Concern about the impacts of water regulation upon the aquatic environment has led to increasingly stringent regulatory constraints on the quantity and timing of freshwater withdrawals. For the time being these regulatory constraints tend to be articulated in terms of limits upon withdrawals, partly because of limited knowledge of the condition and resilience of the aquatic ecosystems. A more sophisticated approach to regulation would be more directly related to indicators of ecological condition. Moreover, it would consider ecosystem response to climatic events not present in the historical record. In this paper we use a combination of empirical evidence of ecosystem condition with simulation to propose and test reductions to regulatory limits on river water withdrawals and downstream minimum flow requirements. The study uses multi-level linear regression to relate the Lotic-invertebrate Index for Flow Evaluation (LIFE) to antecedent flow statistics observed in the Lee catchment, England. The selected flow statistics included extreme low (Q90) and high (Q10) flows in the summer season (April-Sept), and the median flows observed in the winter season (Oct-Mar). The derived model is used to forecast the response of the macroinvertebrate index to future flow scenarios and demand forecasts, incorporating the uncertainties in ecosystem response. Simulation is used to evaluate the sensitivity of the indices to different regulatory limits. Results indicate that macroinvertebrate health will worsen under 21st Century climate conditions, and that the existing regulation policy must be modified to maintain historically observed LIFE scores into the future. The framework demonstrates how regulations could move from precautionary limits on withdrawals to an approach based on observations, forecasting and simulation, allowing planners to refine the trade-offs between river health and reliable water supply in the face of uncertainty.

对水监管对水生环境的影响的关注已导致对淡水抽取的数量和时间越来越严格的监管限制。目前，这些管制方面的限制往往倾向于限制捕捞，部分原因是对水生生态系统状况和复原力的了解有限。一种更复杂的监管方法将与生态状况指标直接相关。此外，它将考虑生态系统对历史记录中未出现的气候事件的响应。在本文中，我们将生态系统状况的经验证据与模拟相结合，提出并测试降低河水取水量和下游最小流量要求的监管限制。这项研究使用了多级线性回归，将洛蒂奇无脊椎动物流量评估指数（LIFE）与在英国Lee流域观测到的先前流量统计数据联系起来。选定的流量统计信息包括夏季（4月至9月）的极低流量（Q90）和高流量（Q10），以及冬季（10月至3月）的中值流量。导出的模型用于预测大型无脊椎动物指数对未来流量情景的响应和需求预测，并纳入了生态系统响应的不确定性。模拟用于评估指标对不同监管限制的敏感性。结果表明，在21世纪的气候条件下，大型无脊椎动物的健康状况将恶化，因此必须修改现有的监管政策，以保持历史上观察到的LIFE分数在未来。