Abstract
The sustainable management of lakes and reservoirs requires the determination of their minimum environmental water level. Even though the assessment of minimum water level depends on a number of biotic and abiotic factors of the lake ecosystem, in many cases these factors are not entirely known and, furthermore, their evaluation is usually a challenging and laborious task. On the other hand, the lakes/reservoirs may comprise an important water resource to meet the requirements arising from economic activities. In this paper, the morphological and hydrological features of four lakes of northern Greece were analysed in order to assess their minimum environmental water level. The hydromorphological analysis was based on the relationship of the lake surface area and volume with water level as well as the water inflow from the lake’s hydrological catchment area, considering as the lake’s critical volume storage, the annual water volume flowing into a lake from its hydrological catchment area with a probability of exceedance 50% of a long time series of hydrological years. By combining morphological and hydrological features, the proposed methodology aimed to extend the analysis based solely on morphological features, and assess more comprehensively the minimum environmental water level in the four lakes, ensuring also the rising from the minimum level to the maximum (overflow) level for most of the hydrological years.
Highlights
Water bodies are an essential source of water to support society’s economic activities, i.e., industry, agriculture, hydroelectricity, etc
The annual water volume flowing into a lake from its hydrological catchment area, with a probability of exceedance 50% of a long time series of hydrological years, was considered to be the lake’s critical volume storage; based on this critical volume, the minimum water level was determined
The minimum environmental water level in Lake Vegoritida, Petron, Cheimaditida and Zazari was estimated according to the lake surface area method and based on the “environmental scenario”, i.e., w1 = 30% and w2 = 70%, and the hydromorphological method based on the water inflow from the hydrological catchment area with probability of exceedance 50%
Summary
Water bodies are an essential source of water to support society’s economic activities, i.e., industry, agriculture, hydroelectricity, etc. The determination of the minimum environmental water level in lakes and reservoirs is a key factor for their sustainable management, as the minimum water level is the critical level below which no further withdrawal should take place to further decrease the water level, ensuring the protection of their ecosystems. Minimum water level assessment methods have not been used widely in lake and reservoir management, because they usually take into consideration only part of the factors that influence the lake ecosystem. The lake morphology analysis methods examine the existence of an inflection point in their water level-surface area-volume curves to determine the minimum water level, but they do not consider the lake’s water potential and hydrological regime. Habitat analysis and species–environment models require intensive and detailed in situ survey for an extended period, and in many cases they avoid incorporating both the hydrologic features of the lake and the water requirements in their assays
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