The robustness of decentralized regional water systems under climate change

大多数关于气候变化对区域水系统影响的研究基本上都假设由一个决策者管理该系统。无论是采用自上而下还是自下而上的办法，都要建立一个优化模型，以最大限度地提高全区域的净效益（最大限度地降低成本），但要受到各种限制，包括从选定的气候变化情景（以气候变化为主导，自上而下）或从一系列可能的气候未来（以敏感性为基础，自下而上）得出的水文投入。此外，采用基于敏感性的方法，水资源系统维斯维斯这些变化的水文气候条件的稳健性也要求为每个业务目标确定可接受的阈值。这些努力是有用的，但由于无法考虑多个决策者（当局），而且最重要的是，无法模拟决策者在不断变化的环境中的互动，因此其范围受到限制。换句话说，由于忽视体制的复杂性，传统的水管理模式在某种程度上脱离了管理和体制现实，而这是成功执行适应措施的两个基本因素。然而，例如，在大多数河流流域，水政策是由经常争夺资源和权力的多种机构制定的。此外，这些机构之间的互动程度并不相同，而且可能会受到压力，因为气候不再是静止的，政策必须调整。更具体地说，用于评估区域水系统对气候变化的鲁棒性的自下而上的方法必须加以扩展，以考虑到（1）多个决策者，（2）决策者之间各种层次和形式的互动（从低层次的协调到全面合作），以及（3）一些利害关系方制定的或与某些业务目标相对应的不精确阈值。我们所提供的创新是将制度复杂性纳入区域水资源管理模型，以评估不同气候变化情景下各种制度安排的稳健性。第二个目标是扩展基于灵敏度的方法，以便在评估系统的鲁棒性时可以适应清晰和模糊的可接受阈值。

Most of the studies dealing with the impact of climate change on regional water systems essentially assume that a single decision maker manages the system. Whether a top-down or a bottom-up approach is implemented, an optimization model is developed to maximize region-wide net benefits (minimizing costs) subject to various constraints including hydrologic inputs derived from selected climate change scenarios (scenario-led, top-down) or from a range of possible climate futures (sensitivity-based, bottom-up). Moreover, with the sensitivity-based approach, the robustness of the water resources system vis-à-vis those varying hydro-climatic conditions also require that acceptability thresholds be defined for each operating objective. These efforts have been useful but their scope is limited by the inability to consider multiple decision makers (authorities) and, most importantly, the inability to simulate the interactions among the decision makers in a changing environment. In other words, by ignoring institutional complexity, traditional water management models are somehow divorced from managerial and institutional realities, two essential factors for the successful implementation of adaptation measures. Yet, in most river basins, for instance, water policies are derived from a multiplicity of institutions often competing for resources and authority. In addition, the level of interaction between these institutions is not homogeneous and will likely be under stress as the climate is no longer stationary and as policies must be adapted. More specifically, the bottom-up approach used to assess the robustness of regional water systems to climate change must be extended to account for (1) multiple decision makers, (2) various levels and forms of interaction among the decision makers (from low-level coordination to full cooperation) and (3) imprecise thresholds formulated by some stakeholders or corresponding to certain operating objectives. What we offer as novel is the incorporation of institutional complexity into regional water resources management models, in order to assess the robustness of various institutional arrangements under different climate change scenarios. A secondary objective is to extend the sensitivity-based approach so that it can accommodate crisp and fuzzy acceptability thresholds when assessing the robustness of the system.