half of the total. In 2000, surface water was the primary source of irrigation water in the arid West and the Mountain States and groundwater was the primary source in the Central States. California, Idaho, Colorado and Nebraska combined accounted for one‐half of the total irrigation water abstractions. California and Idaho accounted for 40% of surface water abstractions and California and Nebraska accounted for one‐third of groundwater abstractions. In general, groundwater abstractions for irrigation have increased significantly. In 1950, groundwater accounted for 23% of total irrigation water, while in 2000 it accounted for 42%.
1.7.3.1 Management and protection of groundwater resources in the United States
Groundwater management in the United States is highly fragmented, with responsibilities shared among a large number of federal, state and local programmes. At each level of government, unique legal authorities allow for the control of one or more threats to groundwater, such as groundwater contamination arising from municipal, industrial, mining and agricultural activities.
Beginning with the 1972 amendments to the federal Water Pollution Control Act, and followed by the Safe Drinking Water Act 1974, the federal government’s role in groundwater management has increased. The introduction of the Resource Conservation and Recovery Act (RCRA) 1976 and the Comprehensive Environmental Response, Compensation and Liability Act (CERCLA) 1980, established the federal government's current focus on groundwater remediation. With these acts, the federal government has directed billions of dollars in public and private resources towards cleaning up contaminated groundwater at ‘Superfund’ sites, RCRA corrective action facilities and leaking underground storage tanks. In 1994, the National Academy of Sciences estimated that over a trillion dollars, or approximately $4000 per person in the United States, will be spent in the next 30 years on remediating contaminated soil and groundwater.
The approach to groundwater protection at the federal level has left the management of many contaminant threats, for example hazardous materials used by light industries (such as dry cleaners, printers or car maintenance workshops), to state and local government authorities. Other groundwater threats, such as over‐abstraction, are not generally addressed under federal law, but left to states and local governments to manage.
In 1984, the US Environmental Protection Agency (USEPA) created the Office of Ground Water Protection to initiate a more comprehensive groundwater resource protection approach and to lead programmes aimed at resource protection. Such programmes include the Wellhead Protection and Sole Source Aquifer Programs, which were established by Amendments to the Safe Drinking Water Act 1986. The Wellhead Protection Program (WHPP) encourages communities to protect their groundwater resources used for drinking water. The Sole Source Aquifer Program limits federal activities that could contaminate important sources of groundwater.
State groundwater management programmes are seen as critical to the future achievement of effective and sustainable protection of groundwater resources. In 1991, the USEPA established a Ground Water Strategy to place greater emphasis on comprehensive state management of groundwater as a resource through the promotion of Comprehensive State Ground Water Protection Programs (CSGWPPs) together with better alignment of federal programmes with state groundwater resource protection priorities (USEPA 1992).
1.7.4 Groundwater abstraction in China
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).
Box 1.5 Groundwater Development of the Quaternary Aquifer of the North China Plain
The Quaternary Aquifer of the North China Plain represents one of the world's largest aquifer systems and underlies extensive tracts of the Hai River Basin and the catchments of the adjacent Huai and Huang (Yellow) River Systems (Fig. 1.13) and beyond. This densely populated area comprises a number of extensive plains, known collectively as the North China Plain, and includes three distinct hydrogeological settings within the Quaternary aquifer system (Fig. 1.14). The semi‐arid climate of north‐eastern China is characterized by cold, dry winters (December–March) and hot, humid summers (July–September).
The Quaternary Aquifer supports an enormous exploitation of groundwater which has led to large socio‐economic benefits in terms of irrigated grain production, farming employment and rural poverty alleviation, together with urban and industrial water supply provision. An estimated water supply of 27 × 109 m3 a−1 in the Hai River Basin alone was derived from wells and boreholes in 1988 (MWR 1992), but such large exploitation of groundwater has led to increasing difficulties in the last few years.
Given the heavy dependence on groundwater resources in the North China Plain, a number of concerns have been identified in recent years (Fig. 1.13) including a falling water table in the shallow freshwater aquifer, declining water levels in the deep freshwater aquifer, aquifer salinization as a result of inadequately controlled pumping and aquifer pollution from uncontrolled urban and industrial wastewater discharges. These issues are interlinked, but do not affect the three main hydrogeological settings equally (Table 1.7). A range of water resources management strategies are considered by Foster et al. (2004) that could contribute to reducing and eventually eliminating the current aquifer depletion and include agricultural water‐saving measures, changes in land use and crop regimes, artificial aquifer recharge of excess surface runoff, re‐use of treated urban
