Management of natural lake water resources: problems and solutions
Published: 01 November 2012
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Conceptually, water resources management means optimization of a goal function which integrates requirements and, and constraints, of, interconnected hydrological, ecological and economic aspects of the water resource management. Establishment of the goal function should allow combining of the economic activities, hydroecological studies and economic valuation within a holistic methodological framework. The set of the management measures allowing the optimization of the goal function under a pre-condition of conservation of the ecosystem services in some predefined reference/desirable state defines sustainable management policy.The examples of the natural waterbodies for which such a goal function has been established are extremely rare if at all they exist (unknown to us). In this presentation, we outlined a methodological framework for sustainable water resource management comprising of ecological monitoring, quantified water quality and an ecosystem model. We tested the proposed framework on the subtropical Lake Kinneret (Israel), a major national water resource. Methodologically, this study linked the economic activities in Lake Kinneret and its watershed (i.e. nutrient loads and water supply regimes) with lake water quality, sustaining of which was considered the management objective. Based on analysis of the monitoring data and model scenario simulations we established quantitative relationships between changes to lake water level and nutrient loading and water quality. We assessed a set of values of nutrient loads from the watershed and water levels that will allow conservation of the lake water quality within predefined limits thereby defining limits for a sustainable management policy for the lake water resources. The defined sustainable management policy is in good correspondence with the loads and permissible water level ranges estimated from lake-based monitoring . Our approach to assessment of the sustainable management policy was based on a single, hydroecological criterion: the necessity to sustain lake water quality within a desirable, reference state. However, in reality, the sustainable management policy should be focused on a social-ecological system and not an aquatic ecosystem per se. Therefore, water resources management should be based on multi-criteria; it should also account for the economic aspects (costs and benefits for society) of the problem. Establishment of the quantitative relationships between economic activities, water quality and total economic value of water resources is a challenging scientific problem. Its solution will be a pivotal step towards adaptive water resources management.