鄂爾多斯陶利水源地地下水開采的植被生態(tài)風險研究

1、鄂爾多斯陶利水源地地下水開采的植被生態(tài)風險研究        【中文摘要】本文通過植被現狀調查分析的方法分析植被與包氣帶巖性、地形地貌以及地下水位埋深之間的關系,并確定水源地的幾種上風植被種群的適生水位區(qū)間。結合現狀地下水位埋深條件下的植被分布特點,確定現狀植被的敏感性分區(qū)。同時,根據水源地的水文地質條件建立地下水流數值模型,模擬未來五年區(qū)內地下水位的變化情況。在此基礎上,根據未來猜測的地下水位埋深和典型植被的分布特點,對研究區(qū)植被生態(tài)風險進行分析研究,并劃分風險性分區(qū)。研究結果表明,水源地植被生態(tài)風險具有地勢較低

2、地區(qū)大于地勢較高地區(qū),水源地中部的風險大于水源地其他地區(qū),開采區(qū)大于非開采區(qū)的特點。持續(xù)開采5年后,研究區(qū)內90%的地區(qū)均勻水位下降1.53m,此時,研究區(qū)生態(tài)水位從最佳生態(tài)水位區(qū)過渡到生長受限水位,在此水位下,灘地低濕植被如芨芨草、馬蘭等植物生長受限,并出現退化跡象,而類似于沙蒿、檸條等沙地旱生植被的生長狀況變化不大。');【Abstract】 The vegetation is fragile in arid and semiarid area in the northwest of China, and it closely correlates the depth to gro

3、undwater su*ce. Exploiting groundwater unreasonably will lead to the groundwater level descending irrationally in this field, and it will deteriorate and desert the vegetation eco-environment.Taoli watersource area is located at the Desert Maowuso, the arid-semiarid area in the northwest of China. G

4、roundwater is very important to the water supply in this area. Vegetation in this field is also fragile and much of it is closely related to the groundwater depth. As a result, to carry out large-scale exploitation of water sources, risks will be caused by the underground water level dropping. So th

5、e factors of vegetation should be taken into account when assessing and planning groundwater resources in the field. This *, based on the item“Investigate of Groundwater in Taoli Wellworks in Ordos Basin”, studied the risk of vegetation under the condition of groundwater withdraw in Taoli which loca

6、ted in the centern of the Maowuso Desert. This article used the data of vegetation investation to study the coverage, richness and dominance of this field, and then to identify the predominant species of vegetation. The most dominant species of vegetation was artemisia, carex, salix psammophila. The

7、 frequency of dominant species under different water level could be employed to work out five intervals of ecological water level such as water level of salinization, reasonable water level, restricted water level, languish water level and dangerous water level.The main salt-tolerant vegetation that

8、 grew at the area whose water level was in range of 0.5m to 1.5m what is the range of the water level of salinization. The best survival water depth was between 1.5 m and 3.0m, within the range all the plants could develop normally and a wide variety of vegetation could grow. The low-humidity vegeta

9、tion growth would be restricted at the level between 3.0 m and 5.0m which was the range of growth limited water depth, but little effect on the Saudi. Languish water level was between 5.0 m and 8.0m, due to low humidity vegetation degradation, drought and some of the sand vegetation growth restricti

10、on, poplar, willow and other trees in a wilting. Dangerous would appear when the water level was more than 8.0 m, only drought-resistant plants such as sand Artemisia and Caragana maintain normal growth.The relationship between coverage and lithology of unsaturated zone, and topography and groundwat

11、er depth could be composed with root depth of dominant species to part the vegetation sensitivity zone.The first sensitive area was located at the low-lying beach and the area surrounding Lake dried up, where the main vegetation was low-humidity vegetation. The second sensitive areas in the study ar

12、ea were covered by masses of eolian sand, where drought-resistant vegetation growth in.Distribution of non-sensitive areas in the eastern and western sand beam which was watershed of groundwater, and it was great depth to the water table in these areas. Plant such as artemisia that was not high rele

13、vance of the water table was the main vegetation.Groundwater flow numenical simulation model based on the condition of hydrogeology in the field was set up to predict the groundwater drawdown in the next five years with three projects which used c of 100 000m3/d, 80 000m3/d and 60 000m3/d. The resul

14、t showed that the area of drawdown between 1.5m and 3.0m had been more than 90% of the field after five years.Risk indexes of vegetation ecology had been established on the base of the result of the three projects.And risk zones were also classified according to the indexes.Whats more, the high risk

15、 zone which was mainly distributed in detailed investigated area would become larger and larger with the augmentation of groundwater withdraw. On the contrary, the area of middle risk and low risk would decrease.High-risk areas were mainly located in the exploitation that caused the groundwater tabl

16、e dropped about from 1.5 to 3m after five years of groundwater resources on the beach areas. Some low-humidity vegetation could not grow normally and even gradually degraded, its original dominant vegetation will be replaced by drought-resistant vegetation. Medium-risk areas were larger than other r

17、isk area and were covered by aeolian sand. The main vegetation was Artemisia who was less affected by the decline of water table depth. But some low-humidity vegetation is locatede in the surrounding areas of drought-lakes. The main plants would be replaced by Artemisia with the increased depth of t

18、he water table caused by development of groundwater. Low-risk areas in the distribution of watersource to the southwestern and northern regions, for the wind-sand covered areas. The growth of vegetation mainly was Artemisia and Salix psammophila who was dry desert vegetation. Water level drop caused by groundwater exploitation could not generate too much risk to these vegetations. Security zones were located in the east an