Karst water protection in Yuntai Mountain spring area

1. Karst springs and karst water environment problems in northern China

Northern my country’s Shanxi, Shandong, Hebei, Henan, Liaoning, Shaanxi, Inner Mongolia, Beijing, Tianjin and other provinces (autonomous regions, self-administered There are large areas of carbonate rock formations distributed in the city, with a total area of ??about 500,000 km2. The karst fissures are rich in groundwater, and there are more than 60 karst springs with an original flow rate of more than 1m3/s. Among them, Niangziguan Spring, Tianqiao Spring and Xin'an Spring in Shanxi Province are not only the largest karst springs in northern my country, but also ranked among the arid and semi-arid in the world. Among the karst springs in the area. Different from the underground rivers in the southern karst, the water-bearing medium in the northern karst is mainly dissolved gaps. The karst spring water flow is stable and concentrated, with excellent water quality and strong underground storage capacity. It has great advantages in water supply and has become the main source of water supply for many cities and industries in the north. Agricultural water supply source area. Many karst springs have landscape and historical value, such as Baotu Spring in Jinan and Jinci Spring in Taiyuan, which are famous tourist attractions. In addition, most of the northern karst areas have coal-water storage systems. Karst water poses a threat to coal mining, and coal mining destroys karst water resources.

Compared with 30 years ago, the water resources and environmental conditions of karst springs in northern my country have changed beyond recognition. The main issues are as follows.

1. The flow of spring water has attenuated or even dried up

For the large karst springs in northern my country with an original flow rate above lm3/s, more than 80% of the spring water flow has declined, and nearly 30% of the spring water has dried up or even dried up. Almost dry. The Baiquan in Huixian County and the Jiuli Mountain Spring in Jiaozuo around the Yuntai Mountain Spring Area have long since dried up.

2. The groundwater level in spring areas continues to decline

Over the past 30 years, the groundwater level in almost all spring areas has been declining, with the decline generally ranging from 20 to 30m, and some reaching 40m. Even in the Tianqiao Spring area, which is recharged by leakage from the Wanjiazhai Reservoir, the water level in the recharge area is declining. The groundwater level continues to decline, indicating that karst groundwater resources are decreasing.

3. The landscape of spring source areas has been destroyed and the ecological environment has deteriorated

Many spring source areas have beautiful scenery, numerous historical sites and towering ancient trees. As springs dried up and water levels dropped, landscapes were destroyed and monuments damaged.

4. Groundwater quality pollution

In the past 30 years, the quality of karst groundwater has generally declined. Increased salinity and hardness have become common phenomena. Harmful elements or components have appeared in some springs. 40 % of spring water suffers from varying degrees of pollution.

5. Triggering environmental geological disasters

Due to the decrease in the groundwater level in the spring area, geological disasters such as karst collapse and ground subsidence have been triggered.

The reasons causing the above problems are as follows:

(1) The impact of climate change on spring water flow. Due to global climate warming, precipitation in North China has decreased by 8% to 9% on average since the 1970s, which is the direct cause of the attenuation of spring flow and the decline of groundwater levels.

(2) The increase in temperature leads to an increase in land surface evaporation and reduces the recharge of karst groundwater from precipitation infiltration.

(3) A large amount of karst groundwater is exploited in the spring area. Due to excessive exploitation of karst groundwater by wells in the spring area, the water level has dropped, causing the spring flow to decrease or even dry up. This phenomenon is very common in the spring areas around Yuntai Mountain, such as the Baiquan Area in Huixian County and the Sangu Spring Area in Jincheng. Excessive drilling of wells to exploit karst water has resulted in many falling funnels.

(4) Water inrush and drainage during coal mining. Most of the coal mines at the southeastern foothills of Taihang Mountain are flooded mining areas. The groundwater level is higher than the coal seam. Water inrush from coal mining and drainage mines has caused damage to the water environment. Not only has the water level dropped, but the water quality has also been polluted. For example, in the Jiaozuo area, mine drainage reaches one million m3 per day, causing springs to dry up and water levels to continue to drop.

(5) Deforestation and land reclamation destroy vegetation and cause changes in the underlying surface. The result is a change in surface runoff conditions, resulting in reduced infiltration, increased surface flooding, and serious soil and water loss.

(6) Sewage discharge from cities, factories, mines and scenic spots pollutes groundwater.

2. Suggestions on water environment protection in the karst springs of Yuntai Mountain

(1) Make every effort to carry out ecological protection, especially in watershed groundwater recharge areas. Farmland should be returned to forests and water source protection forest belts should be built. This is a century-old plan to keep the spring flowing.

(2) It is prohibited to dig wells to obtain water within the spring area. In the watershed area, people in Lingchuan, Shanxi Province are currently diverting water from a double-headed spring. When the water level drops and the spring water cannot flow by itself, water pumps are used to lift the water. It is recommended to build a dam at the mouth of the spring and build an underground reservoir (Figure 64). Its functions are: ① to store floods; ② to raise the groundwater level, increase the amount of infiltration, and increase the recharge of karst groundwater; ③ to facilitate the diversion and use of water by nearby residents; ④ It is conducive to regulating the water flow of waterfalls in scenic spots. A feasibility study is recommended.

Figure 64 Schematic diagram of Shuangtouquan underground reservoir

(3) The environmental capacity in the scenic area is limited, and sewage discharge in the scenic area is completely prohibited.

(4) The Yu River on the north side of Zifanggou and the Shanmen River on the southwest side of the Yuntai Mountain Spring Area may be adjacent spring areas. Their hydrogeological conditions and development and utilization status are still unclear. It is recommended to carry out appropriate Investigate to determine whether there will be any impact on this spring area.

(5) It is recommended to establish a spring water quantity, water quality and vegetation observation and monitoring system in the spring area to obtain long-term observation data of water quantity, water quality and ecological changes to provide scientific basis for the sustainable use and protection of the scenic spot.

(6) It is recommended to work with relevant counties and cities in Shanxi to build water source protection forest belts or ecological garden tourist areas in the watershed area.

Develop the forestry and fruit industry, reduce planting industry, and protect the fragile ecological environment of the mountains.