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1.

Because of the human exploitation and utilization of water resources in the Tarim Basin, the water resources consumption has changed from mainly natural ecosystem to artificial oasis ecosystem, and the environment has changed correspondingly. The basic changes are: desertification and oasis development coexist, both “the human being advance and the desert retreat” and “the desert advance and the human being retreat” coexist, but the latter is dominant. In the upper reaches, water volume drawing to irrigated agricultural areas has increased, artificial oases have been enlarging and moving from the deltas in the lower reaches of many rivers to the piedmont plains. In the middle and lower reaches of the Tarim River, the stream flow has decreased, old oases have declined, natural vegetations have been degenerating, desertification has been enlarging, and the environment has deteriorated. The transition regions, which consist of forestlands, grasslands and waters between the desert and the oases, have been decreasing continuously, their shelter function to the oases has been weakened, and the desert is threatening the oases seriously.

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2.
Because of the human exploitation and utilization of water resources in the Tarim Basin,the water resources consumption has changed from mainly natural ecosystem to artificial oasisecosystem, and the environment has changed correspondingly. The basic changes are: desertifi-cation and oasis development coexist, both "the human being advance and the desert retreat" and"the desert advance and the human being retreat" coexist, but the latter is dominant. In the upperreaches, water volume drawing to irrigated agricultural areas has increased, artificial oases havebeen enlarging and moving from the deltas in the lower reaches of many rivers to the piedmontplains. In the middle and lower reaches of the Tarim River, the stream flow has decreased, old oa-ses have declined, natural vegetations have been degenerating, desertification has been enlarging,and the environment has deteriorated. The transition regions, which consist of forestlands, grass-lands and waters between the desert and the oases, have been decreasing continuously, theirshelter function to the oases has been weakened, and the desert is threatening the oases seri-ously.  相似文献   

3.
Natural ecosystems in the region of the lower Tarim River in northwestern China strongly deteriorated since the 1950s due to an expanding desertification. As a result, the downstream Tarim River reaches became permanently dry land. This historical evolution in land‐use change is typically the result of the anthropogenic impact on natural ecosystems. On the basis of a spatially distributed hydrological catchment model bidirectionally linked with a fully hydrodynamic MIKE11 river model, land‐use changes characterized by historical changes in leaf area index (LAI) of vegetation, as well as the evolution of irrigated surface areas, can be causally related to changes in water resources (groundwater storage and surface water resources). An increased surface area of irrigated (agricultural) land, together with a majority of inefficient irrigation methods, did lead to a strong increase of water resources consumption of the farmlands located in the upper Tarim River area. Evidently, this evolution influenced available water resources downstream in the Tarim basin. As a result, farmland has been gradually relocated to the upstream regions. This has led to reduced flows from the upper Tarim stream, which subsequently accelerated the dropping of the groundwater level downstream in the basin. This study moreover demonstrates that land surface biomass changes (cumulative LAI) along the lower Tarim River are strongly related to the changes in groundwater storage. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

4.
新疆艾比湖是典型的干旱区湖泊,具有特殊的湿地-干旱生态系统。晚更新世晚期开始,由于气候逐渐变干,艾比湖不断萎缩。20世纪50～80年代末,由于湖区人口的激增及其对水土资源的不合理开发利用加速了湖泊干缩的进程。本文对艾比湖干缩引起的生态响应进行了初步的分析,分析指出,艾比湖湖滨荒漠自然植被呈退化衰败趋势,生物多样性面临严重威胁;干涸湖底盐漠化,湖滨沙丘活化,沙漠扩展,浮尘天气成百倍增长;绿洲与荒漠之间缓冲空间日益缩小,盐碱化趋势增大。艾比湖的干缩是自然因素和人为因素共同作用的结果,但人为因素是第一位的,其中以河流上游大量截流引水和大规模开荒为主要原因。  相似文献   

5.
Water scarcity is a media darling often times described as a trigger of conflict in arid regions, a by‐product of human influences ranging from desertification to climate change, or a combination of natural‐ and human‐induced changes in the water cycle. A multitude of indexes have been developed over the past 20 years to define water scarcity to map the “problem” and guide international donor investment. Few indexes include groundwater within the metrics of “scarcity.” Institutional communication contributes to the recognition of local or regional water scarcity. However, evaluations that neglect groundwater resources may incorrectly define conditions as scarce. In cases where there is a perception of scarcity, the incorporation of groundwater and related storage in aquifers, political willpower, new policy tools, and niche diplomacy often results in a revised status, either reducing or even eliminating the moniker locally. Imaginative conceptualization and innovative uses of aquifers are increasingly used to overcome water scarcity.  相似文献   

6.
Desert coexists with oasis in long time, and the existence and development of oasis system demand better oasis vegetation ecological system. Oasis scale of arid zone plain encircling water should be determined in case of desertification caused by land over-reclamation under the circumstance of water resources shortage. Steady oasis with virtuous circle must have appropriate land use structure for agriculture, forestry and graziery. The study on the suitable scale and developmental space of oasis will provide theoretical and applicable foundation for effective construction of oases. By analyzing the hydrothermal, water and soil balance, an optimal mathematical model has been established. Based on hydrometeorology data collected for years in Weigan River plain, and by the principle of water balance, a calculation has been made of the water resources for evapotranspiration and the optimal acreage of oasis and cultivated land, which shows that the water resources for evapotranspiration in the Weigan River plain oasis is 22.32×108 m3 and the optimal oasis acreage under the condition of conventional irrigation mode is 3716.06 km2, in which the suitable cultivated land acreage is 1564.79 km2. Under the condition of water-saving irrigation, the suitable oasis acreage is 5515.49 km2, in which the suitable cultivated land acreage is 2322.31 km2. The oasis area had reached 4123 km2, and the cultivated land acreage had reached 1507 km2 after the Agriculture Irrigation Drainage Water Project of World Bank Loan in Weigan River basin was finished in 1997. The oasis and cultivated land acreage will be more suitable, and the oasis scale can be enlarged moderately by means of water saving irrigation.  相似文献   

7.

The strategic mineral resource exploration has important influence on the modern urban system in arid areas. Large amounts of investment on oil and gas industry have important effect on the infrastructure which includes cities and communications, and this will become an important factor of changing the urban structure of Xinjiang. In the 1950s, Kelamayi and Dushanzi cities have appeared by the petroleum exploration in the west of the Juggar Basin, which not only changed the single role of Xinjiang oasis agricultural city but also made the distribution of cites broken from natural oasis for the first time, and the network trend of urban spatial structures emerged. In recent years, the large-scale petroleum exploration in Tuha, Juggar and Tarim Basins gives local cities more chance of rapid development. Especially, a large-scale communication construction, with the 552 km desert highway as representative, totally changed the traditional oasis spacial structure of the urban system in the Tarim Basin. The influence on the spacial structure of the urban system by oil exploration in a large-scale reserve basin can be divided into four stages.

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8.
The Heihe River Basin (HRB) is the second largest inland river basin in the arid region of northwestern China. An agricultural oasis is a typical landscape in arid regions providing precious fertile soil, living space and ecological services. The agricultural oasis change has been one of the key issues in sustainable development in recent decades. In this paper, we examined the changes in the agricultural oasis in HRB and analyzed the socio-economic and climatic driving forces behind them. It was found that the agricultural oasis in HRB expanded by 25.11% and 14.82% during the periods of 1986–2000 and 2000–2011, respectively. Most of the newly added agricultural oases in HRB were converted from grassland (40.94%) and unused land (40.22%). The expansion in the agricultural oasis mainly occurred in the middle reaches of HRB, particularly in the counties of Shandan, Minle, Jinta and Jiuquan city. Changes in the rural labor force, annual temperature and precipitation have significant positive effects on agricultural oasis changes, while the ratio of irrigated agricultural oases has significant negative effects on agricultural oasis changes. The agricultural oasis expansion in HRB is the combined effect of human activity and climate change.  相似文献   

9.
Abstract

Abstract The Shiyang River basin is a typical interior river basin that faces water shortage and environmental deterioration in the arid northwest of China. Due to its arid climate, limited water resources and some inappropriate water-related human activities, the area has developed serious loss of vegetation, and gradual soil salinization and desertification, which have greatly impeded the sustainable development of agriculture and life in this region. In this paper, the impacts of human activities on the water–soil environment in Shiyang River basin are analysed in terms of precipitation, runoff in branches of the river, inflow into lower reaches, water conveyance efficiency of the canal system and irrigation water use efficiency in the field, replenishment and exploitation of groundwater resources, soil salinization, vegetation cover and the speed of desertification. The results show that human activities and global climate change have no significant influence on the precipitation, but the total annual runoff in eight branch rivers showed a significant decrease over the years. The proportion of water use in the upper and middle reaches compared to the lower reach was increased from 1:0.57 in the 1960s, to 1:0.27 in the 1970s and 1:0.09 in the 1990s. A reduction of about 74% in the river inflow to the lower reaches and a 15-m drop in the groundwater table have occurred during the last four decades. Strategies for improving the water–soil environment of the basin, such as the protection of the water resources of the Qilian Mountains, sustainable use of water resources, maintenance of the balance between land and water resources, development of water-saving agriculture, diverting of water from other rivers and control of soil desertification, are proposed. The objective of this paper is to provide guidelines for reconstruction of the sustainable water management and development of agriculture in this region.  相似文献   

10.
Abstract

Changes in development and use of water resources over the last 30 years have led to significant environmental and hydrological degradation of the River Heihe basin in the People's Republic of China. Water discharge of the lower reaches has been seriously compromised and more than 30 tributaries and terminal lakes have dried up. The water output of springs has dropped significantly. Also water quality problems have been observed, in both surface waters and groundwater. Hydrological changes have resulted in a marked degradation of aquatic habitats, and have caused substantial, and expanding, land salinization and desertification. Solving these problems, which have been largely caused by human activities, requires massive and long-lasting concerted efforts.  相似文献   

11.
The Ejina basin, which is located in arid and semi‐arid areas of northwest China, has experienced severe environmental deterioration in the past several decades, and an exploratory project was launched by the Chinese Government in 2001 to restore this degraded ecosystem. In this study, multi‐scale remotely sensed data and field investigations were used to quantify the responses of vegetation to the implementation of integrated water management under this project. In terms of the seasonal accumulated Normalized Difference Vegetation Index (SAN) variation, (1) the vegetation in 80·4% of the oasis regions showed an increasing or recovering trend, and increasing SAN trends with a magnitude greater than 0·14 a?1 mainly resulted from cultivated land reclamation; (2) the vegetation in 91·5% of the desert regions presented an increasing trend, and the statistically significant trends mainly appeared in the middle and lower Ejina basin; (3) the vegetation in 19·6% of oasis and 5·1% of desert regions showed a decreasing or degrading trend, mainly where rivers diminished and along artificial concrete canals; and (4) opposite signs of vegetation trends occurred simultaneously along some natural rivers experiencing water reduction, with a decreasing trend generally appearing in the high SAN regions, whereas an increasing trend was seen in the low SAN regions. The broad vegetation recovery observed was due to the comprehensive improvement of the water environment, which was attributed to both the increase in runoff entering the Ejina basin and the adoption of engineering measures. Vegetation degradation in the area mainly resulted from deterioration of the local water environment, which was closely related to the problems of water management. The results of this study can be used as a reference for adjusting the current water resource management strategy to effectively restore this ecosystem. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

12.
Desertification is a change in soil properties, vegetation or climate, which results in a persistent loss of ecosystem services that are fundamental to sustaining life. Desertification affects large dryland areas around the world and is a major cause of stress in human societies. Here we review recent research on the drivers, feedbacks, and impacts of desertification. A multidisciplinary approach to understanding the drivers and feedbacks of global desertification is motivated by our increasing need to improve global food production and to sustainably manage ecosystems in the context of climate change. Classic desertification theories look at this process as a transition between stable states in bistable ecosystem dynamics. Climate change (i.e., aridification) and land use dynamics are the major drivers of an ecosystem shift to a “desertified” (or “degraded”) state. This shift is typically sustained by positive feedbacks, which stabilize the system in the new state. Desertification feedbacks may involve land degradation processes (e.g., nutrient loss or salinization), changes in rainfall regime resulting from land-atmosphere interactions (e.g., precipitation recycling, dust emissions), or changes in plant community composition (e.g., shrub encroachment, decrease in vegetation cover). We analyze each of these feedback mechanisms and discuss their possible enhancement by interactions with socio-economic drivers. Large scale effects of desertification include the emigration of “environmental refugees” displaced from degraded areas, climatic changes, and the alteration of global biogeochemical cycles resulting from the emission and long-range transport of fine mineral dust. Recent research has identified some possible early warning signs of desertification, which can be used as indicators of resilience loss and imminent shift to desert-like conditions. We conclude with a brief discussion on some desertification control strategies implemented in different regions around the world.  相似文献   

13.
The strategic mineral resource exploration has important influence on the modern urbansystem in arid areas. Large amounts of investment on oil and gas industry have important effect onthe infrastructure which includes cities and communications, and this will become an importantfactor of changing the urban structure of Xinjiang. In the 1950s, Kelamayi and Dushanzi cities haveappeared by the petroleum exploration in the west of the Juggar Basin, which not only changedthe single role of Xinjiang oasis agricultural city but also made the distribution of cites broken fromnatural oasis for the first time, and the network trend of urban spatial structures emerged. In recentyears, the large-scale petroleum exploration in Tuha, Juggar and Tarim Basins gives local citiesmore chance of rapid development. Especially, a large-scale communication construction, with the552 km desert highway as representative, totally changed the traditional oasis spacial structure ofthe urban system in the Tarim Basin. The influence on the spacial structure of the urban system byoil exploration in a large-scale reserve basin can be divided into four stages.  相似文献   

14.
新疆平原沙漠区湖泊干缩现象的初步评价   总被引：2，自引：2，他引：0  
王晓峰  章海生 《湖泊科学》1994,6(4):333-339
对新疆平原沙漠区湖泊干缩现象作了初步评价,指出这一现象是干旱、半干旱地区农业灌溉和国民经济发展到一定规模时所必然产生的现象,因而可以视为正常。同时指出,平原区湖泊之存亡既取决于自然条件,更取决于社会经济发展的需要。现存湖泊资源的开发与保护,既要立足于生态环境价值论,也要立足于经济价值论。  相似文献   

15.
Designation and Assessment of Artificial and Heavily Modified Water Bodies under the EC Water Framework Directive The EC Water Framework Directive allows the Member States to designate artificial and heavily modified water bodies under specific conditions. For those water bodies the ecological assessment and the resulting programmes of measures will be based on the “maximum ecological potential” as reference conditions and not on the “high ecological status”, which has to be used for natural water bodies. Such designation is possible only, if the hydromorphology of the water bodies concerned has been substantially changed in character to maintain specified uses. The criteria for the designation are fulfilled, if restoration measures needed to meet the high ecological status would have significant adverse effects on the uses and if no other better environmental options would exist to maintain the specified uses. In late 1999 the EC‐Working Group on Heavily Modified Water Bodies (HMWB) has been established to develop criteria for the designation of artificial and heavily modified water bodies as well as for the determination of the maximum ecological potential. The working group has produced the guidance document “Identification and Designation of Artificial and Heavily Modified Water Bodies” in November 2002, which has been agreed by the European Water Directors on 21 November 2002 in Copenhagen. The guidance document is focusing on two time borders, the provisional identification of heavily modified water bodies until 2004 and the legally binding designation as artificial and heavily modified in the first river basin management plan in 2009 at the latest. The guidance document considered the main findings of 34 case studies for rivers, lakes, transitional and coastal waters carried out in 11 European countries. The results of the case studies as well as a summarizing synthesis were used as a fundamental basis to produce the guidance document. The practical examples given by the case studies were compiled as a toolbox which supplements the guidance for the purpose of its better application.  相似文献   

16.
三十多年来,人们对水生野生动物保护中的保护地建设、迁地保护、人工保种、人工驯养、人工繁育、人工养殖、增殖放流、生态修复等保护方式一直存在着激烈的争论.这反映了人们对水生野生动物保护目标、保护方式认识不一致甚至对立的问题,而其根本在于缺乏一个能够适应水生野生动物保护需求和特征的理论话语体系.本文基于对水生野生动物保护目标认知和设置的差异,基于对水生野生动物保护中人工干预方式的差异,尝试以“物种保护与生态保护”、“主动保护与被动保护”两个维度为框架建立水生野生动物保护的理论话语体系,然后着重分析水生野生动物物种保护中的主动保护与被动保护的状况与成效,指出部分水生野生动物保护地由于其整体生态格局已被改变或依然处于恶化的趋势中,并且无法避免人类活动的干扰和影响,导致了相应水生野生动物的就地保护效果不理想,而获得足够主动保护努力介入的物种在获得人工保种、人工繁育、人工养殖之后,其物种灭绝的风险已基本解除,甚至部分已野外绝迹物种还存在野外种群重建的机会.而后,以长江三种鲟鱼的保护和效果为例,对比展示了主动保护对于水生野生动物保护的必要性.建议就水生野生动物保护而言,在不遗余力抓保护地建设等被动保护的同时,更要积极地推动人工繁育、人工养殖等主动保护来对物种兜底.  相似文献   

17.
Climatic changes in the Tarim River basin since 12 kaBP were divided into four stages based on the analyses of sedimentary phase, the features of some climatic and environmental biomarks in the sedimentary strata and desert evolution. During the Holocene, cool-dry and temperate-dry climates resulted in apparent alluvial-fluvial and weak aeolian activities. During 10–8 kaBP, the climate was dry and cold, large-scale sand dunes activities led to regional deeert expansion. During the hypsithermal (8–3 kaBP), the climate was dry and warm, shifting sand areas decreased and a lot of sand dunes were fixed along the banks of the Tarim River and its tributaries, lowlands and lakes. As a result, fluvial-alluvial areas increased. Since 3 kaBP, the aeolian activity and sandstorms have been enhancing due to the combined influences of climatic warming and illogicill exploitation of land and water resources. The climate in the Tarim River basin have been persistently dry and alternated by warm and cold periods. Consequently, the sedimentary environments have varied fmm desert steppe to desert, and strongly influenced by periphery mountains and global climatic fluctuations.  相似文献   

18.
In arid northwestern China, as many inland areas around the world with arid or semi-arid climate, inland river flow recharges groundwater; vegetation pattern depends on the water table, which characterizes the landscapes of oasis, transition zone and desert, within different distances from an inland river. The water table conditions play an important role in water and land management—a high water table causes salinization within the oasis while a low water table causes desertification around the oasis. This study applies a theoretical-empirical method to calculating critical groundwater depths including the depth of critical groundwater level causing salinization (DCGS) and the depth of critical groundwater level causing desertification (DCGD); the calculations are validated with field observations in the Luocheng Irrigation District located in the middle reach of the Heihe River, an inland river of the northwestern China. Specifically, the calculated DCGS is 1.29 m for the case study area and the range of water table depth at the locations with saline soil is 0.5-1.2 m. The calculated DCGD for three vegetation communities, Nitraria tangutorum + Glycyrrhiza uralensis Fisch community, Tamarix chinensis + Phragmites australis community, and Alhagi sparsifolia + Phragmites communis, are 8.26, 11.26, and 13.26 m, respectively, basically within an observed range of 6.0-13.0 m in the study area. The critical depths can be used to design an engineering approach to control water tables and mitigate salinization and desertification problem for ecosystem restoration in the study region.  相似文献   

19.
The hydrocarbons and other organic compounds generated through abiogenic or inorganic processes are closely related to two science subjects,i.e.,energy resources and life’s origin and evolution."The earth’s primordial abiogenic hydrocarbon theory"and"the serpentinization of abiogenic hydrocarbon theory"are the two mainstream theories in the field of related studies.Serpentinization generally occurs in slow expanding mid-ocean ridges and continental ophiolites tectonic environment,etc.The abiogenic hydrocarbons and other organic compounds formed through the serpentinization of ultramafic rocks provide energy and raw materials to support chemosynthetic microbial communities,which probably was the most important hydration reaction for the origin and early evolution of life.The superposition of biological and abiological processes creates big challenge to the identification of the abiogenic organic materials in serpentinite-hosted ecosystem.Whether abiotic(inorganic)process can form oil and gas resource is a difficult question that has been explored continuously by scientific community for more than a century but has not yet been solved.However,some important progress has been made.The prospecting practice of abiogenic hydrocarbons in commercial gases from the Songliao Basin,China,provides an important example for exploring abiogenic natural gas resources.  相似文献   

20.
Shi Qi  Wei Liu  Heping Shu  Fei Liu  Jinzhu Ma 《水文研究》2020,34(20):3941-3954
The sources and storage of soil NO3− in the western Tengger Desert, Northwest China, were explored using water chemistry analysis and stable isotope techniques. In line with the expansion and development of oases, part of the desert has been transformed into cultivated land and artificial forest land. The mean soil NO3− contents found in areas of cultivated land and artificial forest were 123.06 mg kg−1 and 1.26 mg kg−1, far higher and slightly lower than the background desert soil values, respectively. The δ15N-NO3− and δ18O-NO3− values in cultivated soils ranged from 1.00 to 11.81 ‰, and from −1.85 to 8.99 ‰, respectively, and the mean mNO3−/Cl− value in cultivated soils was 2.3. These figures would appear to demonstrate that the rapid increase in the nitrate content in soils is principally due to the use of nitrogen fertilizer. Such increases in soil NO3− storage is likely to promote the leaching of nitrogen into the groundwater where coarsely textured soils exist, the pollution of water sources used for irrigation water, and extreme precipitation events. The δ15N-NO3− and δ18O-NO3− values in groundwater ranged from 3.72 to 6.54 ‰, and from −0.19 to 12.06 ‰, respectively, mainly reflecting the nitrification of soil nitrogen. These values appeared similar to those measured in the soil water in adjacent areas of cultivated land and vegetated desert, indicating that the groundwater has been affected by both natural and artificial NO3−. Artificial afforestation of desert regions would therefore seem to be a useful way of reducing the threat posed by anthropogenic sources to the circulation of NO3−-N within arid regions, as well as promoting wind sheltering and sand fixation. This study explored the NO3− storage and groundwater quality responses to oasis development in arid areas in an attempt to provide effective information for local agricultural organizations and agricultural nitrogen management models.  相似文献   

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