甘肃梨园河流域地下水来源及其水化学特征

通过分析水化学与氢氧稳定同位素的关系,研究梨园河流域地下水的补给机理和水化学演化规律。地下水总溶解固体（TDS）自西南向东北递增,最大值为1 258 mg/L。沿流程方向,深层地下水的水化学类型由Ca-HCO₃→Ca-Mg-HCO₃、Mg-SO₄→Na-SO₄型。浅层地下水的水化学类型由Ca-HCO₃→Mg-HCO₃-SO₄→Mg-SO₄型。地表水的水化学类型无分异,主要为Ca-HCO₃型。深层和浅层地下水沿途均发生了水岩融滤作用。Na⁺含量沿程增大,一是地下水中Ca²⁺与岩石中Na⁺发生阳离子交换作用,二是硅酸盐矿物的风化作用产生Na+。Phreeqc软件模拟显示,深层地下水中方解石先沉淀后溶解;CO₂、石膏、白云石和岩盐溶解。浅层地下水中,方解石由不饱和逐渐变为饱和;石膏、岩盐一直溶解。地下水的δ²H和δ¹⁸O值大部分位于大气降水线上方,反应了山区现代降水或雪冰融水通过出山地表径流补给,交替更新快,且深层地下水向上补给浅层地下水和地表水。地表、地下水相互转化是该区水循环的主要特征。     

人类活动对亚洲中部水环境安全的威胁

主要依赖河流出山口的径流量维系山地-绿洲-荒漠间脆弱生态平衡的亚洲中部干旱区,其水分循环过程完全不同于湿润区。平原区不产生径流,地表水和地下水同源于山区,一个流域就是一个以地表水和地下水相互依赖的生态功能单元,其中河流是纽带,连接山区径流形成区与平原径流散失区或消耗区,以水分循环为主体,并与生物、生态系统紧密相联系,构成一个独特而又完整的內陆水分循环体系。自然要素的变化,特别是人类的参与或介入,改变了水分循环的规律,对亚洲中部干旱区水和环境的形成具有很大的威胁。用多年的观测数据来讨论人类活动的影响,并提出维系和保持干旱区水环境的建议。     

Integrating water use systems and soil and water conservation measures into a hydrological model of an Iranian Wadi system

Water resources are precious in arid and semi-arid areas such as the Wadis of Iran. To sustainably manage these limited water resources, the residents of the Iranian Wadis have been traditionally using several water use systems (WUSs) which affect natural hydrological processes. In this study, WUSs and soil and water conservation measures (SWCMs) were integrated in a hydrological model of the Halilrood Basin in Iran. The Soil and Water Assessment Tool (SWAT) model was used to simulate the hydrological processes between 1993 and 2009 at daily time scale. To assess the importance of WUSs and SWCMs, we compared a model setup without WUSs and SWCMs (Default model) with a model setup with WUSs and SWCMs (WUS-SWCM model). When compared to the observed daily stream flow, the number of acceptable calibration runs as defined by the performance thresholds (Nash-Sutcliffe efficiency (NSE)≥0.68, -25%≤percent bias (PBIAS)≤25% and ratio of standard deviation (RSR)≤0.56) is 177 for the Default model and 1945 for the WUS-SWCM model. Also, the average Kling-Gupta ef?ciency (KGE) of acceptable calibration runs for the WUS-SWCM model is higher in both calibration and validation periods. When WUSs and SWCMs are implemented, surface runoff (between 30% and 99%) and water yield (between 0 and 18%) decreased in all sub-basins. Moreover, SWCMs lead to a higher contribution of groundwater flow to the channel and compensate for the extracted water by WUSs from the shallow aquifer. In summary, implementing WUSs and SWCMs in the SWAT model enhances model plausibility significantly.     

近50年来石家庄市水资源与水环境的演化特征

从水文循环系统理论出发,采用演绎与归纳方法,分析近50年来石家庄市的大气降水、地表水资源、地下水资源、地表水环境和地下水环境的演化特征及正负反馈作用,系统研究水资源与水环境的过去与现状,并结合人类活动、全球气候变化与南水北调中线工程,突出水文循环与水资源和水环境之间的内在联系与相互作用,探讨了复杂环境下石家庄市未来水资...     

中国干旱区浅层地下水的形成、分布与运移

地球陆地浅层地下水的形成过程是大气降水、地表水与地下水相互转化的过程.主要依赖山区河流出山口径流维系生存和发展的中国干旱区,浅层地下水的形成过程完全不同于我国东部湿润区和青藏高寒区.研究表明:中国干旱区山地地下水以降水(雪冰融水)入渗补给为主,且最终转变为地表水补给河流,并参与平原盆地浅层地下水的形成过程;而盆地平原浅...     

Hydrochemical characteristics and evolution of groundwater in the dried-up river oasis of the Tarim Basin,Central Asia

Intense human activities in arid areas have great impacts on groundwater hydrochemical cycling by causing groundwater salinization. The spatiotemporal distributions of groundwater hydrochemistry are crucial for studying groundwater salt migration, and also vital to understand hydrological and hydrogeochemical processes of groundwater in arid inland oasis areas. However, due to constraints posed by the paucity of observation data and intense human activities, these processes are not well known in the dried-up river oases of arid areas. Here, we examined spatiotemporal variations and evolution of groundwater hydrochemistry using data from 199 water samples collected in the Wei-Ku Oasis, a typical arid inland oasis in Tarim Basin of Central Asia. As findings, groundwater hydrochemistry showed a spatiotemporal dynamic, while its spatial distribution was complex. TDS and δ¹⁸O of river water in the upstream increased from west to east, whereas ion concentrations of shallow groundwater increased from northwest to southeast. Higher TDS was detected in spring for shallow groundwater and in summer for middle groundwater. Pronounced spatiotemporal heterogeneity demonstrated the impacts of geogenic, climatic, and anthropogenic conditions. For that, hydrochemical evolution of phreatic groundwater was primarily controlled by rock dominance and evaporation-crystallization process. Agricultural irrigation and drainage, land cover change, and groundwater extraction reshaped the spatiotemporal patterns of groundwater hydrochemistry. Groundwater overexploitation altered the leaking direction between the aquifers, causing the interaction between saltwater and freshwater and the deterioration of groundwater environment. These findings could provide an insight into groundwater salt migration under human activities, and hence be significant in groundwater quality management in arid inland oasis areas.     

松嫩平原高氟地下水的分布特征及防氟改水研究

选取具有典型意义的吉林省通榆县等地氟病高发区和松嫩平原作为研究区,对地下水及含水层进行系统取样,运用描述性统计分析及相关性分析等方法,综合研究松嫩平原地下水中氟的分布、来源及影响因素。结果表明:松嫩平原高氟地下水主要分布于第四系潜水中,平原四周及含水层组富氟的地质环境是其主要来源区,地貌条件、气候因素及水化学条件影响地下水中氟的富集与扩散,研究区第四系及前第四系承压水水量丰富,水质良好,氟含量低于规范要求,可作为地氟病区防氟改水的主要供水目的层。     

Stable oxygen-hydrogen isotopes reveal water use strategies of Tamarix taklamakanensis in the Taklimakan Desert,China

Tamarix taklamakanensis,a dominant species in the Taklimakan Desert of China,plays a crucial role in stabilizing sand dunes and maintaining regional ecosystem stability.This study aimed to determine the water use strategies of T.taklamakanensis in the Taklimakan Desert under a falling groundwater depth.Four typical T.taklamakanensis nabkha habitats(sandy desert of Tazhong site,saline desert-alluvial plain of Qiemo site,desert-oasis ecotone of Qira site and desert-oasis ecotone of Aral site)were selected with different climate,soil,groundwater and plant cover conditions.Stable isotope values of hydrogen and oxygen were measured for plant xylem water,soil water(soil depths within 0–500 cm),snowmelt water and groundwater in the different habitats.Four potential water sources for T.taklamakanensis,defined as shallow,middle and deep soil water,as well as groundwater,were investigated using a Bayesian isotope mixing model.It was found that groundwater in the Taklimakan Desert was not completely recharged by precipitation,but through the river runoff from snowmelt water in the nearby mountain ranges.The surface soil water content was quickly depleted by strong evaporation,groundwater depth was relatively shallow and the height of T.taklamakanensis nabkha was relatively low,thus T.taklamakanensis primarily utilized the middle(23%±1%)and deep(31%±5%)soil water and groundwater(36%±2%)within the sandy desert habitat.T.taklamakanensis mainly used the deep soil water(55%±4%)and a small amount of groundwater(25%±2%)within the saline desert-alluvial plain habitat,where the soil water content was relatively high and the groundwater depth was shallow.In contrast,within the desert-oasis ecotone in the Qira and Aral sites,T.taklamakanensis primarily utilized the deep soil water(35%±1%and 38%±2%,respectively)and may also use groundwater because the height of T.taklamakanensis nabkha was relatively high in these habitats and the soil water content was relatively low,which is associated with the reduced groundwater depth due to excessive water resource exploitation and utilization by surrounding cities.Consequently,T.taklamakanensis showed distinct water use strategies among the different habitats and primarily depended on the relatively stable water sources(deep soil water and groundwater),reflecting its adaptations to the different habitats in the arid desert environment.These findings improve our understanding on determining the water sources and water use strategies of T.taklamakanensis in the Taklimakan Desert.     

Groundwater hydrochemistry and isotope geochemistry in the Turpan Basin,northwestern China

The Turpan Basin is located in the arid zone of northwestern China and is a typical closed inland basin surrounded by high mountains. It is one of the most arid regions in the world and, as a result, the groundwater in this area is very important for both domestic and agricultural uses. In the present study, the relationships of major elements（K＋, Na＋, Ca2＋, Mg2＋, HCO3-, SO42- and Cl-） and environmental isotopes（δ18O, δ2H and T） in groundwater were analyzed to investigate the evolution of the regional hydrochemistry within the Turpan Basin. The hydrochemistry results demonstrate that groundwater with high total dissolved solids（TDS） concentration is dominated by sodium chloride（Na-Cl） and sodium sulfate（Na-SO4） type water, whereas that with low TDS concentration（typically from near mountain areas） is dominated by calcium bicarbonate（Ca-HCO3） type water. The evolution of groundwater hydrochemistry within the Turpan Basin is a result of calcium carbonate precipitation, evaporation concentration, cation exchange and dissolution of evaporites（i.e. halite, mirabilite and gypsum）. Furthermore, evaporite dissolution associated with irrigation practice plays a key role in the groundwater salinization, especially in the central part of the basin. Environmental isotopes reveal that the groundwater is recharged by precipitation in the mountain areas and fast vertical infiltration of irrigation return flow. In the southern sub-basin the shallow groundwater and the deep groundwater is separated at a depth of about 40 m, with substantial differences in terms of hydrochemical and isotopic characteristics. The results are useful for decision making related to sustainable water resource utilization in the Turpan Basin and other regions in northwestern China.     

民勤绿洲地下水环境动态研究

根据民勤绿洲1999～2008年51眼地下水位观测井资料和2010年采集的30个地下水水样资料,利用传统统计学和地统计学分析方法对该地区新时期地下水位时空变化动态和地下水化学特性进行了研究。结果表明:民勤绿洲地下水位近10年来总体呈逐年下降的趋势,年均降幅达0.52m;在引黄民调工程、石羊河流域分水方案等政策措施的影响下,2005、2007和2008年地下水位降幅均呈现减小趋势,并在2007年首次出现0.01m的回升;坝区和泉山区地下水位年均降幅较湖区分别高0.23m和0.52m,下降速度明显快于湖区;整个绿洲区地下水平均矿化度为3.34g/L,沿地下水流动方向,地下水化学类型变化较大,由坝区和泉山区南部的SO42--HCO-3-Na+或SO42--HCO-3-Ca2+型淡水-微咸水逐渐变为湖区的SO2-4-C1--Na+-Mg2+咸水-苦咸水。     

闪电河流域“三水”季节变化特征

分析水体中氢(H)、氧(O)稳定同位素(δD、δ~(18)O)的变化,可以判断出不同水体的变化特征及相互关系。通过2014年5、8、10月对内蒙古正蓝旗境内闪电河流域地表水、浅层地下水及大气降水等样品的连续采集,得到地表水样21个、地下水样69个、大气降水样21个,在对"三水"样品δD、δ~(18)O值测试分析的基础,进一步讨论了"三水"变化特征及相互关系,结果显示:1闪电河流域"大气降水线"表达式为:δD=8.01δ~(18)O+6.83‰(r=0.962 1),反映了研究区蒸发量远大于降水量的气候特征。而不同月份d(氘盈余参数)出现差异,降水最多的8月d值最低,降水最少的10月d值最高,显示了大气降水次数或强度对二次蒸发作用产生了一定程度的影响。2闪电河流域地下水与地表水中δD、δ~(18)O值,不仅位于"大气降水线"之下,而且不同月份地表水与地下水中δD、δ~(18)O值的变化区间也出现差异。5月,各断面地下水与地表水中δD、δ~(18)O值差异不大,说明地下水与地表水得到充分混合;8月和10月,地表水中δD、δ~(18)O值比地下水明显偏重且各断面中大气降水所占比例较高,显示了大气降水过程对地表水H、O同位素变化的影响。此外,闪电河流域自上游到下游地表水中δD、δ~(18)O值在8月相近,而在10月逐渐出现偏大,指示了10月强烈蒸发作用对地表水中δD、δ~(18)O值变化的影响。     

地下水位下降对区域气候影响的虚拟试验

利用数值模拟方法,研究我国西北地区地下水位大幅度下降对干旱、半干旱气候变化的影响,并对地下水位变化和大气降水相互作用的反馈机制进行探讨.结果表明,地下水位大幅降落可以引发显著的气候效应,不仅引起降水的大幅度减少和近地面的增温,而且通过对土壤水状况的改变,引起了边界层结构和陆-气通量交换的变化.这些变化引起了局地对流层中低层大气环流的调整,进一步影响干旱气候.通过虚拟试验,反映了地下水变化对土壤水和大气降水等水分循环过程和干旱气候的巨大影响.     

Impacts of climate change and human activities on water resources in the Ebinur Lake Basin,Northwest China

Changing climatic conditions and extensive human activities have influenced the global water cycle. In recent years, significant changes in climate and land use have degraded the watershed ecosystem of the Ebinur Lake Basin in Xinjiang, Northwest China. In this paper, variations of runoff, temperature, precipitation, reference evapotranspiration, lake area, socio-economic water usage, groundwater level and water quality in the Ebinur Lake Basin from 1961 to 2015 were systematically analyzed by the Mann-Kendall test methods(M-K) mutation test, the cumulative levelling method, the climate-sensitive method and land-use change index. In addition, we evaluated the effects of human activities on land use change and water quality. The results reveal that there was a significant increase in temperature and precipitation from 1961 to 2015, despite a decrease in reference evapotranspiration. The Wenquan station was not significantly affected by human activities as it is situated at a higher altitude. Runoff at this station increased significantly with climate warming. In contrast, runoff at the Jinghe station was severely affected by numerous human activities. Runoff decreased without obvious fluctuations. The contributions of climate change to runoff variation at the Jinghe and Wenquan stations were 46.87% and 58.94%, respectively; and the contributions of human activities were 53.13% and 41.06%, respectively. Land-use patterns in the basin have changed significantly between 1990 and 2015: urban and rural constructed lands, saline-alkali land, bare land, cultivated land, and forest land have expanded, while areas under grassland, lake, ice/snow and river/channel have declined. Human activities have dramatically intensified land degradation and desertification. From 1961 to 2015, both the inflow into the Ebinur Lake and the area of the lake have declined year by year; groundwater levels have dropped significantly, and the water quality has deteriorated during the study period. In the oasis irrigation area below the runoff pass, human activities mainly influenced the utilization mode and quantity of water resources. Changes in the hydrology and quantity of water resources were driven primarily by the continuous expansion of cultivated land and oasis, as well as the growth of population and the construction of hydraulic engineering projects. After 2015, the effects of some ecological protection projects were observed. However, there was no obvious sign of ecological improvement in the basin, and some environmental problems continue to persist. On this basis, this study recommends that the expansion of oasis should be limited according to the carrying capacity of the local water bodies. Moreover, in order to ensure the ecological security of the basin, it is necessary to determine the optimal oasis area for sustainable development and improve the efficiency of water resources exploitation and utilization.     

Quantification of groundwater recharge and evapotranspiration along a semi-arid wetland transect using diurnal water table fluctuations

Groundwater is a vital water resource in arid and semi-arid areas. Diurnal groundwater table fluctuations are widely used to quantify rainfall recharge and groundwater evapotranspiration(ET_g). To assess groundwater resources for sustainable use, we estimated groundwater recharge and ET_g using the diurnal water table fluctuations at three sites along a section with different depths to water table(DWT) within a wetland of the Mukai Lake in the Ordos Plateau, Northwest China. The water table level was monitored at an hourly resolution using a Keller DCX-22 A data logger that measured both the total pressure and barometric pressure, so that the effect of barometric pressure could be removed. At this study site, a rapid water table response to rainfall was observed in two shallow wells(i.e., Obs1 and Obs2), at which diurnal water table fluctuations were also observed over the study period during rainless days, indicating that the main factors influencing water table variation are rainfall and ET_g. However, at the deep-water table site(Obs3), the groundwater level only reacted to the heaviest rainfalls and showed no diurnal variations. Groundwater recharge and ET_g were quantified for the entire hydrological year(June 2017–June 2018) using the water table fluctuation method and the Loheide method, respectively, with depth-dependent specific yields. The results show that the total annual groundwater recharge was approximately 207 mm, accounting for 52% of rainfall at Obs1, while groundwater recharge was approximately 250 and 21 mm at Obs2 and Obs3, accounting for 63% and 5% of rainfall, respectively. In addition, the rates of groundwater recharge were mainly determined by rainfall intensity and DWT. The daily mean ET_g at Obs1 and Obs2 over the study period was 4.3 and 2.5 mm, respectively, and the main determining factors were DWT and net radiation.     

Spatio-temporal dynamics of vegetation in Jungar Banner of China during 2000-2017

It is known that the exploitation of opencast coal mines has seriously damaged the environments in the semi-arid areas. Vegetation status can reliably reflect the ecological degeneration and restoration in the opencast mining areas in the semi-arid areas. Long-time series MODIS NDVI data are widely used to simulate the vegetation cover to reflect the disturbance and restoration of local ecosystems. In this study, both qualitative (linear regression method and coefficient of variation (CoV)) and quantitative (spatial buffer analysis, and change amplitude and the rate of change in the average NDVI) analyses were conducted to analyze the spatio-temporal dynamics of vegetation during 2000-2017 in Jungar Banner of Inner Mongolia Autonomous Region, China, at the large (Jungar Banner and three mine groups) and small (three types of functional areas: opencast coal mining excavation areas, reclamation areas and natural areas) scales. The results show that the rates of change in the average NDVI in the reclamation areas (20%-60%) and opencast coal mining excavation areas (10%-20%) were considerably higher than that in the natural areas (<7%). The vegetation in the reclamation areas experienced a trend of increase (3-5 a after reclamation)-decrease (the sixth year of reclamation)-stability. The vegetation in Jungar Banner has a spatial heterogeneity under the influences of mining and reclamation activities. The ratio of vegetation improvement area to vegetation degradation area in the west, southwest and east mine groups during 2000-2017 was 8:1, 20:1 and 33:1, respectively. The regions with the high CoV of NDVI above 0.45 were mainly distributed around the opencast coal mining excavation areas, and the regions with the CoV of NDVI above 0.25 were mostly located in areas with low (28.8%) and medium-low (10.2%) vegetation cover. The average disturbance distances of mining activities on vegetation in the three mine groups (west, southwest and east) were 800, 800 and 1000 m, respectively. The greater the scale of mining, the farther the disturbance distances of mining activities on vegetation. We conclude that vegetation reclamation will certainly compensate for the negative impacts of opencast coal mining activities on vegetation. Sufficient attention should be paid to the proportional allocation of plant species (herbs and shrubs) in the reclamation areas, and the restored vegetation in these areas needs to be protected for more than 6 a. Then, as the repair time increased, the vegetation condition of the reclamation areas would exceed that of the natural areas.     

Identifying water vapor sources of precipitation in forest and grassland in the north slope of the Tianshan Mountains,Central Asia

Identifying water vapor sources in the natural vegetation of the Tianshan Mountains is of significant importance for obtaining greater knowledge about the water cycle,forecasting water resource changes,and dealing with the adverse effects of climate change.In this study,we identified water vapor sources of precipitation and evaluated their effects on precipitation stable isotopes in the north slope of the Tianshan Mountains,China.By utilizing the temporal and spatial distributions of precipitation stable isotopes in the forest and grassland regions,Hybrid Single-Particle Lagrangian Integrated Trajectory(HYSPLIT)model,and isotope mass balance model,we obtained the following results.(1)The Eurasia,Black Sea,and Caspian Sea are the major sources of water vapor.(2)The contribution of surface evaporation to precipitation in forests is lower than that in the grasslands(except in spring),while the contribution of plant transpiration to precipitation in forests(5.35%)is higher than that in grasslands(3.79%)in summer.(3)The underlying surface and temperature are the main factors that affect the contribution of recycled water vapor to precipitation;meanwhile,the effects of water vapor sources of precipitation on precipitation stable isotopes are counteracted by other environmental factors.Overall,this work will prove beneficial in quantifying the effect of climate change on local water cycles.     

石羊河流域中下游浅层地下水水化学特征及其成因

为系统研究石羊河流域中下游浅层地下水水化学特征及主要离子来源,于2018年6-8月采集地下水水化学样品62组。综合运用数理统计、Gibbs图、离子比例关系和水文地球化学模拟等方法,分析了石羊河流域中下游浅层地下水的水文地球化学特征,探讨了水化学演化过程及主要离子来源。结果表明:研究区浅层地下水在水平方向上呈现明显的水化学分带,从中游至下游地下水水化学类型由SO4·HCO3-Na·Ca型过渡为SO4·Cl-Na·Mg型,TDS含量也随之升高,流域中游为TDS含量小于1g/L的淡水,至下游演化为TDS含量高于1g/L的微咸水和咸水。该区浅层地下水水化学组分主要受水岩作用和蒸发浓缩作用控制,Ca²⁺、Mg²⁺主要来源于硅酸盐岩和碳酸盐岩的溶解,碳酸盐岩以白云石风化溶解为主,部分水样点存在方解石的风化溶解,阳离子交换作用是影响研究区地下水化学组分的重要过程。模拟结果表明沿地下水流向,地下水离子组分浓度呈递增趋势,岩盐、白云石和石膏发生溶解,方解石沉淀;从中游到下游地下水中阳离子交换作用越来越强烈,且阳离子交换作用强于溶解沉淀作用。     

Dynamics of groundwater recharge near a semi-arid Mediterranean intermittent stream under wet and normal climate conditions

In arid and semi-arid stream-dominated systems, the temporal variability in groundwater recharge has not been widely addressed. Various questions remain about the sources of groundwater recharge, its patterns, and the appropriate measuring techniques. Hence, the main objective of the present study was to assess the changes that might affect the pattern of groundwater recharge under wetter than normal surface water availability. Therefore, the groundwater depth was monitored near a semi-arid Mediterranean intermittent stream on the piedmont of the High Atlas Mountains in the mountain catchment of the Wadi Rheraya over two hydrological years (2014-2016) with different climate conditions: extreme wet and normal conditions. Groundwater recharge was assessed using the episodic master recession algorithm. During the two years, the pattern of groundwater recharge was dominated by episodic events and by a high seasonality from wet seasons to dry seasons. In the wet year (2014-2015), the highest groundwater recharge was recorded following an extreme flood, which deeply replenished groundwater. Furthermore, an exceptional steady state of the groundwater depth was induced by a steady groundwater recharge rate. For several groundwater recharge events, the assessed recharge had multiple sources, mainly from streamflow at the local scale, but possibly from precipitation, underflow, deep percolation or irrigation return from the upstream part of the catchment. Local recharge by streamflow was likely to be short-lived, and lateral recharge was likely to last longer. Consequently, the episodic master recession algorithm estimated the total groundwater recharge that could encompass various sources. In the future, more studies and multidisciplinary approaches should be carried out to partition these sources and determine their specific contributions. In semi-arid stream-dominated systems, different groundwater recharge patterns induced by extreme hydrological events (e.g., wet events) and various potential sources of groundwater recharge should be considered when assessing and predicting groundwater recharge.     

西北地区煤炭开发利用对水环境影响预测分析

西北地区煤炭资源丰富,将成为我国未来能源供应的主要基地。由于自然条件原因,水资源极其贫乏,生态环境十分脆弱。然而,煤炭资源的开发利用必将影响地表生态和环境,也将扰动地下水资源。采用情景分析法,对西北地区未来二十年煤炭开发利用造成的水环境影响进行了预测,为西北煤炭工业发展和生态环境保护提供决策依据。