Runoff variation and its response to climate change in Huolin River catchment, Northeast China

The Huolin River catchment (HRC) is located in the semi-arid region of Northeast China, which is very sensitive to climate change. The runoff in HRC is closely related to the recovery of local vegetation in the Greater Khingan Mountains and the survival of downstream wetlands. Dramatic runoff fluctuations and increasing no-flow days confirmed the water crisis in this area. Hence, it is extremely urgent to study the current situation and characteristics of runoff. In this study, hydrological and meteorological data of HRC during 1956-2018 were analyzed to elucidate the processes, characteristics, trends of the river runoff and revealed its response to climate change. The Mann-Kendall test and linear regression method showed that runoff in the HRC demonstrated a downward trend over the study period with a marked annual variation. The runoff in the high flow years was 100 times that of the low flow years, showing a typical continental climatic river characteristic. There are two runoff peak flows in the intra-annual runoff distribution in March and July, whereas two runoff valleys occurred around May and September to February. The runoff positively correlates with precipitation in summer and temperature in early spring. Snowmelt influenced by rising temperatures in April and precipitation in July is the main driving factor for the two peaks flow. Evaporation rose with precipitation decline and temperature increased, which may influence the runoff decrease. The annual runoff is well synchronized with the annual precipitation, and precipitation change is the main driving factor of variation and abrupt change points of annual runoff in the catchment. This study would be beneficial for water resource management in developing adaptation strategies to offset the negative impact of climate change in HRC.