Impact Of Climatic And Land Use Changes On Long Term Mean Annual And Peak Runoff In The Southern Alps

Roberto Ranzi, Paolo Caronna, Massimo Tomirotti

Thursday 2 july 2015

9:10 - 9:30h at Europe 1 (level 0)

Themes: (T) Special session, (ST) Adaptation to global changes in water resources management

Parallel session: 10J. Special session - Adaptation to Global Changes in Water Resources Management

Long term statistics of mean annual flow for five major Italian rivers in the Central Alps, including the inflow to the four major prealpine lakes, are presented. Data are compared with precipitation, temperature and land use changes for some of the investigated areas. In particular a new hydrometric series for the Adige river dating back to 1862 is presented and compared with sparse precipitation and temperature data available for the same period. For the same basin a land use classification in some representative cadastral maps dating back to mid XIX century show dramatic changes in the land use, thus indicating how the natural afforestation in Europe occurring over the last century may be a major anthropogenic factor influencing runoff, more than climatic ones. Impact of other factors, as constructions of reservoirs on riverflow regimes are further discussed as a likely reason of a decreasing trend of annual maxima of daily runoff observed for the Adda river time series dating back to 1845. This decline in extremes is observed also for other rivers in the region showing that hydraulic structures can be effective in compensating potential climate change impact on hydrological extremes.