Simulation of groundwater table dynamics based on Feflow in the Minqin Basin,China

As groundwater table declination is an important factor resulting in degradation of eco-environment in the Minqin Basin, China, it is significant to investigate and understand the groundwater table dynamics in this area. According to the physical and geographical conditions of the Minqin Basin, a hydrogeological conceptual model and a mathematical model were established, and the mathematical model was figured out by using Finite Element subsurface Flow system （Feflow）. Accurate hydrogeological parameters were acquired, and the spatio-temporal distribution dynamics of groundwater table for 1983-2001 were also simulated. The model performed well with a correlation coefficient of 0.977 and a mean error of 0.9768 m. The inflow and outflow of the groundwater system were predicted by time series analysis, and the groundwater table dynamics for 2011 were further acquired. Gen- erally the groundwater table in the Minqin Basin would continue to decline. The groundwater table would decline during spring and summer irrigation, while it would rise during autumn-winter irrigation. The groundwater depression cones would expand with the increase of center depths. Therefore, regulatory measures should be taken to prevent the declination of groundwater table and improve the eco-environment of this area.

Effects of Groundwater with Various Salinities on Evaporation and Redistribution of Water and Salt in Saline-sodic Soils in Songnen Plain,Northeast China

Groundwater mineralization is one of the main factors affecting the transport of soil water and salt in saline-sodic areas.To investigate the effects of groundwater with different levels of salinity on evaporation and distributions of soil water and salt in Songnen Plain,Northeast China,five levels of groundwater sodium adsorption ration of water(SARw)and total salt content(TSC mmol/L)were conducted in an oil column lysimeters.The five treated groundwater labeled as ST0:0,ST0:10,ST5:40,ST10:70 and ST20:100,were prepared with NaCl and CaCl2 in proportion,respectively.The results showed the groundwater evaporation(GWE)and soil evaporation(SE)increased firstly and then decreased with the increase of groundwater salinity.The values of GWE and SE in ST10:70 treatment were the highest,which were 2.09 and 1.84 times the values in the ST0:0 treatment with the lowest GWE and SE.There was a positive linear correlation between GWE and the Ca^(2+)content in groundwater,with R^(2)=0.998.The soil water content(SWC)of ST0:0 treatment was significantly(P<0.05)less than those of other treatments during the test.The SWC of the ST0:0 and ST0:10 treatments increased with the increase of soil depth,while the other treatments showed the opposite trend.Statistical analysis indicated the SWC in the 0–60 cm soil layer was positively correlated with the groundwater TSC and its ion contents during the test.Salt accumulation occurred in the topsoil and the salt accumulation in the 0–20 cm soil layer was significantly(P<0.05)greater than that in the subsoil.This study revealed the effects of the salinity level of groundwater,especially the Ca^(2+)content and TSC of groundwater,on the GWE and distributions of soil water and salt,which provided important support for the prevention and reclamation of soil salinization and sodificaton in shallow groundwater regions.

The Role of Groundwater in the Salt Lakes in the Badain Jaran Desert,China

The Badain Jaran Desert is the second largest desert in China with tallest sand dunes on the earth.In contrast to the extremely dry climate,there are about 100 lakes spreading regularly over the depressions among high

Effects of water and salt for groundwater-soil systems on root growth and architecture of Tamarix chinensis in the Yellow River Delta,China

To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were chosen as the research object.Groundwater with four salinity levels was created,and three groundwater level(GL)were applied for each salinity treatment to measure the root growth and architecture indexes.In the fresh water and brackish water treatments,the topological index(TI)of the T.chinensis roots was close to 0.5,and the root architecture was close to a dichotomous branching pattern.In the saline water and saltwater treatments,the TI of the T.chinensis roots was large and close to 1.0,and the root architecture was close to a herringbone-like branching pattern.Under different GLs and salinities,the total root length was significantly greater than the internal link length,the external link length was greater than the internal link length,and the root system showed an outward expansion strategy.The treatment with fresh water and a GL of 1.5 m was the most suitable for T.chinensis root growth,while the root growth of T.chinensis was the worst in the treatment with saline water and a GL of 0.3 m.T.chinensis can adapt to the changes in soil water and salt by regulating the growth and morphological characteristics of the root system.T.chinensis can adapt to high-salt environments by reducing its root branching and to water deficiencies by expanding the distribution and absorption area of the root system.

降水和地下水开采对通辽市科尔沁区潜水位的影响

变化环境下(气候变化和人类活动)潜水位动态演化过程识别是当前我国乃至全球水资源领域面临的主要科学问题。为了分析多影响因素下的潜水位时空动态变化,以降水和地下水开采为例,基于通辽市科尔沁区2016年1月—2019年12月实测地下水位动态数据,采用Mann-Kendall(MK)趋势检验和栅格代数法分析了区域潜水位的时空变化规律,并利用交叉小波分析、斯皮尔曼相关系数和多元线性回归法进一步量化分析了不同区域降水和地下水开采对潜水位的影响。结果表明:研究时段内科尔沁区潜水位总体呈下降趋势,年均降幅为0.36 m,中部和西部地区潜水位下降较为严重;根据潜水位差值空间分布特征,将研究区划分为潜水位基本平衡区、下降区和严重下降区,其分别占研究区总面积的9.88%、49.65%和40.47%;基本平衡区的潜水位受降水因素影响显著,受地下水开采变化影响极小,下降区和严重下降区潜水位受地下水开采的影响相较于降水影响更大。

Vegetation dynamics induced by groundwater fluctuations in the lower Heihe River Basin,northwestern China

Aims Since 2000,the environmental flow controls project has been implemented in the lower Heihe River Basin,a typical arid inland river basin in northwest China,to restore the deteriorated ecological environment in this region.The aim of this study was to explore the impacts of groundwater fluctuations on vegetation dynamics.Our results can be used as a reference for water resources planning and management to maintain proper environmental flows in arid areas.Methods The location(by Global Positioning System)and depth of the monitoring wells,as well as groundwater table depth and salinity were measured in situ at each site from July to August 2009.Based on the measurements of the groundwater table depth and salinity following the implementation of environmental flow controls project(EFCP)in the lower Heihe River Basin,the groundwater fluctuations during the period from 2001 to 2009 were analyzed.Descriptive statistics and Pearson’s correlation were used to analyze the relationship between vegetation changes and groundwater table fluctuations.Additionally,the spatial distributions of the groundwater table depth and salinity were interpolated using the simple kriging method.Trend analysis was applied to the time series of integrated Moderate Resolution Imaging Spectroradiometer normalized difference vegetation index data to identify interannual vegetation dynamics.The relationship between vegetation status and groundwater environment was investigated at different spatial scales by analyzing and comparing the time series and trends.Important Findings(i)The groundwater table and salinity increased significantly in most of the study area with spatial heterogeneity.On average,the groundwater table rose;0.5 and 1.5 m in the upper and lower Ejina Basin,respectively,and the groundwater salinity increased across the study area by 0–4%.(ii)A notable correlation between the vegetation status and the groundwater table was revealed when the groundwater table depth fluctuated between 1.8 and 3.5 m,whereas the vegetation did not show an obvious response to groundwater table changes when the groundwater table depth was more than 5–6 m.(iii)Vegetation restoration mainly occurred in riparian areas within 500–1000 m of from natural rivers,where the groundwater table depth varied from 2 to 4 m,and salinity was<5%,whereas vegetation degradation appeared at some locations where groundwater environment had deteriorated.

华北平原禹城地区地下水埋深对地下水及土壤水分和盐分分布的试验研究

【目的】研究不同浅层地下水埋深下的土壤水盐分布规律及其对作物产量的影响。【方法】在体积蒸渗仪样地中设置4个地下水埋深处理,分别为G0(无地下水埋深)、G1(地下水埋深40 cm)、G2(地下水埋深70 cm)、G3(地下水埋深110 cm)和G4(地下水埋深150 cm),监测夏玉米在自然蒸发条件下的浅层地下水盐分离子量变化和夏玉米收获后土壤水分和盐分的垂直变化。【结果】(1)地下水埋深越深,表层(0~20 cm)土壤含水率与含盐量越低。与G0处理相比,G1处理和G2处理表层土壤含水率分别显著增加27.54%和26.97%,G3处理增加8.25%,而G4处理仅增加2.18%;G1、G2、G3处理表层土壤含盐量分别增加0.79、0.47、0.43 g/kg,而G4处理则减少了0.01g/kg。G1、G2、G3处理下的盐分主要积累在表层土壤,G4处理主要积累在40~70 cm土层;(2)地下水埋深与表层(0~20 cm)土壤含水率与含盐量呈线性关系,地下水埋深每增加0.1 m,表层土壤含水率降低0.53%,含盐量降低0.065 g/kg。(3)浅层地下水中的主要阳离子为Na^(+)、Mg^(2+),主要阴离子为SO_(4)^(2-)和HCO_(3)^(-),集中降水使浅层地下水中离子由Na-Cl·SO_(4)向Na-HCO_(3)转化;(4)在强烈的地表蒸发下,地下水埋深越浅,地下水中离子浓度上升越快。其中HCO_(3)^(-)浓度在各处理中波动较大,总体呈上升趋势;而NO_(3)^(-)由于施肥的影响,地下水埋深越浅,NO_(3)^(-)在浅层地下水中达到峰值的速度越快,且浓度越高。【结论】增加浅层地下水埋深可有效降低表层土壤水盐量,减小浅层地下水受蒸发、降水的影响。浅层地下水埋深为1.2 m最适宜夏玉米生长,产量最优。研究不同浅层地下水埋深对农田土壤水分和盐分的影响有助于掌握农业生态系统中水盐迁移以及地下水与土壤的相互作用机制,对于防止土壤盐渍化、保障作物产量具有重要意义。

河套灌区农田地下水化学特征与不同地类水盐迁移

为确定深度节水背景下河套灌区农田地下水的化学特征与不同类型农田间的水盐迁移转化关系,选取河套灌区典型灌溉农田作为试验区,利用经典统计学、主成分分析与溶质动力学原理,分析典型灌溉农田浅层地下水离子与浅层地下水埋深变化特征,确定影响地下水水质的主要地下水特征因子;讨论作物种植前后土壤离子变化情况;运用定位通量法确定了地下水对不同类型农田间盐分的贡献,并建立水盐均衡模型。结果表明:(1)浅层地下水阳离子以Na^(+)+K^(+)为主,占阳离子总量的53.22%,阴离子以SO_(4)^(2-)为主,占阴离子总量的41.04%,地下水主要化学类型为HCO_(3)·SO_(4)^(-)Na型,通过主成分分析得出影响地下水水质的主要特征因子为TDS、Na^(+)+K^(+)、HCO_(3)^(-)、SO_(4)^(2-)。(2)作物种植前后盐分积聚以NaCl和Na_(2)SO_(4)为主。(3)不同类型田块的蒸散量不同,荒地、葵花地、玉米地的ET分别为422.6 mm、475.6 mm、625.8 mm。(4)玉米、葵花、荒地土壤均处于积盐状态,通过水平渗透进入荒地的盐分为1924 kg·hm^(-2),占荒地积盐量的22.00%。(5)荒地与耕地存在盐分过渡带,荒地附近推荐种植葵花等耐盐性较好经济作物。研究可以为当地水资源高效利用、土壤盐渍化调控和农业可持续发展提供指导意义。

察汗淖尔干涸湖区土壤盐渍化对地下水位响应

土壤盐渍化是产生坝上高原盐尘暴的主要物质来源,干涸湖区土壤盐渍化防控对于京津冀地区空气质量安全具有重要意义。本次研究以坝上高原察汗淖尔干涸湖区为例,探究地下水位埋深和溶解性总固体(total dissolved solids, TDS)与土壤盐渍化的影响,确定土壤盐渍化的地下水位防控阈值,为地表土壤盐渍化治理提供依据。室内实验获取研究区土壤含盐量、沙粒、黏粒百分含量,地下水TDS值,野外调查地下水位埋深,收集研究区蒸发量、降雨量资料,利用皮尔逊相关系数法及协方差矩阵分析选取线性关系较小的影响因素,绘制回归曲线探究土壤含盐量与地下水位埋深之间的关系。研究结果表明,TDS为0~1 000 mg/L、1 000~3 000 mg/L、3 000~6 000 mg/L、6 000~23 000 mg/L及0~23 000 mg/L时,土壤发生盐渍化的阈值分别为4.08、5.47、6.84、7.94、7.37 m;TDS为0~3 000 mg/L时土壤基本不发生盐化。TDS值为3 000~6 000 mg/L、6 000~23 000 mg/L及0~23 000 mg/L时土壤盐化阈值分别为2.05、2.44、1.97 m。本文研究利用回归分析,确定察汗淖尔流域平原区各TDS分区不同盐渍化程度对应的地下水位埋深,可针对性进行地下水位调控。

新密市超化泉域地下水环境特征及成因研究

为了深入探讨超化泉域地下水环境特征与规律,以新密市超化泉域为研究对象,通过收集大量实地监测数据,结合地质、水文地理等信息,系统调查了该地区多年来的地下水动态变化,并分析了其成因机制。研究结果表明,新密市超化泉域地下水环境受季节、人类活动以及地质构造等因素的影响较大,呈现出明显的周期性变化。进一步分析发现,地下水位下降与土地利用变化、水文补给不足等因素密切相关,为了更好地管理和维护超化泉域的地下水资源,有必要制定相应的地下水资源管理策略。

敦煌西湖保护区地下水埋深对表层土壤盐离子含量的影响

土壤盐分含量和地下水埋深是评估土壤盐碱化防治和保护区植被恢复的重要指标。该研究在敦煌西湖保护区羊圈湾、后坑、马圈湾、盐池湾和火烧湖设置样地,通过野外土壤采样和实验室分析测试,系统分析地下水埋深与表层(0—5 cm)土壤盐分离子含量之间的关系。结果显示:地下水位埋深较浅的地点主要出现硫酸盐型和氯化物-硫酸盐型土壤盐渍化,而地下水位埋深较深的地点主要表现为硫酸盐-氯化物型土壤盐渍化;随着地下水位埋深的由浅变深,八大离子中(Na^(+)、Ca^(2+)、Mg^(2+)、SO_(4)^(2-)、Cl^(-)、HCO_(3)^(-))在表层(0—5 cm)土壤的含量呈现先增加后减少的趋势,而K+和CO_(3)^(2-)离子的变化规律不太明显。地下水埋深对土壤盐分的影响显著,需要通过控制地下水位埋深在适当的范围内,实现防止土壤盐渍化的进一步加剧。

石羊河流域环境现状及其演化趋势分析

石羊河流域下游地区蒸发强度大、地下水循环速度慢,加之近年来地表水供给量的严重不足,过度开采地下水已引发了区域性地下水位下降、植被退化、盐渍化、沙漠化等一系列生态环境问题的不断恶化。地下水位的下降与矿化度的增高存在着明显的正相关性,特别是流域下游地区地下水矿化度的增高趋势明显。根据影响地下水动态的主要影响因素可将石羊河流域地下水的动态类型划分为蒸发型、开采型、径流开采型、渗入型和蒸发开采型5种,在此基础上,结合多年地下水位和水质变化的实测资料,对石羊河流域地下水下降趋势和亏空状况进行模拟分析,表明该区近40a来地下水位持续下降,亏空量不断增加,并且具有明显的加速趋势。1960年武威和民勤盆地地下水亏空量为1 74×108m3,1998年已达4 52×108m3,如不采取有力措施加以治理,预计2010年将达到6 7×108m3,这将对该区生态环境产生严重的影响。

新疆喀什地下水浅埋区弃荒地表层土壤积盐与地下水的关系

为了研究新疆喀什地下水浅埋区弃荒地表层土壤积盐与地下水的定量关系，对试验区自然状况下的土壤含水量、表层土壤含盐量、地下水埋深、地下水矿化度和潜水蒸发量进行了原位监测，模拟了潜水蒸发量与地下水埋深的关系，定量分析了弃荒地自然条件下地下水埋深、地下水矿化度对土壤表层盐分的影响，建立了表层土壤含盐量与地下水埋深、地下水矿化度的经验模型。结果表明：在5-50 cm土层，土壤质量含水率随土层深度增加而增大；地下水埋深、地下水矿化度对表层土壤盐分有显著的影响，当地下水埋深为定值时，表层土壤含盐量与地下水矿化度呈线性正相关；当地下水矿化度为定值时，表层土壤含盐量与地下水埋深呈线性负相关；土壤盐分表聚现象明显，不同地下水埋深条件下表层土壤含盐量随累计潜水蒸发量的增加而增大，表层土壤积盐速率随地下水埋深的增大而减小，地下水埋深为25 cm条件下表层土壤积盐速率约是地下水埋深为50 cm的表层土壤积盐速率的2倍多。

排水地段土壤盐分变化特征分析

根据田间排水地段实测的土壤含盐量与地下水埋深和矿化度，分析了土壤盐分组成变化特征以及覆膜种植对抑制土壤积盐的效应。根据潜水蒸发特点，确定了建立地下水埋深与土壤含盐量间单一函数关系的方法，为根据土壤含盐量确定地下水临界深度提供指导。

渤海湾西岸滨海盐渍土的盐渍化特征分析

渤海湾西岸滨海盐渍土的盐渍化特征与滨海平原的地面高程、气候条件、盐渍土的理化性状、地下水的矿化度及人类活动等密切相关。就土盐渍化的程度而言,地面高程较高处的土高于地面高程较低处的土,上层土高于下层土。受蒸发和降水影响,地下水位以上土的盐渍化敏感深度为1 m左右。随着气候的变化,滨海盐渍土显现出春季蒸发,上层土积盐;夏季淋洗,土中盐分向下移动的盐渍化特征。随着深度的增加,土的含盐量逐渐减少,至地下水位附近出现轻微增长。从剖面上地表至地下水位间可划分为3个不同聚盐形态和含盐量的土盐渍化程度分区带,即土蒸发浓缩聚盐带、土盐化变动带和土饱水溶盐带;平面上向海岸线方向延伸,土逐渐由非盐渍土变为弱盐渍土、中盐渍土和强盐渍土,含盐量和盐渍化程度也越来越高。地下水位浅和地下水矿化度高,则上层土的盐渍化程度就愈高。

地下水作用条件下土壤积盐规律研究

用粉砂壤土土柱进行了为期一年的室内模拟试验 ,对不同地下水埋深及其矿化度作用条件下 0～ 40cm深度土壤的盐分运动规律进行了深入研究。地下水埋深 85cm、1 0 5cm情况下 ,0～ 40cm深度土壤电导率与地下水矿化度呈良好正相关关系。地下水埋深 1 5 5cm、试验设定条件下 ,各土柱 0～ 40cm深度土壤积盐强度都较小 ,并且相互之间差异不明显。获得了各土柱 0～ 40cm深度土壤电导率关于地下水埋深、地下水矿化度的统计模型。对土壤电导率动态规律进行了深入分析 ,并建立了地下水明显影响到该深度土壤后土壤电导率动态模型。

塔里木河流域荒漠河岸植物对应急输水的生理响应

选择塔里木河沿岸典型样地,以乔木树种胡杨(Populuseuphratica)、灌木柽柳(Tamarixspp.)和草本植物罗布麻(Apo-cynumvenetum)为研究材料,垂直距离输水河道500m范围内,间隔100m设置一个采样断面。监测并分析塔里木河下游应急输水前后5个断面地下水位、地下水含盐量及3种植物叶片游离脯氨酸、可溶性糖、内源植物激素脱落酸(ABA)和细胞分裂素(CTK)含量的变化。研究3种荒漠植物对水盐双重胁迫环境的生理响应及适应策略。结果表明:盐胁迫显著增加3种植物叶片或同化枝的可溶性糖浓度,断面间不同植物叶片或同化枝可溶性糖积累存在差异;输水后断面间随地下水位不同程度的抬升,胡杨和柽柳叶片或同化枝脯氨酸含量出现了成比例的下降;柽柳同化枝可溶性糖与脯氨酸积累相关性最小,发展了不同于另外两种植物的通过有机溶剂积累适应胁迫环境的策略,即同化枝可溶性糖与脯氨酸作为响应于地下水位变化的功能物质独立地起作用,可溶性糖积累对盐胁迫的响应明显,而脯氨酸积累对干旱胁迫的响应更为明显;对与胁迫抗性有关的植物内源激素ABA、CTK浓度及浓度增长量变化进行分析,发现胡杨具有不同于其他两种植物的内源ABA、CTK浓度增量变化趋势;胡杨和罗布麻叶片ABA积累量与脯氨酸积累百分量(△[脯氨酸])而柽柳中ABA积累量与可溶性糖积累百分量(△[可溶性糖])显著相关。

滨海盐荒地不同高度台田地下水动态变化与脱盐效果

为给大面积滨海盐渍荒地农业开发利用提供高效的技术支撑,在黄河三角洲滨海盐渍荒地上,设计135 cm、145 cm和175 cm高度台田处理,以未做台田处理的盐荒地为对照,定位监测挖深沟修台田后2年的地下水埋深与矿化度的变化动态,以及连续种植5年后台田土体含盐量的变化。研究表明:连续2年3种高度台田均能有效增加地下水的埋深,盐渍荒地地下水埋深变化为0.65～2.10 m,3种高度台田地下水埋深变化为2.20～3.63 m。3种高度台田的地下水矿化度同盐渍荒地相比均呈现升高趋势,表明台田土体盐分通过灌溉和降雨作用淋洗进入地下水中。修建台田前荒地0～30 cm土壤含盐量为4.90～7.33 g.kg-1,台田引黄灌溉洗盐后土壤含盐量降低到1.37 g.kg-1以下,土壤脱盐率为81.31%～89.05%。连续种植5年后,不同高度台田0～120 cm土体盐分含量均低于盐荒地,尤其0～30 cm和30～60 cm土层的盐分含量与盐荒地相比降低显著;其中135 cm和145 cm台田各土层盐分含量均小于1.62 g.kg-1。因此,"台田-深沟"模式是改良滨海重度盐渍土的一种有效工程措施,考虑到开发成本和台田有效面积比,台田高度可优先选择145 cm。

盐碱地改良技术集成示范区水土环境变化研究初报

采用"脱硫废弃物施用+平整土地+深松耕+水盐调控+平衡施肥+耐盐作物种植"的盐碱地改良技术集成模式在惠农核心试验示范区开展盐碱地改良技术集成示范,经过2年的改良,示范区地下水位下降了50cm左右,土壤总盐及有害盐分离子含量也有了较大幅度的下降,油葵出苗率和产量显著提高,出苗率为70%以上,平均产量为1534.3kg/hm2,示范区水土环境有了较大的改善,表明以脱硫废弃物施用为切入点的盐碱地改良技术集成模式对轻度碱化盐荒地具有良好的改良效果。