Articles | Volume 19, issue 4
Research article
24 Apr 2015
Research article |  | 24 Apr 2015

Effects of snow ratio on annual runoff within the Budyko framework

D. Zhang, Z. Cong, G. Ni, D. Yang, and S. Hu

Abstract. A warmer climate may lead to less precipitation falling as snow in cold seasons. Such a switch in the state of precipitation not only alters temporal distribution of intra-annual runoff but also tends to yield less total annual runoff. Long-term water balance for 282 catchments across China is investigated, showing that a decreasing snow ratio reduces annual runoff for a given total precipitation. Within the Budyko framework, we develop an equation to quantify the relationship between snow ratio and annual runoff from a water–energy balance viewpoint. Based on the proposed equation, attribution of runoff change during the past several decades and possible runoff change induced by projected snow ratio change using climate experiment outputs archived in the Coupled Model Intercomparison Project Phase 5 (CMIP5) are analyzed. Results indicate that annual runoff in northwestern mountainous and northern high-latitude areas are sensitive to snow ratio change. The proposed model is applicable to other catchments easily and quantitatively for analyzing the effects of possible change in snow ratio on available water resources and evaluating the vulnerability of catchments to climate change.

Short summary
1. Catchments with higher snow ratio tend to have larger runoff index. 2. A modified Budyko method is proposed to illustrate the snow effect on runoff. 3. Snow ratio change has a significant contribution to runoff change, according to historical observations and projected future climate scenarios, especially in northwestern mountainous and northern high-latitude areas of China.