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1.
Estimation of groundwater recharge using water balance model   总被引：3，自引：0，他引：3  
The main purpose of this paper is to apply a water balance concept with two models in the Ching-Shui watershed to describe the groundwater recharge. First of all, a soil moisture budget model is established to estimate the infiltration, runoff, evapotranspiration, and groundwater recharge in the watershed, where the moisture content of the soil is tracked through time. Secondly, the groundwater recharge was also estimated by the model of the base-flow-record estimation, with the assumption that groundwater evaporation is negligible. In addition, since the analyzed base-flow trends are high, when executing model analysis, the depths of infiltration estimated by stable-base-flow analysis is used to obtain more reasonable groundwater recharge value. The coefficients of groundwater recharge by the precipitation in the Ching-Shui watershed estimated from the established soil moisture budget model and the base-flow model were 12.40% and 9.92%, respectively. Comparison show the result of both models to be close.  相似文献   

2.
Information on water balance components such as evapotranspiration and groundwater recharge are crucial for water management. Due to differences in physical conditions, but also due to limited budgets, there is not one universal best practice, but a wide range of different methods with specific advantages and disadvantages. In this study, we propose an approach to quantify actual evapotranspiration, groundwater recharge and water inflow, i.e. precipitation and irrigation, that considers the specific conditions of irrigated agriculture in warm, arid environments. This approach does not require direct measurements of precipitation or irrigation quantities and is therefore suitable for sites with an uncertain data basis. For this purpose, we combine soil moisture and energy balance monitoring, remote sensing data analysis and numerical modelling using Hydrus. Energy balance data and routine weather data serve to estimate ET0. Surface reflectance data from satellite images (Sentinel-2) are used to derive leaf area indices, which help to partition ET0 into energy limited evaporation and transpiration. Subsequently, first approximations of water inflow are derived based on observed soil moisture changes. These inflow estimates are used in a series of forward simulations that produce initial estimates of drainage and ETact, which in turn help improve the estimate of water inflow. Finally, the improved inflow estimates are incorporated into the model and then a parameter optimization is performed using the observed soil moisture as the reference figure. Forward simulations with calibrated soil parameters result in final estimates for ETact and groundwater recharge. The presented method is applied to an agricultural test site with a crop rotation of cotton and wheat in Punjab, Pakistan. The final model results, with an RMSE of 2.2% in volumetric water content, suggest a cumulative ETact and groundwater recharge of 769 and 297 mm over a period of 281 days, respectively. The total estimated water inflow accounts for 946 mm, of which 77% originates from irrigation.  相似文献   

3.
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4.
Two methods for estimation of groundwater recharge, both based on groundwater level fluctuations, were applied in a moraine area in southeastern Sweden. The first method utilized a onedimensional soil water model which was tested against observed groundwater levels. The boundary conditions were defined by using standard meteorological data and submodels for precipitation, snow dynamics, interception, evapotranspiration and horizontal groundwater outflow. The second method directly transformed groundwater level fluctuations to equivalent amounts of water from a constructed recession curve and the specific yield concept. Conceptually the two methods could be characterized as inflow and response methods respectively.

A good fit between observed and simulated groundwater levels was obtained by the soil water modelling. The results were, however, shown to be rather insensitive to displacement in the water balance between evapotranspiration and groundwater outflow, giving a good fit for a simulated net groundwater recharge ranging between 134 and 197 mm. The results from the attempts to use groundwater level fluctuations directly were discouraging. Compared to the soil water simulations the results were unstable and quite different for different years. It was impossible to use a constant specific yield or even different specific yields depending on depth.

The conclusion was that the possibilities to use groundwater level data for quantitative water balance studies are limited under the studied climatical and hydrogeological conditions. The modelling effort clearly demonstrated the need for a better quantitative knowledge on soil properties if water balance information is to be deduced. The soil water model though, could be a valuable tool studying variations within and between different years as well as processes and single events.  相似文献   


5.
A combination of micro-meteorological, soil physical and groundwater chemical methods enabled the water balance of a tropical eucalypt savanna ecosystem in Northern Australia to be estimated. Heat pulse and eddy correlation were used to determine overstory and total evapotranspiration, respectively. Measurements of soil water content, matric suction and water table variations were used to determine changes in soil moisture storage throughout the year. Groundwater dating with chlorofluorocarbons was used to estimate net groundwater recharge rates, and stream gauging was used to determine surface runoff. The wet season rainfall of 1585 mm is distributed as: evapotranspiration 810 mm, surface runoff (and shallow subsurface flow) into the river 410 mm, groundwater recharge 200 mm and increase in soil store 165 mm. Of the groundwater recharge, 160 mm enters the stream as baseflow in the wet season, 20 mm enters as baseflow in the dry season, and the balance (20 mm) is distributed to and used by minor vegetation types within the catchment or discharges to the sea. In the dry season, an evapotranspiration of 300 mm comprises 135 mm rainfall and 165 mm from the soil store. Because of the inherent errors of the different techniques, the water balance surplus (estimated at 20 mm) cannot be clearly distinguished from zero. It may also be as much as 140 mm. To our knowledge, this is the first time that such diverse methods have been combined to estimate all components of a catchment's water balance.  相似文献   

6.
ABSTRACT

The aim of this paper is to estimate the effect that climate change will have on groundwater recharge at the Yucatan Peninsula, Mexico. The groundwater recharge is calculated from a monthly water balance model considering eight methods of potential and actual evapotranspiration. Historical data from 1961–2000 and climate model outputs from five downscaled general circulation models in the near horizon (2015–2039), with representative concentration pathway (RCP) 4.5 and 8.5 are used. The results estimate a recharge of 118 ± 33 mm·year–1 (around 10% of precipitation) in the historical period. Considering the uncertainty from GCMs under different RCP and evapotranspiration scenarios, our monthly water balance model estimates a groundwater recharge of 92 ± 40 mm·year–1 (RCP4.5) and 94 ± 38 mm·year–1 (RCP8.5) which represent a reduction of 23% and 20%, respectively, a result that threatens the socio-ecological balance of the region.  相似文献   

7.
Abstract

Estimating groundwater recharge is essential to ensure the sustainable use of groundwater resources, particularly in arid and semi-arid regions. Soil water balances have been frequently advocated as valuable tools to estimate groundwater recharge. This article compares the performance of three soil water balance models (Hydrobal, Visual Balan v2.0 and Thornthwaite) in the Ventós-Castellar aquifer, Spain. The models were used to simulate wet and dry years. Recharge estimates were transformed into water table fluctuations by means of a lumped groundwater model. These, in turn, were calibrated against piezometric data. Overall, the Hydrobal model shows the best fit between observed and calculated levels (r2 = 0.84), highlighting the role of soil moisture and vegetation in recharge processes.

Editor D. Koutsoyiannis; Associate editor X. Chen

Citation Touhami, I., et al., 2014. Comparative performance of soil water balance models in computing semi-arid aquifer recharge. Hydrological Sciences Journal, 59 (1), 193–203.  相似文献   

8.
Abstract

Many of the hydrological and ecological functions of alluvial flood plains within watersheds depend on the water flow exchanges between the vadoze soil zone and the shallow groundwater. The water balance of the soil in the flood plain is investigated, in order to evaluate the main hydrological processes that underlie the temporal dynamics of soil moisture and groundwater levels. The soil moisture and the groundwater level in the flood plain were monitored continuously for a three-year period. These data were integrated with the results derived from applying a physically-based numerical model which simulated the variably-saturated vertical water flow in the soil. The analysis indicated that the simultaneous processes of lateral groundwater flow and the vertical recharge from the unsaturated zone caused the observed water table fluctuations. The importance of these flows in determining the rises in the water table varied, depending on soil moisture and groundwater depth before precipitation. The monitoring period included two hydrological years (September 2009–September 2011). About 13% of the precipitation vertically recharged the groundwater in the first year and about 50% in the second. The difference in the two recharge coefficients was in part due to the lower groundwater levels in the recharge season of the first hydrological year, compared to those observed in the second. In the latter year, the shallow groundwater increased the soil moisture in the unsaturated zone due to capillary rise, and so the mean hydraulic conductivity of the unsaturated soil was high. This moisture state of soil favoured a more efficient conversion of infiltrated precipitation into vertical groundwater recharge. The results show that groundwater dynamics in the flood plain are an important source of temporal variability in soil moisture and vertical recharge processes, and this variability must be properly taken into account when the water balance is investigated in shallow groundwater environments.

Citation Pirastru, M. and Niedda, M., 2013. Evaluation of the soil water balance in an alluvial flood plain with a shallow groundwater table. Hydrological Sciences Journal, 58 (4), 898–911.  相似文献   

9.
A recharge model for high altitude,arid, Andean aquifers   总被引：1，自引：0，他引：1  
John Houston 《水文研究》2009,23(16):2383-2393
Evidence for groundwater recharge in arid zones is mounting, despite early ideas that recharge was unlikely where evaporation greatly exceeded precipitation. The mechanisms and magnitude of groundwater recharge in the Andes and Atacama Desert are not well known but the subject of current research. Diffuse recharge is expected to be limited to high altitude areas with coarse‐grained soils devoid of vegetation. A recharge model for this environment is developed based on a simple soil moisture budgeting technique and the calculation of actual evaporation based on empirical studies. The model is run with data for the Linzor basins, over 4000 m elevation at 22·2°S on the west slope of the Andes. It is checked against independent estimates based on the chloride mass balance (CMB) method and flood events measured downstream in the Río Salado and found to provide robust and reliable results. The results indicate that irregular and volumetrically limited amounts of diffuse recharge occur at high elevations in half of all years, with a tendency to cluster during La Niña episodes. For the Linzor Basins, mean annual recharge is found to be equivalent to 28 mm a?1, although no recharge occurs in years with precipitation less than 120 mm, and increases proportionately with annual rainfall amounts above this limit. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

10.
A reliable estimate of rainfall recharge is essential for groundwater system managements. This study develops a method based on regression equations for estimating rainfall recharge at unconfined sandy aquifers with an equatorial climate. The developed method (GR-I method) is generally efficient for estimating long-term regional recharge, as the computational procedures could be formulated and executed easily using Microsoft's Excel spreadsheet. More importantly, its application could be extended to sand textures different from the sand texture used in developing the regression equations. To evaluate its reliability, the method was applied to estimate monthly gross recharge percentages at the Changi reclaimed land. When ignoring the effect of rainfall clusters, the GR-I method was found to underestimate the monthly gross recharge percentages for those months with high monthly rainfall depths. By integrating the effect of rainfall clusters, the GR-I method yields reliable estimates of monthly gross recharge percentages. By including daily potential evaporation as an additional input variable, the Extended GR-I method was found to be not superior to the GR-I method, implying that soil moisture availability is the major governing factor for actual soil evaporation in the highly porous sand medium, instead of atmospheric demand represented by the potential evaporation rate. Using the GR-I method, the mean annual net recharge percentage of the study site was found to fall between 56·9 and 69·9%, which corresponds to a net recharge depth of 1073·8–1745·8 mm. Although the developed method provides a good alternative to other widely used methods, its recharge estimates still needs to be collaborated with estimates from other methods, as multiple techniques are highly recommended in any groundwater recharge estimations. Copyright © 2007 John Wiley & Sons, Ltd.  相似文献   

11.
The use of the sulphate mass balance (SMB) between precipitation and soil water as a supplementary method to estimate the diffuse recharge rate assumes that the sulphate in soil water originated entirely from atmospheric deposition; however, the origin of sulphate in soil and groundwater is often unclear, especially in loess aquifers. This study analysed the sulphur (δ34S-SO4) and oxygen (δ18O-SO4) isotopes of sulphate in precipitation, water-extractable soil water, and shallow groundwater samples and used these data along with hydrochemical data to determine the sources of sulphate in the thick unsaturated zone and groundwater of a loess aquifer. The results suggest that sulphate in groundwater mainly originated from old precipitation. When precipitation percolates through the unsaturated zone to recharge groundwater, sulphates were rarely dissolved due to the formation of CaCO3 film on the surface of sulphate minerals. The water-extractable sulphate in the deep unsaturated zone (>10 m) was mainly derived from the dissolution of evaporite minerals and there was no oxidation of sulphide minerals during the extraction of soil water by elutriating soil samples with deionized water. The water-extractable concentration of SO4 was not representative of the actual SO4 concentration in mobile soil water. Therefore, the recharge rate cannot be estimated by the SMB method using the water-extractable concentration of SO4 in the loess areas. This study is important for identifying sulphate sources and clarifying the proper method for estimating the recharge rate in loess aquifers.  相似文献   

12.
为研究乌伦古湖矿化度和氟化物浓度与各水量因子间的定量关系,本研究以水量平衡和物质平衡为基础,把影响湖水水质的原因分为降雨、蒸发、河流补给、地下水补给以及地下水流出5个水量因子,定量分析湖水矿化度和氟化物浓度与各水量因子之间的关系,并且预测了湖水矿化度和氟化物浓度的动态变化.结果表明,地下水输出流量决定了湖水中矿化度和氟化物浓度,地下水输出流量越大,湖水中的矿化度和氟化物浓度越小.2010年至今乌伦古湖水位的升高导致了地下水输出流量增大,乌伦古湖内的矿化度和氟化物浓度均呈缓慢下降趋势,模型预测新的稳态下湖水中矿化度为1.68 g/L,氟化物浓度为1.70 mg/L,在地下水输出流量不变的情况下达到新的稳态所需时间大约为50 a.  相似文献   

13.
Accurate estimation of groundwater recharge (GR) and evapotranspiration (ET) are essential for sustainable management of groundwater resources, especially in arid and semi-arid regions. In the Manas River Basin (MRB), water shortage is the main factor restricting sustainable development of irrigated agriculture, which relies heavily on groundwater. Film-mulched drip irrigation significantly changes the pattern and dominant processes of water flow in the unsaturated zone, which increases the difficulty of GR and ET estimation. To better estimate GR and ET under film-mulched drip irrigation in the MRB, bromide tracer tests and soil lithologic investigation were conducted at 12 representative sites. A one-dimensional variably saturated flow model (HYDRUS-1D) was calibrated at each site using soil evaporation data inferred from the bromide tracer tests. The results showed that average annual soil evaporation in uncultivated lands calculated from bromide trace tests was 25.55 mm. The annual GR ranged from 5.5 to 37.0 mm under film-mulched drip irrigation. The annual ET ranged from 507.0 to 747.1 mm, with soil evaporation between 35.7 and 117.0 mm and transpiration between 460.9 and 642.3 mm. Soil evaporation represented 7% to 16% of the total ET and more than 70% of precipitation and irrigation water was used by cotton plants. Spatial variations of soil lithology, water table depth and initial soil water content led to the spatial differences of GR and ET in the MRB. Our study indicated that bromide tracer tests are useful for inferring ET in the arid and semi-arid oases. The combination of bromide tracer tests and HYDRUS-1D enhances reliability for estimation of GR and ET under film-mulched drip irrigation in the MRB and shows promise for other similar arid inland basins around the world.  相似文献   

14.
Abstract

Accurate estimation of groundwater recharge is essential for the proper management of aquifers. A study of water isotope (δ2H, δ18O) depth profiles was carried out to estimate groundwater recharge in the Densu River basin in Ghana, at three chosen observation sites that differ in their altitude, geology, climate and vegetation. Water isotopes and water contents were analysed with depth to determine water flow in the unsaturated zone. The measured data showed isotope enrichment in the pore water near the soil surface due to evaporation. Seasonal variations in the isotope signal of the pore water were also observed to a depth of 2.75 m. Below that depth, the seasonal variation of the isotope signal was attenuated due to diffusion/dispersion and low water flow velocities. Groundwater recharge rates were determined by numerical modelling of the unsaturated water flow and water isotope transport. Different groundwater recharge rates were computed at the three observation sites and were found to vary between 94 and 182 mm/year (± max. 7%). Further, the approximate peak-shift method was applied to give information about groundwater recharge rates. Although this simple method neglects variations in flow conditions and only considers advective transport, it yielded mean groundwater recharge rates of 110–250 mm/year (± max. 30%), which were in the same order of magnitude as computed numerical modelling values. Integrating these site-specific groundwater recharge rates to the whole catchment indicates that more water is potentially renewed than consumed nowadays. With increases in population and irrigation, more clean water is required, and knowledge about groundwater recharge rates – essential for improving the groundwater management in the Densu River basin – can be easily obtained by measuring water isotope depth profiles and applying a simple peak-shift approach.

Citation Adomako, D., Maloszewski, P., Stumpp, C., Osae, S. & Akiti, T. T. (2010) Estimating groundwater recharge from water isotope (δ2H, δ18O) depth profiles in the Densu River basin, Ghana. Hydrol. Sci. J. 55(8), 1405–1416.  相似文献   

15.
Groundwater age is often used to estimate groundwater recharge through a simplified analytical approach. This estimated recharge is thought to be representative of the mean recharge between the point of entry and the sampling point. However, given the complexity in actual recharge, whether the mean recharge is reasonable is still unclear. This study examined the validity of the method to estimate long-term average groundwater recharge and the possibility of obtaining reasonable spatial recharge pattern. We first validated our model in producing reasonable age distributions using a constant flux boundary condition. We then generated different flow fields and age patterns by using various spatially varying flux boundary conditions with different magnitudes and wavelengths. Groundwater recharge was estimated and analysed afterwards using the method at the spatial scale. We illustrated the main findings with a field example in the end. Our results suggest that we can estimate long-term average groundwater recharge with 10% error in many parts of an aquifer. The size of these areas decreases with the increase in both the amplitude and the wavelength. The chance of obtaining a reasonable groundwater recharge is higher if an age sample is collected from the middle of an aquifer and at downstream areas. Our study also indicates that the method can also be used to estimate local groundwater recharge if age samples are collected close to the water table. However, care must be taken to determine groundwater age regardless of conditions.  相似文献   

16.
巴丹吉林沙漠气候干旱,蒸发强烈,与之形成鲜明对比的是沙漠腹地湖泊群的长久不衰,目前对于湖泊水分的补给来源仍存在争议.本文以水量均衡为基础,在苏木吉林湖区开展了降水、蒸发及湖水位和地下水位的动态监测,结合已有的水文地质资料建立地下水流动三维模型,重现湖区地下水位的季节动态变化,并基于模型进行水均衡分析.结果表明:苏木吉林湖区降水入渗补给量不足以平衡湖泊蒸发量,湖泊需要深层承压水的越流补给;湖水位和地下水位均呈现正弦曲线形态,11月最低,4月达到峰值,水位变幅分别为22和18 cm;湖区地下水多年平均总补给量为11620 m3/d,其中降水和承压水越流分别约占13%和87%,降水补给量夏季高、冬季低,承压水越流补给量季节变化不明显;承压水越流补给量可能主要来源于沙漠周边山区降水,未发现明显的水量亏空需要断裂导水来弥补.研究结果为巴丹吉林沙漠地下水资源分析及合理利用提供科学依据.  相似文献   

17.
To increase the resilience of regional water supply systems in South Africa in the face of anticipated climatic changes and a constant increase in water demand, water supply sources require diversification. Many water-stressed metropolitan regions in South Africa depend largely on surface water to cover their water demand. While climatic and river discharge data is widely available in these regions, information on groundwater resources – which could support supply source diversification – is scarce. Groundwater recharge is a key parameter that is used to estimate groundwater amounts that can be sustainably exploited at a sub-watershed level. Therefore, the objective of this study was to develop a reliable hydrological modelling routine that enables the assessment of regional spatio-temporal variations of groundwater recharge to discern the most promising areas for groundwater development. Accordingly, we present a semi-distributed hydrological modelling approach that incorporates water balance routines coupled with baseflow modelling techniques to yield spatio-temporal variations of groundwater recharge on a regional level. The approach is demonstrated for the actively managed catchment areas of the Amathole Water Supply System situated in a semi-arid part of the Eastern Cape of South Africa. In the investigated study area, annual groundwater recharge exhibits a high spatio-temporal heterogeneity and is estimated to vary between ~0.5% and 8% of annual rainfall. Despite some uncertainties induced by limited data availability, calibration and validation of the model were found to be satisfactory and yielded model results similar to (point) data of annual groundwater recharge reported in earlier studies. Our approach is therefore found to derive crucial information for efficiently targeting more detailed groundwater exploration studies and could work as a blueprint for orientating groundwater potential exploration in similar environments.  相似文献   

18.
Ninghu Su 《Journal of Hydrology》1994,160(1-4):123-135
This paper presents a formula for computation of time-varying recharge of groundwater. The formula is derived from the basic equation of groundwater flow on an inclined impervious base. This analytical expression can also be used to compute evaporation rate if there is no recharge of groundwater. Readings from electronic data loggers show that recharge of groundwater is highly variable depending on the patterns of rainfall and antecedent conditions of the soil.  相似文献   

19.
Understanding soil water dynamics and the water balance of tropical coral islands is important for the utilization and management of their limited freshwater resources, which is only from rainfall. However, there is a significant knowledge gap in the influence of soil water on the water cycle of coral islands. Soil water dynamics and the water balance of Zhaoshu Island, Xisha Archipelago were thus investigated using soil moisture measurements and the Hydrus-1D model from October 2018 to September 2019. Over the study period, vegetation transpiration, soil evaporation, groundwater recharge and storage in the vadose zone were approximately 196, 330, 365 and 20 mm, occupying 22%, 36%, 40% and 2% of annual rainfall total (911 mm), respectively. For the wet season (from May to October) these values became 75, 202, 455 and 40 mm, occupying 10%, 26% and 59% and 5% of the seasonal rainfall total (772 mm), respectively. During the dry season (from November to April), a dry soil layer between 40 and 120 cm depth of the soil profile was identified that prevented water exchange between the upper soil layers and the groundwater resulting in the development of deep roots so that vegetation could extract groundwater to supplement their water requirements. Vegetation not only consumes all dry season rainfall (140 mm) but extracts water deeply from groundwater (90 mm) as well as from the vadose layer (20 mm). As such, the vegetation appears to be groundwater-dependent ecosystems. The research results aid us to better understand the process of water dynamics on coral islands and to protect coral island ecosystems.  相似文献   

20.
基于水平衡模型的呼伦湖湖泊水量变化   总被引：2，自引：2，他引：0  
针对北方寒旱区呼伦湖水位下降、水面萎缩的现象,根据气候特征,利用月水量平衡模型探究湖泊水文过程并揭示其变化规律.在此基础上,利用不同气候条件下各水平衡项对于湖泊水位的影响程度确定水位升降的直接原因.基于1963-1980年间水位的实测数据,根据水量平衡原理及其他辅助计算判断出湖泊与周边区域存在着地下水的交换,且具有一定的规律性,即历年11月至次年3月期间的累积降雪融化渗入土壤中形成浅层径流补给湖泊,而7、8月份湖泊补给周边草原.基于以上规律,根据周边坡面汇流、地下水与湖泊交换量的年内变化特征,利用水平衡方程式推算湖泊1981-2008年逐月水位变化,并与其他研究成果比较,吻合度较高.不同气候条件下,径流量对于湖泊水位的影响程度最为突出,是水位变化的主控因子.  相似文献   

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