Can Remote Sensing Fill the United States’ Monitoring Gap for Watershed Management? Water

Remote sensing has been heralded as the silver bullet in water quality modeling and watershed management, and yet a quantitative mapping of where its applicability is likely and most useful has not been undertaken so far. Here, we combine geospatial models of cloud cover as a proxy for the likelihood of acquiring remote scenes and the shortest time of travel to population centers as a proxy for accessibility to ground-truth remote sensing data for water quality monitoring and produce maps of the potential of remote sensing in watershed management in the United States. We generate several maps with different cost-payoff relationships to help stakeholders plan and incentivize remote sensing-based monitoring campaigns. Additionally, we combine these remote sensing potential maps with spatial indices of population, water demand, ecosystem services, pollution risk, and monitoring coverage deficits to identify where remote sensing likely has the greatest role to play. We find that the Southwestern United States and the Central plains regions are generally suitable for remote sensing for watershed management even under the most stringent costing projections, but that the potential for using remote sensing can extend further North and East as constraints are relaxed. We also find large areas in the Southern United States and sporadic watersheds in the Northeast and Northwest seaboards and the Midwest would likely benefit most from using remote sensing for watershed monitoring. Although developed herein for watershed decision support in the United States, our approach is readily generalizable to other environmental domains and across the world.

遥感（remote sensing）一直被视为水质建模与流域管理领域的灵丹妙药，但迄今为止，尚未有研究对其适用场景与最优应用领域开展定量制图分析。本研究结合以云量作为遥感影像获取概率代理指标的地理空间模型，以及以抵达人口中心的最短通行时间作为水质监测遥感数据地面验证（ground-truth）可达性的代理指标，绘制了美国境内遥感技术在流域管理中的应用潜力分布图。我们生成了多种不同成本收益关系的潜力分布图，以辅助利益相关方规划并激励基于遥感的监测项目。此外，我们将上述遥感潜力分布图与人口、水资源需求、生态系统服务、污染风险及监测覆盖缺口的空间指数相结合，识别出遥感技术最能发挥效用的区域。研究发现，即便在最严格的成本预估场景下，美国西南部与中部平原地区通常也适合采用遥感技术开展流域管理；而随着约束条件放宽，遥感应用潜力可进一步向北、向东拓展。我们还发现，美国南部的大片区域，以及东北部、西北部沿海地带与中西部的零散流域，或将从遥感流域监测中获得最大收益。尽管本研究方法是针对美国流域决策支持场景开发的，但可轻松推广至全球其他环境领域及其他国家/地区。