (CBA). The other method concerns the multi year water allocation system (MYWAS), which uses water demand curves to evaluate economic scenarios. It is concluded that the highest cost effectiveness of WH/MAR measures in upper Wadi Fara' basin is reached when water is stored as soil water. However, this is a politically disputed measure in the Israel-Palestine shared aquifer. Both models are useful tools in decisive stakeholder participation processes.

Evaluation of water harvesting and managed aquifer recharge potential in Upper Fara' basin in Palestine: comparing MYWAS and water productivity approaches

The Upper Wadi Fara' basin, located at the West Bank, Palestine, has an average annual rainfall of 500 mm, which occurs only during winter. Agriculture uses stored soil water and complimentary irrigation from groundwater. Water harvesting (WH) and managed aquifer recharge (MAR) therefore is essential for sustainable water resources management in the basin. This study focuses on the comparison between two methods to determine best practices for WH/MAR. The first method uses the change in water productivity and can be considered a one parameter cost benefit analysis (CBA). The other method concerns the multi year water allocation system (MYWAS), which uses water demand curves to evaluate economic scenarios. It is concluded that the highest cost effectiveness of WH/MAR measures in upper Wadi Fara' basin is reached when water is stored as soil water. However, this is a politically disputed measure in the Israel-Palestine shared aquifer. Both models are useful tools in decisive stakeholder participation processes.

Integrating complex economic and hydrologic planning models: An application for drought under climate change analysis

Climate change can affect a region's environment and economy through changes in water resource flows and allocations. The hydrologic and economic components of these impacts require complex models to reflect both the environment's physical and individuals' behavioral responses to climate change. This paper describes a model that combines the strengths of the State Wide Economic Agricultural Production Model (SWAP), an agricultural economic optimization model, and Water Evaluation and Planning (WEAP), a climate-driven hydrological model. A step function approximation of water demand curves from SWAP is used in an iterative search process to estimate crop land allocation based on annual regional water availability and economic value. SWAP value functions serve as input for an optimal discretization of water demand functions. The methodological integration of the SWAP and WEAP models creates the EconWEAP model. This paper shows the improved analytic ability of this integration by comparing agricultural revenues from WEAP vs. EconWEAP. Results for EconWEAP runs in the California's Central Valley show a significant increase in revenues for the Central Valley, maintaining the same hydrology, through the economically optimal allocation of water. This integration approach can be applied to other types of economic and hydrologic models.

Improving Allocative Efficiency of Scarce Water in Southern Alberta

Using a positive mathematical programming (PMP) model with improved ‘wide-scope’ calibration, this study demonstrates how allocative efficiency of scarce water could be improved in the Bow- and Oldman River Sub Basins (BRSB and ORSB) of Southern Alberta, where 12 irrigation districts, two cities and three major industrial/commercial users withdraw bulk of the surface water for irrigation, municipal, industrial and commercial needs. Earlier studies ironically neglected the larger ORSB even though it is subject to the same water licensing and regulation policies as the BRSB. The inclusion of nine irrigation districts and non-irrigation users of ORSB enables this model to estimate allocative efficiency gains in a more comprehensive manner than before. Results indicate that ORSB has a relatively less elastic water demand curve primarily due to its more reliance on irrigation and less water saving/supply options. It is also less responsive to allocations with alternative policies as reflected in net returns, land use and cropping pattern changes due to its less elastic water demand.

An assessment of farmers' willingness to participate in water trading in southern Spain

This study applies contingent valuation to assess farmers' willingness to trade irrigation water. We analyse farmers' willingness to pay for water and their willingness to accept the selling of water through a seasonal market, under both normal rainfall and drought conditions. A survey of 241 farmers (irrigators and non-irrigators) in the Guadalquivir River Basin and in the Mediterranean (Almanzora) Basin in southern Spain is used as a basis to construct the irrigation water supply and demand curves for both basins. Assuming that each basin operates as a single country, an international commerce framework is applied to study inter-basin trading. Results show that there is scope for both intra-basin and inter-basin markets. The equilibrium market price increases from 0.17 EUR/m3 in the baseline scenario to 0.21 EUR/m3 under drought conditions. These results are in line with observed market prices during 2006–2007. We also find a threshold volume under which start-up costs for irrigation infrastructure make it unprofitable for non-irrigators to enter the market. Finally, we conclude that farmers' ethical perspective of considering irrigation water as a non-tradable commodity constrains them from participating in such markets.

Smart meters for enhanced water supply network modelling and infrastructure planning

To design water distribution network infrastructure, water utilities formulate daily demand profiles and peaking factors. However, traditional methods of developing such profiles and peaking factors, necessary to carry out water distribution network modelling, are often founded on a number of assumptions on how top-down bulk water consumption is attributed to customer connections and outdated demand information that does not reflect present consumption trends; meaning infrastructure is often unnecessarily overdesigned. The recent advent of high resolution smart water meters allows for a new novel methodology for using the continuous ‘big data’ generated by these meter fleets to create evidence-based water demand curves suitable for use in network models. To demonstrate the application of the developed method, high resolution water consumption data from households fitted with smart water meters were collected from the South East Queensland and Hervey Bay regions in Australia. Average day (AD), peak day (PD) and mean day maximum month (MDMM) demand curves, often used in water supply network modelling, were developed from the herein created methodology using both individual end-use level and hourly demand patterns from the smart meters. The resulting modelled water demand patterns for AD, PD and MDMM had morning and evening peaks occurring earlier and lower main peaks (AD: 12%; PD: 20%; MDMM: 33%) than the currently used demand profiles of the regions’ water utility. The paper concludes with a discussion on the implications of widespread smart water metering systems for enhanced water distribution infrastructure planning and management as well as the benefits to customers.

Simulating water markets with transaction costs.

This paper presents an optimization model to simulate short-term pair-wise spot-market trading of surface water abstraction licenses (water rights). The approach uses a node-arc multicommodity formulation that tracks individual supplier-receiver transactions in a water resource network. This enables accounting for transaction costs between individual buyer-seller pairs and abstractor-specific rules and behaviors using constraints. Trades are driven by economic demand curves that represent each abstractor's time-varying water demand. The purpose of the proposed model is to assess potential hydrologic and economic outcomes of water markets and aid policy makers in designing water market regulations. The model is applied to the Great Ouse River basin in Eastern England. The model assesses the potential weekly water trades and abstractions that could occur in a normal and a dry year. Four sectors (public water supply, energy, agriculture, and industrial) are included in the 94 active licensed water diversions. Each license's unique environmental restrictions are represented and weekly economic water demand curves are estimated. Rules encoded as constraints represent current water management realities and plausible stakeholder-informed water market behaviors. Results show buyers favor sellers who can supply large volumes to minimize transactions. The energy plant cooling and agricultural licenses, often restricted from obtaining water at times when it generates benefits, benefit most from trades. Assumptions and model limitations are discussed.Key PointsTransaction tracking hydro-economic optimization models simulate water marketsProposed model formulation incorporates transaction costs and trading behaviorWater markets benefit users with the most restricted water access

Economic concepts to address future water supply–demand imbalances in Iran, Morocco and Saudi Arabia

In Middle East and North Africa (MENA) countries, renewable groundwater and surface water supply are limited while demand for water is growing rapidly. Climate change is expected to increase water demand even further. The main aim of this paper is to evaluate the water supply–demand imbalances in Iran, Morocco and Saudi Arabia in 2040–2050 under dry, average and wet climate change projections and to show on the basis of the marginal cost and marginal value of water the optimum mix of supply-side and demand-side adjustments to address the imbalance. A hydrological model has been used to estimate the water supply–demand imbalance. Water supply and demand curves have been used to explore for which (marginal value of) water usage the marginal cost of supply-enhancement becomes too expensive. The results indicate that in the future in all cases, except in Iran under the wet climate projection, the quantity of water demanded has to be reduced considerably to address the imbalance, which is indeed what is currently happening already.

Full cost recovery in the urban residential sector according to the Water Framework Directive

Full cost recovery is a major and complex issue that has gained high recognition in recent years. The Water Framework Directive promotes the idea that water charging should act as an incentive for the sustainable use of water resources. Thus, all Member States should take into consideration the principle of recovery of the total cost of water services, which includes environmental and resource costs as well. In order to evaluate various aspects of current water policy, to investigate the perspectives of water saving, to explore new approaches toward sustainable water management in the water supply sector and to evaluate water price elasticity, a survey has been performed recently in the city of Volos, concerning the residential sector. The influence of some selected variables is examined, residential water demand curve and water price elasticity are calculated. Estimations of future water demand under different pricing policies are also performed. Finally, the full water cost for the city of Volos is estimated and essential conclusions concerning water pricing and public participation are drawn.

Establecimiento de un precio óptimo ambiental y social para el agua de riego mediante la internalización de los costes ambientales y el uso de matrices de contabilidad social. Aplicación a la Comunidad Foral de Navarra

This work develops a methodology to obtain a “social ad environmental optimal price” for water in the Comunidad Foral de Navarra (CFN) in order to maximize the internalization of the water environmental cost generated by agricultural consumption without affecting the general level of the regional economy. The economical model is built over a Geographical Information System (GIS) that allows quantifying and valuing in economical terms environmental water costs in different basins. Elements that have been considered to describe the water resource value are volume, quality and hazard to affect aquatic and bank ecosystems. Values have been estimated with Environmental Economy methods. A demand curve for water is also built and a Social Accounting Matrix (SAM) is used to watch if regional economy supports a price that internalizes total water value. Potential water prices are established ranging from prices that minimize negative economic regional impacts –social optimal priceto those that internalize totally the environmental costs of water- environmetnal optimal price.

Estimating the own-price elasticity of demand for irrigation water in the Musi catchment of India

► A new and superior method of estimating the demand for water and its resultant own-price elasticity of demand. ► Using an accepted method to determine the data on the willingness-to-pay for water in a catchment. ► Understanding that a range of elasticity estimates exist for water used in a catchment. ► Coming to terms with the fact that a significant quantity of the water used in irrigation is perfectly elastic. ► Yet for some uses, water is highly price inelastic. As irrigation water is an input into a production process, its demand must be ‘derived’. According to theory, a derived demand schedule should be downward sloping and dependent on the outputs produced from it, the prices of other inputs and the price of the water itself. Problems arise when an attempt is made to estimate the demand for irrigation water and the resulting own-price elasticity of demand, as the uses to which water is put are spatially, temporarily and geographically diverse. Because water is not generally freely traded, what normally passes for an estimate of the own-price elasticity of demand for irrigation water is usually a well argued assumption or an estimate that is derived from a simulation model of a hypothesized producer. Such approaches tend to provide an inadequate explanation of what is an extremely complex and important relationship. An adequate explanation of the relationship between the price and the quantity demanded of water should be one that not only accords with the theoretical expectations, but also accounts for the diversity of products produced from water (which includes the management practices of farmers), the seasons in which it is used and over the region within which it is used. The objective in this article is to present a method of estimating the demand curve for irrigation water. The method uses actual field data which is collated using the Residual Method to determine the value of the marginal product of water deployed over a wide range of crops, seasons and regions. These values of the marginal products, all which must lie of the input demand schedule for water, are then ordered from the highest value to the lowest. Then, the amount of irrigation water used for each product, in each season and in each region is cumulatively summed over the range of uses according to the order of the values of the marginal products. This data, once ordered, is then used to econometrically estimate the demand schedule from which the own-price elasticity of demand for irrigation water can be derived. To illustrate the method, the values of the marginal product of water deployed in the Musi catchment in India are used to determine an own-price elasticity of demand for irrigation water which has some positive value to producers of approximately −0.64. For water that is most highly valued, the elasticity was found to be highly elastic at −2.12, while less valued water used in agriculture was far more inelastic at −0.44. Finally, for almost 36% of water deployed in the catchment the elasticity was logically determined to be perfectly elastic.

Establishment of Environmental Water in the Murray-Darling Basin: An Analysis of Two Key Policy Initiatives

Policy to protect river ecosystems has changed rapidly in Australia, and the mechanisms to both establish and manage environmental water are still evolving. Policy has moved from providing a fixed environmental target (albeit varying between years) to one in which the environment can actively participate in the market, with the possibility of better fulfilling variable water requirements. However, the inherent nature of the sustainable diversion limit (SDL), established under the Water Act 2007, is that it represents a fixed allocation to the environment. This paper considers the interaction of the new SDL for the Murray-Darling Basin and potential issues arising from the interaction with the government buyback initiative. While both the SDL and buyback have been discussed extensively, the interaction between the two policies has received little debate. Pairing these two policy initiatives will have implications for the flexibility of management of the environmental water, and the ability for on-going trade between the environment and consumptive water users. Our position is that the SDL, or preferably rules-based water, should reflect an absolute minimum limit on environmental water requirements, while the buyback should provide the environmental water as tradable water rights with the flexibility to respond to shifts in the environmental water demand curve by providing environmental water over and above the SDL. If both a buyback and minimum flow rules are in place, the SDL will provide little additional benefits but increase administrative costs and reduce flexibility. This has significant implications for the way the SDL and buyback strategy are structured.