A Simple and Affordable System for Installing Shallow Drive Point Piezometers

This paper describes a drive point system for installing small‐diameter (15 to 25 mm ID) piezometers to depths of several metres in unconsolidated sediments. The system fills the gap between (1) heavy duty drive point systems powered by drilling rig hydraulics or air hammers that are capable of installing large diameter drive points to depths of many tens of metres and (2) manually driven systems that typically install 10 mm ID or smaller tubing to depths of <2 m. Unlike many existing systems, which install piezometers inside an outer casing that is later removed, our system protects the piezometer screen inside the casing and extends it only once the casing is driven to the desired depth. This avoids clogging of the screen during installation and the risk of creating an annulus around the piezometer, which can provide a preferential pathway for water movement. The piezometer has a larger diameter than most manually driven systems, and thus has a higher yield; it also permits use of most commercially available pressure transducers and electrical conductivity sensors. The piezometers have been successfully installed to depths of up to 6 m using an electric hammer. The system overcomes some issues associated with existing systems and provides the advantages of affordability, rapid installation, mechanical assistance and manual portability.     

Impact of grout curtains on karst groundwater behaviour: an example from the Dinaric karst

Grout curtains are vertical grout walls installed in the ground. In karst terrains, their construction is primarily connected with dams and reservoirs. Their main role is to increase water tightness and to prevent progressive erosion, blocking possible seepage paths along karst fissures and conduits. In this article, changes in the behaviour of the groundwater level (GWL) and the water temperature in nine deep piezometers, which were caused by the construction of a grout curtain at the ?ale Reservoir on the Cetina River (Croatia), were analysed. The total length of the grout curtain is 3966 m. It spreads 120 m below the dam. The most analysed data are from the period after the dam had been built. Only few data and figures concern the comparison between pre‐ and post‐dam periods. The hourly data of the GWL and the water temperature were analysed for the period between 1 September 2008 at 02:00 h to 31 December 2009 at 23:00 h (11 687 h total) in six deep piezometers (marked in the text and figures as 1, 2, 3, 4, 5 and 6). For three piezometers (marked in the text and figures as A, B and C), some discontinuous measurements of the GWL and the water temperature were available for analysis. The construction of the grout curtain made strong, sudden and possibly dangerous changes to the characteristics of the aquifer and the circulation of groundwater in the local area. Special attention is paid to analyses of the behaviour of the hourly GWL data measured in the piezometers pairs (two neighbouring piezometers, one inside and the other outside of the grout curtain). During more than 80% of the analysed period, the GWL was higher in the piezometer inside the grout curtain than the one outside of it. The intensity and range of the dynamics of GWL was higher in piezometer outside the grout curtain than the inside ones. After the construction of the grout curtain, the maximum measured hydrostatic pressure on some parts of the grout curtain was approximately 40 m. It changes quickly in both time and direction. The water temperature was found to be similar in all of the measured piezometers, and it varies between 10.2 and 15.7 °C with an average value of 12.7 °C. Copyright © 2011 John Wiley & Sons, Ltd.     

Vertical variation of apparent and palaeoclimatically corrected heat flow densities in the central baltic shield

The vertical variation of heat-flow density in the Central Baltic Shield was studied in 17 drill holes (389–1060 m deep). Apparent heat-flow densities calculated in 100 m depth sections, with typical determination errors smaller than 2 mW/m², showed a variation of up to 15 mW/m² in single holes. A palaeoclimatic correction for surface temperature variations during the last million years was calculated as a function of depth for each hole with a homogeneous half-space conduction model. If the bedrock temperatures are controlled only by conduction of heat, and the temperature history is accurately known, the palaeoclimatically corrected heat-flow densities should have the same (steady-state) value at all depths throughout a drill hole. In practice, the quality of the correction is indicated by decrease or increase in the standard errors of the drill-hole means of heat-flow density. When the corrections were applied to the measured data, the standard errors decreased in only eight drill holes, and the vertical variation in palaeoclimatically corrected values ranged from a few mW/m² to 10 mW/m². In some of the holes, this variation can be attributed to heat-flow refraction at inclined conductivity interfaces, resulting in local heat-flow anomalies. However, the most important cause of the variation seems to be groundwater flow in bedrock, i.e., heat transfer disturbing the conductive regime. This notion is supported by heat-flow density-depth plots and temperature-depth plots and the decrease in observed heat-flow variation below 500 m depth, which is the typical depth of rapidly changing fresh groundwater, below which more saline (and stagnant) groudwaters are usually encountered. The present results indicate the following: 1) Groundwater flow can be fairly common in the upper parts of bedrock in the Baltic Shield, and purely conductive circumstances do not necessarily prevail everywhere; 2) palaeoclimatically corrected heat-flow values must be used with great precaution, especially when signs of groundwater flow are present in the data; 3) the palaeoclimatic correction can be applied to study groundwater flow in bedrock indirectly and to test whether a conductive regime prevails or not.     

A numerical investigation of bedrock groundwater recharge and exfiltration on soil mantled hillslopes

Here we use Richards Equation models of variably saturated soil and bedrock groundwater flow to investigate first-order patterns of the coupling between soil and bedrock flow systems. We utilize a Monte Carlo sensitivity analysis to identify important hillslope parameters controlling bedrock recharge and then model the transient response of bedrock and soil flow to seasonal precipitation. Our results suggest that hillslopes can be divided into three conceptual zones of groundwater interaction, (a) the zone of lateral unsaturated soil moisture accumulation (upper portion of hillslope), (b) the zone of soil saturation and bedrock recharge (middle of hillslope) and (c) the zone of saturated-soil lateral flow and bedrock groundwater exfiltration (bottom of hillslope). Zones of groundwater interaction expand upslope during periods of precipitation and drain downslope during dry periods. The amount of water partitioned to the bedrock groundwater system a can be predicted by the ratio of bedrock to soil saturated hydraulic conductivity across a variety of hillslope configurations. Our modelled processes are qualitatively consistent with observations of shallow subsurface saturation and groundwater fluctuation on hillslopes studied in our two experimental watersheds and support a conceptual model of tightly coupled shallow and deep subsurface circulation where groundwater recharge and discharge continuously stores and releases water from longer residence time storage.     

利用核磁共振方法探查基岩裂隙水

基岩裂隙水是我国分布最为广泛的地下水类型之一。本文阐述了基岩裂隙水的特点：含水层产状不规则、其赋存空间介质不均匀、同一含水层埋深不同、地下水运动状态复杂等。这些特殊的地质、地球物理特征,给常用的物探找水方法带来许多困难。本文通过对直接找水的新方法一核磁共振（ＮｕｃｌｅａｒＭａｇｎｅｔｉｃ　Ｒｅｓｏｎａｎｃｅ,缩写为ＮＭＲ）测深与间接找水的电阻率测深的对比分析,论述了ＮＭＲ测深直接找水的实质。并以实例说明了ＮＭＲ测深在探查基岩裂隙水中的应用效果。     

Inferring Heterogeneity in Aquitards Using High-Resolution δD and δ18O Profiles

Vertical depth profiles of pore water isotopes (δD and δ¹⁸O) in clay-rich aquitards have been used to show that solute transport is dominated by molecular diffusion, to define the timing of geologic events, and to estimate vertical hydraulic conductivity. The interpretation of the isotopic profiles in these studies was based on pore water samples collected from piezometers installed in nests (typically 4 to 15 piezometers) over depths of 10 to 80 m. Data from piezometer nests generally have poor vertical resolution (meters), raising questions about their capacity to reveal the impact of finer scale heterogeneities such as permeable sand bodies or fractured till zones on solute transport. Here, we used high-resolution (30-cm) depth profiles of δD and δ¹⁸O from two continuously cored boreholes in a till aquitard to provide new insights into the effects of sand bodies on solute transport. High-resolution core-derived profiles indicate that such heterogeneities can cause major deviations from one-dimensional diffusion profiles. Further, comparison of piezometer-measured values with best-fit diffusion trends shows subtle deviations, suggesting the presence of heterogeneities that should not be ignored. High-resolution profiles also more clearly defined the contact between the highly fractured oxidized zone and the underlying unoxidized zone than the piezometers.     

A low‐dimensional model of bedrock weathering and lateral flow coevolution in hillslopes: 2. Controls on weathering and permeability profiles,drainage hydraulics,and solute export pathways

The advance of a chemical weathering front into the bedrock of a hillslope is often limited by the rate weathering products that can be carried away, maintaining chemical disequilibrium. If the weathering front is within the saturated zone, groundwater flow downslope may affect the rate of transport and weathering—however, weathering also modifies the rock permeability and the subsurface potential gradient that drives lateral groundwater flow. This feedback may help explain why there tends to be neither “runaway weathering” to great depth nor exposed bedrock covering much of the earth and may provide a mechanism for weathering front advance to keep pace with incision of adjacent streams into bedrock. This is the second of a two‐part paper exploring the coevolution of bedrock weathering and lateral flow in hillslopes using a simple low‐dimensional model based on hydraulic groundwater theory. Here, we show how a simplified kinetic model of 1‐D rock weathering can be extended to consider lateral flow in a 2‐D hillslope. Exact and approximate analytical solutions for the location and thickness of weathering within the hillslope are obtained for a number of cases. A location for the weathering front can be found such that lateral flow is able to export weathering products at the rate required to keep pace with stream incision at steady state. Three pathways of solute export are identified: “diffusing up,” where solutes diffuse up and away from the weathering front into the laterally flowing aquifer; “draining down,” where solutes are advected primarily downward into the unweathered bedrock; and “draining along,” where solutes travel laterally within the weathering zone. For each pathway, a different subsurface topography and overall relief of unweathered bedrock within the hillslope is needed to remove solutes at steady state. The relief each pathway requires depends on the rate of stream incision raised to a different power, such that at a given incision rate, one pathway requires minimal relief and, therefore, likely determines the steady‐state hillslope profile.     

A New Multilevel Ground Water Monitoring System Using Multichannel Tubing

A new multilevel ground water monitoring system has been developed that uses custom-extruded flexible 1.6-inch (4.1 cm) outside-diameter (O.D.) multichannel HOPE tubing (referred to as Continuous Multichannel Tubing or CMT) to monitor as many as seven discrete zones within a single borehole in either unconsolidated sediments or bedrock. Prior to inserting the tubing in the borehole, ports are created that allow ground water to enter six outer pie-shaped channels (nominal diameter = 0.5 inch [1.3 cm]) and a central hexagonal center channel (nominal diameter = 0.4 inch [1 cm]) at different depths, facilitating the measurement of depth-discrete piezometric heads and the collection of depth-discrete ground water samples. Sand packs and annular seals between the various monitored zones can be installed using conventional tremie methods. Alternatively, bentonite packers and prepacked sand packs have been developed that are attached to the tubing at the ground surface, facilitating precise positioning of annular seals and sand packs. Inflatable rubber packers for permanent or temporary installations in bedrock aquifers are currently undergoing site trials. Hydraulic heads are measured with conventional water-level meters or electronic pressure transducers to generate vertical profiles of hydraulic head. Ground water samples are collected using peristaltic pumps, small-diameter bailers, inertial lift pumps, or small-diameter canister samplers. For monitoring hydrophobic organic compounds, the CMT tubing is susceptible to both positive and negative biases caused by sorption, desorption, and diffusion. These biases can be minimized by: (1) purging the channels prior to sampling, (2) collecting samples from separate 0.25-inch (0.64 cm) O.D. Teflon sampling tubing inserted to the bottom of each sampling channel, or (3) collecting the samples downhole using sampling devices positioned next to the intake ports. More than 1000 CMT multilevel wells have been installed in North America and Europe to depths up to 260 feet (79 m) below ground surface. These wells have been installed in boreholes created in unconsolidated sediments and bedrock using a wide range of drilling equipment, including sonic, air rotary, diamond-bit coring, hollow-stem auger, and direct push. This paper presents a discussion of three field trials of the system, demonstrating its versatility and illustrating the type of depth-discrete data that can be collected with the system.     

Groundwater flow and implications for groundwater contamination north of Prewitt,New Mexico,U.S.A.

In the southern San Juan Basin, New Mexico, strata of Permian and younger age dip gently toward the center of the basin. Most previous investigators believed that recharge to these strata occurred by precipitation on the outcrops and groundwater flowed downdip to the north and northeast. Recent water-level measurements in an undeveloped part of the basin near Prewitt, New Mexico, show that groundwater at shallow depths in alluvium and bedrock flows southward, opposite to the dip direction, and toward a major ephemeral drainage in a strike valley. North of this area, groundwater in deep bedrock aquifers does appear to flow northward. This information suggests that there are two groundwater circulation patterns; a shallow one controlled by topography and a deeper one controlled by geologic structure.Significant amounts of recharge to sandstone aquifers by infiltration through outcrops is unlikely due to the near-vertical exposures on cliffs, the gentle dip of the strata, and small annual precipitation. Numerical model results suggest that recharge to bedrock aquifers may be from downward leakage via aquitards over large areas and leakage from narrow alluvial aquifers in the subcrop area. The recharge mechanism is controlled by the hydraulic conductivity of the strata.As the flow path is controlled by hydraulic conductivity contrasts, geologic structure, and topography, contamination movement from surface impoundments is likely to be difficult to predict without a thorough hydrogeological site investigation.     

Role of bedrock groundwater in the rainfall–runoff process in a small headwater catchment underlain by volcanic rock

The role of bedrock groundwater in rainfall–runoff processes is poorly understood. Hydrometric, tracer and subsurface water potential observations were conducted to study the role of bedrock groundwater and subsurface flow in the rainfall–runoff process in a small headwater catchment in Shiranui, Kumamoto prefecture, south‐west Japan. The catchment bedrock consists of a strongly weathered, fractured andesite layer and a relatively fresh continuous layer. Major chemical constituents and stable isotopic ratios of δ¹⁸O and δD were analysed for spring water, rainwater, soil water and bedrock groundwater. Temporal and spatial variation in SiO₂ showed that stream flow under the base flow condition was maintained by bedrock groundwater. Time series of three components of the rainstorm hydrograph (rainwater, soil water and bedrock groundwater) separated by end member mixing analysis showed that each component fluctuated during rainstorm, and their patterns and magnitudes differed between events. During a typical mid‐magnitude storm event, a delayed secondary runoff peak with 1·0 l s⁻¹ was caused by increase in the bedrock groundwater component, whereas during a large rainstorm event the bedrock groundwater component increased to ≈ 2·5 l s⁻¹. This research shows that the contribution of bedrock groundwater and soil water depends strongly on the location of the groundwater table, i.e. whether or not it rises above the soil–bedrock interface. Copyright © 2010 John Wiley & Sons, Ltd.     

Impact of complex aquifer geometry on groundwater storage in high‐elevation meadows of the Sierra Nevada Mountains,CA

Recent research has indicated that Sierra Nevada meadows are hydrologically more complex than previously considered. Improved understanding of the effects of aquifer parameters and climate change on water resources in and downstream of meadows is critically needed to effectively manage mountain meadows for ecosystem services and watershed contributions. This research investigates the roles of bedrock geometry, saturated hydraulic conductivity, and meadow gradient in affecting groundwater storage dynamics and surface‐water outflows in site‐scale high‐elevation meadows. Under current and projected lower snowpack conditions, we modeled groundwater flow in representative high‐elevation meadows considering 2 conceptual aquifer thickness models: uniform and variable thickness. Spatially, variable aquifer thicknesses interpreted from bedrock depths (0–28 m) were identified from a high‐resolution ground‐penetrating radar survey conducted at Tuolumne Meadows, CA. Our interpreted bedrock surface indicated several buried U‐shaped valleys including a buried ridge that separates 2 U‐shaped valleys. Groundwater flow simulations show that an increase in meadow gradient and hydraulic conductivity led to a decrease in seasonal storage and an increase in surface‐water outflow. However, models with varying bedrock geometries change the magnitude and timing of these processes. Uniform thickness models overestimated storage at the model edges and resulted in higher projected volumes of water being released to streams earlier than previously observed.     

Reconstruction of groundwater levels to impute missing values using singular and multichannel spectrum analysis: application to the Ardabil Plain,Iran

ABSTRACT

Groundwater-level time series often have a substantial number of missing values which should be taken into consideration before using them for further analysis, particularly for numerical groundwater flow modelling applications. This study aims to comprehensively compare two data-driven models, singular spectrum analysis (SSA) and multichannel spectrum analysis (MSSA), to reconstruct groundwater-level time series and impute the missing values for 25 piezometric stations in Ardabil Plain, northwest Iran. The reconstructed groundwater-level time series are assessed against the complete observed groundwater time series, while the imputed values are appraised against the artificially created gap values. The results show that both SSA and MSSA demonstrate a solid competency in imputation and reconstruction of groundwater-level data. However, depending on the spatial correlation between the piezometers, and the most suitable probability distribution function (pdf) fitted to the time series of each piezometer, the performance may vary from piezometer to piezometer.     

New Method for Continuous Transmissivity Profiling in Fractured Rock

A new method is presented to search for hydraulically transmissive features in open boreholes in bedrock. A flexible borehole liner made of a watertight, nylon fabric is filled with water to create a constant driving head to evert (reverse of invert) the liner down the hole so that the liner pushes the borehole water out into transmissive fractures or other permeable features. The descent rate is governed by the bulk transmissivity of the remaining permeable features below the liner. Initially, the liner descent rate or velocity is a measure of transmissivity (T) of the entire hole. As the everting liner passes and seals each permeable feature, changes in the liner velocity indicate the position of each feature and an estimate of T using the Thiem equation for steady radial flow. This method has been performed in boreholes with diameters ranging from 96 to 330 mm. Profiling commonly takes a few hours in holes 200‐ to 300‐m long. After arrival of the liner at the bottom of the hole, the liner acts as a seal preventing borehole cross connection between transmissive features at different depths. Liner removal allows the hole to be used for other purposes. The T values determined using this method in a dolostone aquifer were found to be similar to the values from injection tests using conventional straddle packers. This method is not a replacement for straddle‐packer hydraulic testing of specific zones where greater accuracy is desired; however, it is effective and efficient for scanning entire holes for transmissive features.     

The origin,typology, spatial distribution and detrimental effects of the sinkholes developed in the alluvial evaporite karst of the Ebro River valley downstream of Zaragoza city (NE Spain)

Three types of sinkhole have been mapped in a 50 km² stretch of the Ebro River valley downstream of Zaragoza: large collapse sinkholes, large shallow subsidence depressions and small cover-collapse sinkholes. The sinkholes relate to the karstification of evaporitic bedrock that wedges out abruptly downstream, giving way to a shale substratum. Twenty-three collapse sinkholes, up to 50 m in diameter by 6 m deep, and commonly hosting saline ponds, have been identified in the floodplain. They have been attributed to the upward stoping of dissolutional cavities formed within the evaporitic bedrock by rising groundwater flows. Twenty-four large shallow subsidence depressions were mapped in the floodplain. These may reach 850 m in length and were formed by structurally controlled interstratal karstification of soluble beds (halite or glauberite? and gypsum) by rising groundwater flow and the progressive settlement of the overlying bedrock and overburden sediments. A total of 447 small cover-collapse, or dropout, sinkholes have been recognized in a perched alluvial level along the southern margin of the valley. These sinkholes result from the upward propagation of voids through the alluvial mantle caused by the downward migration of detrital sediments into dissolutional voids. The majority of these sinkholes, commonly 1·5–2 m in diameter, are induced by human activities. Over the karstic bedrock, there is a significant increase in sinkhole density downstream. This is interpreted as being a result of the evaporitic bedrock wedging out and the convergence of the groundwater flow lines in the karstic aquifer. The collapse sinkholes in this area, locally with a probability of occurrence higher than 140 sinkholes/km²/year, cause substantial damage to the linear infrastructures, buildings and agriculture, and they might eventually cause the loss of human lives. Copyright © 2006 John Wiley & Sons, Ltd.     

CRT-Hole Closure

The long-term stability of deep holes 1.75 inches. (4.4 cm) in diameter by 98.4 feet (30 m) created by cone penetration testing (CPT) was monitored at a site in California underlain by Holocene and Pleistocene age alluvial fan deposits. Portions of the holes remained open both below and above the 28.6-foot (8.7 m)-deep water table for approximately three years, when the experiment was terminated. Hole closure appears to be a very slow process that may take decades in the stiff soils studied here. Other experience suggests holes in softer soils may also remain open. Thus, despite their small diameter, CPT holes may remain open for years and provide paths for rapid migration of contaminants. The observations confirm the need to grout holes created by CPT soundings as well as other direct-push techniques in areas where protection of shallow ground water is important.     

A Single Packer Method for Characterizing Water Contributing Fractures in Crystalline Bedrock Wells

Water levels and water quality of open borehole wells in fractured bedrock are flow-weighted averages that are a function of the hydraulic heads and transmissivities of water contributing fractures, properties that are rarely known. Without such knowledge using water levels and water quality data from fractured bedrock wells to assess groundwater flow and contaminant conditions can be highly misleading. This study demonstrates a cost-effective single packer method to determine the hydraulic heads and transmissivities of water contributing fracture zones in crystalline bedrock wells. The method entails inflating a pipe plug to isolate sections of an open borehole at different depths and monitoring changes in the water level with time. At each depth, the change in water level with time was used to determine the sum of fracture transmissivities above the packer and then to solve for individual fracture transmissivity. Steady-state wellbore heads along with the transmissivities were used to determine individual fracture heads using the weighted average head equation. The method was tested in five wells in crystalline bedrock located at the University of Connecticut in Storrs. The single packer head and transmissivity results were found to agree closely with those determined using conventional logging methods and the dissolved oxygen alteration method. The method appears to be a simple and cost-effective alternative in obtaining important information on flow conditions in fractured crystalline bedrock wells.     

How to model shallow water‐table depth variations: the case of the Kervidy‐Naizin catchment,France

The aim of this work is threefold: (1) to identify the main characteristics of water‐table variations from observations in the Kervidy‐Naizin catchment, a small catchment located in western France; (2) to confront these characteristics with the assumptions of the Topmodel concepts; and (3) to analyse how relaxation of the assumptions could improve the simulation of distributed water‐table depth. A network of piezometers was installed in the Kervidy‐Naizin catchment and the water‐table depth was recorded every 15 min in each piezometer from 1997 to 2000. From these observations, the Kervidy‐Naizin groundwater appears to be characteristic of shallow groundwaters of catchments underlain by crystalline bedrock, in view of the strong relation between water distribution and topography in the bottom land of the hillslopes. However, from midslope to summit, the water table can attain a depth of many metres, it does not parallel the topographic surface and it remains very responsive to rainfall. In particular, hydraulic gradients vary with time and are not equivalent to the soil surface slope. These characteristics call into question some assumptions that are used to model shallow lateral subsurface flow in saturated conditions. We investigate the performance of three models (Topmodel, a kinematic model and a diffusive model) in simulating the hourly distributed water‐table depths along one of the hillslope transects, as well as the hourly stream discharge. For each model, two sets of parameters are identified following a Monte Carlo procedure applied to a simulation period of 2649 h. The performance of each model with each of the two parameter sets is evaluated over a test period of 2158 h. All three models, and hence their underlying assumptions, appear to reproduce adequately the stream discharge variations and water‐table depths in bottom lands at the foot of the hillslope. To simulate the groundwater depth distribution over the whole hillslope, the steady‐state assumption (Topmodel) is quite constraining and leads to unacceptable water‐table depths in midslope and summit areas. Once this assumption is relaxed (kinematic model), the water‐table simulation is improved. A subsequent relaxation of the hydraulic gradient (diffusive model) further improves water‐table simulations in the summit area, while still yielding realistic water‐table depths in the bottom land. Copyright © 2004 John Wiley & Sons, Ltd.     

Contributions of bedrock groundwater to the upscaling of storm‐runoff generation processes in weathered granitic headwater catchments

We examined the contributions of bedrock groundwater to the upscaling of storm‐runoff generation processes in weathered granitic headwater catchments by conducting detailed hydrochemical observations in five catchments that ranged from zero to second order. End‐member mixing analysis (EMMA) was performed to identify the geographical sources of stream water. Throughfall, hillslope groundwater, shallow bedrock groundwater, and deep bedrock groundwater were identified as end members. The contribution of each end member to storm runoff differed among the catchments because of the differing quantities of riparian groundwater, which was recharged by the bedrock groundwater prior to rainfall events. Among the five catchments, the contribution of throughfall was highest during both baseflow and storm flow in a zero‐order catchment with little contribution from the bedrock groundwater to the riparian reservoir. In zero‐order catchments with some contribution from bedrock groundwater, stream water was dominated by shallow bedrock groundwater during baseflow, but it was significantly influenced by hillslope groundwater during storms. In the first‐order catchment, stream water was dominated by shallow bedrock groundwater during storms as well as baseflow periods. In the second‐order catchment, deeper bedrock groundwater than that found in the zero‐order and first‐order catchments contributed to stream water in all periods, except during large storm events. These results suggest that bedrock groundwater influences the upscaling of storm‐runoff generation processes by affecting the linkages of geomorphic units such as hillslopes, riparian zones, and stream channels. Our results highlight the need for a three‐dimensional approach that considers bedrock groundwater flow when studying the upscaling of storm‐runoff generation processes. Copyright © 2014 John Wiley & Sons, Ltd.     

A Multilevel Ground Water Monitoring System for Casing Advance and Bedrock Drilling Methods

A single-hole multilevel sampling piezometer system (MLSPS) has been designed by the Geological Survey of Canada (GSC) to be installed using drilling systems that continuously core (e.g., Rotosonic) or continuously sample (e.g., hollow-stem auger, Becker hammer) overburden and that have the flexibility of allowing additional coring (diamond drilling) or sampling (hammer drilling) of bedrock. The GSC-MLSPS (under license to Solinst Canada Ltd.) uses a patented GSC dry injection system for accurate emplacement of filter packs and seals. This system permits (a) the use of variable screen lengths; (b) the complete evacuation of piezometers before introduction of new ground water (no bailing); (c) the use of a number of types of hydraulic tests (e.g., slug, withdrawal/recovery, vacuum, pressure-pulse); (d) ground water sampling under a nitrogen atmosphere; (e) dissolved gas sampling; (f) a great deal of flexibility in the use of design materials; and (g) the elimination of bridging and collapse of filter packs and seals.