Tradable water saving certificates to improve urban water use efficiency: an ex‐ante evaluation in a French case study

This paper proposes a system of tradable Water Saving Certificates to improve the efficiency of water allocation between Drinking Water Utilities at river basin level. A market institutional set‐up, inspired from recent policy developments in the energy sector, is proposed. An original analytical price‐endogenous model is developed to simulate trade intensity, equilibrium price and efficiency gains in this urban water market. The economic model is implemented in a French case study using mathematical programming. It is used for conducting an ex‐ante evaluation of trade possibilities and efficiency gains, considering different spatial restrictions aimed at controlling environmental externalities. Our modelling exercise provides evidence of the benefits of the proposed Water Saving Certificate scheme.     

Spot water markets and risk in water supply

Water availability patterns in semiarid regions are typically extremely variable. Even in basins with a highly developed infrastructure, users are subject to unreliable water supplies, incurring substantial economic losses during periods of scarcity. More flexible instruments, such as voluntary exchanges of water among users, can help users to reduce risk exposure. This article looks at the effects of spot water markets on the economic risk caused by water availability variations. Our theoretical and empirical risk analyses are based on the random profits of water users. Profit probability density functions are formally and graphically characterized for both water sellers and buyers under several possible market outcomes. We conclude from this analysis that, where water supply is stochastic, water markets unambiguously reduce both parties' risk exposure. The empirical study is conducted on an irrigation district in the Guadalquivir Valley (Southern Spain), where there is a high probability of periods of extreme water scarcity. Water demand functions for the district representative irrigators and a spatial equilibrium model are used to simulate market exchanges and equilibrium. This programming model is combined with statistical simulation techniques. We show that the profit probability distribution of a representative irrigator is modified if water exchanges are authorized, leading to risk reductions. Results also indicate that if the market were extended to several districts and users that are subject to varying hydrological risk exposure, extremely low‐profit events would be less likely to occur. In sum, we show that exchanging water in annual spot markets can reduce farmers' economic vulnerability caused by water supply variability across irrigation seasons. These results support the water policy reform carried out in Spain in 1999 to allow for voluntary water exchanges among right holders.     

Reconciling sustainability and discounting in Cost–Benefit Analysis: A methodological proposal

The incorporation of the intergenerational equity objective has rendered the traditional Cost–Benefit Analysis (CBA) approach obsolete for the evaluation of projects presenting an important number of environmental externalities and for those whose impacts extend throughout a long period of time.Based on the assumption that applying a discount rate rewards current consumption and, therefore, that it is only possible to introduce a certain intergenerational equity in a Cost–Benefit Analysis, in this work we propose an approach to discounting based on a different rationale for tangible and intangible effects. We designed two indicators of environmental profitability: a) the Intergenerational Transfer Amount (ITA), which quantifies in monetary units what the current generation is willing to pass on future generations when an environmental restoration project is carried out, and b) the Critical Environmental Rate (CER), measures the implicit environmental profitability.These concepts were tested through an empirical case study pertaining to the assessment of an Erosion Control Project in the southeast of Spain. The results yield traditional profitability indicators that are higher — and probably closer — to the real values set by the contemporary society. The information provided by the environmental profitability indicators proposed renders more transparency to the quantification of the levels of intergenerational equity applied, thereby facilitating the difficult reconciliation of the CBA technique with the objective of sustainability.     

Optimisation of water procurement decisions in an irrigation district: the role of option contracts

Water supply instability is one of the main risks faced by irrigation districts and farmers. Water procurement decision optimisation is essential in order to increase supply reliability and reduce costs. Water markets, such as spot purchases or water supply option contracts, can make this decision process more flexible. We analyse the potential interest in an option contract for an irrigation district that has access to several water sources. We apply a stochastic recursive mathematical programming model to simulate the water procurement decisions of an irrigation district's board operating in a context of water supply uncertainty in south‐eastern Spain. We analyse what role different option contracts could play in securing its water supply. Results suggest that the irrigation district would be willing to accept the proposed option contract in most cases subject to realistic values of the option contract financial terms. Of nine different water sources, desalination and the option contract are the main substitutes, where the use of either depends on the contract parameters. The contract premium and optioned volume are the variables that have a greater impact on the irrigation district's decisions.     

Designing Policy for Reducing the Off‐farm Effects of Soil Erosion Using Choice Experiments

Soil erosion produces both on‐site private costs and off‐site social costs, such as desertification, rural depopulation, siltation of waterways and reductions in biodiversity. To design efficient policies, land use planners and decision makers need information on the relative weights of changes in these consequences, since policy alternatives, such as different management restrictions, will have varying impacts on these consequences of erosion. The research presented here uses the choice experiment method to evaluate these relative weights, using a case study in the Alto Genil and Guadajoz watersheds in southern Spain. We find that reductions in desertification, protection of water quality, protection of biodiversity, the area covered by the scheme, and the number of rural jobs safeguarded are all significant determinants of preferences over alternative policy designs.