1. the change of flow field and the formation and development of water level drop funnel in Junggar basin
In Junggar Basin, the area where the groundwater level drop funnel is formed is the confined water area in the lower reaches of Hutubi River Basin (Table 4- 1), and the formation of the drop funnel has gone through three historical stages:
1) The first stage was before 1970, and the area was still in the stage of land reclamation. There is little cultivated land in the lower reaches of the river, which is irrigated by surface water, and the groundwater is in a natural balance state.
2) The second stage is 1970 ~ 2000. During this period, with the increase of population, the expansion of cultivated land area and the rapid development of social economy, groundwater was widely developed and utilized as regulating water for irrigation season; After the reform and opening up in the 1980s, large-scale land reclamation made this area a grain and cotton base. The amount of groundwater exploitation is increasing year by year, which is 890.9× 105 and 106 respectively, accounting for 1700× 6504m3 of the exploitable resources. During the period of 1999, the production is about 2528× 104m3, and the groundwater level drops by 8 ~ 9m between 1989 ~ 1999, and the falling funnel gradually forms.
3) In the third stage, after 2000, the output of 105 and 106 in 2000 was 1952× 1043, and the overexploitation was 252× 1043. By the end of 2003, the depth of the center of the funnel reached 54.25m, and the area above the funnel water level10m reached 1500km2, which was the development period of the funnel.
2. The underground water level drop funnel in Yinchuan City
Yinchuan city takes the exploitation of the first confined aquifer group as the main target layer, forming the water level drop funnel of the first confined aquifer group.
1) The first stage is in a state of natural balance before 1970.
2) In the second stage 1970 ~ 1985, when the prototype of the landing funnel is formed, a local funnel is formed, and the centers of the landing funnel are located in Xixia District and jinfeng district City respectively.
3) The third stage 1986 ~ 2000, funnel development period 1986 ~ 1990. The area of the descending funnel increases at a speed of 30.205km2/a, and the central water level decreases at a speed of 0.884m/a; 199 1 ~ 1995, the increase rate of the area of the falling funnel is 10. 10km2/a, and the decrease rate of the central water level is 0.7695m/a, which is the period when the water level drops and the area of the falling funnel increases rapidly. 1996 By 2000, the water level had dropped to the lowest level, gradually increased, and the area of the landing funnel had increased to the maximum, and the landing funnel had become a piece.
4) The fourth stage is after 200 1 year. In the stable period of the funnel, the area of the descending funnel has been reduced to a certain extent and gradually stabilized. The water level in the center of the funnel shows an upward trend compared with 1996. From 1996 to 2003, the area of the descending funnel increased at the speed of 1.73km2/a, and the water level of the descending funnel remained relatively stable.
Table 4- 10 List of Change Trend of Water Level Drop Funnel of the First Confined Aquifer Group in Yinchuan Monitoring Area
sequential
(According to Wu et al., 2009)
3. The underground water level drop funnel in Hohhot.
Since 1980s, the water level drop funnel of the confined aquifer in Hohhot has gradually formed, and it has gone through the evolution stage from local funnel to regional funnel.
1) 1965 is preceded by the natural flow field stage. The utilization rate of groundwater is very low, and the exploitation amount is very small. Groundwater dynamics belongs to the type of precipitation infiltration recharge-evaporation runoff discharge, and confined water dynamics is mainly runoff recharge-runoff discharge; The general trend of natural flow field is from the south and west of piedmont plain.
2) 1976 ~ 1995 is the embryonic stage. From 1965 to 1975, with the development of agriculture, industry and towns, the amount of groundwater exploitation gradually increased, and some areas began to concentrate on groundwater exploitation, and the head of confined aquifer dropped sharply. The annual decline rate of the confined aquifer head in the central city of Hohhot is 0.9m/a, and the funnel has not yet formed, but the direction of groundwater flow changes, and the original flow field converges to the center of Hohhot. 1975 ~ 1995 With the increase of groundwater exploitation, the head of confined aquifer generally declines, and the rate of head decline of deep confined aquifer in Hohhot reaches 1.2 ~ 1.6/a, Kongjiaying in Huimin District, Gongren West Village in the north of Hohhot, Dongyuan Labor and Technology School in Hohhot and Yuquan District Garrison.
After 3) 1995, it is a stage of rapid development. The groundwater drop funnel gradually converges from a small group of local water level drop funnels into a single large water level drop funnel, and the center of the funnel is located in Kongjiaying, west of Hohhot. In 2000, the enclosed area bounded by the pressure-measuring water level elevation of confined aquifer 1022m was 0.64km2, accounting for 0.5% of the total urban area. When it reaches 20 10, the water level in the center of the funnel will drop to 10 16m. The closed area of 10 16m isobar is 8.4km2 In ten years, the water level in the center of the funnel has dropped by 25m.
4. Taiyuan groundwater level drop funnel.
According to the investigation results of Han Ying et al. (2009), the flow field of shallow porous aquifer in Taiyuan Basin has little change, while the flow field of middle-deep porous aquifer has great change, forming a deep groundwater level drop funnel in Taiyuan City.
1) 1959 is preceded by the natural flow field stage. The development and utilization of groundwater in Taiyuan city mainly focuses on the exploitation of karst water from marginal rocks. The amount of pore water exploitation is less than 4× 104m3/d, and the natural flow field has not been seriously disturbed.
2) 1960 ~ 1970 is the embryonic stage. The development and utilization of pore water in Taiyuan City is limited to the exploitation of shallow water and some middle aquifers. Taking 1965 as an example, the exploitation amount is only 32.93× 104m3/d/d ... The urban funnel was first discovered in 1965, with the zoo water plant and Caiyuan water plant as the center and the central water level buried at 16. 15km2. 1972 The closed area of the 770m isohydrograph reached 74km2, the buried depth of the central water level was 33m, the water level elevation was 750m, and the area of Beiying funnel was expanded to 17km2. The buried depth of the central water level is 23m, and the water level elevation is 755m.
3)1971~1990, which is a rapid development stage. 1971~1,the exploitation of Taiyuan porous aquifer entered the stage of over-exploitation, the water level dropped greatly, and the regional water level drop funnel began to form. 1976 Beiying funnel is integrated with the urban funnel centered on the zoo and Caiyuan Waterworks, and the center of the funnel moves to the southwest. The buried depth of the central water level is 46.0m, the water level elevation is 737.80m, 198 1 year, the funnel rises rapidly, and the water level of the zoo water plant drops the most, with the buried depth of 67m, the water level elevation of 7 16m, and the buried depth of the urban funnel center of 1990 is 85.7/kloc-0. The descending speed of Beiying Funnel is accelerated, and the buried depth of the central water level reaches 9 1.38m at 1990, with a descending speed of 4.7m/a (Han Ying et al., 2009).
At this stage, there is a deep aquifer water level drop funnel at 1982 in Xizhang area, with the lowest water level elevation of 776.9 1m, the closed area of 780m isobar is 15km2, the closed area of 1984m isobar is expanded to 48.2km2, and the central water level elevation is 768.74m
After 4) 199 1 year, the funnel area expanded. During this period, the amount of pore water exploitation in Taiyuan City has not decreased significantly. In 2002, the buried depth of urban funnel was 104.36m, which was lower than 1990 by 18.65m, with a decreasing rate of 65,433. In 2002, the elevation of the isoline of Xizhang closed water level was 745.0m, the area expanded to 6 1.2km2, and the buried depth of the central water level was 79.62m, which was 1 1.48m lower than that of 1.90, and the descending speed slowed down to 2.33m/a (high in Lushan Mountain)
5. The underground water level drop funnel in Linfen City
The middle-deep confined aquifer in Linfen basin is the main mining horizon. The intense exploitation of groundwater caused the regional groundwater level to drop sharply, and the groundwater level drop funnel was formed in the middle and late 1970s (Table 4-8), and the groundwater flow field changed.
1) 1958 is preceded by the natural flow field stage. Before 1958, the amount of groundwater exploitation in Linfen city was small, and groundwater exploitation never had a significant impact on pore water level.
2) 1958 ~ 1980 is the formation and development stage of water level drop funnel. During the period of 1958 ~ 1976, the amount of groundwater pumped by urban industrial and agricultural water gradually increased, and during the period of 19, the groundwater level decreased by 1.90m, with an average annual decrease of 0. 1m, and the water level decreased slowly. During the five years from 1976 to 1980, the groundwater level plummeted by 3.35m, with an average annual decline of 0.67m, and the rate of decline was obviously accelerated. Moreover, due to the rapid development of cities and industries in the middle and late 1970s, the groundwater level in the middle and deep layers of concentrated mining areas continued to decline year by year, and a water level drop funnel began to form. Near 1976, the funnel is located in the northern and urban areas of Linfen. The closed isobar water level in the center of the funnel is 380m, and the closed line water level in the periphery of the funnel is 400m, with an area of 50km2.
3)1981~1999 is the rapid development stage of floor funnel. 1985 or so, the water levels in the center and periphery of the funnel are maintained at 380m and 400m, but the lowest water level elevation in the center of the funnel is 373m, and the funnel area reaches 74km2. 1988, the water level elevation of the funnel center is 357m, the water level elevation of the closed line around the funnel is 390m, and the funnel area is 85km2；; The funnel area is expanded from 1998 to114km2; 1999, the funnel area expanded to 123km2.
4) After 2000, the funnel was stable and recovered. When it reaches 200 1, the central water level of the funnel reaches the lowest value of 340.7m, the elevation of the peripheral closed line water level is 380m, and the funnel area reaches the maximum value of 124km2. Since 200 1, the closed line around the landing funnel has remained unchanged at 380m, while the funnel area has gradually decreased, and the water level in the center of the funnel tends to be stable. In 2004, the water level in the center of the funnel was 323.4m m. From 1986 to 2004, the water level in the center of the funnel decreased by 37.08m, with an average rate of decrease of 2.06m/a (Figure 4-25).
6. houma city groundwater level drop funnel
1)1971~1980, and the groundwater level drop funnel is formed. In the early 1970s, houma city began to exploit a lot of groundwater. Due to the concentrated exploitation of middle and deep aquifers by industry, agriculture and urban life, the water level continues to decline. From the end of 1970s to the beginning of 1980s, houma city formed a funnel of groundwater level decline.
2) From 198 1 to 1999, the water level drop funnel developed rapidly. 1983, the elevation of the central water level of the funnel was 369.63m m. In the middle and late 1990s, the descending funnel developed rapidly and the central water level dropped sharply. To 1995, the elevation of the central water level is 356.89m, the water level of the closed line of the funnel is 366m, and the funnel area is 21.5km2; ; In 1999, the elevation of the central water level of the funnel was 347m, the water level of the closed line of the funnel was 376m, and the largest area of the funnel was 89.3km2. During 1983 ~ 1995 and 12, the central water level of the funnel decreased12.74 m.
3) After 2000, the expansion trend of the funnel area gradually slowed down, and the falling speed of the water level in the center of the funnel gradually slowed down. In 2004, the elevation of the water level in the center of the funnel was 345.88m, the water level in the closed line of the funnel was 37 1m, and the area of the funnel was 84.7km2. From 1983 to 2004, the water level in the center of the funnel decreased by 23.75m with an average rate of1.13 m/.
7. Yuncheng underground water level drop funnel
1) Before the 1960s, it was a natural flow field stage, and the depth of mining wells was mostly within 100m, with a small amount of groundwater exploitation. The deep aquifer is basically in a natural state, and the groundwater mainly moves to the drainage area of the middle and deep groundwater in the basins around Yanchi and Nitrochi in Yuncheng.
2) From the mid-1960s to the early 1980s, it was the formation stage of water level drop funnel. 196 1 ~ 1964, the scale of deep confined water mining has begun to take shape, forming the prototype of funnel. According to the data of 196 1 year, the 330m isobar of the aquifer funnel in the middle of the basin is distributed around the salt pond and the nitrate pond, the central water level of the funnel is lower than 330m, and the internal area of the 330m isobar circle is106km2. . The deep aquifer is similar to the natural funnel of the middle aquifer, and the elevation of the central water level is higher than that of the middle aquifer, generally about 340m, and the 340m isohydrograph is distributed around the salt pond, covering an area of about 42km2. In 1970s, the middle aquifer was mainly mined, resulting in large-scale disorderly mining. With the increase of the exploitation of the middle aquifer, the water level continues to decline and the falling funnel continues to expand. At the same time, many water level drop funnels with different areas have been formed in the basin, such as Yongji Chengguan Funnel, Zengjiaying Funnel at the junction of Yongji in Yuncheng, Anyi Funnel in Yuncheng and Xiaxian Road Funnel. With the gradual development and rapid increase of the deep aquifer, the water level began to decline, the center of the funnel shifted, and the funnel area continued to expand. By 1980, the central aquifer and the deep aquifer in the basin have formed a unified flow system, and the center position, distribution direction and water level elevation of the funnel are basically the same (Figure 4-26).
Figure 4-25 Deep Water Descending Funnel in Linfen Basin
(According to Han Ying et al., 2009)
After 3) 1980, the falling funnel of middle aquifer and deep aquifer has become a unified mixed falling funnel. 1984 ~ 1993, during this period, middle and deep aquifers were still mainly mined, and small regional funnels were connected into larger funnels. 1986, the elevation of the central water level of the middle and deep groundwater level drop funnel in the basin is 30 1.43m, and the area within the 330m isobath is 682km2. 1990, the water level elevation in the center of the funnel is 29 1.04m, and the area within the 330m contour circle is 839km2；; 1995, the elevation of the central water level of the funnel is 27 1.70m, and the area within the 330m isobar1163km2; By 2000, the elevation of the water level in the center of the funnel will be 250.03m, and the internal area of the 330m isobar circle will be1567km2; . In 2005, the central water level of the funnel was 234.70m, and the area within the 320m isobar1614.15km2. From 1986 to 2005, the water level in the center of the funnel dropped by 64.73 meters, with an average rate of 3.24 meters/year.
Figure 4-26 Cross-sectional view of the middle and deep groundwater level drop funnel in Yuncheng Basin
(According to Han Ying et al., 2009)
8. The groundwater level drop funnel in Hebei Plain.
Shallow groundwater level drop funnels in Hebei plain are mainly distributed in the junction zone between piedmont plain and central-eastern plain, while deep groundwater level drop funnels are distributed in urban centralized mining areas and agricultural centralized mining areas in central-eastern plain. See table 4- 1 1 for each funnel element.
Table 4- 1 1 Table of Changes in Elements of Groundwater Level Drop Funnel in Hebei Plain
sequential
(According to Zhang et al., 2009)
The formation of funnel has gone through four historical stages:
Before 1) 1964, the utilization degree of groundwater was very low, the exploitation amount was very small, and most of them were shallow wells. The dynamic change of shallow groundwater is natural, controlled by precipitation and evaporation, and belongs to the type of precipitation infiltration recharge-evaporation runoff discharge; Deep groundwater is mainly runoff recharge-jacking discharge and runoff discharge. The general trend of natural flow field is from piedmont to Bohai Sea, and the hydraulic gradient is from large (1 ‰ ~ 2 ‰) to small (0. 1‰). There are many artesian waters such as Zeze, Qian Qing, Wen 'anwa in the coastal areas of Cangzhou, Tangshan and the lakes near the mainland. This period is the natural state of groundwater.
2) 1965 ~ 1972, in the early stage of economic development, with the development of agriculture, industry and towns, the amount of groundwater exploitation gradually increased, and some areas began to concentrate on groundwater exploitation, and the mining intensity was too high, forming a funnel for local water level decline.
3) 1973 ~ 1985, groundwater began to be exploited in large quantities, the water level generally declined, and the water level in the center of the funnel dropped sharply, forming a number of underground water level drop funnels, and the expansion speed of the funnels showed a significant growth trend, with the deep water level drop rate reaching 3m/a (Hengshui Funnel) and the shallow water level drop rate reaching 0.9m/a (Shijiazhuang Funnel).
After 4) 1986, groundwater exploitation entered the stage of controlled exploitation. During the period of 1985 ~ 1995, the decline trend of water level slowed down obviously, and the decline rate of deep aquifer was 2m/a, and that of shallow aquifer (Shijiazhuang funnel) was 0.6 m/a. After 1995, many areas began to control the exploitation of groundwater, and the water level decreased obviously (Figure 4-27 and Figure 4-28). Affected by the 1996 precipitation recharge, the shallow water level has rebounded. By 2004, the water level in some areas (such as Cangzhou Plain) rose, and the shallow groundwater level in some areas (such as Qinhuangdao Plain) was basically stable.
9. Drop funnel of groundwater level in Tongliao City
Before 1950s, the water cycle in the West Liaohe Plain was in a natural hydrological state. Since 1950s, the groundwater flow field has been disturbed by human activities. Since 1970s, the groundwater exploitation has increased year by year, and the groundwater flow field has changed. In Naiman, Kailu, Horqin District of Tongliao City, Zuo Yi Zhongqi of Horqin and other major agricultural irrigation areas in the plain, the shape of the flow field has changed seriously. In Tongliao City, a regional water level drop funnel (Figure 4- 14) has been formed with the eastern suburb of Horqin District as the center and extending to the upstream and downstream agricultural strong mining areas, and the runoff direction has changed greatly. In the 1980s, the exploitation of groundwater began. After 1980s, the output decreased and the water level in the center of the funnel increased, but the center of the descending funnel gradually moved eastward and the area increased.
The formation and development of groundwater drop funnel in Tongliao City, West Liaohe Plain, has roughly experienced three periods (Li Zhi et al., 2009).
Figure 4-27 Duration Curve of Water Level Buried in the Center of Shallow Water Level Drop Funnel in Hebei Plain
(According to Zhang et al., 2009)
Figure 4-28 Duration Curve of Water Level Buried in the Center of Deep Water Level Drop Funnel in Hebei Plain
(According to Zhang et al., 2009)
1) the first stage: the initial stage of the formation of the floor funnel. Funnel was formed in the mid-1970s. There were no landing funnels before the 1970s. Since 1970s, due to the development of industry and agriculture, the exploitation of groundwater has increased year by year. At that time, the disorder of groundwater exploitation led to over-exploitation in some areas. By the mid-1970s, funnels were formed, with the central water level elevation of 1976 of 167.24 and the distribution area of 463.42km2
2) Phase II: the period when the water level in the center of the funnel drops sharply. In 1980s, the industrial development in this area started rapidly, the groundwater exploitation increased, and the water level in the center of the funnel continued to drop, which was the fastest period for the development of the descending funnel. 1985 funnel center water level elevation164.55m.
3) The third stage: the period when the water level in the center of the funnel is stable and the funnel area is enlarged. 1997 funnel center water level elevation 164. 1, with a distribution area of 863km2. By 2003, the water level in the center of the funnel will be 163. 16m. The distribution area of the funnel is 1290.5438+0km2.
10. Water level drop funnel of Quaternary confined aquifer in Harbin
The prototype of the water level drop funnel of the Quaternary confined aquifer in Harbin was formed in 1970 ~ 1982 (Phase II), and five small underground water level drop funnels with a total area of about 100km2 were formed centering on the heavy machinery factory, the welding electrode factory, the Songjiang Canning Factory, the municipal ice hockey factory and the Daoli Gas Company.
From 1985 to 1990 (the third stage), five small funnels spread out with each other, forming a water level falling funnel (#TC 1 188+088) centered on the heavy machinery factory (Figure 4-29),/kloc-0. During the period of 1987, the water level dropped significantly, with the center of the funnel dropping at a rate of 0.8 ~ 1.7m/a, and the maximum dropping rate at the periphery of the funnel at a rate of 0.2 ~ 1.0m/a, and the funnel area was about 30km2, and it moved southward at a rate of 0.5 ~ 0.75km/a .. 1990, the funnel area expanded to 260km2, and the water level in the center of the funnel dropped by 27.3m, with a dropping rate of 0.74m/a (Figure 4-30).
Figure 4-29 Diagram of the Decline Range and Rate of Groundwater Level in Harbin
(According to Zhao et al., 2009)
Figure 4-30 Variation Curve of Water Level in Funnel Center of Harbin City
(According to Zhao et al., 2009)
Since 199 1 (the fourth phase), Harbin began to control the amount of groundwater exploitation, and the urban exploitation was controlled at (1.46 ~1.57) ×1083/a, and the water level began to slow down, and the funnel center and its northern section were underground. 1995, the funnel area developed to 300km2. During this period, the groundwater exploitation in Harbin decreased from1991.86×1083 in 0 years to 1.35× 1083. By 2005, the funnel area will basically remain at about 380km2 (Figure 4-3 1), the buried depth of the central water level is 54.42m, and the water level elevation is 107.49.
Fig. 4-3 1 funnel area and mining change curve in Harbin
(According to Zhao et al., 2009)
1 1. Water level drop funnel of Quaternary confined aquifer in Daqing City
The large-scale exploitation of Quaternary confined water in Daqing City began with the oil battle of 1960. Before that, the buried depth of water level was mostly less than 5m, and only 5 ~ 10 m locally.
During the period of 1960 ~ 1972, the groundwater exploitation increased, and the water level of 1963 began to decrease. The buried depth of the water level in the center of the funnel is 19.62m, and the water level drops by 9 ~ 14 m, forming a groundwater level drop funnel.
During the period of 1973 ~ 1995, the amount of groundwater exploitation continued to increase and the water level continued to decrease. 1976, the production was 1.4 1× 1083, and the water level in the center of the funnel was buried to 29.50m, which was the fastest development period of the funnel. By 1986, the output reached 2.0× 1083, and the buried depth of the central water level of the funnel reached 34.24m, from 1986 to 1988, the output decreased slightly, and the buried depth of the central water level of the funnel returned to 33.28m,1. By 1993, the output reached 3.05× 108m3, and the funnel area reached 4500km2.
Since 1996, Daqing city has started to control the exploitation of groundwater. 1997, the groundwater exploitation has been reduced to 2. 19× 1083, and the funnel area has been reduced to 4000km2, but the buried depth of the central water level of the funnel is still decreasing. After 200 1 year, the water level in the center of the funnel decreased to 4 1.7m, and the water level tended to be stable and rose somewhat. In 2004, the groundwater exploitation decreased to 1.086× 1083. In 2005, the buried depth of the central water level of the funnel was restored to 37. 19m, and the funnel area was about 3600km2. See Figure 4-32 for the changes of water level and production in the groundwater drop funnel.
Fig. 4-32 Variation curve of water depth in the center of Quaternary confined water funnel and annual output in western Daqing placanticline.
(According to Zhao et al., 2009)
12. Water level drop funnel of Quaternary confined aquifer in Qiqihar City
The exploitation of Quaternary confined water in Qiqihar City began in 1970' s, and by 1988, a prototype funnel was formed, with an initial area of only 2.78km2 and a buried depth of 5.32m in the center of the funnel, which was lower than 19721.59m.. From 1988 to 2000, with the increase of groundwater exploitation, the funnel area continued to expand, and the water level dropped the most at 1990, with a drop of 0.95m that year. By 1995, the funnel area reached 14.38km2, and then the groundwater level showed a slow downward trend. By 2000, the funnel area was expanded by about102.5km2; ; After 2000, due to the increase of surface water supply, the industrial water consumption decreased, the exploitation of Quaternary confined water decreased, and the water level in the center of the funnel did not drop significantly (Figure 4-33). By 2004, the buried depth of the central water level of the funnel was 6.79m, only 0.29 lower than that of 1990, and the funnel area was about 92.0km2.
Figure 4-33 Variation Curve of Central Water Level and Funnel Area of Quaternary Confined Water Funnel in Qiqihar
(According to Zhao et al., 2009)