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1.
It is important to understand how groundwater recharge responds to precipitation variability in space and time, especially in those areas such as Yanqing Basin (China), where groundwater represents the sole water resource. A simple soil-water balance method is applied for spatio-temporal simulation of groundwater recharge in Yanqing Basin from 1981 to 2000. It was implemented on a monthly time step considering the effects of land use and soil texture. The area-average recharge associated with various land uses and soil textures was then compared with zonal analysis using a geographic information system (GIS). The main findings include: (1) the variation of groundwater recharge follows precipitation changes, either at yearly or seasonal intervals, (2) land use plays a more influential role in groundwater recharge than soil texture in this area, and (3) the water table quickly rises in response to recharge in the shallow parts of the aquifer, while there is a delay of 0.5–1.0?years where the groundwater level is at depth 4–10?m. The application demonstrates how spatio-temporal analysis can be utilized for groundwater-recharge estimation through distributed modeling and GIS.  相似文献   

2.
Gravity Recovery and Climate Experiment (GRACE) derived groundwater storage (GWS) data are compared with in-situ groundwater levels from five groundwater basins in Jordan, using newly gridded GRACE GRCTellus land data. It is shown that (1) the time series for GRACE-derived GWS data and in-situ groundwater-level measurements can be correlated, with R 2 from 0.55 to 0.74, (2) the correlation can be widely ascribed to the seasonal and trend component, since the detrended and deseasonalized time series show no significant correlation for most cases, implying that anomalous signals that deviate from the trend or seasonal behaviour are overlaid by noise, (3) estimates for water losses in Jordan based on the trend of GRACE data from 2003 to 2013 could be up to four times higher than previously assumed using estimated recharge and abstraction rates, and (4) a significant time-lagged cross correlation of the monthly changes in GRACE-derived groundwater storage and precipitation data was found, suggesting that the conventional method for deriving GWS from GRACE data probably does not account for the typical conditions in the study basins. Furthermore, a new method for deriving plausible specific yields from GRACE data and groundwater levels is demonstrated.  相似文献   

3.
Groundwater drought is a specific type of hydrological drought that concerns groundwater bodies. It may have a significant adverse effect on the socio-economic, agricultural, and environmental conditions. Investigating the effect of different climatic and anthropogenic factors on groundwater drought provides essential information for sustainable planning and management of (ground) water resources. The aim of this study is to identify the influencing factors on groundwater drought in north-western Bangladesh, to understand the forcing mechanisms. A multi-step methodology is proposed to achieve this objective. The standardised precipitation index (SPI) and reconnaissance drought index (RDI) have been used to quantify the aggregated deficit between precipitation and the evaporative demand of the atmosphere, i.e. meteorological drought. The influence of land-cover patterns on the groundwater drought has been identified by calculating spatially distributed groundwater recharge as a function of land cover. Groundwater drought is defined by a threshold method. The results show that the evapotranspiration and rainfall deficits are determining meteorological drought, which shows a direct relation with groundwater recharge deficits. Land-cover change has a small effect on groundwater recharge but does not seem to be the main cause of groundwater-level decline (depletion) in the study area. The groundwater depth and groundwater-level deficit (drought) is continuously increasing with little correlation to meteorological drought or recharge anomalies. Overexploitation of groundwater for irrigation seems to be the main cause of groundwater-level decline in the study area. Efficient irrigation management is essential to reduce the growing pressure on groundwater resources and ensure sustainable water management.  相似文献   

4.
In the cool temperate region of South Korea, oxygen and hydrogen isotopes of groundwater, lake water, and precipitation were studied to determine the season of groundwater recharge. All the groundwater samples, irrespective of season, on δ18O–δ2H scale plotted along the summer precipitation, suggesting summer precipitation largely modulates recharge. The deuterium excess values of groundwater (d-excess) show clear seasonal difference, higher in winter (> 18‰) and lower in summer (< 10‰). And its resemblance to the summer precipitation d-excess value further suggests dominant role of summer precipitation in groundwater recharge. Based on the mass balance equation, with end-member d-excess values of seasonal precipitation and groundwater as input variables, groundwater is composed of 66% summer and 34% winter precipitation. Despite the study area being heavily forested, summer rainfall contribution higher than winter suggests that evapotranspiration effect is minimal in the region; may be due to thin sand–gravel-based porous soil overlying highly weathered granitic rock system.  相似文献   

5.
A conceptual model of groundwater occurrence was developed for a dike-intruded aquifer system in M??kaha valley, O??ahu, Hawai??i, USA, and used to explain the impacts of water resource development on groundwater levels and streamflow. Time-series analyses were applied to two subsets of daily rainfall, total flow, and baseflow??from the third (1946?C1968) and fourth (1968?C1991) periods of development??to evaluate changes in streamflow response. Autocorrelation, cross-correlation, squared coherency and phase functions were used to estimate the decorrelation lag time, and the correlation length, linearity with frequency, and frequency response delay between rainfall and streamflow. The decorrelation lag time for total flow and baseflow declined by 16?C20?days (d). The correlation length between rainfall and streamflow declined 4?C7?d for total flow and 10?C13?d for baseflow. The squared coherency function indicates an overall decline in linearity between rainfall and total flow across most frequencies. The changes in hydrologic response following increased water-resource development is consistent with a model of groundwater depletion resulting in less groundwater discharge and more induced groundwater recharge. Changes in streamflow response are inconsistent with observed changes in rainfall and imply that streamflow decline is more likely to be the result of groundwater pumping.  相似文献   

6.
Groundwater plays a critical and important role in many landslides. Heavy precipitation can raise the groundwater level within a hillslope and lead to instability. The purpose of this paper is to present a model by means of continuity equation to predict groundwater level fluctuations in hillslope in response to hourly precipitation rates. The linear reservoir method is employed to describe the travel time distribution of infiltration, and Darcy??s law is then used to establish the groundwater flux rate of control volume. The governing equation shows that the changing rate of groundwater level fluctuation can be interpreted by two new defined variables (Sink Number and Rise Number) in this study. The application of the model is demonstrated using the rainfall-induced landslide at Lu-Shan, Nantou County, Taiwan. Data from one storm event are used to calibrate the model and estimate parameters by using the heuristic algorithm. Post-storm rainfall data from another storm event are employed to verify the calibrated parameters. The contribution of this study shows that a small Sink Number results in a fast recession and a large Rise Number yields a fast rise of groundwater level. This method may be practical to have better understanding on the rainfall-induced landslide.  相似文献   

7.
The sustainable use of groundwater has become increasingly challenging due to extreme hydrological events and anthropogenic activity. In this study, the basin-scale groundwater response to precipitation variation was analyzed using an integrated model that comprises lumped models for land and river recharges and a distributed model for groundwater. The integrated model was applied to the Chih-Ben watershed, Taiwan, using 20?years (1988?C2007) of data. The hydrological data were analyzed for trends using statistical tests. Based on decreasing trends in precipitation and groundwater levels and an increasing trend in stream flow, the oblique-cut method was applied to precipitation and excess infiltration to assess land and streambed recharge. Distributed numerical groundwater modeling was used to simulate the basin-scale groundwater responses to precipitation variation and anthropogenic pumping. The model was calibrated using stable-isotope and groundwater-level data. The safe yields were estimated for the Chih-Ben watershed for dry, wet, and normal precipitation scenarios. The safe yield of groundwater was shown to vary with precipitation, which does not guarantee the sustainable use of groundwater resources. Instead, water resources should be assessed at a basin scale, taking into account the whole ecosystem, rather than only considering water for human consumption in the alluvium.  相似文献   

8.

Waterlogging (WL) refers to the process by which water flow is resisted in vertical and horizontal directions and thus water stagnates for a short or long span of time; it is induced by a combination of human and natural factors. In the southwestern region of Bangladesh, including Natore District, WL is a significant issue that needs to be addressed if agricultural activity is to be successful. This study aimed to identify surface WL in Natore District and to characterise the WL scenario in the study area in terms of hydrogeology. Waterlogged areas were identified with a geographic information system using satellite images corresponding to the premonsoon and postmonsoon periods. Using groundwater level data (1990–2017), the pre- and postmonsoon scenarios of the waterlogged areas were indicated by seasonal and perennial types of WL. Groundwater recharge scenarios were classified as long and short lag times. Most of the study area was characterised by thick clay or silty clay surficial layers with low water penetration rates, resulting from low porosity and low hydraulic conductivity. The cross-correlation between rainfall and groundwater level revealed the response of groundwater to rainfall, with a lag time of 1–5 months. Long lag time areas exhibited slow groundwater recharge and significant groundwater level fluctuation, with lower hydraulic conductivity values of 49.37–76.24 m/day. In contrast, short lag time areas displayed rapid groundwater recharge and small groundwater fluctuation due to a good proportional relationship with rainfall and higher hydraulic conductivity values of 74.74–117.79 m/day.

  相似文献   

9.
The first comprehensive use of wavelet methods to identify non-stationary time-frequency relations between North Atlantic ocean-atmosphere teleconnection patterns and groundwater levels is described. Long-term hydrogeological time series from three boreholes within different aquifers across the UK are analysed to identify statistically significant wavelet coherence between the North Atlantic Oscillation, East Atlantic pattern, and the Scandinavia pattern and monthly groundwater-level time series. Wavelet coherence measures the cross-correlation of two time series as a function of frequency, and can be interpreted as a correlation coefficient value. Results not only indicate that there are common statistically significant periods of multiannual-to-decadal wavelet coherence between the three teleconnection indices and groundwater levels in each of the boreholes, but they also show that there are periods when groundwater levels at individual boreholes show distinctly different patterns of significant wavelet coherence with respect to the teleconnection indices. The analyses presented demonstrate the value of wavelet methods in identifying the synchronization of groundwater-level dynamics by non-stationary climate variability on time scales that range from interannual to decadal or longer.  相似文献   

10.
The Kucuk Menderes River Basin in western Turkey has been facing continuous groundwater-level decline for decades. Previous studies have suggested that, to avoid aquifer depletion in the basin, artificial recharge structures should be constructed. To assess artificial aquifer recharge potential in one of the subbasins, a two-dimensional (2-D) groundwater model was set up using SEEP/W software. The material functions and parameters used in the model for both saturated and unsaturated conditions were taken from previous studies. The model has been calibrated under transient conditions. The excess runoff volume that could be collected in the recharge basins was estimated from flood frequency analysis. Various scenarios were simulated to observe the change in groundwater level and storage with respect to different exceedance probabilities. Simulation results suggest that a significant increase in groundwater storage is achieved by applying surface artificial-recharge methods. In addition to the recharge basins, to reinforce the effect of artificial recharge, simulations are repeated with underground dam construction at the downstream side of the basin. Although groundwater storage is increased with the addition of the dam, the increase in groundwater storage was not sufficient to warrant the construction.  相似文献   

11.
Mountain Lake in Giles County, Virginia, USA, has a documented history of severe natural lake-level changes involving groundwater seepage that extends over the past 4,200?years. The natural lake was full during a large part of the twentieth century but dried up completely in September 2008 and levels have yet to recover. The objective of the study was to understand the hydrogeologic factors that influence lake-level changes using a daily water balance, electrical resistivity, water sampling and geochemical analysis, and well logging. Results from the water balance demonstrate the seasonal response to precipitation of a forested first-order drainage system in fractured rock. The resistivity surveys suggest discrete high-permeability areas may provide pathways for lake drainage. Imagery, well logs, and field observations appear to confirm the presence of a fault which crosses the Eastern Continental Divide to the east of the lake that had not previously been discussed in literature on the lake; the position of the lake within local and intermediate groundwater flow systems is considered. Historical data suggest that either significant precipitation or artificial intervention to mitigate seepage would be required for lake-level recovery in the near future.  相似文献   

12.
The Nyamandhlovu aquifer is the main water resource in the semi-arid Umguza district in Matebeleland North Province in Zimbabwe. The rapid increase in water demand in the city of Bulawayo has prompted the need to quantify the available groundwater resources for sustainable utilization. Groundwater recharge estimation methods and results were compared: chloride mass balance method (19–62 mm/year); water-table fluctuation method (2–50 mm/year); Darcian flownet computations (16–28 mm/year); 14C age dating (22–25 mm/year); and groundwater modeling (11–26 mm/year). The flownet computational and modeling methods provided better estimates for aerial recharge than the other methods. Based on groundwater modeling, a final estimate for recharge (from precipitation) on the order of 15–20 mm/year is believed to be realistic, assuming that part of the recharge water transpires from the water table by deep-rooted vegetation. This recharge estimate (2.7–3.6% of the annual precipitation of 555 mm/year) compares well with the results of other researchers. The advantages/disadvantages of each recharge method in terms of ease of application, accuracy, and costs are discussed. The groundwater model was also used to quantify the total recharge of the Nyamandhlovu aquifer system (20?×?106–25?×?106 m3/year). Groundwater abstractions exceeding 17?×?106 m3/year could cause ecological damage, affecting, for instance, the deep-rooted vegetation in the area.  相似文献   

13.
The Meitanba Coal Mine area in Hunan province, China, had been impacted by severe cover collapse sinkholes since 1982 due to mine dewatering. After the coal mine was closed in February 2015, the groundwater level has increased significantly. A series of sinkholes were recorded in the study area during groundwater-level recovery. Analysis of monitoring results and in-situ investigation indicated that 13 sinkhole collapses were more likely induced by abrupt change of groundwater–air pressure in response to heavy rainfall from March 2015 to July 2016 when the groundwater level increased by as much as 76 m. When the karst conduit was flooded, a relatively sealed environment was formed between saturated sediments and flooded karst conduit. Implosion of entrapped air might have caused the cave roof to collapse followed by surface collapses in a short time. On the other hand, four sinkholes occurred in November 2016 when the groundwater levels were near the soil–bedrock interface at elevations between 52.5 and 58.9 m amsl and the groundwater-level increase was at slower paces. Field measurements indicate that the groundwater-level fluctuation at the soil–bedrock interface could enlarge the soil cavity and accelerate the subsoil erosion process.  相似文献   

14.
尹立河  张茂省  董佳秋 《地质通报》2008,27(8):1151-1156
红碱淖是毛乌素沙地最大的内陆湖泊,是集旅游、渔业和生态湿地于一体的功能区。近年来,红碱淖面积萎缩,影响了其综合功能的发挥。为了查明红碱淖面积的变化趋势及其影响因素,在收集前人资料和研究成果的基础上,借助MODIS遥感数据反演了湖面面积,建立了2000年以来红碱淖面积的时间序列。在分析红碱淖面积的变化特征和影响因素后发现,早期红碱淖面积变化主要受气象因素的影响,湖泊面积呈周期性有规律的变化;后期在自然因素的基础上叠加了上游截流、地下水开采等人为因素的影响,湖泊面积在周期性变化的基础上总体呈现出萎缩的趋势。  相似文献   

15.
Geochemistry and environmental tracers were used to understand groundwater resources, recharge processes, and potential sources of contamination in the Rio Actopan Basin, Veracruz State, Mexico. Total dissolved solids are lower in wells and springs located in the basin uplands compared with those closer to the coast, likely associated with rock/water interaction. Geochemical results also indicate some saltwater intrusion near the coast and increased nitrate near urban centers. Stable isotopes show that precipitation is the source of recharge to the groundwater system. Interestingly, some high-elevation springs are more isotopically enriched than average annual precipitation at higher elevations, indicating preferential recharge during the drier but cooler winter months when evapotranspiration is reduced. In contrast, groundwater below 1,200 m elevation is more isotopically depleted than average precipitation, indicating recharge occurring at much higher elevation than the sampling site. Relatively cool recharge temperatures, derived from noble gas measurements at four sites (11–20 °C), also suggest higher elevation recharge. Environmental tracers indicate that groundwater residence time in the basin ranges from 12,000 years to modern. While this large range shows varying groundwater flowpaths and travel times, ages using different tracer methods (14C, 3H/3He, CFCs) were generally consistent. Comparing multiple tracers such as CFC-12 with CFC-113 indicates piston-flow to some discharge points, yet binary mixing of young and older groundwater at other points. In summary, groundwater within the Rio Actopan Basin watershed is relatively young (Holocene) and the majority of recharge occurs in the basin uplands and moves towards the coast.  相似文献   

16.
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   

17.
西北内陆盆地降水稀少，一年中有较长时间的冻结期，了解其降水入渗补给规律的季节性变化对于准确评估其地下水资源量和解释气候变化对其地下水补给的影响非常重要。采用新疆昌吉地下水均衡试验站27套地中蒸渗仪1992—2015年试验资料，应用拉依达法则筛选出长系列观测资料中的异常值，结合昌吉试验场相关气象要素观测资料划分西北内陆盆地冻结期、冻融期和非冻结期的时间区间，分析不同时期影响降水入渗补给地下水的主要因素；计算不同时期多年平均降水入渗补给量占多年平均年降水入渗补给量的百分比，确定不同季节对年降水入渗补给的重要性；依据多年平均降水入渗补给量随潜水埋深的变化规律，确定冻融期、非冻结期不同土质降水入渗的最佳潜水埋深。结果表明:在试验条件下，砂卵砾石和细砂非冻结期最佳潜水埋深为0.5 m，轻黏土非冻结期最佳潜水埋深0.1 m；细砂冻融期最佳潜水埋深为1.0 m，砂卵砾石冻融期最佳潜水埋深为0.5 m，轻黏土冻融期最佳潜水埋深为0.1 m；冻结期地下水位埋深对土壤入渗能力的影响十分明显，潜水埋深和降水入渗补给量之间没有显著的线性关系；冻融期是西北内陆盆地浅埋型地下水降水入渗补给的重要时期，冻结期是西北内陆盆地深埋型地下水降水入渗补给的重要时期。  相似文献   

18.
Groundwater response to stream stage fluctuations was studied in two unconfined alluvial aquifers using a year-long time series of stream stages from two pools along a regulated stream in West Virginia, USA. The purpose was to analyze spatial and temporal variations in groundwater/surface-water interaction and to estimate induced infiltration rate and cumulative bank storage during an annual cycle of stream stage fluctuation. A convolution-integral method was used to simulate aquifer head at different distances from the stream caused by stream stage fluctuations and to estimate fluxes across the stream–aquifer boundary. Aquifer diffusivities were estimated by wiggle-matching time and amplitude of modeled response to multiple observed storm events. The peak lag time between observed stream and aquifer stage peaks ranged between 14 and 95 hour. Transient modeled diffusivity ranged from 1,000 to 7,500 m2/day and deviated from the measured and calculated single-peak stage-ratio diffusivity by 14–82 %. Stream stage fluctuation displayed more primary control over groundwater levels than recharge, especially during high-flow periods. Dam operations locally altered groundwater flow paths and velocity. The aquifer is more prone to surface-water control in the upper reaches of the pools where stream stage fluctuations are more pronounced than in the lower reaches. This method could be a useful tool for quick assessment of induced infiltration rate and bank storage related to contamination investigations or well-field management.  相似文献   

19.
Based on the actual meteorological data that characterize statistically significant changes in the air temperature and the amount of precipitation in the southwest of the Moscow artesian basin, the conditions that form the water balance and groundwater recharge are modeled. The comparison of the calculated longterm average values for the previous (1965–1988) and recent (1989–2012) periods made it possible to estimate the climate changes in the elements of water balance and groundwater recharge. Based on the maps of longterm average groundwater recharge for these periods, which were constructed using the results of modeling, the estimation of the change in natural resources of groundwater in the territory was performed, showing an increase of 9% (780000 m3/day).  相似文献   

20.
Assessing the seasonal variation of groundwater recharge is important for effective management of groundwater resources. Stable isotopes of oxygen and hydrogen were used to estimate the sources of groundwater and seasonal contributions of precipitation to groundwater recharge in Chih-Pen Creek basin of eastern Taiwan. Based on the isotopes of precipitation (n = 177), two different local meteoric water regression lines (LMWL) can be obtained for the different seasons: δD = 8.0618O + 10.08 for wet season precipitation (May through October) and δD = 8.65δ18O + 17.09 for dry season precipitation (November through April). The slope and intercept of regression line for wet season precipitation are virtually identical to the global meteoric water line (GMWL) of Craig (1961). In contrast to during dry season precipitation due to evaporation effect the intercept of 17.09 is much higher than of the GMWL of 10. The results show the stable isotopes compositions of precipitation decrease with increasing rainfall amount and air temperature, due to the amount effect of precipitation is pronounced. The amount effect is clearly but do not show the temperature effect from January to December 2007. Using a mass-balance equation, a comparison of deuterium excess or d values of precipitation and groundwater indicates the groundwater consist of 76% wet season precipitation and 24% dry season precipitation, representing a distinct seasonal variation of groundwater recharge in study area. About 79% of the groundwater is recharged from the river water of the mountain watershed and 21% is from the rain that falls on the basin.  相似文献   

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