How does climate change degrade Watersheds?

Predicted Climate Change impacts on Watersheds: The increase in extreme climate events such as flooding and droughts predicted by the general circulation models (GCMs) is expected to significantly affect hydrological processes, erosive dynamics, and their associated nonpoint source (NPS) pollution, resulting in a major challenge to water availability for human life and ecosystems.

CONCLUSIONS: Substantial increases in air temperature, precipitation intensity, frequency of heavy rains and rainstorms, and annual maximum duration of drought were predicted in future climate scenarios. In addition, the interacting factors affecting hydrology and water quality in response to rainfall patterns and drought conditions were identified. Precipitation, as a driving factor, played a major role in water balance and determined the amount of runoff. This caused serious soil erosion, nutrient losses, and outputs of fecal coliform by the interactive effects of raindrop and surface runoff. Hydrology and water quality were particularly vulnerable to short-term transient heavy rain and rainstorm events after a prolonged drought, with the comprehensive effects of antecedent soil water, antecedent drought duration, current precipitation amount and intensity, and antecedent precipitation characteristics. The results of this study can help to reveal the complex interactions of the various processes conditioning the water balance and linking agricultural NPS pollution and can guide a robust adaptive management system for future drinking water supply.

Qiu, J., Shen, Z., Leng, G. et al. Synergistic effect of drought and rainfall events of different patterns on watershed systems. Sci Rep 11, 18957 (2021).

Stormwater Runoff enters the ocean in South Maui. Photo: Vernon Kalanikau
Climate change is predicted to increase erosion, flooding, and increased pollution from stormwater entering the ocean. Photo: Vernon Kalanikau