Impacts of climate change and human activities on streamflow of Upper
Yongding River Basin, North China
Abstract
Streamflow plays a key role in ecosystem and human society, 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.