Major environmental geological problems and countermeasures in karst regions
of southwest China
Yuan Daoxian Qin zhengjiao Guo Fang
This project was funded by China Geological Survey. Investigation in Yunnan, Guizhou,
Guangdong province, Guangxi Autonomous Region, and Chongqing city with a long journey
from 2008 to 2009 in southwest China showed five environmental geological problems are
common: serious surface water pollution, waterlogging and drought in karst areas, rock
desertification, more and more threaten and degree of contamination for groundwater quality
and quantity, increased impact of transportation construction on groundwater quality and
quantity.
(1)Water quality. Typical water samples showed water type in karst areas were changed from
single HCO3-Ca or HCO3-Ca.Mg to multi water types, indicating they suffered from different
kinds of pollution. For example, pH was only 2.17 in tailings water of Dabao Mountain,
Guangdong province. SO42-, Al3+, TFe and Zn were 2046mg/l, 92.13mg/l, 212.5mg/l, and
68.04mg/l, respectively. After flowing a long way, pH in Shangba river increased to 3.48, and
SO42- was 321mg/l. The contents of heavy metals were still high. Water from wells in Shangba
village was obviously polluted. The content of PO43- was 11.17mg/l in inlet of Dayu cave
underground river in Dafang County, Guizhou Province, which origined from sewage of Dafang
County. An outlet of underground river which discharged to Wujiang river was polluted by
phosphorus factory with low pH of 2.9. SEC and PO43- were 1606µs/cm, and 914.31mg/l,
respectively.
(2) Water quality in the past 30 years. Lingshui spring is a large spring with an average
discharge of 4000 l/s in Wuming County, Guangxi. It is water supply for the county and a famous
scenic spot in Nanning city. Comparing with 1977, water discharge has a tendency of decrease,
and some ions such as NO3- were obviously increased, indicating water quality was impacted by
human activities. To address this issue we carried out a project called “Study on source of
Lingshui”, cooperating with Wuming County Political Consultative Conference and Wuming
County Water Supply Company. An online station of water quality was set up. The local
government paid much attention to this.
Human activities have a great impact on water quality. Comparing water quality in three
stages in Diaojiang river, Guanxi clearly shows this. Exceeding rate was only 4.3% during 1975 to
1982. Contaminated index were nitrate and nitrite, which came from domestic pollution. During
2003 and 2004, exceeding rate was 12.4%. Contaminated index was mainly iron, manganese,
secondly nitrate and nitrite. From November 2006, Hechi City and Nandan County People's
Government re-started Diaojiang water pollution treatment project. Monthly monitoring in
Diaojiang river for about one year showed dealing with pollution in the basin have a certain effect.
(3)Straighten out the summary and comprehensive integration ways for major environmental
geological problems in Southwest karst mountain areas. Karst Disturbance Index (KDI) put
forward by Van Beynen and Townsend in 2005 was a good thinking. According to this, Karst
Disturbance Index in Guangxi can be concluded by Mining, quarrying, pesticides, fertilizers, flood,
drought, transportation infrastructure and tourism, et al. Based on these indicators we can evaluate
human activities on the karst environment, and thus to identify causes of environmental problems
and to propose solutions.
(4) Straighten out the thinking of mapping major environmental geological problems in
southwest karst mountain areas. Hydro-geological maps, land-use maps and other basic maps have
been collected. Maps of mine distribution and others are being collected.