VEGETOS: Um Jornal Internacional de Pesquisa Vegetal

Estimating the Sensitivity of Annual Runoff to Climate Change Across a Small Forest Basin in North China

Yang Zhao, Jianbo Jia, Zhihua Tu, Wenhong Cao, Chen Cheng, Xiaolin Yin,Gang Xie, Xiaoming Zhang

Estimating the Sensitivity of Annual Runoff to Climate Change Across a Small Forest Basin in North China

Long term average runoff depends largely on climatic conditions and is expected to change as climate change progresses, but to what degree is uncertain. It is critical to understand the impact of changes in climate on water yield to provide a scientific basis for future management of water resources, especially in the water source protection zones in North China. The Banchengzi Watershed, located in North China, was selected for the evaluation of its hydrological sensitivity to changes in climate. An empirical model, Zhang01, was used to estimates the hydrological sensitivity, measured as the percentage change in mean annual runoff to changes in precipitation (P) and potential evaporation (PET). The results indicate that mean sensitivities of 0.29% change in mean annual runoff for every 1% change in mean annual precipitation. All precipitation sensitivities have a lower limit of 0.18% and show upper limits of 0.4%. The results for PET change are -0.09% for every 1% increase in mean annual PET, with changes precipitation being approximately 3.22 times more sensitive than changes in PET for each 1% change in climate. Moreover, the sensitivity of the annual runoff response to variations of P and PET decreased with the increase in watershed dryness (PET/P). This study also indicates that sensitivity decreases with a higher proportion of woody cover and leaf area index. These findings have the potential to help water managers to target planning activities that seek to mitigate potential effects of a changing climate on water resources.