The streamflow trend in Tangwang River basin in northeast China and its difference response to climate and land use change in sub-basins

In this study, the hydro-climatic trends (1964–2006) of Tangwang River basin (TRB) were examined using the Kendall’s test. Moreover, the impacts of climate variability and land use change on streamflow in each sub-basin were assessed using the Soil and Water Assessment Tools (SWAT) model. The results indicated that annual mean flow and peak flow showed insignificant decreasing trends (−0.14 m3 s−1 year−1, 1 %; −8.67 m3 s−1 year−1, 40 %), while annual low flow exhibited a slightly increasing trend (0.02 m3 s−1 year−1, 11 %). Correspondingly, the annual precipitation for the entire basin decreased by 0.02 mm year−2, while the annual means of daily mean, maximum and minimum temperature increased significantly by 0.07, 0.10 and 0.02 °C year−1, respectively. On the other hand, with the implementation of “Natural Forest Protection Project” and “Grain for Green Project”, the forests in TRB totally increased by 744.5 km2 (4.00 %) from 1980 to 2000. Meanwhile, the grasslands and the farmlands decreased by 378.0 km2 (−1.98 %) and 311.9 km2 (−1.63 %), respectively. Overall, land use changes played a more important role for the streamflow reduction than climate change for SUB1, SUB2 and SUB3, in which the primary conversions were from grassland, farmland and bare land to forests. Conversely, in SUB4, the influence of climate variability was predominant. The results obtained could be a reference for water resources planning and management under changing environment.