Deforestation Intensifies the Indirect Effects of Global Change on Reservoir Water Quality
Abstract
Deforestation has recently become a serious issue due to rising environmental concerns arising from climate change. Drought-induced forest die-off are currently changing landscape and catchment characteristics faster than ever. Water managers, therefore require future projections of how deforestation, as an indirect effect, will interact with other direct effects of climate change with respect to catchment dynamics and water quality in downstream reservoirs. To tackle this issue, here we investigated a paired catchment-reservoir system with two reservoirs having discrete trophic conditions (meso- and eutrophic), which both drain into Germany's largest drinking water reservoir. Long droughts periods from 2015 to 2018 caused a high loss of forest area (17.1% loss only in 2020) in the catchment of the mesotrophic reservoir. In this study, the process-based catchment nutrient model (HYPE) and reservoir ecosystem model (GOTM-WET) were coupled. The model was validated for the deforestation period which ensures the robustness of the model for future projections. The validated model was then used for three different deforestation scenarios (0%, 50% and 80% deforestation) combined with climate change. By simulating response times from 2020 - 2035, we showed that mesoscale reservoir can turn into a eutrophic state due to enormous deforestation of 80% causing massive nutrient flux from the catchment part. Our study emphasized the more dominant impact of deforestation on the water quality of downstream ecosystems as compared to the direct climate change effect. This dominance of indirect effects of deforestation over direct effects from climate change calls for a careful integration of indirect effects into climate impact studies. Results conclude that such vast-scale deforestation with the combined effect of climate change can lead mesotrophic reservoirs to a eutrophic state in a short span of time.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2022
- Bibcode:
- 2022AGUFM.H32U1183G