共查询到20条相似文献，搜索用时 31 毫秒
1.
S. O. Grinevskii 《Moscow University Geology Bulletin》2011,66(3):189-201
This paper considers models of the transpiration root water uptake and principles for substantiating their parameters when
calculating unsaturated flow in the vadose zone and estimating infiltration groundwater recharge. The possible use of generalized
parameters for different landscape and soil conditions is substantiated based on analyzing the natural patterns of water balance
formation in the vadose zone and the sensitivity of transpiration models. Recommendations are given for selecting the models
of transpiration water uptake and substantiating their parameters, which enables one to minimize the errors in estimating
infiltration groundwater recharge. 相似文献
2.
《Geomechanics and Geoengineering》2013,8(2):129-138
Issues related to the numerical simulation of moisture migration patterns in the unsaturated zone and in the vicinity of mature trees are explored in this paper. The research is based on the use of Richard's equation for unsaturated moisture flow incorporating a sink term. A numerical solution has been achieved via the finite-element method for spatial discretization along with a finite-difference time-marching scheme. An axisymmetric solution is developed to represent water uptake near an established tree. The approach adopted utilizes radial symmetry and assumes a linear distribution of water extraction rates with both depth and radius. The model has been validated by direct comparison with field measurements recorded (by others) for a mature lime tree located on a boulder clay subsoil. Non-linear hydraulic properties have been obtained from independent published data. A good correlation between field data and simulated results has been achieved. The simulation covers a full annual cycle starting from field capacity in winter, extending through a full spring–summer drying period and subsequent autumn recharge. It is believed that this is the first attempt to simulate the behaviour of an established tree over such a time-scale. This relatively straightforward approach is thought to be suitable for development and application to a range of geo-engineering problems (e.g. slope stability, shrinkage/heave prediction, etc). 相似文献
3.
包气带在干旱半干旱地区地下水补给研究中的应用 总被引：3，自引：0，他引：3
在干旱半干旱地区,包气带的溶质和同位素剖面不但可以提供较长时间尺度上的地下水补给信息,而且记录了过去气候变化与环境变化信息。本文基于学科组近10年的研究成果,以鄂尔多斯盆地为例（包括南部的黄土高原和北部的沙漠高原）,将包气带和饱和带结合起来,利用多种环境示踪技术,提升了包气带在干旱半干旱地区地下水研究中的潜力,并将其应用到地下水补给历史重建、地下水补给机制确定、植被变化对地下水补给影响评价和地下水污染物全过程示踪中。研究表明,由于在干旱半干旱地区,包气带较厚且补给量有限,地下水和现今的浅表水文过程未达到水力平衡,如在沙漠高原西部,近2 500 a降水尚储存在包气带13 m以浅,地下水是4 000 a以前补给的,其水化学特征与浅部包气带水差异巨大;而在黄土高原,补给量较大,但包气带巨厚,年降水仍需要几十到上百年时间入渗到地下水（但并不意味着没有补给,其土壤水在包气带中平均入渗速率为0.1~0.3 m·a-1）,包气带浅部溶质含量较深部和地下水中的高;典型黄土塬区的地下水均不含氚,地下水年龄在几百到上万年。黄土内部层状均匀的土壤质地特征和相对较老的地下水年龄揭示的均匀活塞流入渗是黄土塬区浅层地下水补给的主要方式。黄土高原退耕还林还草和沙漠区植被恢复导致地下水补给呈现不同程度的减少,反映在包气带上表现为溶质含量的增加,可用于定量化确定地下水补给量的变化。本文强化了包气带在干旱半干旱地区地下水补给研究中的作用,在未来地下水资源评价、地下水污染全过程刻画中应得到重视。 相似文献
4.
准确计算地下水的垂向入渗补给量是合理评价和利用地下水资源的基础.EARTH模型是一种集中参数的水文模型,可刻画水流在包气带中的运移过程,弥补黑箱模型的不足.以中国科学院栾城农业生态试验站的地下水位观测资料以及气象资料为基础,综合运用降水、蒸发、土壤水、地下水动态观测资料,利用EARTH模型计算了河北平原地下水垂向入渗补给量.计算结果表明,2003年1月1日至2005年8月31日期间,栾城农业生态试验站在降水量1404.1 mm、灌溉量1050.0 mm的条件下地下水入渗补给量为487.2 mm,平均年入渗补给量为182.6 mm, 占降水和灌溉总量(2454.1 mm)的19.9%.在模拟结果的基础上,对不同年份的降水量(含灌溉)和入渗补给量分布的对比分析表明,河北栾城地下水补给滞后现象明显,在研究时间段内峰值滞后18～35 d. 相似文献
5.
Tianming Huang Zhonghe Pang Jilai Liu Jinzhu Ma John Gates 《Hydrogeology Journal》2017,25(7):2049-2065
Assessing groundwater recharge characteristics (recharge rate, history, mechanisms (piston and preferential flow)) and groundwater age in arid and semi-arid environments remains a difficult but important research frontier. Such assessments are particularly important when the unsaturated zone (UZ) is thick and the recharge rate is limited. This study combined evaluations of the thick UZ with those of the saturated zone and used multiple tracers, such as Cl, NO3, Br, 2H, 18O, 13C, 3H and 14C, to study groundwater recharge characteristics in an integrated loess tableland in the Loess Plateau, China, where precipitation infiltration is the only recharge source for shallow groundwater. The results indicate that diffuse recharge beneath crops, as the main land use of the study area, is 55–71 mm yr?1 based on the chloride mass balance of soil profiles. The length of time required for annual precipitation to reach the water table is 160–400 yrs. The groundwater is all pre-modern water and paleowater, with corrected 14C age ranging from 136 to 23,412 yrs. Most of the water that eventually becomes recharge originally infiltrated in July–September. The Cl and NO3 contents in the upper UZ are considerably higher than those in the deep UZ and shallow groundwater because of recent human activities. The shallow groundwater has not been in hydraulic equilibrium with present near-surface boundary conditions. The homogeneous material of the UZ and relatively old groundwater age imply that piston flow is the dominant recharge mechanism for the shallow groundwater in the tableland. 相似文献
6.
The rapid expansion of agriculture, industries and urbanization has triggered unplanned groundwater development leading to severe stress on groundwater resources in crystalline rocks of India. With depleting resources from shallow aquifers, end users have developed resources from deeper aquifers, which have proved to be counterproductive economically and ecologically. An integrated hydrogeological study has been undertaken in the semi-arid Madharam watershed (95 km2) in Telangana State, which is underlain by granites. The results reveal two aquifer systems: a weathered zone (maximum 30 m depth) and a fractured zone (30–85 m depth). The weathered zone is unsaturated to its maximum extent, forcing users to tap groundwater from deeper aquifers. Higher orders of transmissivity, specific yield and infiltration rates are observed in the recharge zone, while moderate orders are observed in an intermediate zone, and lower orders in the discharge zone. This is due to the large weathering-zone thickness and a higher sand content in the recharge zone than in the discharge zone, where the weathered residuum contains more clay. The NO3 ? concentration is high in shallow irrigation wells, and F? is high in deeper wells. Positive correlation is observed between F? and depth in the recharge zone and its proximity. Nearly 50 % of groundwater samples are unfit for human consumption and the majority of irrigation-well samples are classed as medium to high risk for plant growth. Both supply-side and demand-side measures are recommended for sustainable development and management of this groundwater resource. The findings can be up-scaled to other similar environments. 相似文献
7.
The processes and rates of groundwater recharge in arid and semiarid environments are highly related to local climate parameters, particularly precipitation. The chloride profile of an unsaturated zone in an arid and semiarid region can be used to infer the recharge history and past changes in climate, by extension. In this study, a 17-m chloride profile was collected from the sandy loess in the northwestern Chinese Loess Plateau, which also lies in the transition zone between desert and loess. A 71-year groundwater recharge history was reconstructed using the chloride mass balance method with an annual Cl? input of 0.84 g/m2/year. The reconstructed history revealed a long-term decline in recharge with multiple shorter-term oscillations. Five recharge stages between 1938–1946, 1947–1955, 1956–1975, 1976–2000, and 2001–2008 AD were identified, where the lowest average recharge value was 25.1 mm/a in 1976–2000 AD and the highest was 71.7 mm/a in 1947–1955 AD. Climate conditions during these five periods were also inferred based on the reconstructed recharge rates with the knowledge that high recharge corresponds to more humid climates. The climate over the past 71 years generally became drier in the study area, despite some fluctuations. The reconstructed recharge rates, calculated from 1/Cl? in the profile, exhibited the same variability as annual precipitation measured in the region, both in long- and short-term oscillations over the period from 1955 to 2008. The chloride concentration variations in the profile, indicating changes in recharge flux, also well correlated with annual precipitation anomalies in the region to the east of 100°E in China for the whole study period. These comparisons verified that it is feasible to study not only groundwater recharge, but also past climate change using a chloride profile from the sandy loess area. The results suggested that unsaturated zones of sandy loess may be valuable archives for reconstructing recharge history and regional paleoclimate changes in the region. 相似文献
8.
地下水可更新能力是评价地下水开发可持续性的关键指标,可更新能力可以用地下水年龄来定量表达。在人类活动影响下,地下水的实际更新状况已与自然条件下截然不同。基于台兰河流域地下水库建设和人工回灌工作现状,通过物理试验和数值模拟相结合的方法分别研究了入渗池位置,回灌强度和包气带厚度对地下水年龄分布规律的影响。结果表明:人工回灌使地下水年龄整体变年轻;入渗池位置和回灌强度的改变对地下水年龄分布的影响显著;包气带厚度的增大使回灌水滞留时间延长,导致地下水年龄增大,该研究可为合理评价区域地下水可更新能力提供技术指导。 相似文献
9.
Using groundwater levels to estimate recharge 总被引：24，自引：4，他引：24
Accurate estimation of groundwater recharge is extremely important for proper management of groundwater systems. Many different
approaches exist for estimating recharge. This paper presents a review of methods that are based on groundwater-level data.
The water-table fluctuation method may be the most widely used technique for estimating recharge; it requires knowledge of
specific yield and changes in water levels over time. Advantages of this approach include its simplicity and an insensitivity
to the mechanism by which water moves through the unsaturated zone. Uncertainty in estimates generated by this method relate
to the limited accuracy with which specific yield can be determined and to the extent to which assumptions inherent in the
method are valid. Other methods that use water levels (mostly based on the Darcy equation) are also described. The theory
underlying the methods is explained. Examples from the literature are used to illustrate applications of the different methods.
Electronic Publication 相似文献
10.
地下水环境脆弱程度图编图方法研究 总被引：7，自引：0，他引：7
由于地下水的过量开采,导致地下水资源乃至地下水环境遭到不同程度的厂址,引起许多与其相关的生态环境问题。为此,本文引用地下水环境脆弱性概念,并以松嫩平原为例,采用先进的理论和方法,以包气带厚度、包气带渗透系数、地下水补给强度及地下水水力坡度等为定量化指标牙分不同脆弱程度地区,编制了为统一协调资源与环境,优化开采提供依据的一种新的地下水环境脆弱程度图。 相似文献
11.
Analysis of soil, soil water and groundwater in the Mount William Creek catchment, southeastern Australia, shows that Mg2+ and Ca2+ within infiltrating rainfall are rapidly depleted by plant uptake and adsorption on clay minerals. Na+ and K+ may exhibit minor enrichment at shallow depths but are quickly readsorbed, so that cation/Cl– ratios typical of groundwater are observed in soil water within the upper 200 cm of the soil profile for all species. The concentrations of K+ and Ca2+ in soil and groundwater are more depleted than Na+ and Mg2+ due to preferential uptake by vegetation. Removal of organic matter results in a continuing, long-term export of all major cations from the soil profiles. The processes of biogeochemical fractionation within the unsaturated zone rapidly modify the cation/Cl– ratios of infiltrating rainfall to values characteristic of seawater. These mechanisms may have reached steady state, because groundwaters with seawater ion/Cl– ratios are thousands of years old; the exchange sites on the soil clays are probably saturated, so cations supplied in rainfall are exported in organic matter and incorporated into recharge infiltrating into the groundwater. Much of the chemical evolution of groundwater traditionally attributed to processes within the aquifer is complete by the time recharge occurs; this evolutionary model may have broad application. 相似文献
12.
Playas are ephemeral, closed-basin wetlands that are hypothesized as an important source of recharge to the High Plains aquifer in central USA. The ephemeral nature of playas, low regional recharge rates, and a strong reliance on groundwater from the High Plains aquifer has prompted many questions regarding the contribution and quality of recharge from playas to the High Plains aquifer. As a result, there has been considerable scientific debate about the potential for water to infiltrate the relatively impermeable playa floors, travel through the unsaturated zone sediments that are tens of meters thick, and subsequently recharge the High Plains aquifer. This critical review examines previously published studies on the processes that control recharge rates and chemistry beneath playas. Reported recharge rates beneath playas range from less than 1.0 to more than 500 mm/yr and are generally 1–2 orders of magnitude higher than recharge rates beneath interplaya settings. Most studies support the conceptual model that playas are important zones of recharge to the High Plains aquifer and are not strictly evaporative pans. The major findings of this review provide science-based implications for management of playas and groundwater resources of the High Plains aquifer and directions for future research. 相似文献
13.
Artificial recharge of groundwater: hydrogeology and engineering 总被引：25，自引：4，他引：25
Herman Bouwer 《Hydrogeology Journal》2002,10(1):121-142
Artificial recharge of groundwater is achieved by putting surface water in basins, furrows, ditches, or other facilities
where it infiltrates into the soil and moves downward to recharge aquifers. Artificial recharge is increasingly used for short-
or long-term underground storage, where it has several advantages over surface storage, and in water reuse. Artificial recharge
requires permeable surface soils. Where these are not available, trenches or shafts in the unsaturated zone can be used, or
water can be directly injected into aquifers through wells. To design a system for artificial recharge of groundwater, infiltration
rates of the soil must be determined and the unsaturated zone between land surface and the aquifer must be checked for adequate
permeability and absence of polluted areas. The aquifer should be sufficiently transmissive to avoid excessive buildup of
groundwater mounds. Knowledge of these conditions requires field investigations and, if no fatal flaws are detected, test
basins to predict system performance. Water-quality issues must be evaluated, especially with respect to formation of clogging
layers on basin bottoms or other infiltration surfaces, and to geochemical reactions in the aquifer. Clogging layers are managed
by desilting or other pretreatment of the water, and by remedial techniques in the infiltration system, such as drying, scraping,
disking, ripping, or other tillage. Recharge wells should be pumped periodically to backwash clogging layers. Electronic supplementary
material to this paper can be obtained by using the Springer LINK server located at http://dx.doi.org/10.1007/s10040-001-0182-4.
Electronic Publication 相似文献
14.
Analysis of subsurface temperature data to quantify groundwater recharge rates in a closed Altiplano basin,northern Chile 总被引：1，自引：0，他引：1
Quantifying groundwater recharge is a fundamental part of groundwater resource assessment and management, and is requisite to determining the safe yield of an aquifer. Natural groundwater recharge in arid and semi-arid regions comprises several mechanisms: in-place, mountain-front, and mountain-block recharge. A field study was undertaken in a high-plain basin in the Altiplano region of northern Chile to quantify the magnitude of in-place and mountain-front recharge. Water fluxes corresponding to both recharge mechanisms were calculated using heat as a natural tracer. To quantify in-place recharge, time-series temperature data in cased boreholes were collected, and the annual fluctuation at multiple depths analyzed to infer the water flux through the unsaturated zone. To quantify mountain-front recharge, time-series temperature data were collected in perennial and ephemeral stream channels. Streambed thermographs were analyzed to determine the onset and duration of flow in ephemeral channels, and the vertical water fluxes into both perennial and ephemeral channels. The point flux estimates in streambeds and the unsaturated zone were upscaled to channel and basin-floor areas to provide comparative estimates of the range of volumetric recharge rates corresponding to each recharge mechanism. The results of this study show that mountain-front recharge is substantially more important than in-place recharge in this basin. The results further demonstrate the worth of time-series subsurface temperature data to characterize both in-place and mountain-front recharge processes. 相似文献
15.
H. Pfletschinger I. Engelhardt M. Piepenbrink F. Königer R. Schuhmann A. Kallioras C. Schüth 《Environmental Earth Sciences》2012,65(5):1523-1533
For the determination of groundwater recharge processes in arid environments, vadose zone water fluxes and water storage should
be considered. To better understand and quantify vadose zone processes influencing groundwater recharge, a soil column experimental
setup has been developed that mimics arid atmospheric conditions and measures water and temperature fluxes in high temporal
and spatial resolution. The focus of the experiment was on the determination of water infiltration, redistribution, evaporation
and percolation under non-isothermal conditions. TDR rod sensors and a specific TDR “Taupe” cable sensor were used for water
content measurements and allowed the infiltration fronts to be traced over the whole column length. Applying single irrigations
of different amount and intensity showed the applicability of the experimental setup for the measurement of water movement
in the unsaturated soil column. 相似文献
16.
零通量面法在沈阳地区地下水资源评价中的应用 总被引：1，自引：1，他引：1
降水对地下水的入渗补给和大气蒸发作用下地下水的消耗是地下水资源的重要组成部分。降水入渗和地下水蒸发这两种作用均是通过包气带进行的。从包气带着手，运用零通量法确定这些量已在实际中得到应用。以沈阳地区为例，针对该区集中频繁降水与蒸发排泄交替进行导致零通量紊乱易变的特点，在对有关问题深入探讨的基础上，对浅层潜水入渗补给量（包括蒸发量）和非饱和渗透系数进行了计算，取得了较好的效果。 相似文献
17.
Unsaturated zone pore water has the potential to record history of recharge, palaeoenvironment, pollution movement and water-rock interaction as it percolates through and moves towards the water table. In this study, two 6-m cores from the Badain Jaran desert (NW China) were collected to explore this potential using directly extracted moisture. Pore waters in these unsaturated zone sediments (1–5% moisture by wet weight) were directly extracted using immiscible liquid displacement and then analysed for major anions, cations and trace elements. Results show enrichment in pore water chemistry in the top 1–2 m where strong temperature and moisture fluxes occur. The enrichment in cations relative to chloride is primarily due to silicate mineral dissolution during infiltration. High nitrate and low iron concentrations indicate the overall oxidizing environment, which allows the mobility of oxyanions, such as uranium, arsenic and chromium. The trace elements show enrichment in the upper zone of fluctuation where chemical gradients are strong, but with lesser reaction lower in the profile. The calculated groundwater recharge rates using the chloride mass balance are negligible in this arid region between 1.5 and 3.0 mm/year. The modern rainfall infiltration signature contrasts with that of the underlying groundwater body, which has a distant, regional recharge signature.This reconnaissance study demonstrates the potential for a new geochemical approach to studying geochemical processes in the unsaturated sediments in semi-arid environments due to both natural and human influences. The use of directly extracted water, rather than extraction by dilution (elutriation), facilitates an improved understanding of hydrological and geochemical processes in the unsaturated zone and into the capillary fringe at the water table, because it avoids potential chemical changes induced during elutriation. 相似文献
18.
大气降雨是华北平原浅层地下水的主要补给来源。长期过量开采地下水造成地下水位持续下降,使原来处于饱水带的透镜体位移到包气带中,形成了厚度大、非均质性更为复杂的包气带。厚层包气带中弱渗透性黏土透镜体对于降雨入渗补给的影响是关系到降水入渗过程及补给量评价的基本问题。用HYDRUS软件建立数值模拟模型,模拟探讨单次降雨条件下,透镜体埋深、宽度比、厚度等要素对入渗路径、入渗补给时间和入渗补给量的影响。结果表明:入渗过程中弱渗透性黏土透镜体两侧会形成较快的绕流;透镜体会减小补给峰值并延长总体补给时间,但不改变补给起始时间;透镜体埋深与极限蒸发深度的相对关系决定了潜在补给量的大小,透镜体埋深或因透镜体形成的上层滞水处于极限蒸发深度以上会减少潜在补给量。 相似文献
19.
种植条件下降雨灌溉入渗试验研究 总被引：2，自引：0，他引：2
基于清水河平原头营和黑城试验场降雨(灌溉)入渗过程土壤水分运移观测试验数据的分析研究,笔者应用能量观点描述了包气带水分运移的分带性、降雨(灌溉)入渗补给地下水的水分条件和地下水入渗补给过程的基本特征。应用蒸散量模型、土壤水分通量模型,计算了作物生长期的蒸发蒸腾量、土壤贮水量的变化量、400cm深度处的土壤水分渗漏量及渗漏系数。从多年的角度分析了深层土壤水分渗漏量、渗漏系数与地下水入渗补给量和补给系数的关系。它对分析降雨(灌溉)入渗对地下水的补给过程和定量分析地下水入渗补给量、入渗补给系数具有重要价值。 相似文献
20.
利用地下水数值模型MODFLOW和非饱和带水平衡模型对处于半干旱半湿润沙丘地区(Sand Hills)地下水位进行了模拟,并分析了含水层补排水量,河流与地下水补排关系,以及区域水平衡过程。揭示了独特沙丘地形和土壤特性对地下水补排量的影响。模拟结果表明,入渗率大、非饱和带厚的沙丘有利于降水入渗补给,减少了地下水蒸散发损失。加上下覆含水层具有良好的地下水储水空间,是该地区储存丰富的地下水量,以维持河流稳定流量,供给众多湖泊和湿地的原因。该研究对我国地下水资源评价和生态环境脆弱地区水资源保护具有指导意义。 相似文献