Department of Agricultural Economics and Social Sciences, Universidad Politécnica de Madrid, ETSI Agrónomos, Av. Complutense s/n, Ciudad Universitaria, 28040 Madrid, Spain.
J Environ Manage. 2013 Oct 15;128:144-60. doi: 10.1016/j.jenvman.2013.04.037. Epub 2013 Jun 1.
Sustaining irrigated agriculture to meet food production needs while maintaining aquatic ecosystems is at the heart of many policy debates in various parts of the world, especially in arid and semi-arid areas. Researchers and practitioners are increasingly calling for integrated approaches, and policy-makers are progressively supporting the inclusion of ecological and social aspects in water management programs. This paper contributes to this policy debate by providing an integrated economic-hydrologic modeling framework that captures the socio-economic and environmental effects of various policy initiatives and climate variability. This modeling integration includes a risk-based economic optimization model and a hydrologic water management simulation model that have been specified for the Middle Guadiana basin, a vulnerable drought-prone agro-ecological area with highly regulated river systems in southwest Spain. Namely, two key water policy interventions were investigated: the implementation of minimum environmental flows (supported by the European Water Framework Directive, EU WFD), and a reduction in the legal amount of water delivered for irrigation (planned measure included in the new Guadiana River Basin Management Plan, GRBMP, still under discussion). Results indicate that current patterns of excessive water use for irrigation in the basin may put environmental flow demands at risk, jeopardizing the WFD's goal of restoring the 'good ecological status' of water bodies by 2015. Conflicts between environmental and agricultural water uses will be stressed during prolonged dry episodes, and particularly in summer low-flow periods, when there is an important increase of crop irrigation water requirements. Securing minimum stream flows would entail a substantial reduction in irrigation water use for rice cultivation, which might affect the profitability and economic viability of small rice-growing farms located upstream in the river. The new GRBMP could contribute to balance competing water demands in the basin and to increase economic water productivity, but might not be sufficient to ensure the provision of environmental flows as required by the WFD. A thoroughly revision of the basin's water use concession system for irrigation seems to be needed in order to bring the GRBMP in line with the WFD objectives. Furthermore, the study illustrates that social, economic, institutional, and technological factors, in addition to bio-physical conditions, are important issues to be considered for designing and developing water management strategies. The research initiative presented in this paper demonstrates that hydro-economic models can explicitly integrate all these issues, constituting a valuable tool that could assist policy makers for implementing sustainable irrigation policies.
维持灌溉农业以满足粮食生产需求，同时维护水生生态系统，这是世界上许多政策辩论的核心，尤其是在干旱和半干旱地区。研究人员和实践者越来越多地呼吁采取综合方法，政策制定者也在逐步支持将生态和社会方面纳入水资源管理计划。本文通过提供一个综合的经济-水文学建模框架，为这一政策辩论做出了贡献，该框架捕捉到了各种政策举措和气候变化的社会经济和环境影响。这种建模集成包括一个基于风险的经济优化模型和一个水文学水资源管理模拟模型，这些模型已经针对西班牙西南部脆弱的干旱易发生农业生态区——瓜迪亚纳河中游流域进行了专门制定。具体来说，研究了两项关键的水政策干预措施：实施最低环境流量（得到欧洲水框架指令的支持，EU WFD），以及减少用于灌溉的法定水量（新的瓜迪亚纳河流域管理计划（GRBMP）中包含的计划措施，仍在讨论中）。研究结果表明，流域内目前过度的灌溉用水模式可能会使环境流量需求面临风险，危及到到 2015 年恢复水体“良好生态状况”的 WFD 目标。在长时间干旱期间，特别是在夏季低流量时期，环境用水和农业用水之间的冲突将更加紧张，此时作物灌溉用水需求会大幅增加。确保最低溪流流量将需要大量减少水稻种植的灌溉用水量，这可能会影响到位于河流上游的小型水稻种植农场的盈利能力和经济可行性。新的 GRBMP 可以有助于平衡流域内相互竞争的用水需求，并提高经济用水生产力，但可能不足以确保按照 WFD 的要求提供环境流量。为了使 GRBMP 符合 WFD 的目标，似乎需要对流域的灌溉用水特许权制度进行彻底修订。此外，研究表明，除了生物物理条件外，社会、经济、制度和技术因素也是设计和开发水资源管理策略时需要考虑的重要问题。本文提出的研究倡议表明，水-经济模型可以明确地整合所有这些问题，是一个有价值的工具，可以协助政策制定者实施可持续的灌溉政策。
