A hydrogeological investigation was carried out on Bracciano and Bolsena lake systems (Central Italy). Both lakes are fed by a complex groundwater circulation hosted in volcanic deposits belonging to the Vulsino and Sabatino volcanic districts. The increasing of withdrawals from lakes and aquifers coupled with the reduction in rainfall produced by the climatic change have deeply influenced the environmental state of lakes. The water levels of Bolsena lake was simulated by means the LAGO model taking into account some climatic scenarios for the next decades. The model indicates that for a rainfall decrease up to the 10%, the minimum vital flow to the outlet could be supplied applying a sensible reduction of withdrawals. For a rainfall decrease higher than 10% and with no withdrawals the lake could become a closed lake as occurred around 1000 B.C. when the level of the lake was about 5 m lower than today. Regarding the Bracciano lake - due to the withdrawals for drinking from 1960s (0.8 m3/s) - the discharge of the lake outlet, became nil in the last decade. Although the water levels have reached in march 2014 values close to those of 60s, this situation is probably due to a very rare event, while most of scenarios of the IPCC suggests a decreasing of average rainfall, corresponding to water shortage. Besides the impact of climate change, there are plans to increase the water supply from the lake and the aquifer: in this context new rational management plans have to be developed.
Influence of climate change and anthropic pressure on lakes: analysis of Bracciano and Bolsena lake systems (Central Italy)
DI MATTEO, Lucio;DRAGONI, Valter Ulderico;VALIGI, Daniela;
2014
Abstract
A hydrogeological investigation was carried out on Bracciano and Bolsena lake systems (Central Italy). Both lakes are fed by a complex groundwater circulation hosted in volcanic deposits belonging to the Vulsino and Sabatino volcanic districts. The increasing of withdrawals from lakes and aquifers coupled with the reduction in rainfall produced by the climatic change have deeply influenced the environmental state of lakes. The water levels of Bolsena lake was simulated by means the LAGO model taking into account some climatic scenarios for the next decades. The model indicates that for a rainfall decrease up to the 10%, the minimum vital flow to the outlet could be supplied applying a sensible reduction of withdrawals. For a rainfall decrease higher than 10% and with no withdrawals the lake could become a closed lake as occurred around 1000 B.C. when the level of the lake was about 5 m lower than today. Regarding the Bracciano lake - due to the withdrawals for drinking from 1960s (0.8 m3/s) - the discharge of the lake outlet, became nil in the last decade. Although the water levels have reached in march 2014 values close to those of 60s, this situation is probably due to a very rare event, while most of scenarios of the IPCC suggests a decreasing of average rainfall, corresponding to water shortage. Besides the impact of climate change, there are plans to increase the water supply from the lake and the aquifer: in this context new rational management plans have to be developed.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
