Competition for freshwater resources is intensifying water scarcity and its impacts on people, economies, and the environment, posing a growing challenge for sustainable development. Meeting these challenges will require incentives to encourage sustainable water use. Prior calls to shift from supply-driven solutions to a soft path of demand management (pricing, markets, behavioral changes) have encountered stubborn obstacles. We undertake a multi-scale assessment of water reallocation and investment in water conservation technologies to understand their potential and limits for addressing different drivers of water scarcity. Our model identifies what drives water scarcity at the subbasin scale, and examines two prominent responses to these drivers. Our analysis distinguishes different types of water scarcity based on the demands for water and their timing, creating nine (9) categories of water competition, which can overlap. Water demand within agriculture contributes to scarcity in 94% of the basins experiencing scarcity, concentrated in central USA, Spain, and India. Urbanization has led to competition between cities and agriculture in 1,596 of 3,057 subbasins (52%). We examine how different institutional mechanisms (incentive-based water reallocation) and technologies (investment in water conservation technologies) can address these different types of water scarcity. This study builds on several local and high-resolution models demonstrating the potential to increase the economic efficiency (and marginal productivity) of water use. The gap between potential and implementation is high, however. Efforts to bridge this gap in priority geographies can link modelling advances with the design of pathways that combine incentives with robust water accounting, caps on water extraction, and enforcement capacity at multiple scales.

对淡水资源的竞争加剧了水资源短缺及其对人类、经济和环境的影响，对可持续发展提出了越来越大的挑战。应对这些挑战将需要鼓励可持续用水的激励措施。之前呼吁从供应驱动的解决方案转向需求管理的软路径（定价、市场、行为改变）遇到了顽固的障碍。我们对水资源再分配和节水技术投资进行多尺度评估，以了解它们在解决水资源短缺的不同驱动因素方面的潜力和局限性。我们的模型确定了导致子流域尺度缺水的原因，并检查了对这些驱动因素的两个突出反应。我们的分析根据对水的需求及其发生的时间来区分不同类型的水资源短缺，创造了九 (9) 类可以重叠的水资源竞争。农业用水需求导致 94% 的水资源短缺，集中在美国中部、西班牙和印度。在 3,057 个子流域中的 1,596 个（52%）中，城市化导致城市和农业之间的竞争。我们研究了不同的制度机制（基于激励的水资源再分配）和技术（节水技术投资）如何解决这些不同类型的水资源短缺问题。这项研究建立在几个本地和高分辨率模型的基础上，这些模型展示了提高用水的经济效率（和边际生产力）的潜力。潜力和实施之间的差距很大，然而。弥合优先地区这一差距的努力可以将建模进展与路径设计结合起来，将激励与强大的水核算、取水上限和多尺度的执法能力相结合。