塔里木沙漠公路防护林生态工程的综合生态环境效应

为了探讨重大工程的生态环境效应,从风沙环境、土壤环境、小气候、生物多样性和地下水环境5个方面对塔里木沙漠公路防护林工程的综合生态环境效应进行了研究.结果表明:(1)防护林改变了近地表风沙运动过程,防沙体系内风速、输沙率降低幅度分别达64%~80%和87.45%~99.02%,风沙流结构、沙物质粒度、地表蚀积状况也发生了明显变化;(2)与自然流沙地相比,防护林土壤容重减小,全盐含量、总孔隙度和含水量增大,土壤肥力质量明显提高,其变化基本呈现"先快后慢"的规律;(3)防护林对于小环境改善作用明显,距地面6m范围内,林地不同高度的空气温度普遍低于自然流沙地,而空气湿度则高于自然流沙地,林地土壤温度也低于自然流沙地;(4)随着防护林内生境的变化,土壤微生物种类显著增加,但不同种类微生物的种群分布并不均匀;(5)目前防护林灌溉抽水对地下水位、地下水矿化度的影响不大,水位在厘米级范围波动,矿化度的变化幅度在±1g·L-1左右,且没有明显的变化趋势

塔里木沙漠公路防护林土壤微生物生物量与土壤环境因子的关系

为探讨极端干旱区风沙土土壤微生物与土壤环境因子的作用规律,采用相关分析法研究了塔里木沙漠公路防护林地土壤微生物生物量与理化因子和酶活性的关系.结果表明:土壤容重和粒径减小(R0.85)时,防护林地中土壤微生物数量和生物量有增大趋势,由容重与微生物量的相关性主导;土壤养分含量与土壤微生物数量和生物量呈正相关,主要由速效养分和放线菌、微生物生物量C、P的相关性所致;土壤酶活性与土壤微生物数量和生物量的相关性差异较大,R在0.51～0.91,主要取决于蔗糖酶、磷酸酶与放线菌、微生物量C的相关;土壤盐分增加不利于土壤微生物生物量的积累(R0.63).实践中应为干旱区林地土壤微生物营造良好的土体,促进土壤物质循环

Spatial and temporal variations of groundwater environment and its response to pumping for the Shelter-forest Project along Tarim Desert Highway

塔里木沙漠公路防护林生态工程是新疆防沙治沙重大工程之一，以其独特的地理位置和建设规模赢得了国内外众多专家、学者的关注和好评。工程采用地下水作为灌溉水源，本文针对地下水环境时空变化等问题，通过设置在沙漠公路沿线的监测断面，利用水位、水质监测及地下水流向-流速测定的数据，分析了防护林工程沿线地下水位、水质、地下水流速流向的时空变化；利用地质统计学方法分析了地下水埋深和地下水矿化度、pH值的空间变异型特征。通过抽水试验、地下水化学分析等资料，分析了地下水环境对水资源开发的响应过程；利用抽水试验资料，输入Modflow，建立了基于Modflow的地下水动力学模型，利用该模型模拟了不同供水方案下的地下水位变化以及地下水流场的变化，预测了抽水期间与停灌期间地下水位及地下水流场的变化情况。所得到的结论如下：（1）沙漠公路沿线地下水埋深主要受地形、地貌因素影响，在沙垄顶部和北民丰隆起地区埋藏较深，在丘间平地埋藏均不深，介于1.31m~13.88m之间。（2）自然条件下地下水离子交替作用较缓慢，地下水化学类型较为单一，属于碱及强酸为主的中性偏碱性的极硬水类型，从补给区至排泄区或相对滞流区，地下水化学类型由Na-Cl-HCO3型水演化至Na-Mg-Cl-SO4和Na-Cl-SO4型水。地下水矿化度总体上表现为由南向北逐渐增加的水平地带性规律，在沿地下水流动方向上，地下水矿化度呈增加趋势。（3）塔里木沙漠公路沿线地下水流速测定结果显示：塔里木沙漠公路沿线地下水的平均流速为：55.94m/a；地下水流动方向在沙漠北部主要以ENE方向为主，沙漠中部除个别井点外主要以EN方向为主，沙漠南部尼雅河下游监测井中流向由ENN方向和WNN方向构成，牙通古斯河断面处以ESS方向为主。（4）地下水位随时间的变化根据其影响因素可分为三种类型：河流流量季节变化影响型，山区径流渗流补给影响型，机井抽水影响型。还有一些风蚀洼地、地下水埋深很浅的丘间平沙地或板结沙地的地下水位变化相对较为显著。这部分的地下水位变动，对荒漠环境的影响不可忽视。（5）在沙漠公路第69号水源井处，利用稳定流抽水试验方法计算了含水层渗透系数为12.85m/d；利用漏斗疏干法计算了潜水含水层给水度为0.05；利用抽水试验曲线拟和方法，计算了抽水实际影响半径为146.479m。（6）从单井水动力学模型预测结果看：按目前开采量及开采时间预测，地下水位在开采期间的最大降深为1.373m；按现状开采量的双倍抽水，地下水位在开采期间的最大降深为1.409m；按现状开采量的三倍抽水，地下水位在开采期的最大降深为1.425m。但是冬季停止抽水后，三种方案地下水流场都可以恢复到初始状态，且有可能到初始水位以上，说明在目前开采量和开采强度下，地下水可以得到稳定的补给，不会造成地下水位的持续下降。The Tarim desert highway shelter forest was irrigated with groundwater, so exploiting and protecting the groundwater is taken many attentions. In this paper, we set up monitoring sections along the desert highway and got the data of water level, water quality, water flowing direction and water flowing velocity, then analyzed the temporal and spatial variations of these factors. Moreover, by geostatistical method, the spatial variation characteristics of depth, quality and pH value of groundwater were studied. Based on the data from several pumping groundwater experiment and analyzing the groundwater samples, the response process on groundwater environment to exploiting groundwater resource was investigated. Finally, inputted the experimental data in Modflow function, from which got a groundwater dynamic model based on pumping well and simulated and the changes of groundwater level and groundwater flow field. The main results are below: (1) The depth of groundwater along the desert highway are mainly influenced by topography and geomorphology, the biggest on top of sand dune and North Minfeng upheaval area, and the groundwater depth of flat sand between sand dunes appeared lower, from 1.31meters to 13.88 meters. (2) Under natural condition, ion alternation of the groundwater relatively slow, chemical type of the groundwater single and belongs to the hardest water type with more alkaline. From water supply area to discharge area or relative stagnating flow area, the groundwater chemical type evolved from Na-Cl-HCO3 to Na-Mg-Cl-SO4 and Na-Cl-SO4. The groundwater mineralization appeared horizontal zonality characteristics of south-to-north increasing gradually, and along the groundwater flowline, the water mineralization increased. (3) The determination result show that: the average velocity of the groundwater along Tarim desert highway is 0.011cm/min, that is 55.94m/a; the groundwater flowing direction mainly appeared ENE direction in north desert, EN direction mainly in middle part except for very few observe well, ENN and WNN direction basically in the south desert at Niya River lower reaches, ESS direction mainly in Ya-Tong-Gu-Si River Section. (4) The change of groundwater level can divided into three types, which are the type influenced by river flow rate, the type influenced by the recharge of runoff and seepage in mountainous area and the type influenced by pumping well water. Furthermore, the changes of groundwater level on wind-erosion low land, flat sany land between sand dunes or harden sandy land were relatively obvious, which imposed great influences on desert environment. (5) Several pumping experiment was processed at No. 69 well along the desert highway, then using the stable flow method got the coefficient of permeability 12.85m/d and determined specific water yield of phreatic aquifer as 0.05 by Funnel transfortation stem method. With curve-fitting method of groundwater level and spatial distance obtained the radius of pumping actual influence is 146.479m. (6) From the result of single well hydrodynamic model we can see the groundwater’s maximum drawdown 1.373cm during exploiting according to present exploitation quantity and time. On the condition of double pumping quantity, we could predict that the maximum drawdown was 1.409m during pumping course; but based on triple pumping quantity, there will be 1.425m maximum drawdown. At all three conditions, when stop pumping water in winter, the groundwater flow field could be restored to the innital status and probably get to the water level above the initial status, which indicates that there is steady supply for the groundwater and the continuous decrease of the groundwater level not existing

塔里木沙漠公路防护林生态工程对地下水位的影响分析

为了解塔里木沙漠公路防护林生态工程对地下水位的影响,在该工程第69#灌溉水源井处设置观测场,通过多个观测井的非稳定流抽水试验,观测井中地下水位的变化情况,确定了研究区域的含水层渗透系数K=13.317m/d、抽水影响半径R=332.04 m。分析了地下水位降落"漏斗"和水位下降、上升随时间和空间的变化规律:在2个抽水应力期内,水位急速下降和上升过程均可在抽水试验开始后的11 min内完成,随着时间的累积,变化趋势逐渐缓慢;抽水结束后,水位可恢复到初始水平。因此,研究认为塔里木沙漠公路防护林生态工程灌溉期抽水不会引起天然地下水位的持续下降,这将为沙漠公路沿线地下水资源的可持续利用和防护林生态工程整体的稳定性及长久运行提供一定的理论依据

塔里木南缘策勒绿洲地下水空间变异性与土地覆盖关系研究

基于策勒绿洲78个取样点的地下水埋深、矿化度和pH值的观测资料,应用遥感、地理信息系统、空间插值和地质统计学分析的方法对所取数据进行空间变异性分析.结果表明:1)地下水埋深和pH值服从正态分布,矿化度服从对数正态分布;2)地下水埋深、矿化度和pH值都具有强烈的空间相关性,在步长为8km范围之内,地下水特征的空间变异是各向同性的,当步长>8km时,四个方向上的半变异函数发生了不同的变化;3)受盆地地形影响,地下水埋深从南到北变浅,东部区域埋深最浅,最小为1.56m;矿化度分布趋势则是从南到北逐渐增大;pH值高值区发生在绿洲东南部和中北部,pH值高的区域矿化度较低,而pH值低的区域矿化度较高;4)绿洲耕地主要分布于地下水位埋深为5～25m,且矿化度2.0g·L-1

塔中沙漠植物园土壤水盐空间变异性及合理取样数研究

本研究运用经典统计学和地质统计学方法,分析了塔中沙漠植物园内下层根系土壤水盐的空间变异特性,结果表明:塔中沙漠植物园下层根系的土壤水盐分布具有中等空间变异性,80cm、100cm、120cm、140cm土层土壤水分变异系数分别为44.16%、41.30%、45.53%、55.44%,盐分变异系数为41.51%、34.00%、42.28%、30.52%。各层土壤质量含水量分别满足指数、高斯、指数和线性模型,土壤电导率变异函数的最佳理论模型分别为球状、球状、线性和线性模型。结合经典统计学和土壤水盐变程及空间分布图,选取并定位了85个土壤剖面监测塔中植物园下层根系的土壤水盐含量。通过结合监测取样容量和土壤水盐分布的空间特性制定出塔中沙漠植物园下层根系土壤水盐变化的监测方案,为塔中植物园的持久性发展提供科学依据

Responses of Ground Water Level to Pumping Water of the Tarim Desert Highway Shelterbelt Project

为了掌握塔克拉玛干沙漠腹地单井抽水过程中，地下水位的变化过程，为沙漠生态防护林工程可持续供水提供理论依据。通过设置在塔里木沙漠公路防护林生态工程灌溉用第69 号水源井处的观测场，观测了一次抽水过程，2 个抽水应力期内，观测井中的水位变化情况，确定了研究区域的几个水文地质参数，分析了抽水过程水位变化规律。研究显示：计算所得渗透系数K=13.32 m/d；抽水影响半径R=332.04 m；给水度μ=5.08%。在2 个抽水应力期内，水位急速下降和急速上升过程均可在其开始后的11min 内完成，之后转为缓慢变化阶段。停止抽水后，水位可以恢复到未抽水之前的水平，没有引起天然地下水位的持续下降