Impacts of increased CO2 on the hydrologic response over the Xijiang (West River) basin, South China

Abstract

Summary Increases in atmospheric carbon dioxide (CO 2 ) concentration levels may affect terrestrial hydrologic processes through changes in evapotranspiration. This study assesses the hydrologic response to the elevated CO 2 levels for the Xijiang (West River) basin in South China by applying the Variable Infiltration Capacity (VIC) model. The standard VIC model is modified by incorporating a mechanistic description of vegetation-type specific responses of both stomatal resistance and leaf area increase based on plant physiological studies. The dynamic (monthly) rises of CO 2 concentration are introduced to estimate the historical impacts of increased CO 2 over the past two decades (1991–2010). The cropland is identified as the most important contributor in the response of streamflow increase for the region. For a doubled atmospheric CO 2 concentration scenario (660 ppm), the streamflow might rise about 3% (i.e. 21.8 mm/yr) under the baseline climatic conditions. Decreases in evapotranspiration and associated streamflow increases in response to ambient CO 2 exposures are expected to episodically increase the frequency and severity of flood and affect flow-dependent aquatic biota in forested watersheds.