Calculation Of Groundwater Recharge Research Articles

Application of DRASTIC method to identify the groundwater vulnerability to pollution in the sub-district of West Limboto and Limboto, Gorontalo Regency, Indonesia

The increment in population and agricultural sectors in West Limboto and Limboto, Gorontalo, affects the increased production of pollutants. The community uses shallow groundwater as the main water source. Since shallow groundwater is vulnerable to pollution due to community activity, this study aims to identify its vulnerability in West Limboto and Limboto. It was identified using the DRASTIC Method that will be integrated with Geographic Information System (GIS) Technique. The used parameters are Depth to Water Table, Recharge, Aquifer Media, Soil Media, Topography, Impact of Vadoze Zone, and Hydraulic Conductivity of the Aquifer. Depth to Water Table data is obtained from direct field measurement. Recharge amount data is obtained from the calculation of groundwater recharge. Aquifer Media, the Impact of Vadoze Zone, and Soil Media data are obtained from surface and subsurface geological data. Topography data is obtained from Digital Elevation Model Map. Hydraulic Conductivity is obtained from Pumping Test Data. The analysis result shows that the groundwater vulnerability of the study area was classified into 2 classes, the high index was in the southern part, and the low index was in the middle to the northern part of the study area.

Effect of snowmelt infiltration on groundwater recharge in a seasonal soil frost area: a case study in Northeast China.

The effect of spring snowmelt infiltration in a seasonal soil frost area on groundwater recharge was evaluated by systematically monitoring meteorological factors, soil temperature and humidity, groundwater table and temperature, electrical conductivity, and the value of δ18O in a small field site over a 2-year period. The variation of soil temperature and humidity, groundwater table during the freezing period, and the snowmelt period respectively, as well as their correspondence to the relevant environmental factors, and the influencing factors of the permeability of frozen layer were analyzed. The results showed that the evaluation of precipitation infiltration in seasonal soil frost areas should be divided into three stages: a non-freezing period, a freezing period, and a snowmelt period. Snow is the main form of precipitation during the freezing period, and groundwater cannot be recharged. During the snowmelt period of spring, the snow cover that accumulated during the freezing period infiltrates together with rainfall and has a significant effect on groundwater recharge. The general precipitation infiltration process occurs after the frozen soil thaws completely. These research results can improve the accuracy of groundwater recharge calculations for snowmelt infiltration in the seasonal soil frost area of Northeast China and provide a scientific basis for the evaluation and management of regional water resources.

Effect of temporal averaging of meteorological data on predictions of groundwater recharge

Abstract Accurate estimates of infiltration and groundwater recharge are critical for many hydrologic, agricultural and environmental applications. Anticipated climate change in many regions of the world, especially in tropical areas, is expected to increase the frequency of high-intensity, short-duration precipitation events, which in turn will affect the groundwater recharge rate. Estimates of recharge are often obtained using monthly or even annually averaged meteorological time series data. In this study we employed the HYDRUS-1D software package to assess the sensitivity of groundwater recharge calculations to using meteorological time series of different temporal resolutions (i.e., hourly, daily, weekly, monthly and yearly averaged precipitation and potential evaporation rates). Calculations were applied to three sites in Brazil having different climatological conditions: a tropical savanna (the Cerrado), a humid subtropical area (the temperate southern part of Brazil), and a very wet tropical area (Amazonia). To simplify our current analysis, we did not consider any land use effects by ignoring root water uptake. Temporal averaging of meteorological data was found to lead to significant bias in predictions of groundwater recharge, with much greater estimated recharge rates in case of very uneven temporal rainfall distributions during the year involving distinct wet and dry seasons. For example, at the Cerrado site, using daily averaged data produced recharge rates of up to 9 times greater than using yearly averaged data. In all cases, an increase in the time of averaging of meteorological data led to lower estimates of groundwater recharge, especially at sites having coarse-textured soils. Our results show that temporal averaging limits the ability of simulations to predict deep penetration of moisture in response to precipitation, so that water remains in the upper part of the vadose zone subject to upward flow and evaporation.

Distribution of isotopes and chemicals in precipitation in Shule River Basin, northwestern China: an implication for water cycle and groundwater recharge

The distribution of stable isotopes and ions in precipitation in the Shule River Basin, northwestern China, were investigated to understand the regional water cycle and precipitation input to groundwater recharge. The study found that the mean annual concentrations of Ca2+, Na+, SO4 2–, Cl–, Mg2+, NO3 –, and K+ in the basin were lower than those in other arid areas of northwestern China. The average concentrations of ions in the lower reaches of the Shule River were higher than those in the upper reaches. The results showed that the main ionic concentrations decreased with the increase of precipitation amount, indicating that heavy precipitation cannot only wash crustal aerosols out of the atmosphere, but also create a dilution effect. Cl– and Na+ in precipitation had a strong and positive correlation, suggesting a common origin for the two ions. However, the excess of Na+, combined with non-marine SO4 2– and NO3 –, indicated that some ions were contributed by terrestrial origins. In the extremely arid regions of northwestern China, the evaporation process obviously changes the original relationship between δ2H and δ18O in precipitation, and leads to dexcess values <8‰. δ18O and temperature were significantly correlated, suggested that temperature strongly affected the characteristics of isotopes in the study area. The δ18O value indicates a dominant effect of westerly air masses and southwest monsoon in warm months, and the integrated influence of westerly and Siberian-Mongolian polar air masses in cold months. The d-excess values were generally lower in warm months than those in cold months, indicating that post-condensation processes played a significant role in the water cycle. The results provide reliable precipitation input information that can be used in future groundwater recharge calculations in the study area.

Use of displacement method with STFT wavelet transformation for groundwater recharges prediction

The main aspiration behind this study was to calculate groundwater recession parameter using recently developed method and to apply calculated parameter for calculation of groundwater recharge. The equation for the hydrograph recession curve can be utilized to predict groundwater recharge during each recession period. The steps involved during recession curve analysis include selection of analytical expression, derivation of recession characteristic and optimization of the parameters. Each segment shows the outflow process which creates short-term or seasonal influence. The variations recession rate causes problems for derivation of recession characteristics. To avoid variations in recession parameters Short Time Fourier Transformation (STFT) was used. While applying STFT in real runoff data recession segments were chosen by user. The selected segments were further used for calculation of groundwater recharge assuming a linear hydrological model. The runoff hydrograph represents consist of three components: surface flow, intermediate flow and base flow. The applications of wavelet transformation can differential those flow components into were short, intermediate and long wavelet periods. The displacement method was used to obtain further information from wavelet transformation and to verify its practical application in groundwater studies. DOI: http://dx.doi.org/10.3126/ije.v4i2.12632 International Journal of Environment Vol.4(2) 2015: 128-135

Characteristics of Groundwater Recharge on the North China Plain

Groundwater recharge is an important component of the groundwater system. On the North China Plain (NCP), groundwater is the main water supply. Because of large-scale overexploitation, the water table has declined, which has produced severe adverse effects on the environment and ecosystem. In this article, tracer experiment and watershed model were used to calculate and analyze NCP groundwater recharge. In the tracer experiment, average recharge was 108 mm/year and recharge coefficient 0.16. With its improved irrigation, vegetation coverage and evapotranspiration modules, the INFIL3.0 model was used for calculation of groundwater recharge. Regional modeling results showed an average recharge of 102 mm/year and recharge coefficient 0.14, for 2001-2009. These values are very similar to those from the field tracer experiment. Influences in the two methods were analyzed. The results can provide an important reference for NCP groundwater recharge.

The composition and distribution of chemicals and isotopes in precipitation in the Shiyang River system, northwestern China

Summary We intensively investigated the composition and distribution of several major ions and stable isotopes (δ2H, δ18O) in precipitation in 2008 and 2009 at three sites in the Shiyang River Basin of northwestern China. The goal was to provide basic data that would help us to understand the geochemical evolution and recharge sources of groundwater in the basin’s Quaternary aquifer. The δ2H and δ18O values for 75 precipitation samples ranged from +35.7‰ to −170.9‰ and from +4.6‰ to −23.3‰, respectively. The relationship between δ2H and δ18O defined a well-constrained local meteoric line, which was nearly identical to the meteoric water line for northern China. The evaporation process in this dry region of northwestern China obviously altered the original relationship between rainfall δ2H and δ18O, resulting in d-excess values SO 4 2 - , NO 3 - , Cl−, NH 4 + , Ca2+, Mg2+, Na+, and K+ in mountain and desert areas were lower than those in most of China’s cities. The majority of the rainfall samples had a Cl− concentration of 1.5–2.5 mg L−1, and the excess of Na+ over Cl−, combined with a strong excess of non-marine SO 4 2 - and the overall precipitation chemistry, indicates that some solutes were contributed from terrestrial sources during the air mass trajectory over land. These values will provide reliable rainfall input information that can be used in future groundwater recharge calculations in the study area.

Combination of soil-water balance models and water-table fluctuation methods for evaluation and improvement of groundwater recharge calculations

Despite a long history of related research, quantifying and verifying recharge is still a major challenge. The combination and comparison of conceptually different methods has been recommended as a strategy for evaluating recharge estimates. In this article, recharge estimates from water-table fluctuation (WTF) methods are combined with and compared to the results of the spatially and temporally discretized soil-water-balance model PROMET (processes of radiation, mass and energy transfer). As PROMET and WTF methods rely on different measurable variables, a comparison of these two contrasting techniques allows improved assessment of the plausibility of recharge estimates. An enhanced approach to WTF methods is presented. The approach assumes that in the case of no recharge, there exists a maximum possible potential decline for any given groundwater level. The primary conclusion is that WTF methods are excellent for determining the plausibility of spatially distributed regional-groundwater-recharge estimation approaches and for detecting inconsistencies in available models. Recharge estimates derived from WTF approaches alone are, however, not suitable for regional-scale recharge estimation due to (1) their strong dependency on local data, applicability of which is limited to only very specific conditions, and (2) their sensitivity to influences other than recharge.

Effects of Soil Moisture Sensor Spacing and Zone of Influence on Recharge Calculations

Quantification of groundwater recharge is essential for water resources management. The water balance method is one of several methods for measuring event-based groundwater recharge. Soil moisture measurement data are essential for quantifying recharge using the water balance method. The spacing and zone of influence of soil moisture sensors used in a study are important factors for the accuracy of recharge calculations. A large lysimeter was used to measure the water balance components to quantify groundwater recharge in South Florida as a function of soil moisture and water table levels. Recharge was calculated using sensor spacings of 10 and 20 cm and zone of influence of 10 and 20 cm for seven major rainfall events. Recharge calculated with a sensor spacing of 20 cm had a relative root mean square error (RRMSE) of 33.1% as compared with the 10-cm spacing. Recharge calculated using a zone of influence of 20 cm had an RRMSE of 38.8% as compared with the 10-cm zone of influence. This error is attributed to soil moisture sensor discretization, which results in averaging the soil moisture in a soil layer containing the saturated and unsaturated zones interface, which leads to an over-estimation of soil moisture in the unsaturated zone and an underestimation of soil moisture in the saturated zone. Vertical spacing of sensors larger than the sensors' zone of influence also gives erroneous results as portions of the soil profile are not measured. For groundwater recharge calculations, selecting a sensor with suitable zone of influence and appropriate sensor spacing can have a significant effect on the accuracy of the calculations.

Comparison of seven models for estimation of evapotranspiration and groundwater recharge using lysimeter measurement data in Germany

AbstractThis study evaluates seven evapotranspiration models and their performance in water balance studies by using lysimeter measurement data at the Mönchengladbach hydrological and meteorological station in Germany. Of the seven evapotranspiration models evaluated, three models calculate actual evapotranspiration directly using the complementary relationship approach, i.e. the CRAE model of Morton, the advection–aridity (AA) model of Brutsaert and Stricker, and the GG model of Granger and Gray, and four models calculate first potential evapotranspiration and then actual evapotranspiration by considering the soil moisture condition. Two of the four potential evapotranspiration models belong to the temperature‐based category, i.e. the Thornthwaite model and the Hargreaves model, and the other two belong to the radiation‐based category, i.e. the Makkink model and the Priestley–Taylor model. The evapotranspiration calculated by the above seven models, together with precipitation, is used in the water balance model to calculate other water balance components. The results show that, for the calculation of actual evapotranspiration, the GG model and the Makkink model performed better than the other models; for the calculation of groundwater recharge using the water balance approach, the GG model and the AA models performed better; for the simulation of soil moisture content using the water balance approach, four models (GG, Thornthwaite, Makkink and Priestley–Taylor) out of the seven give equally good results. It can be concluded that the lysimeter‐measured water balance components, i.e. actual evapotranspiration, groundwater recharge, soil moisture, etc., can be predicted by the GG model and the Makkink model with good accuracy. Copyright © 2005 John Wiley &amp; Sons, Ltd.

Empirical equations of groundwater recharge patterns

ABSTRACT This paper emanates from attempts at fitting empirical equations to describe the patterns of groundwater recharge in the regolith of the Middle Osun Valley in the Nigerian Basement Complex. Equations of both the temporal and spatial patterns of groundwater recharge were derived empirically by analysing sample data on saturated zone thickness using a least-squares curvilinear regression technique. The temporal pattern for the study period conforms with the prevailing rainfall regime and is optimally described by fourth-degree polynomial regression equations. The spatial pattern is optimally described by quadratic equations and suggests that an almost uniformly thick annual groundwater recharge zone of about 2.4 m overlies the gross spatial distribution of saturated zone thickness from the major river channel to the major water divide. The quantitative methodology of this study is universally applicable and could greatly facilitate direct calculation of groundwater recharge and rainfall-recharge correlation if reliable information about relevant parameters of Basement Complex regolith aquifers is available.

Abschätzung der Grundwasserneubildung aus Saugspannungsmessungen

Abschätzung der Grundwasserneubildung aus Saugspannungsmessungen