Subsequent effects of overdraft

As the groundwater table falls, producers face a number of impacts; above all, of course, the cost of pumping rises. According to our data, for every meter by which the groundwater table falls, pump costs rise by 0.005 yuan/m3 (or about 2% of the mean level of pumping costs in 2004). In addition, wells may have to be replaced and the costs of investment increased, although in many cases new wells have been sunk for reasons other than the falling water table. The average cost of drilling a deep tube well (90 m) was more than five times the cost of drilling a shallow tube well (37 m). According to our data, well owners in China have sunk an enormous number of new wells in the last decade. On average, from 2002 to 2004, the typical groundwater-using village sank about 22 new wells, 5 deep and 17 shallow. Although a percentage of new wells (6 of the 22) were being installed because olds wells were abandoned, it should be noted that, according to the opinions of our respondents, only 2 of the 6 wells were abandoned because of the falling water table. In many cases, wells were replaced for other reasons (e.g. when a well structure collapsed).

Beyond the increases in pumping costs and well installation, there are also a number of other potential consequences of overdraft (Ministry of Water Resources and Nanjing Water Institute, 2004). One of the most commonly cited consequences is land subsidence. For example, in Hebei province alone, by 1995 more than 5000 km2 had subsided more than 600 mm. In Tianjin municipality, the total exceeded 7000 km2.17 Groundwater overdraft may also lead to the intrusion of seawater into freshwater aquifers (Ministry of Water Resources and Nanjing Water Institute, 2004). By the mid-1990s overdrafting allowed sea water to intrude and contaminate aquifers under more than 1500 km2 of land, especially in the coastal provinces of northern China such as Liaoning, Hebei and Shandong. The MWR has also been concerned about the impact of groundwater overdraft on desertification and depletion of stream flow that was previously supplied by natural groundwater discharge.

Although the consequences of overdraft are widely discussed in the literature and equated with China's water problems in general, interestingly none of these problems appears to be in any way associated with rural areas. According to our survey of more than 400 villages, no village leader ever reported that there was any land subsidence problem. Likewise, in no case did a village leader report that his or her village's groundwater was contaminated by sea water intrusion. Finally, there also was no evidence that villages that were using groundwater - both those that were drawing down their water table and those that were not - experienced a fall in cultivated area due to desertification. Clearly, although the attention that these problems get in the literature means that they are serious and require addressing, there appear to be no rural area problems.

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