HYDROLOGIC BENEFITS OF URBANIZING THE NORTH CHINA PLAIN

Water is the most vital and limiting resource of the 320,000-km² North China Plain, China’s most important agricultural region and home to more than 200 million people. Natural streamflow has almost completely ceased because of diversions to urban, industrial, and agricultural uses. Ground-water depths are declining steadily, salt water is intruding into previously fresh-water aquifers, and in some places the land surface is subsiding.

Detailed water-balance analysis of Luancheng County and Shijiazhuang City, Hebei Province, indicates that an eventual shift from irrigation to other, less consumptive water uses is the only means to stabilize declining water levels. Compared to irrigated cropland, urban areas deplete less water per unit land area. Thus, urbanization potentially could decrease rates of regional ground-water decline. For social and economic reasons, China’s central government and the World Bank also advocate urbanization.

However, even the North China Plain’s largest cities, which receive highest priority for water distribution, endure repeated water-shortage crises. Shijiazhuang, a typical urban area, withdraws ground water from beneath the city, uses water inefficiently, and discharges sewage and runoff downstream. Consequently, Shijiazhuang has depleted two-thirds of its 60-meter aquifer thickness. But these are local and not regional phenomena, and can be rectified through municipal and industrial water-use efficiency improvements and artificial recharge. Concurrent wastewater treatment and reuse would prevent pollution problems from further exacerbating ground-water quantity concerns.

Hydrologists and hydrogeologists are crucial not only for their traditional roles in identifying and developing new water supplies, but also for allocating and protecting existing supplies by (1) quantifying urban and regional water balances, (2) designing artificial recharge systems, (3) mitigating and remediating water pollution, and (4) illuminating the tradeoffs between competing water uses in closed basins. Most importantly, it is incumbent upon these geoscientists to maintain dialogs with policy makers to ensure that sustainable natural resource management is among – and not counter to – the social and economic benefits of urbanization.