Decreasing Water Table Research Articles

Spatiotemporal evolution characteristics study on the precipitation infiltration recharge over the past 50 years in the North China Plain

The spatiotemporal evolution characteristics of precipitation infiltration recharge during the past 50 years are discussed in this paper. This research is significant for groundwater resource rational utilization. The distribution of precipitation infiltration recharge coefficients in the 1960s, 1980s, and 2000s can be obtained using unsaturated zone lithology and depth to water table at different times. The amount of precipitation infiltration recharge in the 1960s, 1980s, and 2000s can be calculated using precipitation infiltration recharge coefficients and precipitation data from the Ministry of Water Resources of China. Results show that the change in the precipitation infiltration recharge coefficient is closely related to the water table decrease. From the 1960s to the 1980s, the precipitation infiltration recharge coefficient clearly increased in all units. From the 1980s to the 2000s, the value slightly increased in the ancient Yellow River alluvial-proluvial and eastern alluvial-marine plains and slightly decreased in the piedmont alluvial-proluvial and central alluvial-lacustrine plains. The piedmont alluvial-proluvial and ancient Yellow River alluvial-proluvial plains exhibited a large precipitation infiltration recharge coefficient for the coarse lithology. The amounts of precipitation infiltration recharges were 16.23×109 (1960s), 19.11×109 (1980s), and 19.42×109 m3/a (2000s). The amount of precipitation infiltration recharge increased from the 1960s to the 1980s then decreased from the 1980s to the 2000s in the piedmont alluvial-proluvial and the central alluvial-lacustrine plains. However, this value increased from the 1960s to the 2000s in the ancient Yellow River alluvial-proluvial and eastern alluvial-marine plains.

Root plasticity of Populus euphratica seedlings in response to different water table depths and contrasting sediment types.

Riparian plants in arid regions face a highly variable water environment controlled by hydrological processes. To understand whether riparian plants adapt to such environments through plastic responses, we compared the root traits, biomass allocation and growth of Populus euphratica Oliv. Seedlings grown in lysimeters filled with clay or clay/river sand sediments under inundation and varying water table conditions. We hypothesized that adaptive phenotypic plasticity is likely to develop or be advantageous in seedlings of this species to allow them to adapt desert floodplain environments. Growth was significantly reduced by inundation. However, rather than following relatively fixed trait and allocation patterns, the seedlings displayed adaptive mechanisms involving the development of adventitious roots to enhance plant stability and obtain oxygen, together with a lower proportion of root biomass. At the whole-plant level, at deeper water table depths, seedlings allocated more biomass to the roots, and total root length increased with decreasing water table depths, regardless of the sediment, consistent with optimal partitioning theory. The sediment type had a significant effect on seedling root traits. P. euphratica displayed very different root traits in different sediment types under the same hydrological conditions, showing a greater first-order root number in clay sediment under shallower water table conditions, whereas rooting depth was greater in clay/river sand sediment under deep water table conditions. In clay sediment, seedlings responded to lower water availability via greater root elongation, while the root surface area was increased through increasing the total root length in clay/river sand sediment, suggesting that seedlings facing deeper water tables are not always likely to increase their root surface area to obtain more water. Our results indicate that P. euphratica seedlings are able to adapt to a range of water table conditions through plastic responses in root traits and biomass allocation.

Groundwater use by plants in a semi-arid coal-mining area at the Mu Us Desert frontier

The hydrogen isotope (deuterium-\( \delta D \)) composition at natural abundance levels of xylem water, soil water, groundwater, river water, and rainwater was used to evaluate whether adult plant species use groundwater and to detect seasonal shifts (dry/wet season) in water sources for plants growing in a semi-arid coal-mining area (located at the frontier of the Mu Us Desert). A direct inference approach and the IsoSource mixing model were used to estimate the contributions of different sources to the plant xylem water. The results showed that (1) the \( \delta D \) values of rainfall fluctuated considerably, while those of groundwater were generally constant during the experimental period; (2) the \( \delta D \) patterns in plant xylem water suggest that groundwater was a significant source of water for transpiration in the dry season, while all five selected species reduced dependence on groundwater sources in the wet season; and (3) soil water from the deep layer (50–100 cm) was used largely by adult species possibly because of interspecific competition. These results indicated that coal mining would significantly affect plant growth by reducing the water supply if it leads to a water table decrease. Therefore, it is necessary to protect groundwater resources during the coal mining operations in the region.

Application and evaluation of universal kriging for optimal contouring of groundwater levels

This paper deals with the application of universal kriging to interpolate water table elevations from their measurements at random locations. Geographic information system tools were used to generate the continuous surface of water table elevations for the Carlsbad area alluvial aquifer located to the southeast of New Mexico, USA. Water table elevations in the 38 monitoring wells that are common to 1996 and 2003 irrigation years follows normal distribution. A generalized MATLAB® code was developed to generate omni-directional and directional semi-variograms (at 22.5° intervals). Low-order polynomials were used to model the trend as the water table profile exhibits a south-east gradient. Different theoretical semi-variogram models were tried to select the base semi-variogram for performing geostatistical interpolation. The contour maps of water table elevations exhibit significant decrease in the water table from 1996 to 2003. Statistical analysis performed on the estimated contours revealed that the decrease in water table is between 0.6 and 4.5 m at 90% confidence. The estimation variance contours show that the error in estimation was more than 8 m2 in the west and south-west portions of the aquifer due to the absence of monitoring wells.

The effects of geological heterogeneities and piezometric fluctuations on groundwater flow and chemistry in a hard-rock aquifer, southern India

Crystalline aquifers of semi-arid southern India represent a vital water resource for farming communities. A field study is described that characterizes the hydrodynamic functioning of intensively exploited crystalline aquifers at local scale based on detailed well monitoring during one hydrological year. The main results show large water-table fluctuations caused by monsoon recharge and pumping, high spatial variability in well discharges, and a decrease of well yields as the water table decreases. Groundwater chemistry is also spatially variable with the existence of aquifer compartments within which mixing occurs. The observed variability and compartmentalization is explained by geological heterogeneities which play a major role in controlling groundwater flow and connectivity in the aquifer. The position of the water table within the fracture network will determine the degree of connectivity between aquifer compartments and well discharge. The presented aquifer conceptual model suggests several consequences: (1) over-exploitation leads to a drop in well discharge, (2) intensive pumping may contribute to the hydraulic containment of contaminants, (3) groundwater quality is highly variable even at local scale, (4) geological discontinuities may be used to assist in the location of drinking-supply wells, (5) modeling should integrate threshold effects due to water-table fluctuations.

Operational Prediction of Groundwater Fluctuation in South Florida using Sequence Based Markovian Stochastic Model

The ecosystem of South Florida is characterized by a vast wetland system, karst surficial hydrogeology, and extended coastal boundary. The ecosystem is poised under risks of: ecological failure due to increased fragmentation by urbanization; groundwater flow disruption because of sinkhole formation; and intrusion of oceanic water with decreasing water table head because of drought or over pumping. It was found important to synthesize the spatiotemporal state of the groundwater hydrology and also develop a forecasting model to support the intensive management and monitoring in place. In this study, an objective was set to develop a stochastic sequence model capable of forecasting groundwater levels on a monthly span at a daily time scale. The groundwater level simulation was conceptualized as a sequence of daily fluctuating states of magnitudes and patterns that has a defined probability of occurrence. The model setup involved representation of daily fluctuation magnitudes in ten states and pattern changes in three states. The sequential occurrence of states of magnitudes and patterns at each time step was used for estimation of the transitional probabilities and employed in a hidden Markov model frame work for ensemble generation and estimation of posterior probabilities. A realization was chosen based on the highest maximum likelihood ratio of 90% and smallest root mean square error of 0.05–0.12 m against the historical data. A monthly forecasting at daily time step was done dynamically incorporating observed data at each time step and revising prior and posterior probability estimation in the hidden Markov model formulation. A case study was conducted at three well sites, which are situated at three different hydrogeologic settings. The model not only reproduced annual groundwater fluctuation patterns but also forecasted preceding monthly fluctuations at maximum likelihood ratio above 90% and root mean square error below 0.15 m. A further study was recommended first to analyze break point parametric estimation for seasonal analysis, and secondly to integrate the approach in other hydrological models for the purpose of synthetic groundwater fluctuation generation.

Responses of CO2 flux components of Alaskan Coastal Plain tundra to shifts in water table

The Arctic stores close to 14% of the global soil carbon, most of which is in a poorly decomposed state as a result of water‐saturated soils and low temperatures. Climate change is expected to increase soil temperature, affecting soil moisture and the carbon storage and sink potential of many Arctic ecosystems. Additionally, increased temperatures can increase thermokarst erosion and flooding in some areas. Our goal was to determine the effects that water table shifts would have on the CO2 sink potential of the Alaskan Coastal Plain tundra. To evaluate the effects of different water regimes, we used a large hydrological manipulation at Barrow, Alaska, where we maintained flooded, drained, and intermediate water levels in a naturally drained thaw lake basin over a period of three seasons: one pretreatment (2006) and two treatment (2007–2008) seasons. To assess CO2 flux components, we used 24 h chamber‐based measurements done on a weekly basis. Increased water table strongly lowered ecosystem respiration (ER) by reducing soil oxygen availability. Flooding decreased gross primary productivity (GPP), most likely by submerging mosses and graminoid photosynthetic leaf area. A decrease in water table increased GPP and ER; however, the increase in root and microbial activity was greater than the increase in photosynthesis, negatively affecting net ecosystem exchange. In the short term, ER is the CO2 flux component that responds most strongly to changes in water availability. Our results suggest that drying of the Alaskan Coastal Plain tundra in the short term could double ER rates, shifting the historic role of some Arctic ecosystems from a sink to a source of CO2.

Nutrient stoichiometry in Sphagnum along a nitrogen deposition gradient in highly polluted region of Central-East Europe

We investigated the variation of N:P and N:K ratio in ombrotrophic Sphagnum plants along a gradient of atmospheric N deposition from 1 to 2.5 g m−2 year−1 in Central-East Europe. The N:P and N:K ratio in Sphagnum capitula increased significantly along the N deposition gradient. Sphagnum species from the Cuspidata section were characterised by significantly lower ratios at low N deposition. When we compared the observed N:P ratios in Sphagnum plants with the values reported in a previous European-wide study, we found a correspondence in nutrient stoichiometry only for a few bogs: higher P concentration in Sphagnum capitula caused a lower N:P ratio in most of the study bogs so that Sphagnum plants still seem N-limited despite their N saturation. Interaction between summer water table decrease and aerial liming of surrounding forests is proposed as an explanation for this discrepancy. Local forestry practice interacting with climate thus alter N:P stoichiometry of Sphagnum along the N deposition gradient.

Control of deformation of buildings affected by subsidence using persistent scatterer interferometry

In this article, satellite radar data are analysed to control the deformation of the buildings of Murcia City (SE Spain) affected by subsidence. This phenomenon has occurred as a result of groundwater overexploitation in drought periods, and special attention is paid to the most recent drought which occurred between 2005 and 2008. In the first part of this work, the study area is presented followed by a description of the characteristics and effects of subsidence on the buildings of the urban area. Persistent scatterer interferometry is used to process a satellite base radar dataset measuring the temporal and the spatial evolution of subsidence. These results are analysed with respect to several factors that control subsidence mechanisms: water table decrease, thickness of the compressible layer and the type of foundation of the buildings. To validate these results, a detailed structural damage analysis of several buildings is presented. According to the results presented in this work, it may be concluded that damage of buildings is triggered by soil consolidation due to groundwater overexploitation, demonstrating that the inclusion of this technique can be particularly interesting in structural monitoring framework of civil infrastructures, as a complementary tool to control subsidence damage.

Holistic assessment of groundwater resources and regional environmental problems in the North China Plain

Water balance components of the North China Plain (NCP) were analyzed, indicating the decrease both in precipitation and evaporation. The decreased precipitation and expansion of water use for agriculture, industrial and domestic purposes have caused a water crisis, which was managed until now by diverting water from the Yellow River and over exploitation of groundwater. The groundwater resource was assessed by estimating its recharge in both upper unconfined and lower confined layers, yielding a total value of 1.65 × 1010 m3/a. Total groundwater use was estimated and judged by the actual water table drawdown. Salt accumulation, water table decrease, fluoride and nitrate pollution were all found to be major regional environmental problems. Furthermore, heavy metals were found in high content in the soil and surface water in suburbs of large cities, posing a potential risk of pollution in the groundwater. It has been verified by isotropic data that dry conditions have occurred since 10 ka and are therefore part of the natural process. Possible solutions for water crises in the NCP are proposed.

Organic matter accumulation in a restored peatland: Evaluating restoration success

Recent advances in peatland restoration techniques have succeeded in establishing Sphagnum moss on the remnant cutover peat surface following peat extraction; however, evaluating restoration success remains a key issue. We argue that a Sphagnum-dominated peatland can only be considered functionally ‘restored’ once organic matter accumulation has achieved a thickness where the mean water table position in a drought year does not extend into the underlying formerly cutover peat surface. Here we monitor the spatio-temporal development of organic matter accumulation in a new peat layer for the first 8 years following the restoration of a Quebec peatland and couple a simple acrotelm carbon accumulation model and ecohydrological model to assess peatland restoration success. We determined that organic matter accumulation increased from 2.3 ± 1.7 cm 4 years post-restoration to 13.6 ± 6.5 cm 8 years post-restoration. For comparison, at an adjacent non-restored section of the peatland organic matter accumulation was significantly lower (p < 0.001 for all years), with mean thicknesses of 0.2 ± 0.6 and 0.8 ± 1.2 cm for 24 and 28 years post-extraction, respectively. Given the mean summer water deficit at the site (−64 mm), our ecohydrological modeling results suggest that a 19-cm-thick moss layer would be required to offset the water table decrease induced by the summer water deficit. Given the current rate of organic matter accumulation, net primary productivity and the new peat layer decomposition rates determined using litter bags, we estimate it will take 17 years post-restoration to accumulate a 19-cm moss layer. Consequently, we argue that successful peatland restoration may be achieved in the medium-term and that our simple modeling approach can be useful in assessing the long-term impact of restoration on atmospheric carbon dioxide sequestration.

Colloidal Control on the Distribution of Rare Earth Elements in Shallow Groundwaters

A 7-year monitoring period of rare earth element (REE) concentrations and REE pattern shapes was carried out in well water samples from a 450 m long transect setup in the Kervidy/Coët-Dan experimental catchment, France. The new dataset confirms systematic, topography-related REE signatures and REE concentrations variability but challenges the validity of a groundwater mixing hypothesis. Most likely, this is due to REE preferential adsorption upon mixing. However, the coupled mixing–adsorption mechanism still fails to explain the strong spatial variation in negative Ce anomaly amplitude. A third mechanism—namely, the input into the aquifer of REE-rich, Ce anomaly free, organic colloids—is required to account for this variation. Ultrafiltration results and speciation calculations made using Model VI agree with this interpretation. Indeed, the data reveal that Ce anomaly amplitude downslope decrease corresponds to REE speciation change, downhill groundwaters REE being mainly bound to organic colloids. Water table depth monitoring shows that the colloid source is located in the uppermost, organic-rich soil horizons, and that the colloid input occurs mainly when water table rises in response to rainfall events. It appears that the colloids amount that reaches groundwater increases downhill as the distance between soil organic-rich horizons and water table decreases. Topography is, therefore, the ultimate key factor that controls Ce anomaly spatial variability in these shallow groundwaters. Finally, the <0.2 μm REE fraction ultimately comes from two solid sources in these groundwaters: one located in the deep basement schist; another located in the upper, organic-rich soil horizon.

Methane fluxes during the initiation of a large‐scale water table manipulation experiment in the Alaskan Arctic tundra

Much of the 191.8 Pg C in the upper 1 m of Arctic soil of Arctic soil organic mater is, or is at risk of, being released to the atmosphere as CO2 and/or CH4. Global warming will further alter the rate of emission of these gases to the atmosphere. Here we quantify the effect of major environmental variables affected by global climate change on CH4 fluxes in the Alaskan Arctic. Soil temperature best predicts CH4 fluxes and explained 89% of the variability in CH4 emissions. Water table depth has a nonlinear impact on CH4 efflux. Increasing water table height above the surface retards CH4 efflux. Decreasing water table depth below the surface has a minor effect on CH4 release once an aerobic layer is formed at the surface. In contrast with several other studies, we found that CH4 emissions are not driven by net ecosystem exchange (NEE) and are not limited by labile carbon supply.

Application of isotopic and geochemical tools for the evaluation of nitrogen cycling in an agricultural basin, the Fucino Plain, Central Italy

Geochemical and isotope data collected in the agricultural area of Fucino Plain, Central Italy provided information about the relationship between the nitrate cycle and agricultural practices and seasonal changes in hydrology, in particular concerning the interaction between groundwater and surface water. The nitrate cycle of the alluvial aquifer of the Plain has been summarized in a seasonal-dependent conceptual model, where the shallow alluvial aquifer plays a fundamental role contributing to contamination of irrigation channels during periods of no manure application. Based on isotopic fingerprinting, chemical characterization and agricultural practices, the main nitrate source involved in the nitrate cycle in the study area is manure that is applied during the fall and winter periods. A nitrogen contribution from the deep alluvial–lacustrine aquifer was also documented in this study. The isotope data also showed the occurrence of denitrification occurring in nitrate pools in the shallow aquifer, which is characterized by low-permeability layers. The nitrate pool in the shallow aquifer is related to infiltration after the application of manure. The isotope and concentration data showed that the increase of nitrate in the irrigation channels under non-runoff conditions is controlled by seepage from the shallow aquifer. The cycle ends with a new application of manure, generating considerable increases of “fresh” nitrate concentration in the channels. The historical trend of decreasing water table conditions and increasing nitrate content in the shallow aquifer threatens the deep aquifer, used for drinking purposes, since heavy pumping can induce the transport of nitrate from the shallow aquifer toward the capture zone of the deep wells.

Long-term effects of drainage and hay-removal on nutrient dynamics and limitation in the Biebrza mires, Poland

To provide a reference for wetlands elsewhere we analysed soil nutrients and the vegetation of floodplains and fens in the relatively undisturbed Biebrza-valley, Poland. Additionally, by studying sites along a water-table gradient, and by comparing pairs of mown and unmown sites, we aimed with exploring long-term effects of drainage and annual hay-removal on nutrient availabilities and vegetation response. In undrained fens and floodplains, N mineralization went slowly (0–30 kg N ha−1 year−1) but it increased strongly with decreasing water table (up to 120 kg N ha−1 year−1). Soil N, P and K pools were small in the undisturbed mires. Drainage had caused a shift from fen to meadow species and the disappearance of bryophytes. Biomass of vascular plants increased with increasing N mineralization and soil P. Annual hay-removal tended to have reduced N mineralization and soil K pools, but it had increased soil P. Moreover, N concentrations in vascular plants were not affected, but P and K concentrations and therefore N:P and N:K ratios tended to be changed. Annual hay-removal had induced a shift from P to K limitation in the severely drained fen, and from P to N limitation in the floodplain. The low nutrient availabilities and productivity of the undisturbed Biebrza mires illustrate the vulnerability of such mires to eutrophication in Poland and elsewhere. In nutrient-enriched areas, hay removal may prevent productivity increase of the vegetation, but also may severely alter N:P:K stoichiometry, induce K-limitation at drained sites, and alter vegetation structure and composition.

A numerical simulation of the effect of water table levels on nocturnal air temperature and frost damage in Mire, Japan

Hemerocallis esculenta suffered frost damage during a night of remarkably low temperatures at Sarobetsu Mire, northern Japan, on 5 June 2002. A numerical model simulation was conducted to evaluate how groundwater conditions affected the nocturnal air temperature at the mire. The numerical model developed in this study reproduced the nighttime cooling process of the air temperature profile at high resolution. The lowest water table level occurred at the site several days before 5 June. The numerical simulation suggested that if the lowest water table occurred on 5 June, under the same water table level, the minimum air temperature 0.2 m above the peat surface would have been 1.2°C higher because of the difference of volumetric water content. The rate of air temperature decrease at 0.2 m height to the water table decrease would be 0.7°C cm−1. Therefore, the minimum air temperature near the peat surface of the mire is affected by both decreases in the water table level and the lowest depth prior to the observation day. Ensuring a high water table level could mitigate extreme low temperatures and frost damage at the mire.

Towards spatial assessment of carbon sequestration in peatlands: spectroscopy based estimation of fractional cover of three plant functional types

Abstract. Peatlands accumulated large carbon (C) stocks as peat in historical times. Currently however, many peatlands are on the verge of becoming sources with their C sequestration function becoming sensitive to environmental changes such as increases in temperature, decreasing water table and enhanced nitrogen deposition. Long term changes in vegetation composition are both, a consequence and indicator of future changes in C sequestration. Spatial continuous accurate assessment of the vegetation composition is a current challenge in keeping a close watch on peatland vegetation changes. In this study we quantified the fractional cover of three major plant functional types (PFTs; Sphagnum mosses, graminoids, and ericoid shrubs) in peatlands, using field spectroscopy reflectance measurements (400–2400 nm) on 25 plots differing in PFT cover. The data was validated using point intercept methodology on the same plots. Our results showed that the detection of open Sphagnum versus Sphagnumcovered by vascular plants (shrubs and graminoids) is feasible with an R2 of 0.81. On the other hand, the partitioning of the vascular plant fraction into shrubs and graminoids revealed lower correlations of R2 of 0.54 and 0.57, respectively. This study was based on a dataset where the reflectance of all main PFTs and their pure components within the peatland was measured at local spatial scales. Spectrally measured species or plant community abundances can further be used to bridge scaling gaps up to canopy scale, ultimately allowing upscaling of the C balance of peatlands to the ecosystem level.

Recharge, upflux and water table response for shallow water table conditions in southwest Florida

A disproportionate increase or decrease in water table in response to minor water input or drainage is observed in shallow water table conditions inside drainage lysimeters. This increase happens because the capillary fringe of the shallow water table reaches up to or near the surface (Wieringermeer effect). The correlations between water table level changes and rainfall, seepage irrigation, drip irrigation, and drainage were analysed. Correlations with rainfall, seepage irrigation, and drainage were high (R2 ranged from 0·46 to 0·97). Drip irrigation had low correlations due to the low rates of application (R2 ranged from 0·26 to 0·44). Conventional methods of calculating recharge, such as multiplying the specific yield with the water table fluctuations, cannot be used for Wieringermeer effect situations. A method using water balance data and soil moisture at different depths in the lysimeters was developed to estimate recharge and upflux. The recharge results were used to develop the apparent specific yield Sya, which could be used to calculate consequent recharge events from water table fluctuation data. Combining the water table fluctuation relationships developed with the Sya value will allow the prediction of recharge from rainfall and irrigation events without the need for soil moisture equipment. Copyright © 2005 John Wiley & Sons, Ltd.

The Water Crisis in the Gaza Strip: Prospects for Resolution

Israel and the Palestinian Authority share the southern Mediterranean coastal aquifer. Long-term overexploitation in the Gaza Strip has resulted in a decreasing water table, accompanied by the degradation of its water quality. Due to high levels of salinity and nitrate and boron pollution, most of the ground water is inadequate for both domestic and agricultural consumption. The rapid rate of population growth in the Gaza Strip and dependence upon ground water as a single water source present a serious challenge for future political stability and economic development. Here, we integrate the results of geochemical studies and numerical modeling to postulate different management scenarios for joint management between Israel and the Palestinian Authority. The chemical and isotopic data show that most of the salinity phenomena in the Gaza Strip are derived from the natural flow of saline ground water from Israel toward the Gaza Strip. As a result, the southern coastal aquifer does not resemble a classic "upstream-downstream" dispute because Israel's pumping of the saline ground water reduces the salinization rates of ground water in the Gaza Strip. Simulation of different pumping scenarios using a monolayer, hydrodynamic, two-dimensional model (MARTHE) confirms the hypothesis that increasing pumping along the Gaza Strip border combined with a moderate reduction of pumping within the Gaza Strip would improve ground water quality within the Gaza Strip. We find that pumping the saline ground water for a source of reverse-osmosis desalination and then supplying the desalinated water to the Gaza Strip should be an essential component of a future joint management strategy between Israel and the Palestinian Authority.

Frost heave and water uptake rates in silty soil subject to variable water table height during freezing

Given a frost-susceptible soil and a sufficiently cold environment, the availability of water is the most influential factor controlling frost heave in pavement structures. In particular, the depth of the water table below the freezing front determines to a large degree the availability of new water that can be imbibed by freezing pavement layers. This research investigated the effect of water table height on the laboratory frost heave behavior of an undisturbed silty soil typical of frost-susceptible pavement subgrades within the jurisdiction of the Swedish National Road Administration. The tested specimen was 590 mm in height, and the water table was varied between 150 and 300 mm above the bottom of the specimen. A test was also conducted in the absence of a water table. The frost penetration rate was maintained at 1.1 mm/hr throughout the testing to facilitate a similar rate of heat extraction for each frost heave test, and the same depth section of the specimen was analyzed for each test. The test results show consistent and measurable reductions in frost heave and water uptake rates with decreasing water table height. However, the frost heave rate declined more slowly than the water uptake rate, leading to increasing ratios of volumetric frost heave to volumetric water uptake. This observation is explained by the intrusion of increasing amounts of air into the frozen zone during tests utilizing lower water tables.