Contribution To Recharge Research Articles

Interbasin flow in the Great Basin with special reference to the southern Funeral Mountains and the source of Furnace Creek springs, Death Valley, California, U.S.

summary Interbasin flow in the Great Basin has been established by scientific studies during the past century. While not occurring uniformly between all basins, its occurrence is common and is a function of the hydraulic gradient between basins and hydraulic conductivity of the intervening rocks. The Furnace Creek springs in Death Valley, California are an example of large volume springs that are widely accepted as being the discharge points of regional interbasin flow. The flow path has been interpreted historically to be through consolidated Paleozoic carbonate rocks in the southern Funeral Mountains. This work reviews the preponderance of evidence supporting the concept of interbasin flow in the Death Valley region and the Great Basin and addresses the conceptual model of pluvial and recent recharge [Nelson, S.T., Anderson, K., Mayo, A.L., 2004. Testing the interbasin flow hypothesis at Death Valley, California. EOS 85, 349; Anderson, K., Nelson, S., Mayo, A., Tingey, D., 2006. Interbasin flow revisited: the contribution of local recharge to high-discharge springs, Death Valley, California. Journal of Hydrology 323, 276–302] as the source of the Furnace Creek springs. We find that there is insufficient modern recharge and insufficient storage potential and permeability within the basin-fill units in the Furnace Creek basin for these to serve as a local aquifer. Further, the lack of high sulfate content in the spring waters argues against significant flow through basin-fill sediments and instead suggests flow through underlying consolidated carbonate rocks. The maximum temperature of the spring discharge appears to require deep circulation through consolidated rocks; the Tertiary basin fill is of insufficient thickness

Recharge sources and hydrogeochemical evolution of groundwater in semiarid and karstic environments: A field study in the Granada Basin (Southern Spain)

Abstract The objective of this study is to refine the understanding of recharge processes in watersheds representative for karstic semiarid areas by means of stable isotope analysis and hydrogeochemistry. The study focuses on the Granada aquifer system which is located in an intramontane basin bounded by high mountain ranges providing elevation differences of almost 2900 m. These altitude gradients lead to important temperature and precipitation gradients and provide excellent conditions for the application of stable isotopes of water whose composition depends mainly on temperature. Samples of rain, snow, surface water and groundwater were collected at 154 locations for stable isotope studies (δ18O, D) and, in the case of ground- and surface waters, also for major and minor ion analysis. Thirty-seven springs were sampled between 2 and 5 times from October 2004 to March 2005 along an altitudinal gradient from 552 masl in the Granada basin to 2156 masl in Sierra Nevada. Nine groundwater samples were taken from the discharge of operating wells in the Granada basin which are all located between 540 and 728 masl. The two main rivers were monitored every 2–3 weeks at three different altitudes. Rainfall being scarce during the sampling period, precipitation could only be sampled during four rainfall events. Calculated recharge altitudes of springs showed that source areas of mainly snowmelt recharge are generally located between 1600 and 2000 masl. The isotope compositions of spring water indicate water sources from the western Mediterranean as well as from the Atlantic without indicating a seasonal trend. The isotope pattern of the Quaternary aquifer reflects the spatial separation of different sources of recharge which occur mainly by bankfiltration of the main rivers. Isotopic signatures in the southeastern part of the aquifer indicate a considerable recharge contribution by subsurface flow discharged from the adjacent carbonate aquifer. No evaporation effects due to agricultural irrigation were detected.

Modeling approach for the assessment of recharge contribution to groundwater from surface irrigation conveyance system

Rice–Wheat rotation system utilizes surface, ground and rain water resources conjunctively. Recent studies have shown increasing contribution of groundwater for crop irrigation. As the system utilizes water pumped from the underlying aquifer and partly seeps back, a cycle of recharge and discharge continues. Sustainability of groundwater system for the on-going drought in the country depends mainly on the recharge of the aquifer. The reported study was, therefore, carried out to measure and assess the recharge contribution of a distributary of canal in Punjab, Pakistan. Assessment of recharge through distributary was carried out using a groundwater flow “MODFLOW” model, which utilized the observed watertable, climatic, crop and soil for a period of about 1 year in addition to hydraulic conductivity, evapotranspiration and aquifer characteristics data. The requisite primary data for “MODFLOW” were collected from field and secondary data from public sector organizations dealing with water. Model calibration involved changing input parameters within reasonable limits until acceptable matches were obtained between the observed and simulated water levels for all observed hydrographs. The external inputs such as, recharge through irrigation, precipitation, stresses due to evaporation, lateral flow and stream were simulated to calculate the monthly water budget of aquifer. As concluded, recharge contribution was 16.5% of the inflow rate of the distributary. Using predicted results of the model a relationship between recharge (R) and discharge (Q) was also developed. Although, the presented results of recharge contribution were limited to one distributary of canal irrigation system, yet the developed methodology can be extended to the other canal systems of the Indus Basin.

Distinguishing Sources of Ground Water Recharge by Using δ2H and δ18O

Stable isotope values of hydrogen and oxygen from precipitation and ground water samples were compared by using a volumetrically based mixing equation and stable isotope gradient to estimate the season and location of recharge in four basins. Stable isotopes were sampled at 11 precipitation sites of differing elevation during a 2-year period to quantify seasonal stable isotope contributions as a function of elevation. Supplemental stable isotope data collected by the International Atomic Energy Association during a 14-year period were used to reduce annual variability of the mean seasonal stable isotope data. The stable isotope elevation relationships and local precipitation elevation relationships were combined by using a digital elevation model to calculate the total volumetric contribution of water and stable isotope values as a function of elevation within the basins. The results of these precipitation calculations were compared to measured ground water stable isotope values at the major discharge points near the terminus of the basins. Volumetric precipitation contributions to recharge were adjusted to isolate contributing elevations. This procedure provides an improved representation of recharge contributions within the basins over conventional stable isotope methods. Stable isotope values from wells and springs at the terminus of each basin were used to infer the elevations of precipitation important for recharge of the regional ground water flow system. Ancillary climatic, geologic, and stable isotope values were used to further constrain the location where precipitation is entering the ground water flow system.

Using fossil spring deposits in the Death Valley region, USA to evaluate palaeoflowpaths

AbstractSpring deposits reveal the timing and environment of past groundwater discharge. Herein, however, the potential for fossil spring deposits to infer water sources and palaeoflowpaths through trace elements and stable and radiogenic isotopes is examined.Past discharge (70 to 285 ka) in the Tecopa Basin in the Death Valley region of southeastern California is represented by tufa deposits, including mounds, pools, cemented ledges and rare calcite feeder veins. δ18O values indicate that spring discharge was a mixture of far‐travelled (regional) water with a significant, and perhaps dominant contribution of local recharge on a nearby range front and alluvial pediment, rather than simply representing an elevated regional water table. δ13C values indicate regional water had a high TDS, whereas solute data imply low overall solute contents, consistent with dilution by a large component of local recharge.Radiogenic isotope data (U‐series, 87Sr/86Sr) for tufa indicate that siliciclastic rocks (a regional aquitard) interacted with discharging water. To access this aquitard, regional flow was probably partitioned into a permeable north–south damage zone of a north–south range‐bounding fault along the foot of the Resting Spring Range, which ultimately controlled the location of groundwater discharge. Existing models for modern discharge in the Tecopa Basin, by contrast, call upon westward interbasin flow in carbonate rocks from the Spring Mountains through the intervening (and nearly perpendicular) Nopah and Resting Spring Ranges. Understanding the controls on regional groundwater flow is critical in this and other arid regions where water is, by definition, a scarce resource. Thus, although it is a case study, this report highlights a fruitful approach to palaeohydrology that can be widely applied. Copyright © 2007 John Wiley & Sons, Ltd.

Interbasin flow revisited: The contribution of local recharge to high-discharge springs, Death Valley, CA

Springs in the Furnace Creek area (Texas, Travertine, and Nevares Springs) of Death Valley National Park exhibit high discharge rates and depleted δ 18O VSMOW (∼−13‰) and δD VSMOW (∼−102‰) values. Isotopic depletion of this magnitude and large spring fluxes (∼10,000 L/min) suggests that modern local recharge in the arid Furnace Creek drainage cannot be responsible for spring fluxes. An alternate explanation, interbasin flow, is difficult to envisage due to the stratigraphic and structural relationships of bedrock in intervening ranges, although it is the most common conceptual model for Furnace Creek spring flows. High-flux springs at Furnace Creek nonetheless respond modestly to modern climate in terms of discharge rate and isotopic composition. Hydrographs show a climate response and variations in time-series stable isotope data of widely spaced springs track one another. Small, but measurable quantities of tritium (<0.2 TU) were found at Nevares Spring, also suggesting a component of modern recharge. Thus, whatever the main source of water for these springs may be, there appears to be a subtle, but recent climatic influence. Estimates of flow at nearby mountain springs produce discharge rates per square kilometer of catchment that, by analogy, could support from 20 to 300% of the flow at large Death Valley springs under the current climate. Yet, 14C model ages suggest valley-bottom springs at Furnace Creek (5500–14,500 yr) contain a large component of older water, suggesting that much of the water was recharged during a pluvial period (Younger Dryas?) when net infiltration would have been much higher and isotopically depleted. 14C model ages are also of similar age, or younger, than many ‘up gradient’ waters, rather than being older as would be expected for interbasin flow. Chemical evolution models of solutes are consistent with both local recharge and interbasin transfer from Ash Meadows. However, when considered with isotopic constraints, interbasin flow becomes obviously untenable. Estimates of the thickness of alluvium and semi-consolidated Tertiary units in the Furnace Creek drainage seem to provide adequate storage, confinement, and upward leakage to accommodate current discharge. Thus, although Death Valley is the ultimate discharge location for regional groundwaters in terms of potential, careful study of these springs suggests that most of their flux is supported by local pluvial recharge, suggesting that a careful re-evaluation of the interbasin transfers be conducted on a case-by-case basis. Furthermore, regional flow models that are built on the concept of interbasin flow provide boundary flux conditions for site-scale models for the proposed nuclear waste repository at Yucca Mountain, Nevada. Thus, site-scale models may over-predict the potential transport of waste from the Yucca Mountain facility.

ESTIMATING RECHARGE FOR BRITISH AQUIFERS

This paper reviews methods of estimating recharge for a wide variety of aquifers in Britain. A soil moisture balance technique is used with direct representation of relevant soil and crop properties. Recharge contributions due to rainfall, runoff from impervious areas and leaking water mains and sewers are considered. In many field situations low permeability strata, which overlie the main aquifer, modify the timing and magnitude of the actual recharge. Runoff from less permeable strata can become runoff-recharge at the aquifer outcrop. Reference is made to several case studies.

Hydrogeological investigations on Balçova geothermal system in Turkey

The Balçova geothermal system is situated within the confines of Izmir City, Turkey. It is located along the Izmir Fault zone, trending E–W. It has formed a hot water reservoir that is currently exploited for district heating of the nearby Balçova-Narlidere area. Geoscientific studies on the area around the Balçova geothermal field indicate that regional tectonics coupled with a major fault system has created NW–N–NE trending permeable pathways for a geothermal system, starting from a delimited intake area on the Seferihisar Horst in the south to the outflowing area in the north. The Balçova geothermal system is a fracture zone system in which hot water ascends over an area of about 2 km along a major fracture zone associated with the Agamemnon Fault, reaching almost boiling temperatures close to the surface. The hot water discharges via two concealed horizontal flows, one in the alluvium (upper 100 m) and another deeper one in more permeable, ill-defined layers in the flysch formation between 400 and 700 m depth. The two concealed outflows and the steeply dipping fracture zone constitute the presently exploited reservoir, which extends for as much as 1.5 km from the feeding fracture zone. The natural direct discharge of the system was 2.5 kg/s; the surface heat discharge of the system is estimated at a minimum of 9.5 MW t. The average max. total production rate of all the production wells was 135 kg/s during the 2000–2001 heating season. The contribution of recharge to Balçova geothermal field production was estimated at about 50 kg/s.

Distribution of oxygen and hydrogen isotopes in shallow groundwaters from Southern India: influence of a dual monsoon system

Oxygen and hydrogen isotopic investigation of groundwater and river water samples from the southern Indian peninsula was undertaken to characterise the isotopic nature of the near surface water sources and provide basic framework for future hydrological studies. It is assumed that the shallow groundwater retains the isotopic signature of the local precipitation averaged over a few tens of years except in a few cases where the same gets modified by post precipitation evaporation and/or recharge contribution from surface water bodies. Therefore, isotopic character of the groundwater can, in principle, be used to determine the relative influence of the different vapour sources contributing to the local/regional precipitation and to characterise the modifications before groundwater recharge. In the present context, vapour sources for two rainy seasons, namely, southwest (SW) and northeast (NE) monsoon, are respectively, the Indian Ocean/Arabian Sea and the Asian continental sources together with the Bay of Bengal. This study shows that: (i) The regions dominated by NE monsoon have distinctly depleted isotopic composition compared to those dominated by SW monsoon. (ii) The δ 18O–δD regression line slope of ∼6 in the east coast region is lower than that expected for local precipitation suggesting secondary evaporation. (iii) The orography of the Western Ghats hill ranges plays a significant role in controlling the isotopic distribution along the west coast region. (iv) The low ‘d-excess’ values in most part of study area indicate secondary evaporation. (v) The high ‘d-excess’ values over the Deccan Plateau region in the NW part of the study area suggest admixture of recycled moisture with the inflowing oceanic vapour.

Drainage of Sloping Lands with Variable Recharge: Analytical Formulas and Model Development

Semianalytical transient equations for shallow subsurface transverse drainage systems installed in sloping lands are developed. They provide a general relationship between drain flow rates, water table elevations, and recharge rates. This relationship demonstrates that, depending on the recharge intensity, several drain flow rates can be observed at a given water table elevation. The recharge contribution is shown to depend on a water table shape factor and to decrease when the water table is low or the slope is steep. For very steep slopes, the recharge intensity no longer influences the drain flow rate. These equations can be used to confirm previous results obtained in steady-state conditions and to determine precisely under which conditions slope needs to be considered in drainage design. They have been incorporated into the field drainage model SIDRA, which simulates hourly values of water table elevations and drain flow rates. The model predictions are compared with the predictions of a steady-state equation and a numerical model, which solves the Boussinesq equation (SLOP model).

Tracing Ground Water Recharge in an Agricultural Watershed with Isotopes

AbstractNitrate and pesticide use in the 800 km2 Raisin River agricultural watershed in eastern Ontario, Canada, threatens the quality of ground water in the highly exploited regional carbonate aquifer overlain by sandy till. To assess local recharge contributions through the cultivated fields, monthly monitoring of ground water levels, geochemistry, and environmental isotopes (δ2H H2O, (δ13CDIC) was carried out for 12 wells over a 14‐month period.Seasonal water level variations suggest that recharge is constrained to spring and late fall when transpiration is minimized and the ground is not frozen. However,2H monitoring shows that early summer precipitation also contributes to recharge. Variations in (δ2H values between monitoring sites suggest a local component to recharge.δ13CDIC was used to distinguish between dissolved inorganic carbon (DIC) originating from natural (C3) vegetation and DIC from the cultivated corridors where corn is grown (C 4 vegetation). Seasonal variations in δ13CDIC are remarkably coherent for all wells, with uniform trends to positive values during periods of low water table elevation. During periods of high water table (spring and late fall), δ13CDIC values are between ‐13 and ‐ 16%c VPDB (Vienna Peedee Belemnite), reflecting DIC originating from a dominantly natural (C3) vegetation. When ground water levels are low (summer and mid‐winter), δ13CDIC values shift to between ‐11 and ‐l%c. The seasonal enrichments in δ13CDIC are clear evidence for a local contribution to recharge by direct infiltration though the fields. This contribution is enhanced during periods of low water level, likely due to drainage from the phreatic aquifer. High DOC (dissolved organic carbon) concentrations (&gt; 10 to 30 mg‐C/L) correlate with periods of high water levels indicating infiltration of labile organics to the carbonate aquifer.The work carried out for this paper shows that the conjunctive use of environmental isotope geochemistry and physical parameters are fundamental to assessing the risk of ground water contamination in agricultural watersheds.

Uncertainty in recharge estimation: impact on groundwater vulnerability assessments for the Pearl Harbor Basin, O'ahu, Hawai'i, U.S.A.

In this paper, uncertainty in recharge estimates is investigated relative to its impact on assessments of groundwater contamination vulnerability using a relatively simple pesticide mobility index, attenuation factor (AF). We employ a combination of first-order uncertainty analysis (FOUA) and sensitivity analysis to investigate recharge uncertainties for agricultural land on the island of O'ahu, Hawai'i, that is currently, or has been in the past, under sugarcane or pineapple cultivation. Uncertainty in recharge due to recharge component uncertainties is 49% of the mean for sugarcane and 58% of the mean for pineapple. The components contributing the largest amounts of uncertainty to the recharge estimate are irrigation in the case of sugarcane and precipitation in the case of pineapple. For a suite of pesticides formerly or currently used in the region, the contribution to AF uncertainty of recharge uncertainty was compared with the contributions of other AF components: retardation factor (RF), a measure of the effects of sorption; soil-water content at field capacity (ΘFC); and pesticide half-life (t1/2). Depending upon the pesticide, the contribution of recharge to uncertainty ranks second or third among the four AF components tested.The natural temporal variability of recharge is another source of uncertainty in AF, because the index is calculated using the time-averaged recharge rate. Relative to the mean, recharge variability is 10%, 44%, and 176% for the annual, monthly, and daily time scales, respectively, under sugarcane, and 31%, 112%, and 344%, respectively, under pineapple. In general, uncertainty in AF associated with temporal variability in recharge at all time scales exceeds AF. For chemicals such as atrazine or diuron under sugarcane, and atrazine or bromacil under pineapple, the range of AF uncertainty due to temporal variability in recharge encompasses significantly higher levels of leaching potential at some locations than that indicated by the AF estimate.

Sources and flow of north Canterbury plains groundwater, New Zealand

Geological, hydrological, isotope (tritium and 18O) and chemical (mainly nitrate and chloride concentrations) evidence is interpreted to give a mutually consistent picture of the recharge sources and flow patterns of the important groundwater resource in the deep glacial and interglacial deposits of the sector of the Canterbury Plains between the Selwyn River and Ashley River. Particular attention is paid to the confined gravel aquifers which presently provide about 300,000 m 3 daily of mainly very high-quality water for the needs of Christchurch city. The study period for tritium measurements extends over 27 years, encompassing the peak and decline of thermonuclear tritium fallout in this region. Major rivers emerging from the hill and mountain catchments to the west of the Plains are depleted in 18O relative to average low-level precipitation. Most of the groundwater is river-recharged, but some areas of significant local precipitation recharge contribution are clearly identified by 18O and chemical concentrations. The pressure distribution, tritium and chemical data reveal that the artesian ground-water underlying Christchurch ascends from deeper aquifers into the shallowest aquifer via gaps in the confining layers; much of this flow is induced by withdrawal, and the data reveal nothing about possible offshore discharge through the seaward extension of the shallowest aquifer, which is known to outcrop 40 km beyond the coast. The Christchurch aquifers are recharged by infiltration from Waimakariri River in its central Plains reaches, and the resulting flow regime is east- and southeast-directed; satisfactory water quality of the deeper Christchurch aquifers appears to be guaranteed for the future provided the river can be maintained in its present condition. Shallow groundwater, and water recharged to depth by other rivers, irrigation and local precipitation on the unconfined western areas of the Plains, are more susceptible to agricultural and other pollutants; none of this water is encountered in the deeper aquifers under Christchurch, but only in shallow aquifers and surface discharges, or else flowing to the southeast, well away from the city area.