Impacts of climate change and human activities on streamflow of Upper
Yongding River Basin, North China
Abstract
Streamflow in semiarid area is facing rapidly decreasing, especially in
North China, which make it important to analyse the characteristics and
influencing factors of streamflow. Using hydro-meteorological data
series during 1961-2017 in the Upper Yongding River Basin (UYRB)(
including Yang River Basin (YRB) and Sanggan River Basin (SRB)),
Spatio-temporal variation characteristics of air temperature,
precipitation and potential evapotranspiration (E 0)
were analysed. Results showed that: precipitation has no significant
trend; temperature shows a significant increase by 0.09–0.52℃ per
decade; E 0 shows a significant decrease from -0.18
mm/yr to -2.04 mm/yr (in 18 stations); the estimated rates of streamflow
change are –0.74, –0.80mm/yr for SRB and YRB. As to spatial
distribution: the YRB presents a higher E 0 value than
the SRB; and the mountain area has more precipitation than the
plain area. And the change points of streamflow occurred in 1982 and
2003. Both Budyko and DMC method were used to evaluate the impacts of
climate change and human activities on mean annual streamflow. In the
variation stage Ⅰ (1983~2003), impacts of human
activities account for 90.6% and 62.7% of the mean annual streamflow
changes in YRB and SRB, respectively. In the variation stage Ⅱ
(2004~2017), the percentages are 99.5% and 93.5%,
respectively. It is also noted that the first change point in streamflow
was indeed at the beginning of China’s land reform, when the farmers can
manage their reallocated lands and therefore increased agricultural
water consumption. The second change point coincided with “Capital
Water Resources Planning” including water conservation projects and
irrigation district construction programs. In general, human activities
were mainly responsible for the significant decline in the annual
streamflow of UYRB. This paper will provide valuable results for water
resources planning and give guidance to the construction of water
conservation function area and ecological environment support area of
capital.