Recent area and volume loss of Alpine glaciers in the Adda River of Italy and their contribution to hydropower production

We computed and analysed the geometry changes affecting an Italian glacierized sector (the Sondrio Province, Adda River Basin). This zone was chosen because i) there is a relative abundance of high resolution remote sensing data covering the last thirty years, ii) it represents an important sector of the glacierized areas of Italy, and iii) it is first ranked within the list of Italian districts featuring highest hydro-power production. We found large glacier reduction, with an area change of −25.41% during 1991–2007, and −30.5% during 1981–2007. Volume change during 1981–2007 was −1353 × 10 6  m 3  ± 27%. The mean thickness change was −14.91 m. The mean annual volume change of the Sondrio glaciers was about −52 × 10 6  m 3  y −1 of ice, or ca. −47 × 10 6  m 3  y −1 of water. We then computed the glaciers' contribution to 25 hydropower plants located in the studied area. For this purpose we divided the study region into two zones. While in the first, Eastern most region (R1) a large share of hydropower is provided by liquid precipitation, in the second Western region (R2) ca. 1/2 of the total water for hydropower is provided by solid water, i.e. snowfall and ice melt. Our results display that in areas like Region R2, where a large share of hydropower production depends upon ice melt, the expected future lack of water under glaciers' down wasting may affect energy production, and requires adaptation strategies.