HGS RESEARCH HIGHLIGHT – Analysis of drought conditions and their impacts in a headwater stream in the Central European lower mountain ranges
Kaule, L. & Frei, S. (2022). Analysis of drought conditions and their impacts in a headwater stream in the Central European lower mountain ranges. In Regional Environmental Change (Vol. 22, Issue 89). American Geophysical Union (AGU). https://doi.org/10.1007/s10113-022-01926-y
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A new study by researchers at the University Bayreuth investigates the impact that climate change may have on drought conditions in forested catchment with riparian wetland, specifically the Lehstenbach catchment in the Fichtel Mountains of South-Eastern Germany. Based on HydroGeoSphere simulations of the catchment over the course of the current century (i.e. until the year 2100, based on the Representative Concentration Pathways (RCP) 2.6, 4.5, and 8.5 climate scenarios), the authors conclude that there will likely be a shift in the water balance resulting in increases drought duration, intensity, and frequency.
Figure 1: Map of the Lehstenbach catchment.
Each climate scenario points to drier summers, resulting in decreased streamflows and an increase in the frequency of Minimum Environmental Flow (MEF) conditions – “quantitative measure of aquatic species’ exposition to abnormally low streamflow conditions”. Overall, the results indicate that climate change will have significantly negative impacts on ecosystem health and it’s ability to deliver ecosystem services.
Figure 4: Visual summary of water balance components averaged over 30 years for near (2021–2050) and far future (2071–2100). The components are depicted as ranges (minimum to maximum) of all climate change projections, where the dotted lines show the near future range, and the solid lines the far future range. A averaged total monthly Precipitation (P) in [mm month-1], B averaged total monthly Actual Evapotranspiration (AET) in [mm month-1], C averaged total monthly Discharge (Q) in [mm month-1], and D averaged total monthly Storage deficit (∆ S) in [mm month-1].
This study (among many others by Aquanty staff, for example here, here and here) provides a potential blueprint for those interested in simulating climate change impacts on hydrology at the catchment scale.
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Abstract:
Headwaters represent a significant fraction of the global stream length and are important for streamflow quality and quantity. Since climate change is predicted to affect runoff generation processes fundamentally, it is essential to understand potential consequences for the water availability in headwater catchments. The Lehstenbach catchment, located in the Fichtel Mountains (Germany), represents many headwater catchments in the lower mountain ranges in Central Europe. This study’s primary objective is to predict and analyze potential shifts in the catchment’s water balance, estimate periods of hydrological drought conditions, and their characteristics. For this purpose, we used an integrated process-based hydrological model to represent surface/groundwater interactions and runoff generation mechanisms for the Lehstenbach catchment until 2100, using a Regional Climate Model Ensemble. The simulations indicate decreased water availability in summer and autumn, mainly due to increased evapotranspiration rates. The Minimum Environmental Flow (MEF), a quantitative measure of aquatic species’ exposition to abnormally low streamflow conditions, implies an increase of low flow conditions towards 2100. A first estimate indicates a possible increase of hydrological drought duration and intensity in the future. These findings suggest severe impacts on ecosystem health and services, such as decreasing water availability, leading to consequences like forest and wetland degradation and declining biodiversity. These findings can be used to implement suitable mitigation strategies to reduce climate change effects on the headwater ecosystems, such as water shortage for irrigation and drinking water supply and loss of flora and fauna.