Changes in groundwater levels and the response of natural vegetation to transfer of water to the lower reaches of the Tarim River

Restoration and reconstruction of the degraded Tarim River ecosystem is an important challenge. A goal of an ecological water conveyance project is to protect and restore the natural vegetation in the lower reaches of Tadm River by transferring water from Bosten Lake, through the river channel, to the lower reaches. This study describes the changes in groundwater depth during the water transfer and the respondence of riparian vegetation to alterations in groundwater levels. The results indicate that groundwater depth along the Tarim River channel has a significant spatial-temporal component. Groundwater levels closest to the river channel show the most immediate and pronounced changes as a response to water transfer while those further away respond more slowly, although the observed change appears to be longer in duration. With a rise in the groundwater level, natural vegetation responded with higher growth rates, biomass and biodiversity. These favorable changes show that it is feasible to protect and restore the degraded natural vegetation by raising the groundwater depth. Plant communities are likely to reflect the hysteresis phenomenon, requiting higher water levels to initiate and stimulate desired growth than what may be needed to maintain the plant community. Because different species have different ecologies, including different root depths and densities and water needs, their response to increasing water availability will be spatially and temporally heterogenous. The response of vegetation is also influenced by microtopography and watering style. This paper discusses strategies for the protection and restoration of the degraded vegetation in the lower reaches of the Tarim River and provides information to complement ongoing theoretical research into ecological restoration in add or semi-arid ecosystems.

Evaluation of oasis stability in the lower reaches of the Tarim River

Oasis stability in the lower reaches of the Tarim River was assessed at the landscape scale（including changes in landscape pattern and land use in the oasis） and at the regional scale（including the cold-island effect and NDVI of the oasis） based on the methods of landscape ecology,GIS and Remote Sensing（RS）.Thematic Mapping（TM） remote sensing images from 1990,2000 and 2009 were employed along with the related meteorological and hydrological data pertaining to the reclamation area of the oasis in the lower reaches of the Tarim River.The results indicated that landscape heterogeneity and oasis complexity increased between 1990 and 2000.The comprehensive index of the degree of land use,the average index of the cold-island effect,NDVI value and oasis stability all decreased.However,the change trends in the indices referred to above were opposite between 2000 and 2009,and oasis stability was enhanced to some extent.

A quantitative assessment on groundwater salinization in the Tarim River lower reaches,Northwest China

Based on monitored data from 840 samples, we assessed the spatial and temporal variability of groundwater salinization in the Tarim River lower reaches combining classical statistics and geostatistics. Results show that total dissolved solids （TDS） is significantly correlated with other related ions, such as Na＋, Mg2＋, Ca2-, C1- and K＋. TDS and underground water level have characteristics of spatial autocorrelation, both of which present the isotropic characteristic and con- form to the spherical model in each year from 2001-2009. TDS is basically greater than 1 g/L but less than 2 g/L in the Tarim River lower reaches, which indicates that salt stagnation pollution is more serious. The most serious salinization （3 g/L 〈 TDS _〈 35 g/L） contaminated area is mainly in the middle and lower part of the study area.

Division of Ecosystem Sensitivity of Natural Landscape in Lower Reaches of Tarim River

By choosing aerial and satellite remote sensing images of the year 1959, 1973, 1989, 2000 and 2008 as data source, combining ground investigation, landscape in lower reaches of Tarim River was classified and landscape classification map was promoted by using GIS technique and landscape ecology theory. Finally landscape classification maps of the five years would be converted into gray scale images which would be used for overlay analysis, and based on this, landscape ecosystem sensitive zone had been identified. The result showed that the extremely sensitive zone took up 10.18% of the study area and sensitive zone occupied 17.95% of the study area. Ecological system of natural landscape in the lower reaches of Tarim River was superior to ecological system of artificial landscape in terms of resistance to wind, dust, salt and drought. Study on division of ecosystem sensitivity area of natural landscape not only provided scientific reference for the formulation of regional policies to prevent and treat ecological environmental problems, but also was beneficial for people to identify treatment focus of ecological environmental problems in different regions and propose countermeasures ameliorating regional ecological environment.

塔里木河下游植被覆盖度图谱分析

基于GEE(google earth engine)平台结合像元二分模型估算了植被覆盖度,并以此构建了地学信息图谱体系。应用该体系对塔里木河下游进行植被覆盖度时空变化特征分析。得出以下结论:塔里木河下游植被覆盖结构以极低植被覆盖为主,占研究区总面积的80%以上;植被覆盖变化图谱中最明显的是极低植被覆盖与其他植被覆盖类型之间的转换,其次是低植被覆盖与其他植被覆盖类型之间的转换;植被覆盖涨落势图谱中涨势最大的分别是低植被覆盖和中植被覆盖,落势最大的是极低植被覆盖;植被覆盖变化模式图谱以稳定不变型为主,后期变化型占比大于前期变化型。整体来看,2000—2022年塔里木河下游生态环境逐渐改善,植被变化情况越来越好。

台特玛湖适宜水面与水量维持初步研究

开展台特玛湖适宜规模与水量维持研究,对于提升流域水资源综合利用效率、促进塔里木河流域生态文明建设,实现人-水-生态和谐具有重要意义。该文基于塔里木河下游水文与遥感监测资料,通过分析台特玛湖湖区水面及湖区生态环境变化特点,构建了湖区水面面积、植被覆盖度及植被面积的关系模型,求解实现生态保护目标的湖区适宜水面规模与生态水量。研究结果表明:基于历史资料与生态安全分析,台特玛湖适宜水面面积规模为30~110 km^(2);当台特玛湖水面为110km^(2)时,对应植被面积为232 km^(2),植被覆盖度为15.1%,可保障湖区天然植被面积、质量达到优良状态,此时塔里木河、车尔臣河入湖水量约为6 400万m^(3);综合考虑天然植被需水、河道基流、地下水补充及河道蒸发等因素,在维持塔里木河与台特玛湖水力联系情况下,塔里木河下游生态需水量为2.48亿m^(3)/a。研究成果为塔里木河流域生态保护及修复工作提供了技术参考。

Analysis on water potential of Populus euphratica oliv and its meaning in the lower reaches of Tarim River,Xinjiang

Combined with materials measured on leaves water potential of Populus euphratica oliv in the process of ecological water delivery in the lower reaches of Tarim River, the influence of ground-water depths and soil salinity on leaves water potential of P. euphratica was analyzed. We found that there was evident negative correlation between the leaves water potential of P. euphratica and ground-water depths. The deeper the ground-water depths were, the lower the leaves water potential of P. euphratica was, the more serious drought stress P. euphratica suffered from. Besides, there was evident negative correlation between the soil salinity and the leaves water potential of P. euphratica. The bigger the soil salinity was, the lower the leaves water potential of P euphratica was, the more serious drought stress was indicated from which P. euphratica suffered. For sections rather distant for Daxihaizi Reservoir as well as for those places of wells rather distant from the river course, ground-water depths and the soil salinity were high; the leaves water potential of P. euphratica was low. The leaves water potential of P. euphratica can reflect the degree at which P. euphratica suffers from drought and salt stress, and has an important reference meaning in analyzing proper ground-water depths for the survival and growth of P. euphratic in the lower reaches of Tarim River.

Corridor effect of the spatial changes of landscape patterns in arid areas:A case study of the river corridor areas in the middle and lower reaches of Tarim River

在 Tarim Riverare 的中间、更低的活动范围的河走廊区域在 Ruoqiang 从 Qara 水库 inYuli 县沿着河节由传统的绿走廊统治了到泰泰马·莱克县，它在 Tarim 河分水岭在社会、经济的发展起一个重要作用与一极其重要的生态的功能。对水路垂直的缓冲区地区从水路在 5-kminterval 开始沿着两个河边被定义(10 km 更宽) 用缓冲区地区分析的方法。每个缓冲区地区的风景模式索引被计算，并且主要风景模式的索引被分析以便在风景和补丁层次上揭示放射的效果和河走廊的特征。放射的宽度通常是在学习区域的 30 km 的结果表演，和罐头直到在潜水艇的 50-70 km -- 区域 FG1 因为学习区域位于二排水盆，与在他们之间的一个生态的空隙的地区。树林和沼泽地的 Thelandscapes 通常在 10 km 缓冲区地区以内被散布(它意味着缓冲区地区是离开水路的 5 km；一样此后) 沿着两个河边。而且，缓冲区地区越靠近到水路，补丁密度和最大的补丁索引是越多 higher。在为学习区域的生态、环境的新生，河走廊的生态的效果的程度必须充分被考虑，并且工程必须科学地并且讲道理地被计划并且设计。

Assessment of water-recharging based on ecological features of riparian forest in the lower reaches of Tarim River

被 mesophytes 种类主要统治的河边的森林的出现和发展与表面水仔细联系。因为到过去的 5 十年年里的 Tarim 河的更低的活动范围没有水分泌物，河边的森林严重地降级。在 2002 和 2003 的 Yingsu， Argan 和 Luobuzhuang 的监视数据的基于的在分析，效果再装 ofwater 被讨论。再装水的工程忽视事实控制在露面，而是对植被的地下水影响的焦点上开拓殖民地于的 Populus euphratica 的过程，这正在泛滥。泛滥的控制背离河边的森林开发的固有的法律，河边的森林的自然新生因此被检查。地下水上的河边的植物的反应范围高举极其狭窄、很河边的社区没被优化。因为 theirphysio 生态的特征被忽略，主导的种类的幼苗都没在充满区域被发现。然而，在溪流的附近的植被变化仅仅在浅地下水上反映 mesophytes 种类的需求为河边的植物的幼苗建立提供合适的产地的 water-re-chargingfails。再装 presentwater 计划是困难的认识到植被恢复。

间歇性输水条件下塔里木河下游地下水时空变化模拟

为确定适宜的输水策略以实现塔里木河下游地下水位的快速抬升,提高生态系统的恢复力,运用GMS软件构建了塔里木河下游地下水动态模拟模型,设计单阶段、双阶段和多阶段输水情景模拟预测了地下水对不同输水情景的时空响应特征。结果表明:制定输水策略时应保证年输水量大于有效水量,当输水总量一定时,延长输水时间、扩大输水间隔有助于地下水位的快速抬升;最佳输水策略是以1月和3—11月为输水期分两个阶段输水4 500万m^(3);地下水埋深和水位变化量沿河道对称分布,地下水埋深与距河道两侧距离成正比,地下水位变化量和抬升量与时间成反比。

塔里木河下游输水模式改进研究——以英苏断面为例

[目的]针对塔里木河下游现状间歇性河道输水中存在补给不均衡,无效蒸发过大,补水范围有限等问题,从空间和时间维度上提出生育期汊河输水、非生育期输水的方式,研究输水模式的改进对地下水位的影响,进一步完善轮渗灌溉生态修复体系,为塔里木河下游生态恢复提供理论依据。[方法]以塔里木河下游英苏监测断面为例,以2012—2021年10次生态输水期间地下水埋深监测资料为依据,运用Modflow模型建立英苏断面地下水剖面二维流运动的数值模拟,并分析英苏断面10次间歇性生态输水的响应过程,并预测和分析了生育期汊河、非生育期以及非生育期汊河输水的地下水位演变及水量变化的过程。[结果](1)生育期汊河、非生育期、非生育期汊河方案下人工汊河两侧地下水位较现状输水分别抬升了2.5,0.7,3.2 m。(2)3种改进方案较现状输水研究区小于8 m的埋深面积分别增加了10.89%,19.33%,26.17%。(3)地下水存储量较现状输水分别增加了10.97%,11.88%,14.39%。[结论]非生育期汊河输水结合了生育期汊河和非生育期输水两者的优势,提高了下泄水量的利用率,解决了现状主河道输水模式下河间地下水位难以恢复的问题,为河间地块生态系统的恢复并使其成为下游生物多样性的安全带创造了条件。

塔里木河下游植被非生长季火灾风险等级遥感评估

以塔里木河下游地区为例,利用已知火灾发生点前后时段卫星遥感数据,计算干枯燃料指数(dead fuel index,DFI)和2种燃烧指数,即归一化燃烧指数(normalized burn ratio,NBR)和燃烧面积指数(burn area index,BAI),分析干枯燃料指数和燃烧指数的相关性,并评估研究区的火灾风险等级。结果表明:燃烧指数可以较为准确地得到过火区域的位置;干枯燃料指数(DFI)与燃烧指数存在一定的相关性,R分别为0.53(NBR)、0.51(BAI);2021年2月发生的火灾处于高风险区域,说明干枯燃料指数可以作为火灾风险等级评估指标,并利用2020—2021年秋冬季分析,得到火灾风险等级图。

塔里木河下游地下水及土壤对胡杨林长势的影响

胡杨(Populus euphratica)是塔里木河重要的物种之一,也是抑制荒漠化进程的“绿色守卫者”。采用样方调查结合取样测试的方法,获取了塔里木河下游恰拉水库至英苏段16个样方的林分因子及水土理化参数。利用单因素方差分析、聚类分级、相关分析的方法研究了地下水及土壤因子对胡杨长势的影响。结果表明:塔里木河下游不同长势胡杨的林分因子差异显著,长势良好的胡杨平均胸径22.51 cm、树高7.26 m、冠幅3.44 m,均明显高于长势极差、较差的样方。受塔里木河影响,林分因子随河道距离增加呈波浪递减的趋势。古河道附近的胡杨通常拥有较大的树高及冠幅,但长势较差,若不加以治理将很快枯萎。地下水理化性质对胡杨长势的影响均显著高于土壤化学性质,其中地下水埋深、距河道的距离对胡杨长势的影响最为显著,相关系数分别为0.922、0.898,80 cm<h≤120 cm土层土壤全盐量对胡杨长势的影响次之,相关系数为0.871。

塔里木河中下游地区湿地景观格局变化

在RS和GIS技术的支持下,结合塔里木河中下游的区域特点,确定了塔里木河中下游湿地景观分类系统.通过采用景观多样性指数、优势度、景观破碎化指数、分布质心和平均斑块形状指数等景观的空间格局指数,较系统地分析了1980～2000年塔里木河中下游湿地景观空间格局变化.结果表明：塔里木河中下游湿地的分布面积呈显著下降趋势.1980～1990年湿地面积减少,斑块数量和密度增加.1990～2000年湿地面积有所增加,斑块数量和密度持续增加;随着人类干扰强度增加,景观多样性增加,优势度降低,湿地的破碎化程度越来越大;湿地景观要素中,河渠湿地、水库坑塘湿地面积有所增加,而湖泊、滩地、沼泽面积均在不断减少,其中沼泽湿地面积减少幅度最大.

干旱胁迫下的胡杨脯氨酸累积特点分析

以塔里木河下游的主要乔木—胡杨为研究样本 ,结合野外地下水位监测资料 ,详细分析了塔里木河下游干旱胁迫环境下胡杨体内脯氨酸的累积与变化。分析研究表明 ,胡杨体内的脯氨酸含量与塔里木河下游地下水位变化存在密切 ,脯氨酸含量随地下水位降低而增加 ,二者相关系数达 0 .913;在不同地下水位埋深条件下 ,脯氨酸含量的增加幅度有差异 ;胡杨体内的脯氨酸含量随干旱胁迫的加深而积累 ,是胡杨对干旱逆境的一种反应 。

3S技术在新疆塔里木河下游生态环境动态研究中的应用

塔里木河下游多年来水量不断减少 ,造成了该地区地下水位普遍下降 ,导致了植被衰败 ,风沙频繁 ,土地沙漠化普遍发生。在 3S技术支持下 ,通过 1 959年、1 983年、1 992年及1 996年航空及航天遥感信息的对比分析发现 ,下游地区生态环境的变化与自然及人为因素密切相关 。

塔里木河下游植物群落分布与衰退演替趋势分析

根据野外样方调查 ,以空间序列推断其时间序列 ,分析了塔里木河下游植物群落的结构与分布 ,并对植物群落的衰退演替及其组分种消长的动态变化进行了分析。分析结果表明 :随着塔里木河下游来水量的不断减少 ,沿河道分布的植被 ,其盖度、物种丰富度均呈递减趋势 ,且植物群落成梯度分布。随着地下水位的不断下降 ,不同物种对环境退变的忍受能力不同 ,退化的先后不同 ,退化顺序表现为浅根系的草本到深根系草本与部分灌木 ,最后衰退的是耐旱性较强的灌木与乔木。在植物群落的衰退演替过程中 ,塔里木河下游不同河段的两种植物群落 ,在优势种的更替、组分种的消长上表现出不同的衰退特征。

塔里木河下游断流河道应急输水与地表植被响应

通过对塔里木河下游5个断面、30个植物样地的调查和对天然植物当年生小枝的长度、当年生小枝上胡杨的叶数、50片以上叶长、宽及叶重、芦苇的高度和叶长、宽、重量等的测试分析,揭示了塔里木河下游断流河道输水后地表植被的响应范围。研究表明,随着输水后地下水位的抬升,地表植被产生了明显变化。在横向上,芦苇的反应敏感区范围在100～150m区间;对胡杨的横向影响范围在200～250m之间;在纵向上,平均叶数从下游上段至下游下段,分别较末端断面增加57%、22 2%、9 2%;河道两岸地下水位较下游下段抬升幅度大,横向上对植被的影响范围也较下游下段宽。输水历时的长短和输水量对塔里木河下游植被恢复密切相关。

塔里木河下游荒漠生态系统退化机制分析

近几十年来,塔里木河下游河道断流,地下水水位剧烈下降,天然植被衰退,土地的沙质荒漠化问题十分严峻。通过对下游退化荒漠生态系统的脆弱性和不稳定性以及干扰体驱动力的分析,阐述了该系统退化的机制,并在此基础上,提出了退化荒漠生态系统的恢复对策。系统的内在脆弱性特征决定了其抗干扰的能力差,退化后恢复的弹性小;强烈的人为干扰体是系统退化的重要驱动力。下游荒漠生态系统的退化是系统内在特性和外在干扰体综合作用的结果。在干旱区严酷的生态环境下,荒漠生态系统的人为干扰结果值得重视。2000年5月以来的塔里木河下游生态输水,使系统的退化形式得到了一定程度的遏制,但系统的恢复是有限的。植被的恢复,必须遵循干旱区植物的生态学性质,密切结合植物发生所需的环境条件,特别是干旱区植被分布格局与地下水的关系。