Water Quality and Health in Southwest China

An estimated 80 to 100 million residents in eight provinces of southwest China live in areas of karst topography, which are typically areas of soluble limestone and characterized by such features as caves, underground rivers, and often a general lack of surface drainage. Of these, some 8 to 10 million live below China’s poverty level. While caves and related karst features may seem like rather obscure geological features to many people, it has been estimated that as many as 25% of the world’s population obtains its drinking water from karst aquifer sources¹.

Karst regions, including those in southwest China, typically present severe challenges in water supply with regard to both quantity and quality of water. Because much of the water in these areas is in the subsurface—often hundreds of meters below the ground—sufficient supplies are not easily available, particularly because the technology for drilling and pumping is lacking in China’s rural areas. Residents of many villages that were developed near small shallow karst springs found themselves without reliable nearby water sources after widespread deforestation in the mid-twentieth century caused soil loss and disruption of these water supplies, a process in China called rocky desertification². The water shortages are exacerbated by a monsoon climate throughout southern China where as little as 30% of annual rainfall can fall over 70% of a typical year³, resulting in prolonged winter dry seasons. Karst groundwater is also exceedingly vulnerable to contamination, so even accessible water supplies are often contaminated by agricultural, industrial, and mining pollution or disease causing bacteria^1,4.

3. Tao, S., and L. Chen, 1987, A review of recent research on the East Asian summer monsoon in China. Monsoon Meteorology, C.P. Chang and T. N. Krishnamurti, Eds., Oxford: Oxford University Press, 60-92.

4. Yuan D. 1991. Karst of China. Beijing: Geological Publishing House.