The maintainance of environmental flows in mountainous areas subjected to surface water abstraction for energy and irrigation purposes is a main issue, also in relationship to climatic change and increasing demand of energy. Many empirical and analytical tools for the calculation of mimimal flow not always seem to fully satisfy regulatory goals with the risk of not properly estimating actual needs of fluvial ecosytems; on the other hand not only and not simply water abstraction is able to adversely affect river ecosystems and other anthropic pressures must be taken into account. Even the hydrogeology of the watershed (occurrence of karst groundwater flow systems) must be considered in order to properly evaluate the potentially maintainable base flow regime of natural rivers. An experimental multidisciplinary study has been applied to three watersheds inside the national park of Dolomiti Bellunesi (Veneto region, Northern Italy) to verify experimentally the effects of base-flow regime modifications. On 14 river sections a continuous monitoring of water flow has been conducted during 2007; sections are located upstream and downstream of main water abstraction plants for energy supply. In the same sections an ecological monitoring programme has been performed, during 2006 and 2007 growing season. Finally the minimum flow, according different empirical and analytical tools based on watershed geomorphology and statistical analysis of historical series of hydrological parameters, has been calculated for each section. A high resilience of river ecosystem in response to water abstraction (between 0.3 and 0.6 upstream natural inflow) has been highlighted, i.e. the ecosystem has shown a good vitality even in presence of different type of perturbations (anthropic - preventing erosion weirs - or natural - geomorphology of river bed) thus suggesting that an estimation of the minimum flow based on standard statistical or modelling procedures alone may be misleading or even too water demanding.
Minimum Flow estimation tools validated through hydrological and ecological monitoring in Alpine rivers
GARGINI, ALESSANDRO;
2009
Abstract
The maintainance of environmental flows in mountainous areas subjected to surface water abstraction for energy and irrigation purposes is a main issue, also in relationship to climatic change and increasing demand of energy. Many empirical and analytical tools for the calculation of mimimal flow not always seem to fully satisfy regulatory goals with the risk of not properly estimating actual needs of fluvial ecosytems; on the other hand not only and not simply water abstraction is able to adversely affect river ecosystems and other anthropic pressures must be taken into account. Even the hydrogeology of the watershed (occurrence of karst groundwater flow systems) must be considered in order to properly evaluate the potentially maintainable base flow regime of natural rivers. An experimental multidisciplinary study has been applied to three watersheds inside the national park of Dolomiti Bellunesi (Veneto region, Northern Italy) to verify experimentally the effects of base-flow regime modifications. On 14 river sections a continuous monitoring of water flow has been conducted during 2007; sections are located upstream and downstream of main water abstraction plants for energy supply. In the same sections an ecological monitoring programme has been performed, during 2006 and 2007 growing season. Finally the minimum flow, according different empirical and analytical tools based on watershed geomorphology and statistical analysis of historical series of hydrological parameters, has been calculated for each section. A high resilience of river ecosystem in response to water abstraction (between 0.3 and 0.6 upstream natural inflow) has been highlighted, i.e. the ecosystem has shown a good vitality even in presence of different type of perturbations (anthropic - preventing erosion weirs - or natural - geomorphology of river bed) thus suggesting that an estimation of the minimum flow based on standard statistical or modelling procedures alone may be misleading or even too water demanding.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
