These are important findings, not least when it comes to the impact of climate change. A previous study found that the annual discharge of the river Emme is decreasing. Between 1999 and 2018, it fell by over 10 per cent per decade, and projections for the years 2070–2099 indicate that the discharge in summer will decrease by between 25 and 45 per cent due to rising air temperatures.
This matches estimates from the report entitled “Effects of climate change on Swiss water bodies”, which was recently published by the Swiss Federal Office for the Environment (FOEN) in relation to the Hydro-CH2018 project. The report states that: “In general, the hydrological scenarios show that there will be a significant reduction in water levels in summer and autumn. This applies both to surface waters and to groundwater.” At the same time, the report states, summer dry periods and heat waves will be more frequent and last longer in the future. “Without climate change mitigation, the low summer flows into areas at altitudes of less than 1,500 metres will fall by 30 per cent during dry periods.”