Читать книгу Hydrogeology - Kevin M. Hiscock - Страница 42

The rapidly growing economy of China, with about 20% of the world’s population but only about 5–7% of global freshwater resources, has a high demand for groundwater. Groundwater is used to irrigate more than 40% of China's farmland and supplies about 70% of drinking water in the dry northern and north‐western regions, with the past few decades having seen groundwater extraction increase by about 2.5 × 10⁹ m³ a⁻¹ to meet these needs. Consequently, groundwater levels below the arid North China Plain have dropped by as much as 1 m a⁻¹ between 1974 and 2000 (Qiu 2010). Further discussion of the significance of groundwater leading to economic development in the rural and expanding urban areas underlain by the Quaternary Aquifer of the North China Plain is presented in Box 1.5.

Currently, the largest threat to sustainable water supplies in China is the growing geographical mismatch between agricultural development and water resources. The centre of grain production in China has moved from the humid south to the water‐scarce north over the past 30 years, as southern cropland is urbanized and more land is irrigated further north. As the north has become drier, increased food production in this region has largely relied on unsustainable overuse of local water resources, especially groundwater. Wasteful irrigation infrastructure, poorly managed water use, as well as fast industrialization and urbanization, have led to a serious depletion of groundwater aquifers, loss of natural habitats and water pollution (Yu 2011).

To provide more sustainable management of groundwater resources, China needs to build an integrated network to monitor surface water and groundwater, and use it to assess and set water policies through an integrated water‐resource management system, backed up by legislation that sets out clear policies on data sharing, and penalties for those who do not comply (Yu 2011). Arguably, the biggest improvement could come in the agriculture sector, which already uses 70% of the China's fresh water. For instance, to boost grain production and help maintain food security, China has a double‐cropping system of growing wheat in winter and maize in summer, an unsustainable system that needs reconsidering. Meanwhile, the Chinese government hopes that a massive system of canals and pipes, to transfer 45 × 10⁹ m³ a⁻¹ from China's wetter south to its arid north, will alleviate groundwater depletion once completed in 2050 (Qiu 2010).