Precipitation Recharge Research Articles

Impact of Coastal Land Reclamation on Ground Water Level and the Sea Water Interface

Land reclamation in coastal areas may have a significant effect on local ground water systems. Steady-state analytic solutions based on Dupuit and Ghyben-Herzberg assumptions are derived to evaluate this effect. Two situations are considered, both with ground water flow resulting from precipitation recharge: the coastal aquifer of an extensive landmass and an island. The results show that after reclamation, the water table rises and the salt water-fresh water interface moves seaward. The degree of these changes depends on the extent of reclamation and the hydraulic conductivity of the fill material. For the island situation, the reclamation displaces the ground water divide and changes the ground water conditions in the entire island. An unintended advantage of the reclamation is an increase of fresh ground water resource because the reclaimed land can be an additional aquifer and rain recharge takes place over a larger area.

Study on vegetation ecological water requirement in Ejina Oasis

The Ecological Water Requirement (EWR) of desert oasis is the amount of water required to maintain a normal growth of vegetation in the special ecosystems. In this study EWR of the Ejina desert oasis is estimated through the relational equation between normalized difference vegetation index (NDVI), productivity and transpiration coefficient, which was established by a combination of the RS, GIS, GPS techniques with the field measurements of productivity. The results show that about 1.53×10 8 m 3 water would be needed to maintain the present state of the Ejina Oasis, and the ecological water requirement would amount to 3.49×10 8 m 3 if the existing vegetation was restored to the highest productivity level at present. Considering the domestic water requirement, river delivery loss, oasis vegetation water consumption, farmland water demand, precipitation recharge, etc., the draw-off discharge of the Heihe River (at Longxin Mount) should be 1.93×10 8 ―2.23 ×10 8 3 to maintain the present state of the Ejina Oasis, and 4.28×10 8 ―5.17×10 8 m 3 to make the existing vegetation be re-stored to the highest productivity level at present.

Recharge to groundwater in the Turi Basin, northern Chile: An evaluation based on tritium and chloride mass balance techniques

Summary The Turi Basin contains an unconfined phreatic aquifer within the Toconce Formation volcano-sedimentary sequence that passes eastwards under the Quaternary volcanic chain and outcrops in the Altiplano. The phreatic aquifer is floored by impermeable welded Miocene ignimbrites. Precipitation captured by the volcanic edifices infiltrates through high permeability soils to recharge the phreatic aquifer. The hydrochemistry of the groundwater in the phreatic aquifer shows little evidence of mixing with geothermal water and therefore approximates to a closed system. Tritium values demonstrate that recharge is occurring under current climatic conditions and takes around 40 years to pass 10+ km from recharge areas on the slopes of the volcanoes and the Altiplano to the center of the basin. The chloride mass balance technique has been used to quantify precipitation recharge at 15,500 m3 d−1. This is significantly less than the flow through the phreatic aquifer (58,000–86,000 m3 d−1) calculated from its physical properties and the difference is interpreted to be due to subsurface inflow through the Toconce Formation from the Altiplano. The results of this study have wider application throughout the Andean hydrological environment of northern Chile.

Mechanical Disturbance of Microbiotic Crusts Affects Ecohydrological Processes in a Region of Revegetation-fixed Sand Dunes

ABSTRACT Microbiotic crusts (MC), also called biological soil crusts or cryptogamic crusts, are formed by cyanobacteria, fungi, blue-green algae, lichens, and mosses, and are widespread in arid and semiarid zones such as the area of sands fixed in place by revegetation near Shapotou at the southeastern edge of China's Tengger Desert. We studied mechanically disturbed and 40-year-old intact MC in this area using a series of soil hydrological experiments and ecological investigations to examine the ecohydrological responses after mechanical disturbance of the MC. Once the MC was disturbed, the MC layer became ore primitive or disappeared entirely, resulting in a 32.8% decrease in the fine particles content of the upper soil layers, a 28.7% increase in soil albedo and a 168.9% decrease in the topsoil's water-retention capacity. These changes greatly altered soil hydrological processes in the disturbed soils: the steady-state infiltration rates in the upper soil layer increased by 693%, the precipitation recharge layer deepened, and the surface evaporation rate decreased by 20.3%. Moreover, the disturbance increased storage of plant-available water in the herbaceous rooting zone and improved the environment for germination and subsequent growth of annual herb species, as shown by a notable increase in the coverage, density, frequency, and biomass of annual plants. We conclude that MC represent a major component of Shapotou's regional ecosystem and that disturbance will significantly alter local ecohydrological processes.

SCS-CN방법을 이용한 평창강 유역의 강수 함양량 선정

The methodology developed by Soil Conservation Service for determination of runoff value from precipitation is applied to estimate the precipitation recharge in the Pyungchang river basin. Two small areas of the basin are selected for this study. The CN values are determined by considering the type of soil, soil cover and land use with the digital map of 1:25,000. Forest covers more than <TEX>$94{\%}$</TEX> of the study area.. The CN values for the study area vary between 47 in the forest area and 94 in the bare soil under AMC 2 condition. The precipitation recharge rate is calculated for the year when the precipitation data is available since 1990. To obtain the infiltration rate, the index of CN and five day antecedent moisture conditions are applied to each precipitation event during the study period. As a result of estimation, the value of precipitation recharge ratio in the study area vary between <TEX>$15.2{\%}\;and\;35.7{\%}$</TEX> for the total precipitation of the year. The average annual precipitation recharge rate is <TEX>$26.4{\%}\;and\;26.8{\%}$</TEX>, meaning 377.9mm/year and 397.5mm/year in each basin.

Using remote sensing to regionalize local precipitation recharge rates obtained from the Chloride Method

Water supply in semiarid Botswana is, to a large extent, based on groundwater. In the planning of a groundwater abstraction scheme, criteria for the sustainability of the abstraction with respect to both quantity and quality have to be satisfied. The most important parameter in the context of quantitative sustainability is the long-term average groundwater recharge together with its spatial distribution. A method is developed to calculate a recharge map that can be used in a groundwater model. The relative distribution of recharge is obtained from remotely sensed data and then calibrated with local values of recharge derived from the Chloride Method. The method was tested for two sites in Botswana, the Chobe Region and Ngamiland.

Using remote sensing to regionalize local precipitation recharge rates obtained from the Chloride Method

Using remote sensing to regionalize local precipitation recharge rates obtained from the Chloride Method

EFFECTS OF A SEVERE DROUGHT ON GROWTH AND WOOD ANATOMICAL PROPERTIES OF QUERCUS FAGINEA

We studied the growth response to drought of a Quercus faginea Lam. stand in a xeric site in NE Spain, that experienced an intense defoliation in 1993–94. This event coincided with very low precipitation from November to February, the period when total monthly precipitation exceeds evapotranspiration. We evaluated the effects of November–February precipitation (recharge precipitation, RP) on internode length, radial growth, and wood anatomy. Quercus faginea showed reduced longitudinal and radial growth during the years with low RP, and most sampled trees did not produce latewood in 1993–94 but showed wide earlywood vessels. We observed the reverse for years with a high RP. Radial growth was enhanced by increased precipitation during January and May of the growth year. If severe droughts become more frequent, due to a greater climatic variability, extensive dieback of marginal Q. faginea populations may be expected.

Groundwater flow, heat transport, and water table position within volcanic edifices: Implications for volcanic processes in the Cascade Range

The position of the water table within a volcanic edifice has significant implications for volcano hazards, geothermal energy, and epithermal mineralization. We have modified the HYDROTHERM numerical simulator to allow for a free‐surface (water table) upper boundary condition and a wide range of recharge rates, heat input rates, and thermodynamic conditions representative of continental volcano‐hydrothermal systems. An extensive set of simulations was performed on a hypothetical stratovolcano system with unconfined groundwater flow. Simulation results suggest that the permeability structure of the volcanic edifice and underlying material is the dominant control on water table elevation and the distribution of pressures, temperatures, and fluid phases at depth. When permeabilities are isotropic, water table elevation decreases with increasing heat flux and increases with increasing recharge, but when permeabilities are anisotropic, these effects can be much less pronounced. Several conditions facilitate the ascent of a hydrothermal plume into a volcanic edifice: a sufficient source of heat and magmatic volatiles at depth, strong buoyancy forces, and a relatively weak topography‐driven flow system. Further, the plume must be connected to a deep heat source through a pathway with a time‐averaged effective permeability ≥1 × 10−16 m2, which may be maintained by frequent seismicity. Topography‐driven flow may be retarded by low permeability in the edifice and/or the lack of precipitation recharge; in the latter case, the water table may be relatively deep. Simulation results were compared with observations from the Quaternary stratovolcanoes along the Cascade Range of the western United States to infer hydrothermal processes within the edifices. Extensive ice caps on many Cascade Range stratovolcanoes may restrict recharge on the summits and uppermost flanks. Both the simulation results and limited observational data allow for the possibility that the water table beneath the stratovolcanoes is relatively deep.

Contribution of storms to groundwater recharge in the semi‐arid region of Karnataka, India

AbstractThis paper describes the application of environmental isotopes and injected tracer techniques in estimating the contribution of storms as well as annual precipitation to groundwater recharge and its circulation, in the semi‐arid region of Bagepalli, Kolar district, Karnataka. Environmental isotopes 2H, 18O and 3H were used to study the effect of storms on the hydrological system, and an isotope balance was used to compute the contribution of a storm component to the groundwater. Some of the groundwater samples collected during the post‐storm periods were highly depleted in stable isotope content with higher deuterium excess relative to groundwater from the pre‐storm periods. Significant variation in deuterium excess in groundwater from the same area, collected in two different periods, indicates the different origin of air masses. The estimated recharge component of a storm event of 600 mm to the groundwater was found to be in the range of 117–165 mm. There was no significant variation in environmental tritium content of post‐storm and pre‐storm groundwater, indicating the fast circulation of groundwater in the system. After completion of the environmental isotope work, an injected radiotracer 3H technique was applied to estimate the direct recharge of total precipitation to the groundwater. The estimated recharge to the groundwater is 33 mm of the 550 mm annual precipitation during 1992. Copyright © 2003 John Wiley &amp; Sons, Ltd.

GEOLOGICAL AND CLIMATIC CONTROLS ON STREAMFLOWS IN THE NEBRASKA SAND HILLS1

ABSTRACT: This paper presents hydrological characteristics of the streamflow of the Dismal, Middle Loup, North Loup, and Cedar Rivers in the Nebraska Sand Hills and their relation to climate and ground water variation. Time series of streamflow, precipitation, temperature, and ground water levels from 1976 to 1998 were used to analyze trends and fluctuations of streamflow and to determine relationships among streamflow, climate, and the ground water system. An increase of precipitation and a decrease of maximum temperature over the period resulted in higher ground water levels and increased streamflow in the region. The high permeability of the soil and the thick unsaturated zone enhance precipitation recharge, limit surface runoff, and prevent ground water losses through evapotranspiration. Thus, an abundance of ground water is stored, supplying more than 86 percent of streamflow in the four rivers. Streamflow is generally more constant in the Sand Hills than elsewhere in the region. The four rivers present different hydrologic characteristics because of the spatial heterogeneity in hydrogeologic conditions. Streamflow of the Dismal and Middle Rivers, which are less sensitive to climatic variation, is much steadier than that of the North Loup and Cedar Rivers.

Statistical evaluation of geochemical parameter distribution in a ground water system contaminated with petroleum hydrocarbons.

A shallow-depth ground water area was investigated to identify the dominant processes governing the distribution of hydrocarbon contaminants and hydrogeochemical parameters. The ground water in the study site has been highly contaminated with petroleum hydrocarbons. A preliminary pump-and-treatment remediation technology was applied for 4 yr at the site. Multivariate analyses were applied to hydrogeochemical data obtained before and after the rainy season. The pump-and-treatment application, indigenous biodegradation, and mixing by precipitation recharge are the major factors or events involved in the distribution of geochemical parameters of the ground water in the study area. Site-specific artificial pavement also played an important role in the evolution of the ground water chemistry. A conventional graphical analysis method (Piper plot) of major ions did not effectively reveal these effects. In this study, we demonstrate the usefulness of multivariate analysis (factor and cluster analyses) using biodegradation indicator parameters, as well as major cations and anions, for the study of the ground water system in the hydrocarbon-contaminated site.

87Sr/86Sr as a tracer of groundwater discharge and precipitation recharge in the Glacial Lake Agassiz Peatlands, northern Minnesota

A contrast in the 87Sr/86Sr ratio of atmospherically derived Sr (∼0.710) and Sr from regional bedrock (&gt;0.730) allows quantification of the proportions of precipitation recharge and groundwater discharge into peat columns of bogs and fens in the Glacial Lake Agassiz Peatlands. Two contrasting bog‐fen pairs were studied: the Lost River peatland located over a regional groundwater discharge zone and the Red Lake peatland situated atop a hydrologic divide where recharge is expected to occur. Bog pore waters consist of 90–100% precipitation in the upper 2 m, below which they mix with groundwater. Adjacent fens consist mostly of groundwater, ranging from ∼30% near the surface to ∼100% with depth. At the Red Lake peatland, mixing relations suggest an additional Sr source that may be peat mineralization. Distinct 87Sr/86Sr and [Ca]/[Sr] ratios for groundwater discharging into bog and fen sites are indicative of distinct groundwater sources and are likely indicative of flow paths at two different length scales.

Nitrate and chloride concentrations in the high plains aquifer, Texas

Groundwater nitrate and chloride concentrations were compiled for 122 wells in a rural, three‐county area of northwest Texas. The counties are located on the High Plains aquifer, a major source of groundwater in the region. Cropland/pasture is the predominant land use in the study area. The area also contains numerous cattle feedlots. Fertilizer and manure associated with those land uses are potential sources of ground‐water contamination. Although locally elevated above background levels, none of the chemical concentrations exceeded the primary drinking water standard of 44.27 mg/L for nitrate (10mg/L for NO3 — N) or secondary standard of 250mg/L for chloride. Rank correlations between nitrate and chloride were statistically significant in two of the three counties, where the solutes may have originated from a common surface source. Denitrification and scant precipitation recharge may account for an absence of nitrate levels above the drinking water standard.

Estimation of the effective precipitation recharge coefficient in an unconfined aquifer using stochastic analysis

Effectively managing groundwater relies heavily on estimating the amount of precipitation that may infiltrate the subsurface and supply groundwater. In this study, we present a novel estimation method based on a stochastic approach to evaluate the quantity of precipitation that may recharge groundwater. The precipitation recharge coefficient is also investigated based on an unconfined aquifer with an unbound, infinitely extended boundary condition. Moreover, a spectrum's relationship to the precipitation and groundwater level variation is also derived. The precipitation recharge coefficient can be obtained from the solution of the spectrum equation. Furthermore, sensitivity analysis is performed in order to determine the key variable on the precipitation recharge coefficient. Analysis results indicate that the location of an observation well affects the estimated precipitation recharge coefficient. If the precipitation recharge area is large enough, the precipitation recharge coefficient becomes insensitive to the location of the observation well. The spectrum's relationship between the precipitation recharge and groundwater level variation is also applied when estimating the precipitation recharge coefficient upstream of the Cho-Shui River alluvial fan. According to those results, the precipitation recharge coefficient is 0·03 and the amount of groundwater recharge from precipitation is 35 million tons of water annually upstream of the Cho-Shui River alluvial fan. Copyright © 2000 John Wiley & Sons, Ltd.

Soil moisture gradients and controls on a southern Appalachian hillslope from drought through recharge

Abstract. Soil moisture gradients along hillslopes in humid watersheds, although indicated by vegetation gradients and by studies using models, have been difficult to confirm empirically. While soil properties and topographic features are the two general physio-graphic factors controlling soil moisture on hillslopes, studies have shown conflicting results regarding which factor is more important. The relative importance of topographic and soil property controls was examined in an upland forested watershed at the Coweeta Hydrologic Laboratory in the southern Appalachian mountains. Soil moisture was measured along a hillslope transect with a mesic-to-xeric forest vegetation gradient over a period spanning precipitation extremes. The hillslope was transect instrumented with a time domain reflectometry (TDR) network at two depths. Soil moisture was measured during a severe autumn drought and subsequent winter precipitation recharge. In the upper soil depth (0-30 cm), moisture gradients persisted throughout the measurement period, and topography exerted dominant control. For the entire root zone (0-90 cm), soil moisture gradients were found only during drought. Control on soil moisture was due to both topography and storage before drought. During and after recharge, variations in soil texture and horizon distribution exerted dominant control on soil moisture content in the root zone (0-90 cm). These results indicate that topographic factors assert more control over hillslope soil moisture during drier periods as drainage progresses, while variations in soil water storage properties are more important during wetter periods. Hillslope soil moisture gradients in southern Appalachian watersheds appear to be restricted to upper soil layers, with deeper hillslope soil moisture gradients occurring only with sufficient drought.

Cálculo de la recarga natural de un acuífero a partir del hidrograma del manantial. Aplicación al manantial de Vozmediano

A method is developed for calculating the natural recharge of an aquifer from the hydrograph of the spring, using a closed multiple cell model. Iterative formulae for modeling are given together with the calibration phases. This methodology is applied to the spring at Vozmediano. The net recharge of precipitation is 37 %, for the average precipitation in the Vozmediano system (714 mm/yr). The results are compared to independent methods of estimating recharge.

Land use and groundwater quality in the Trinity Group outcrop of North-Central Texas, USA

Concentrations of nitrate, chloride, and bromide in groundwater were obtained for 57 wells in a rural, three-county area of north-central Texas. The counties straddle the outcrop of the Trinity Group, an important source of groundwater in the region. Predominant land uses in the area are cropland/pasture and rangeland. The highest nitrate concentrations were associated with cropland/pasture. In general, nitrate concentrations increased as well depth decreased. However, well depth did not influence chloride or bromide concentrations. Outliers were as high as 1.3 g/L for chloride and 8.40 mg/L for bromide. There are numerous oil and gas wells in the study area, which may account for elevated chloride and bromide concentrations. Neither chloride nor bromide was correlated with nitrate, but they were strongly correlated with each other. Dry farming and scant precipitation recharge may account for an absence of nitrate levels above the drinking water standard (45 mg/L). Collectively, the results suggest that agricultural fertilizer and oil field brine are likely sources of groundwater contamination in the study area.

Springs in Spain: Classification According to Their Flows and Lithologies and Their Hydraulic Contributions

AbstractThis paper presents an approach to regional hydrological balance where the number and integrated discharge of springs are used to estimate recharge. This technique is applied to Spain, where approximately two‐thirds of the country has an inventory of spring lithology and discharge (17,000 springs). The data are used to extrapolate results to the entire region and are compared to independent methods of estimating recharge. This is an informative use of commonly available information and it could be applied to other regions with a similar data base.From this sample, a distribution of the spring flow volume contribution in Spain is estimated (a) according to flow spring discharge, (b) as a limit of a lognormal distribution, which in our sample is simplified in a potential formula a(x) = 24,101.x −0.91. In this way it is calculated that the total flow volume of the springs is 14,877 hm3/yr. The study does not take into account seepage (diffuse discharge) draining to seas, rivers, or lakes but only water at the spring source. The most permeable lithological groups considered are the source of 94.2% of the total flow supplied by the springs. Limestone is especially significant, contributing 66.2%. The net recharge of precipitation to ground water varies widely according to lithologies. It reaches to 20.3% in limestones and drops to less than 1% for quartzites, slates, and plutonic rocks.

Preliminary Assessment of the Occurrence and Possible Sources of MTBE in Groundwater in the United States, 1993−1994

The 1990 Clean Air Act Amendments require fuel oxygenates to be added to gasoline used in some metropolitan areas to reduce atmospheric concentrations of carbon monoxide or ozone. Methyl tert-butyl ether (MTBE) is the most commonly used fuel oxygenate and is a relatively new gasoline additive. Nevertheless, out of 60 volatile organic chemicals analyzed, MTBE was the second most frequently detected chemical in samples of shallow ambient groundwater from urban areas that were collected during 1993-1994 as part of the U.S. Geological Survey's National Water-Quality Assessment program. Samples were collected from five drinking water wells, 12 springs, and 193 monitoring wells in urban areas. No MTBE was detected in drinking water wells. At a reporting level of 0.2 μg/L, MTBE was detected most frequently in shallow groundwater from urban areas (27% of 210 wells and springs sampled in eight areas) as compared to shallow groundwater from agricultural areas (1.3% of 549 wells sampled in 21 areas) or deeper groundwater from major aquifers (1.0% of 412 wells sampled in nine areas). Only 3% of the shallow wells sampled in urban areas had concentrations of MTBE that exceed 20 μg/L, which is the estimated lower limit of the United States Environmental Protection Agency draft drinking water health advisory. Because MTBE is persistent and mobile in groundwater, it can move from shallow to deeper aquifers with time. In shallow urban groundwater, MTBE generally was not found with benzene, toluene, ethylbenzene, or xylene (BTEX) compounds, which commonly are associated with gasoline spills. This disassociation causes uncertainty as to the source of MTBE. Possible sources of MTBE in groundwater include point sources, such as leaking storage tanks, and non-point sources, such as recharge of precipitation and stormwater runoff.