Importance of cryosphere water resources to China’s socio-economy: Based on multi-level basins analysis

Abstract

Cryosphere water resources (CWR) play indispensable roles in ecological security and socio-economic development in cold and arid regions of the world. The amount of melt water will continue to decrease once it reaches the maximum (peak water) due to climate change, while the sustainable and rapid development of socio-economy puts higher demand for water resources, which causes an increasing risk of regional water shortage. Therefore, a national assessment on the relationship between CWR and socio-economy is notable. The supply and demand of CWR are linked at the river basin scale, although the upper, middle and lower reaches of the river vary in the contribution of CWR to water availability. Here we analyze the spatial distribution characteristics of China’s CWR and the spatial-temporal patterns of population and GDP in cryosphere-fed-areas (CFA) at three-level basins scale. Then we present an Importance Index, which ranks all basins in terms of their water-supplying role and the downstream dependence of socio-economy. We conclude that: (1) CFA covers 7 primary basins, 38 secondary basins and 84 tertiary basins in China. (2) The top three with large glacier reserves are Tarim River, Qiangtang Plateau and the Yalu Tsangpo River Basin. Central Tibetan Plateau and the Songhua River Basin have high permafrost coverage. Songhua River Basin, northern Xinjiang and the southwest of the Tibetan Plateau have large average snow depth. (3) In 2015, population and GDP in CFA are about 263 million and 11.4 trillion yuan respectively, accounting for 23.1% and 16.5% of the total China, mainly distribute in the southeast and north of the boundary of the first and second steps and the north of the third step of topography of China. From 1995 to 2015, the proportion of population in the CFA increased from 24.4% to 26.8%, while the proportion of GDP in the whole country decreased from 21% to 19%. (4) For the CFA, the larger the socio-economic amounts, the higher the importance of water resources. However, the amount of water supply does not completely match the socio-economic distribution. Although the cryosphere water resources are abundant in the southwest of Tibetan Plateau, the socio-economic demand is small, representing a lower water service there. We have noticed that at the secondary basin scale, 26.8% of people were populated in the CFA, and nearly one-fifth (19%) of economic activities took place there in 2015. This indicates a lager dependence on CWR in socio-economy, especially in the arid northwest China. These conclusions quantitatively support the previous understanding. However, the multi-scale method we used can analyze the small watershed deeply. For example, the Huntai River Basin are of great importance due to its high water supply and demand index, which is conducive to guiding the optimal allocation of water resources and a deep understanding of the importance of water resources.