Separating the Impacts of Climate Variation and Human Activities on Runoff in the Songhua River Basin, Northeast China

Abstract

Climate variation and human activities are commonly recognized as two major factors affecting basin hydrology. However, quantifying their individual effect on runoff is challenging. In this study, long-term (1960-2009) river discharge and weather data in the Songhua River Basin (SRB, 556,800 km 2 ), Northeast China, were gathered to separate the impacts of climate variation and human activities on runoff in five sub basins of the SRB. Mann-Kendall test, moving t-test and precipitation-runoff double cumulative curve were utilized to identify trends and change points of the hydrometeorlogical variables. Based on the change point, the 50-year study period was divided into two time series : 1960-1974 where minimal human activities took place and 1975-2009 where extensive land use change occurred and river engineering projects were undertaken. Subsequently, individual contributions of climate and human factors were assessed through a hydrologic sensitivity analysis. Our study found a significant decline in runoff of the SRB over the past 50 years. Contribution of climate variation and human activities to the change varied temporally and spatially. For the 1975-2009 period, human activities made a greater contribution (62%-82%) to the total runoff decline of the SRB. However, climate variation played a bigger role in runoff reduction in two sub river basins (63%-65%) between 1975 and 1989, OPEN ACCESSWater 2014, 6 3321 as well as in runoff increase in other two sub river basins (85%-86%) between 1990 and 1999. Spatially, the effect of human activities on runoff decline was relatively stronger in the lower basin areas in the 1960s and 1970s while showing an increasing role in the upper basin areas in the past two decades.

Attribution of Runoff Change for the Xinshui River Catchment on the Loess Plateau of China in a Changing Environment

“…In recent years, hydrologists have put great efforts into attribution analysis of changes in runoff [16][17][18][19][20][21][22][23][24][25][26]. Broadly, the attribution analysis methods can be mainly divided into five categories: (1) Paired catchment studies.…”

Runoff Response to Climate Warming and Forest Disturbance in a Mid-Mountain Basin

“…In past decades, climate change, including changes in precipitation, temperature, vapor pressure, and wind speed, has directly or indirectly altered hydrological regimes [1][2][3][4], and studies that identify the linkage between warmer air temperatures and the occurrence of extreme hydrological events or basins' water yield have drawn decision-makers' attention to natural resource management [5][6][7][8].…”

Assessing Climate Change Impacts on Water Resources in the Songhua River Basin

“…The current area of cultivated land in the SRB is 216,000 km 2 , of which 25,930 km 2 is paddy land. In order to become China's major grain production base by 2020, the area of cultivated land, especially paddy land, has largely been expanded in recent years [13,41]. In addition, crops' water demand and irrigation requirement in this region will have a 10% increase under future climate change scenarios [39], which implies more water consumption in agriculture.…”

“…Wetlands in the SRB have suffered from severe degradation, with an area deduction of 13.1% from 1975 to 2005 [41]. Climate change is considered as an important factor in the degradation of wetland in the SRB [24,42].…”