(1. Henan Institute of Land and Resources Science, Zhengzhou 450016; 2. School of Environment and Water Conservancy, Zhengzhou University, Zhengzhou 450002)
Journal of Henan Normal University (Natural Science Edition), article number:1000-2367-(2007)-02-0195-04.
Shiyang River Basin is an area with high utilization rate of water resources and serious ecological environment damage in the development of inland river basins in China. It is of great significance and urgency to study the water resources management and sustainable development of Shiyang River Basin. Combined with the actual situation of Shiyang River Basin, this paper analyzes the present situation of water supply and use in the basin, summarizes the ecological environment problems caused by over-exploitation and utilization of water resources in arid areas, and finally puts forward reasonable suggestions on the sustainable utilization of water resources in the basin from the aspects of industrial structure adjustment, ecological environment management and water transfer project.
Keywords: Shiyang River Basin, resource crisis, environmental sustainable development
1 Overview of the study area
Shiyang River Basin is located in the east of Hexi Corridor in Gansu Province, which is connected with Baiyin and Lanzhou in the southeast, Qinghai in the southwest, Zhangye in the northwest and Inner Mongolia Autonomous Region in the northeast, with a total basin area of 4 1.6× 103 km2. The administrative divisions of the river basin include all Gulang County, Liangzhou District, Minqin County and Tianzhu County in Wuwei area, all Yongchang County and Jinchuan District in Jinchang area, and parts of Sunan Yugur Autonomous County and Shandan County in Zhangye area. The river basin * * * involves 3 cities and 8 counties. The basin is located in the hinterland of the mainland and belongs to the continental temperate arid climate. The climate is characterized by strong solar radiation, abundant sunshine, short and hot summer, long and cold winter, large temperature difference, less precipitation, strong evaporation and dry air.
The drainage system of the basin originates from Qilian Mountain and consists of eight rivers from east to west: Dajing River, Gulang River, Huangyang River, Zamu River, Jinta River, Xiying River, Dongdahe River and Xidahe River. The average annual precipitation in the basin is 28 1.2mm, and the surface water resources are 1.566× 109m3, which are mainly produced in Qilian Mountain area, with the runoff yield area of1.1×103. Groundwater resources are underground recharge of surface water, including precipitation recharge, lateral inflow of desert and lateral inflow of Qilian Mountain, totaling 0. 1× 109m3. The total water resources in the whole basin is the sum of two items, * * * 1.666× 109m3.
As far as water quality is concerned, the mountain source water quality in the basin is excellent (reaching Class I) and can be applied to various purposes; The main streams of Jinchuan River, Hongshui River and Shiyang River in the plain area are seriously polluted (Grade V or worse than Grade V) due to the discharge of industrial and domestic garbage from Jinchang and Wuwei City, and the water contains arsenic, Cr6+ and some heavy metal ions. The water quality of Jinchuanxia Reservoir and Hong Yashan Reservoir in the lower reaches is poor, which belongs to the inferior V category. The results of groundwater quality evaluation show that the water quality in Dajing, Wuwei and Yongchang basins is still good (above Class III), and the water quality in Minqin and Changning basins is deteriorated (worse than Class V) due to the pollution and reuse of inferior surface water and the reduction of groundwater recharge, which is not only inedible but also unsuitable for irrigation (Li Youlin, 2000).
2 Analysis of the present situation of water resources development and utilization
2. 1 Analysis of water supply situation
After more than 50 years of construction after the founding of New China, the water conservancy projects in Shiyang River Basin have reached a considerable scale, forming a development model of reservoir regulation in the upper reaches of mountainous areas, water delivery in the middle reaches of plain channels, well irrigation by machine wells or mixed irrigation in wells and canals in the lower reaches. Among the eight rivers out of the mountain, all the other rivers have built reservoirs except one river on the Miscellaneous Wood River. At present, water transfer projects of a certain scale have been built in other river basins, such as the project of diverting sulfur (sulfur ditch) and benefiting gold (Jinchuan River) and the second phase expansion project of Jingdian Power Station. The total designed water supply of the whole basin project is 3.482× 109m3, and the actual water supply in 2005 is 2.663× 109m3. Generally speaking, water supply is mainly based on water storage, groundwater extraction and water diversion projects. See table 1 for the water supply quantity of each water supply project in the basin in 2005.
Table1Statistics of Actual Water Supply in 2005
Watershed water supply sources are divided into surface water sources and underground water sources. The source of surface water is the precipitation and melting water of snow and ice in Qilian Mountain. Through analysis, it can be seen that the water flow out of the mountain pass of Qilian Mountain is relatively stable for many years, while the surface runoff entering the downstream Minqin Basin is decreasing year by year, from 0.464× 109m3 in 1950s to 0.083× 109m3 in the early 20th century (Figure 1). 90% of groundwater resources are supplemented by surface water. With the gradual improvement of surface water utilization rate, the groundwater recharge in the whole basin decreased from 1.28× 109 m3 in 1980s to 0.86× 109 m3 in 2005. Due to the drop of groundwater level, more than 800 pumping wells in the whole basin were scrapped, and the exploitation of groundwater gradually changed from shallow to deep.
Figure 1 Annual inflow of Hong Yashan Reservoir
Figure 1 Annual Runoff of Hong Yashan Reservoir
2.2 Analysis of the current situation of water use
Through engineering measures, the utilization rate of water resources in the basin is very high. In 2005, the development and utilization of water resources reached 154% of the total water resources (excluding inter-basin water transfer projects), far exceeding the carrying capacity of water resources. In 2005, the total water consumption of all social and economic departments in the whole basin was 2.678× 109m3, and the water consumption is shown in Table 2. According to the Comprehensive Report on Sustainable Development of Water Resources in China, 1997, the industrial water consumption accounts for 20.2% of the total water consumption, and the agricultural water consumption accounts for 75.3%, indicating that the agricultural water consumption in Shiyang River Basin is obviously high.
Table 2 Statistics of Actual Water Consumption in 2005
The water intake quota of 10,000 yuan industrial output value in the basin is 1.53 m3, which is 62m3 higher than the national average. This is because the industries in the basin are mainly water-consuming enterprises such as smelting and brewing, and the share of high-tech industries is small. The repetition rate of industrial water is 49%, which is higher than the national average. The net quota of agricultural irrigation is 0.556m3/m2, which is obviously higher than the national and provincial level, which is determined by its special climatic conditions. The irrigation water utilization coefficient is 0.52, which is roughly equivalent to the national average. The water consumption per 10,000 yuan GDP is 368 1 m3, which is about five times the national average. Generally speaking, the water use efficiency of the basin needs to be further improved.
3 Analysis of ecological and environmental problems
Shiyang River Basin is a typical area that develops economy at the expense of environment. Its current problem is mainly the deterioration of the ecological environment caused by the water crisis, which is highlighted in the following aspects:
(1) The vegetation in the runoff producing area is destroyed, and the water conservation capacity is reduced. Qilian Mountain is the formation area of water resources in the whole Shiyang River basin, and forest vegetation and alpine grassland are water conservation areas. Due to man-made deforestation, overgrazing, herb picking and land reclamation, the cultivated forests and grasslands are nearly 1.500 km2, the remaining water source forests are less than 550km2, and the vegetation coverage rate in mountainous areas is only about 40%. The shrub line in Qilian Mountain is 40m higher than that in 1950s, and 30% of the shrub is grassland and desertification (Chang Zhaofeng et al., 2005).
(2) The carrying capacity of water resources is not fully considered in economic development. The lack of scientific planning in the utilization of water resources in the basin, the excessive irrigation area, especially the unreasonable multiple cropping area and planting structure, lead to excessive agricultural water consumption and serious crowding out of ecological water by production water. At the same time, the development of the upper and middle reaches competes for water resources, regardless of natural laws and without constraints, which leads to increasingly serious water crisis and ecological environment problems.
(3) The surface water entering the downstream is decreasing year by year, and Minqin Oasis is facing a crisis of survival. The rapid development of large-scale industrial and mining enterprises and local "five small" enterprises has led to a sharp increase in water consumption in the upper reaches of Qilian Mountain, the construction of reservoirs to increase water storage capacity, the lining of irrigation channels in the middle reaches, and the rapid development of large-scale industrial and mining enterprises and local "five small" enterprises, which has led to a sharp drop in water consumption in the lower reaches of Shiyang River into Minqin Oasis. In order to maintain the artificial oasis and water for people and livestock, Minqin people increased the exploitation of groundwater, which led to the continuous decline of groundwater level at the edge of oasis, the sharp shrinkage of natural oasis and the intensification of desertification. According to the calculation (Dou Ming et al., 2005), during the 30 years from 197 1 to 2000, the amount of water entering Minqin at Jiawan decreased by 3.0× 109m3, and the amount of water leaving Minqin decreased by 2.5× 109m3, with an average annual decrease. In recent 30 years, the groundwater level in the oasis has decreased by 42.4m, with an average annual decrease of 1.44m, forming a deep funnel in the center of the oasis, and the vegetation on the edge of the oasis has declined in a large area.
(4) Land desertification and sandstorms have intensified. In 2005, the area of land desertification in the whole basin reached 2. 149× 103km2, the area of grassland degradation reached 1.50× 104km2, and the farmland was buried by quicksand for 3.2× 102km2. The windbreak and sand fixation forests, grasses and farmland shelterbelts in the northern desert area decreased by 2.0× 103km2. The desert advances to the oasis at the rate of 3 ~ 4m per year. Due to the increasing desertification area and the death area of desert grassland, sandstorms threaten Minqin, Jinchang and Wuwei, and even affect the whole northern region.
(5) Environmental pollution is becoming more and more serious. With the rapid development of local economy and the strengthening of urbanization trend, the consumption of natural resources has increased rapidly, making the burden of environmental resources increasingly serious. Especially in the urban areas with relatively concentrated population and prosperous economy, the discharge of "three wastes" has obviously increased, and the environment in some areas has obviously deteriorated and expanded to the surrounding areas. By 2005, the wastewater discharge in jinchang was 35.478× 106t, which was 47.3% higher than that in 1990s. The output of industrial solid waste is 4.737× 106t, which is 56.8% higher than that in 1990s. Water pollution, white pollution and chemical pollution are becoming more and more serious in Wuwei city. In 2005, the production and domestic wastewater discharged into Shiyang River reached 2.5351×103 t. Due to the small surface runoff in the basin, the self-purification ability of the water body is weak, the surface water pollution is serious, and the groundwater is also polluted to varying degrees due to the leakage of urban sewage and various pollutants on the ground.
4 Discussion on sustainable utilization of water resources
At present, the deterioration of the ecological environment in Shiyang River basin has attracted the attention of administrative departments at all levels, academia and all sectors of society, and Shiyang River has become another hot spot after the comprehensive management of Tarim River and Heihe River. The author believes that the sustainable development and water resources management of Shiyang River Basin should start with the following points:
4. 1 Reasonable adjustment of industrial structure
Strategically adjust the socio-economic layout, accelerate the process of urbanization and industrialization in the whole basin, give priority to the development of industry and service industry, and control and reduce the scale of agriculture in order to improve the utilization efficiency and output of water resources per unit. At present, agricultural irrigation is a big water user in all economic and social sectors of the basin, and there are problems such as too large cultivated land area and high irrigation quota, so agricultural water-saving potential is great, and appropriately shrinking agricultural scale can effectively alleviate the pressure of domestic and industrial water use (Liu Changming et al., 1996).
4.2 Adjust agricultural planting structure to improve agricultural water-saving efficiency.
At present, the planting ratio of grain, economy and forage is 68: 21:kloc-0/1,the planting ratio of grain and cash crops is 76: 24, and the planting ratio of multiple crops (sets) is 22.2%. It is suggested that the planting proportion of grain, grain and feed should be adjusted to 5 1: 29: 20, the planting proportion of grain and cash crops should be 63: 37, and the planting proportion of various crops should be 15%.
At present, the main irrigation methods in the basin are "canal irrigation", accounting for 97.7% of the total area, pipe irrigation accounting for 1.5%, and efficient water-saving irrigation accounting for only 0.8%. It is suggested that the well irrigation area in the basin should be fully irrigated by pipeline. On this basis, sprinkler irrigation is 2.1102km2, micro irrigation1.85x100km2, accounting for 15.7% of the total irrigation area, and the rest is pipe irrigation. Small border irrigation is fully implemented in river irrigation area, accounting for 79.3% of the total irrigation area.
4.3 Accelerate the ecological environment construction and comprehensive management.
According to the geographical location and natural conditions of the basin, we must implement the principle of "forest is suitable for forest, animal husbandry is suitable for animal husbandry, agriculture is suitable for agriculture, drought is suitable for drought", and define the production areas of agriculture, forestry and animal husbandry and the scope of returning farmland to forest and grassland. Actively and steadily adjust the structure of agriculture, forestry and animal husbandry, and implement natural enclosure adjustment for 6.67× 102km2 farmland irrigation land with concentrated groundwater exploitation and poor cultivated land quality or near desert and Gobi marginal areas. At the same time, the irrigation area in the downstream Minqin area will initially realize 4.33× 102km2 of returning farmland to forests, establish a desert nature reserve with Minqin oasis and desert transition zone as the core, and implement enclosure. Use groundwater and natural precipitation to ensure the restoration of natural vegetation and establish a sand storm barrier.
Shut in the well to reduce the amount of groundwater exploitation. At present, there are 0.5 million electromechanical wells/kloc-0 in the * * river basin, and the annual over-exploitation of groundwater reaches 0. 1.8× 1.09 m3. In view of the situation that there are too many electromechanical wells and the groundwater is seriously over-exploited, 1 300 old wells are closed before 20 10 (according to Shiyang river basin).
Increase the intensity of sewage treatment and recycling. In the form of joint investment by the state and local governments, 3-4 large and medium-sized sewage treatment plants will be built in Jinchang and Wuwei urban areas, and the local governments will be responsible for the operation and management, so as to realize the recycling and advanced treatment and reuse of urban domestic sewage and industrial wastewater.
4.4 Implement water transfer project and ecological resettlement project.
As far as the current situation is concerned, to completely solve the water resources dilemma in Shiyang River basin, water must be transferred from other basins. In order to solve the industrial water consumption in jinchang, the ecological environment and agricultural water consumption in Minqin County, the planned "Datong River westward" water transfer project was put forward. The project plans to transfer 0.25× 109m3 of water from Datong River every year, which can alleviate the shortage of water resources in the basin after the project is completed. At the same time, on the basis of existing water transfer facilities, increase water transfer and supplement ecological water, create conditions for the survival of natural vegetation as much as possible, and win time for comprehensive management of the ecological environment in the whole basin.
In addition, it is necessary to appropriately reduce the population pressure in ecologically fragile areas and buffer zones and do a good job in ecological migration. There are roughly two directions for migration: one is the oasis in the middle reaches, that is, resettling some immigrants through population urbanization; Second, the diversion project outside the basin, the Shule River project, the Jingdian and Xingbaozichuan irrigation areas along the Yellow River can also accommodate some immigrants.
refer to
Li Youlin. 2000. Groundwater environment in Shiyang River Basin. Groundwater, 22 (3):113 ~116.
Dou Ming, Sun Xuetao, Zuo Qiting. 2005. Study on water resources transformation model and its application in Shiyang River Basin. Journal of Zhengzhou University (Engineering Edition), 26 (3):109 ~112.
Chang Zhaofeng, Han, Zhong Shengnian, et al. 2005. Natural and artificial factors of desertification in the lower reaches of Shiyang River and their replacement. Geography of arid areas, 28 (2): 150 ~ 155.
Liu Changming, He Xiwu. 1996.water problems in China in the 20th century. Beijing: Science Press.
Xiao Duning, Li Xiaoyu, Song Dongmei. 2005. Landscape changes and ecological restoration countermeasures of Shiyang River Tail Oasis. Journal of Ecology, 25 (10): 2477 ~ 2483.
Thoughts on over-exploitation and utilization of water resources in Shiyang River Basin
Xing Yongqiang 1 Li Jinrong 2 Dou Ming 2
(1. Henan Institute of Land and Resources Science, Zhengzhou 450016; 2. School of Environment and Water Conservancy, Zhengzhou University, Zhengzhou 450002)
Abstract: Shiyang River Basin is an inland area with high utilization of water resources and serious destruction of ecological environment. The research on water resources management and sustainable development in Shiyang River Basin is of great significance and necessity. Based on the actual situation of Shiyang River, this paper evaluates and analyzes the present situation of water resources supply and demand, and summarizes the problems in the process of water resources development and utilization. Finally, some reasonable suggestions on the sustainable utilization of water resources are put forward from the aspects of economic structure adjustment, ecological environment management and water transfer project application.
Key words: Shiyang River Basin; Water crisis; Ecological environment; sustainable development