18.4 Water Resources
421
from 1956 to 2006, mainly deriving from glacier water (Wang et al. 2008). Yet
due to human use, runoff from the Aksu River to the Tarim River decreased 15.9%
from 1961 to 2000 (Zhang 2008). In the last 50 years, in the source rivers of the
Tarim River, runoff increased somewhat from the end of the 1950s to 1980 and
significantly increased after the 1990s (Fu et al. 2008). Runoff from the Tianshan
Mountains to Tarim River also increased; given the precipitation increase and
warming temperatures after 1986, runoff in the 1990s was 18% greater than in the
1980s (Gao 2008), and in the source region, runoff from 1991 to 2002 was 6.5%
greater than from 1956 to 1990 (Jiang and Xia 2007). In the Kaidu catchment, one
of the source rivers of the Tarim River, there was a significant increase in runoff
from 1987 to 2002 (Zhang et al. 2004), and this trend continues into the 2010s
(Liu 2019).
• In the Shiyang River Basin, runoff from mountainous areas decreased 4.58 billion
m
3 in the past 55 years (Huang et al. 2008). Runoff decreased by 37% in the 1970s
and 70% in the 1990s compared to the 1960s. In Zhangye Prefecture in the Hei
River Basin, runoff was greater in the 1950s and 1980s, lower in the 1960s and
1970s, and has increased since the end of the 1990s (Liu et al.2008). In the Hei
River Basin, runoff from the mountains has increased in the last 60 years (Zhang
et al. 2007).
18.4.2 Estimates
According to China’s National Assessment Report on Climate Change and the Water
Information Centre of MWR, based on the population projection of 1.62 billion
people in China in 2050 and in 2100, a VIC distribution hydrological model and
PRECIS 50 km*50 km SRES A2 and B2 scenarios projected that climate change
would have a significant impact on water resources across China. In the next 50–
100 years, the mean annual runoff is likely to decrease in several northern provinces
and regions, including Ningxia, Gansu, Shaanxi, Shanxi, and Hebei. At the same time,
annual runoff would increase significantly in water-abundant southern provinces and
regions, including Hubei, Hunan, Jiangxi, Fujian, Guangxi, Guangdong, and Yunnan.
These changes indicate that climate change will increase the frequency of flood and
drought events, and water scarcity tends to continue in Northern China, especially in
Ningxia and Gansu, where water resources per capita are likely to further decrease.
For most provinces, water supply and demand would generally be imbalanced over
the next 50–100 years, and gaps between water resource supply and demand might
grow in Inner Mongolia, Xinjiang, Gansu, and Ningxia (Compiling group 2007).
Given the precipitation changes (0, ± 25%, ± 50%) and temperature changes
(0°C, ± 1°C, ± 2°C), the sensitivity analysis indicated that in the Yellow River, Han
River, Gan River, Huai River, and Hai River, runoff would be more sensitive than
temperature. Surface runoff would be more impacted than the total runoff, and semihumid areas and semi-arid areas would be less sensitive than the semi-arid and semihumid areas, with a significant increase from south to north and from mountainous
421
from 1956 to 2006, mainly deriving from glacier water (Wang et al. 2008). Yet
due to human use, runoff from the Aksu River to the Tarim River decreased 15.9%
from 1961 to 2000 (Zhang 2008). In the last 50 years, in the source rivers of the
Tarim River, runoff increased somewhat from the end of the 1950s to 1980 and
significantly increased after the 1990s (Fu et al. 2008). Runoff from the Tianshan
Mountains to Tarim River also increased; given the precipitation increase and
warming temperatures after 1986, runoff in the 1990s was 18% greater than in the
1980s (Gao 2008), and in the source region, runoff from 1991 to 2002 was 6.5%
greater than from 1956 to 1990 (Jiang and Xia 2007). In the Kaidu catchment, one
of the source rivers of the Tarim River, there was a significant increase in runoff
from 1987 to 2002 (Zhang et al. 2004), and this trend continues into the 2010s
(Liu 2019).
• In the Shiyang River Basin, runoff from mountainous areas decreased 4.58 billion
m
3 in the past 55 years (Huang et al. 2008). Runoff decreased by 37% in the 1970s
and 70% in the 1990s compared to the 1960s. In Zhangye Prefecture in the Hei
River Basin, runoff was greater in the 1950s and 1980s, lower in the 1960s and
1970s, and has increased since the end of the 1990s (Liu et al.2008). In the Hei
River Basin, runoff from the mountains has increased in the last 60 years (Zhang
et al. 2007).
18.4.2 Estimates
According to China’s National Assessment Report on Climate Change and the Water
Information Centre of MWR, based on the population projection of 1.62 billion
people in China in 2050 and in 2100, a VIC distribution hydrological model and
PRECIS 50 km*50 km SRES A2 and B2 scenarios projected that climate change
would have a significant impact on water resources across China. In the next 50–
100 years, the mean annual runoff is likely to decrease in several northern provinces
and regions, including Ningxia, Gansu, Shaanxi, Shanxi, and Hebei. At the same time,
annual runoff would increase significantly in water-abundant southern provinces and
regions, including Hubei, Hunan, Jiangxi, Fujian, Guangxi, Guangdong, and Yunnan.
These changes indicate that climate change will increase the frequency of flood and
drought events, and water scarcity tends to continue in Northern China, especially in
Ningxia and Gansu, where water resources per capita are likely to further decrease.
For most provinces, water supply and demand would generally be imbalanced over
the next 50–100 years, and gaps between water resource supply and demand might
grow in Inner Mongolia, Xinjiang, Gansu, and Ningxia (Compiling group 2007).
Given the precipitation changes (0, ± 25%, ± 50%) and temperature changes
(0°C, ± 1°C, ± 2°C), the sensitivity analysis indicated that in the Yellow River, Han
River, Gan River, Huai River, and Hai River, runoff would be more sensitive than
temperature. Surface runoff would be more impacted than the total runoff, and semihumid areas and semi-arid areas would be less sensitive than the semi-arid and semihumid areas, with a significant increase from south to north and from mountainous