Construction et évaluation expérimentale d'une sanction collective différenciée adaptée aux prélèvements diffus d'eau agricole

International audienceLes prélèvements d'eau souterraine à des fins d'irrigation sont parfois méconnus, car non déclarés ou non mesurés par des compteurs d'eau. Nous présentons ici un instrument de gestion qui vise à la fois à inciter les agriculteurs à déclarer leurs forages, à installer des compteurs et à garantir le respect d'un volume prélevable défini à l'échelle d'une unité de gestion hydro-géologiquement cohérente, suivant en cela les prescriptions de l'article 21 de la Loi sur l'Eau et les Milieux Aquatiques de 2006. Ces prélèvements présentent un contexte informationnel proche de celui des pollutions diffuses. La littérature économique propose alors une gestion se basant sur l'observation du comportement agrégé des irrigants : la sanction collective (Segerson 1988). S'il y a dépassement d'un niveau piézométrique de référence préétabli et connu des irrigants, chacun se voit imposé une sanction proportionnelle au dépassement de ce niveau. Cet instrument soulève des questions d'application pratiques et politiques : (1) il est peu acceptable politiquement car injuste : un irrigant vertueux peut payer la sanction alors qu'il supporte déjà les coûts associés à la réduction de ses prélèvements d'eau ; (2) la sanction peut être perçue par un irrigant comme une charge fixe si beaucoup d'irrigants sont concernés ; elle n'incite alors pas à réduire ses prélèvements. Nous nous inspirons de cet instrument pour développer une sanction collective différenciée (partie 1) que nous avons évaluée expérimentalement avec des étudiants, institutionnels et agriculteurs (partie 2)

From a blind truncheon to a one-eyed stick: testing in the lab an optional target-based mechanism adapted to groundwater withdrawals

International audienceThis paper proposes an optional target-based mechanism to improve the management of groundwater withdrawals when farmers’ behavior is imperfectly monitored. It combines a classical ambient tax (a blind truncheon), paid by the group of farmers when the water table level falls below a pre-defined target, with an optional individual contract that enables signatory farmers to signal their withdrawals and to avoid the collective sanction if they comply with an individual quota (a one-eyed stick). This mechanism is expected to be more acceptable than the ambient tax and to help reduce information asymmetries between the regulator and farmers. It is tested experimentally in the lab with a contextualized protocol. First results show that such mechanism reduces withdrawals but that subjects are able to coordinate in a repeated setting to extract an informational rent

One Hundred Years of Observations of the Be Star HDE 245770 (the X-ray Binary A0535+26/V725 Tau): The End of an Active Phase

UBV observations of the X-ray binary system A0535+26/V725 Tau at the Crimean Station of the Sternberg Astronomical Institute in 1980-1998 are presented. Based on our and published data, we analyze the photometric history of the star from 1898.Comment: Translated from Pis'ma Astronomicheskii Zhurnal, Vol. 26, No. 1, 2000, pp. 13-2

Advanced methods for analyzing in-situ observations of magnetic reconnection

There is ample evidence for magnetic reconnection in the solar system, but it is a nontrivial task to visualize, to determine the proper approaches and frames to study, and in turn to elucidate the physical processes at work in reconnection regions from in-situ measurements of plasma particles and electromagnetic fields. Here an overview is given of a variety of single- and multi-spacecraft data analysis techniques that are key to revealing the context of in-situ observations of magnetic reconnection in space and for detecting and analyzing the diffusion regions where ions and/or electrons are demagnetized. We focus on recent advances in the era of the Magnetospheric Multiscale mission, which has made electron-scale, multi-point measurements of magnetic reconnection in and around Earth's magnetosphere.Comment: submitted to Space Science Reviews (116 pages, incl. 31 figures, 7 tables

Controlling Groundwater Exploitation Through Economic Instruments: Current Practices, Challenges and Innovative Approaches

Groundwater can be considered as a common-pool resource, is often overexploited and, as a result, there are growing management pressures. This chapter starts with a broad presentation of the range of economic instruments that can be used for groundwater management, considering current practices and innovative approaches inspired from the literature on Common Pool Resources management. It then goes on with a detailed presentation of groundwater allocation policies implemented in France, the High Plains aquifer in the USA, and Chile. The chapter concludes with a discussion of social and political difficulties associated with implementing economic instruments for groundwater management

Disentangling the complexity of groundwater dependent social-ecological systems

Groundwater resources are part of larger social-ecological systems. In this chapter, we review the various dimensions of these complex systems in order to uncover the diversity of elements at stake in the evolution of an aquifer and the loci for possible actions to control its dynamics. Two case studies illustrate how the state of an aquifer is embedded in a web of biophysical and sociopolitical processes. We propose here a holistic view through an IGM-scape that describes the various possible pathways of evolution for a groundwater related social-ecological system. Then we describe the elements of this IGM-scape starting with physical entities and processes, including relations with surface water and quality issues. Interactions with society bring an additional layer of considerations, including decisions on groundwater abstraction, land use changes and even energy related choices. Finally we point out the policy levers for groundwater management and their possible consequences for an aquifer, taking into account the complexity of pathways opened by these levers

A broader role for AmyR in Aspergillus niger: regulation of the utilisation of d-glucose or d-galactose containing oligo- and polysaccharides

AmyR is commonly considered a regulator of starch degradation whose activity is induced by the presence of maltose, the disaccharide building block of starch. In this study, we demonstrate that the role of AmyR extends beyond starch degradation. Enzyme activity assays, genes expression analysis and growth profiling on d-glucose- and d-galactose-containing oligo- and polysaccharides showed that AmyR regulates the expression of some of the Aspergillus niger genes encoding α- and β-glucosidases, α- and β- galactosidases, as well as genes encoding α-amlyases and glucoamylases. In addition, we provide evidence that d-glucose or a metabolic product thereof may be the inducer of the AmyR system in A. niger and not maltose, as is commonly assumed

Gestion économique d’une ressource commune sous hypothèses d’information imparfaite et de substituabilité : le cas de l’exploitation de l’aquifère multicouche de la plaine du Roussillon par le secteur agricole

The allocation of water supply is a key issue for the development of the Languedoc-Roussillon region. Agriculture withdraws on both surface and groundwater systems and represents an important part of water consumptions. While surface water withdrawals are generally well managed, groundwater is often withdrawn by farmers away from the gaze of authorities. Following an applied approach, this study aims at designing and assessing groundwater management instruments that are acceptable for the agricultural sector, tailored to multi-resource systems and effective in a context of imperfect information. We develop an empirical methodology combining mathematical programming, lab and field experiments and post-experiment debriefing with stakeholders. This methodology is carried out in the Roussillon floodplain. On the theoretical side, we extend the literature on nonpoint source pollution management by ambient taxes to the case of groundwater withdrawals under imperfect information. We develop the so-called “differentiated ambient tax”, a management tool relying on information disclosure and combining a quota system, an ambient tax and a control of individual withdrawals within a contractual approach. The instrument performs relatively well theoretically and in the lab in terms of both effectiveness and equity. Our methodology however points out some field-related limitations to the implementation of the differentiated ambient tax. First, the informational problem may remain unsolved due to mistrust between stakeholders. Second, authorities seem to be practically unable to undertake controls and sanctions at an incentive level. Third, the principle of ambient tax is rejected by groundwater users.Le partage de la ressource en eau est un enjeu majeur pour le développement du Languedoc-Roussillon. L’agriculture, un des principaux consommateurs, prélève à la fois dans les eaux de surface et dans les nappes. Si les prélèvements agricoles de surface sont dans l’ensemble maîtrisés, les eaux souterraines sont plus difficiles à gérer car les prélèvements n’y sont qu’imparfaitement observables. Cette thèse, à visée opérationnelle, a pour objectif de développer et d’évaluer des mécanismes acceptables de gestion de l’eau souterraine d’irrigation dans un contexte d’information imparfaite et de substitution entre ressources. Appliquée au cas de la plaine du Roussillon, elle utilise une méthodologie combinant modèles de programmation mathématique, expériences en laboratoire (lab experiment) et de terrain (framed field experiment) et débats avec des usagers, des représentants d’usagers et des gestionnaires. Elle a donc une portée empirique importante. D’un point de vue théorique, elle élargit au problème des prélèvements diffus la littérature sur les sanctions collectives relative à la gestion des pollutions diffuses. Nous développons un instrument de type contractuel – la « sanction collective différenciée » - visant à faire respecter un système de quotas en combinant sanction collective, mécanisme de révélation d’information et contrôle des prélèvements individuels. Si les performances théoriques et en laboratoire de la sanction collective différenciée en termes d’efficacité et d’équité sont intéressantes, notre méthodologie identifie des freins à sa mise en place. Premièrement, la résolution du problème informationnel par un mécanisme contractuel nécessite l’établissement d’un lien de confiance entre irrigants et gestionnaires. Deuxièmement, les moyens de contrôle et de sanction à la disposition des autorités interdisent sa mise en place à un niveau théoriquement incitatif. Enfin, le principe de sanction collective est rejeté par les usagers

Durabilité de la tarification de l'eau d'irrigation : déterminants, tendances et obstacles

International audienceAn increasing number of countries are facing the limited nature of water resources in such extend that they shift from the "hydraulic stage" to the "hydroeconomic age" defined by Margat (1987). This induces the need for a paradigmatic change from a supply-oriented management to a demand-driven one under which price signal should play a key role. Irrigation represents the first consumptive use worldwide and the management of irrigation demand should thus constitute a central concern for policy makers. Water pricing in irrigation systems must then be addressed in a comprehensive manner in order to favour a sustainable use of water without impacting much the undeniable positive effects of irrigation food safety,climatic risk reduction, land requirement or local development