| Title | An analysis of the impact of climate change on the hydrogeology of glacial lakes: the case of Lake Candia |
| Abstract | The problem of interaction between groundwater and surface water is essential in defining a correct management policy of water resources, considering in particular climate change and human uses. Hydrological and hydro-geological flow system of a lake is often characterized by a continuous exchange between surface and ground water, whose reciprocal contribution depends expecially on the genesis of the lake and on the geology of its catchment area. In particular, moraine lakes are characterized by a large contribution from groundwater which often regulates level and quality. In this type of lakes every change in groundwater, due to human uses or climate change, creates a lot of problems and needs of protection for the whole lake ecosystem. This is the case of Lake Candia, a shallow moraine lake situated in the North of Italy, in the Dora Baltea basin, located into the Ivrea moraine amphitheatre. The lake area is about 1,47 km2 and its maximum depth is 7,7 m. There are no tributaries, but some irrigation artificial channels drain the agricultural catchment, transporting water and pollutants (nitrogenous and phosphorous) into the groundwater and in the lake. The only outflow is connected with a wetland. The hydro-geological system is very complicated and there is only some information regarding the groundwater system. In order to understand the importance of groundwater in the system dynamics, a hydrological balance, where the groundwater variable is the unknown quantity, was calculated; the other main variables - lake outflow, direct rain on the lake, run-off and water from irrigation - have been reckoned using data of rainfall, wind (velocity and direction), solar radiation, humidity, air temperature and lake level available from a meteorological instrument located near the lake since 1986. This balance pointed out that the lake is related to the groundwater for more than 60% on average, while the contributions of direct rain, run-off and irrigation are respectively 30%, 8% and 1%. This result shows that defining the impact of climate change on hydro-geological equilibrium is necessary to understand the relationship among surface, groundwater, climate change and human uses. Therefore, the first step was the connection of the last 9 years changes to the reference period 1987-2000 (unfortunately the 30 years meteorological standard normal is not available), in order to evaluate changes in the groundwater influence in the hydrological balance; in fact the annual precipitation has decreased of 7% on average, with maximum reductions of about 49% in April and 44% in October and the annual air temperature has increased on the average about 2°C with maximum raise values about 3°C in June and 2.5°C in November. The second step was developing a numerical groundwater model in order to apply it such as a modflow code, to define the correct influence of climate change and human uses, and to manage correctly water resources. |
| Source | IAHR: IV International Groundwateer symposium, Valencia, Spagna, 22-24 settembre 2010 |
| Keywords | Cambiamento climaticoIdrogeologiaLago morenicoModellizzazioneBilancio idrologico |
| Year | 2010 |
| Type | Presentazione |
| Authors | Marzia Ciampittiello; Claudia Dresti; Helmi Saidi; Alessandro Oggioni |
| Text | 127880 2010 Cambiamento climatico Idrogeologia Lago morenico Modellizzazione Bilancio idrologico An analysis of the impact of climate change on the hydrogeology of glacial lakes the case of Lake Candia Marzia Ciampittiello; Claudia Dresti; Helmi Saidi; Alessandro Oggioni CNR ISE VB The problem of interaction between groundwater and surface water is essential in defining a correct management policy of water resources, considering in particular climate change and human uses. Hydrological and hydro geological flow system of a lake is often characterized by a continuous exchange between surface and ground water, whose reciprocal contribution depends expecially on the genesis of the lake and on the geology of its catchment area. In particular, moraine lakes are characterized by a large contribution from groundwater which often regulates level and quality. In this type of lakes every change in groundwater, due to human uses or climate change, creates a lot of problems and needs of protection for the whole lake ecosystem. This is the case of Lake Candia, a shallow moraine lake situated in the North of Italy, in the Dora Baltea basin, located into the Ivrea moraine amphitheatre. The lake area is about 1,47 km2 and its maximum depth is 7,7 m. There are no tributaries, but some irrigation artificial channels drain the agricultural catchment, transporting water and pollutants nitrogenous and phosphorous into the groundwater and in the lake. The only outflow is connected with a wetland. The hydro geological system is very complicated and there is only some information regarding the groundwater system. In order to understand the importance of groundwater in the system dynamics, a hydrological balance, where the groundwater variable is the unknown quantity, was calculated; the other main variables lake outflow, direct rain on the lake, run off and water from irrigation have been reckoned using data of rainfall, wind velocity and direction , solar radiation, humidity, air temperature and lake level available from a meteorological instrument located near the lake since 1986. This balance pointed out that the lake is related to the groundwater for more than 60% on average, while the contributions of direct rain, run off and irrigation are respectively 30%, 8% and 1%. This result shows that defining the impact of climate change on hydro geological equilibrium is necessary to understand the relationship among surface, groundwater, climate change and human uses. Therefore, the first step was the connection of the last 9 years changes to the reference period 1987 2000 unfortunately the 30 years meteorological standard normal is not available , in order to evaluate changes in the groundwater influence in the hydrological balance; in fact the annual precipitation has decreased of 7% on average, with maximum reductions of about 49% in April and 44% in October and the annual air temperature has increased on the average about 2°C with maximum raise values about 3°C in June and 2.5°C in November. The second step was developing a numerical groundwater model in order to apply it such as a modflow code, to define the correct influence of climate change and human uses, and to manage correctly water resources. Un lago morenico privo di immissari deve contare soprattutto sulla presenza di acque sotterranee per la sua alimentazione. Il cambiamento climatico ha effetti anche sulle acque sotterranee e di conseguenza crea un impatto al bilancio idrologico di un lago morenico, soprattutto se poco profondo come quello di Candia. La quota parte di alimentazione delle acqua sotterranee, per il lago di Candia, varia a secondo degli anni da un minimo del 30% ad un massimo del 60% in anni particolarmente siccitosi, rispetto alle diverse entrate. Per approfondire meglio la dinamica di alimentazione e necessario l implementazione di un modello numerico sulle acque sotterranee; l applicazione del modello e ad oggi agli inizi. Published version Ciampittiello M., C. Dresti, H. Saidi e A. Oggioni. 2010. An analysis of the impact of climate change on the hydrogeology of glacial lakes the case of Lake Candia. IAHR International Groundwateer symposium, Valencia, 22 24 settembre 2010. IAHR IV International Groundwateer symposium Valencia, Spagna 22 24 settembre 2010 Internazionale Contributo PPT 2010_PPT_IAHR_Lake_Candia.pdf Presentazione claudia.dresti DRESTI CLAUDIA helmi.saidi SAIDI HELMI marzia.ciampittiello CIAMPITTIELLO MARZIA alessandro.oggioni OGGIONI ALESSANDRO TA.P02.014.002 Impatto dei cambiamenti globali sugli ecosistemi acquatici |
