Researchers, policy experts and agency managers have long recognized that water resources are influenced both by global climate processes and by regional environmental dynamics. In a close examination of an economically important region in the Swiss Alps, reseachers recently found that land use change have a much smaller impact on glacier and snow melt than climate change. An assessment of stream flow during different times of year also revealed a lower peak flow and an earlier start to peak flows driven by melting snow and glaciers. The findings support previous research on annual melt in the region, and strengthen the understanding of the causes of the changes. By emphasizing the importance of climate change, this research can help shape policies to address declining water resources.
Water flowing from high altitudes in the Alps plays a significant role in Switzerland’s tourism industry, hydroelectricity production and feeds into the Rhone River and Lake Geneva. Every summer, runoff from snowmelt and the Rhone Glacier enters the Rhone River, which, at 167.5 kilometers in length, is one of the longest and most important in the country.
“The entire upper Rhone watershed is of paramount importance because 11 large hydropower plants are located in this watershed,” the authors wrote. “Therefore, a model could lead to a better understanding of the current inflow situation and scenario analysis could help in planning better downstream water management.”
By using data to create land maps and developing models, researchers from Stanford University, the University of Geneva and the Wegener Center for Climate and Global Change in Graz, Austria, found that if the world continues on a business as usual trajectory in which greenhouse gas emissions are not curbed, streamflow from the Swiss Alps will be greatly reduced as a result of glacier loss. Climate change will also lead to reduced agricultural production, which in turn will promote forest growth as farmers take lands out of cultivation. This change will also impact stream flow, since trees will absorb precipitation and reduce runoff into streams, though the impact of climate change was found to be more significant. This importance could be related to lower levels of land use change in high altitudes, the authors concluded.
Models were developed to assess glacier melt and land use change for two periods, between 2011 and 2025, and between 2026 and 2050. The models included a number of physical processes, including ocean precipitation, transpiration, snow melt and glacier melt. Researchers also used a Soil and Water Assessment Tool to determine water flow.
“Since the runoff in this watershed is driven by snow and glacier melt, the early melt could lead to several consequences, the most severe of which is on hydropower based energy production,” the authors wrote. “Early melt will cause an early filling of reservoirs and result in a shortage during peak flows. Therefore, the result obtained from this study can be useful for water management in the Rhone Valley.” In this way, their findings correspond to other studies elsewhere in Europe, in Latin America and Asia, which also show that glacier retreat will have negative effects on hydropower–a source of renewable energy which could reduced the dependence of global economies on fossil fuels. Studies such as these are thus of great importance for formulating responses to climate change.