An integrated approach for early warning of water stress in shallow lakes: a case study in Lake Baiyangdian, North China.

Water stress is a critical issue threatening the ecosystem health of many shallow lakes. Most lake management methods, however, employ indicators that are individually related to either water quantity or water quality to assess resource-induced and pollution-induced water stress. Based on the system dynamics principle, an integrated method was proposed for early warning of water stress in shallow lakes that considered interactions among 3 systems: water quantity, water quality, and aquatic ecosystems. By adopting the principal component analysis approach to analyze the indicators of these systems, a comprehensive assessment indicator covering 5 early warning levels was extracted to reflect the status of water stress. This method was applied to Lake Baiyangdian in North China, a lake with serious water-related problems. The results indicated that: (a) by comprehensively evaluating the 3 systems, water stress was serious throughout the year, which is more reliable than individual assessment with respective indicators, and the period from April to December had a high water-stress level and should be identified as a crucial early warning period requiring more attention; (b) due to the inherent long-term water stress in the lake, natural water replenishment could not alleviate water stress, even during a year with relatively abundant rainfall; and (c) the proposed method could provide an integrated indicator system to identify water stress status in shallow lakes subject to intensive anthropogenic activities. These findings could provide decision-making support for water resources management. [ABSTRACT FROM AUTHOR]