Interactions between groundwater seepage and sediment porewater sulphate concentration profiles in lake anna,Virginia

Most sulphur diagenesis models predict that SO₄^2- concentrations decrease exponentially with increasing sediment depth and are lower than that of the overlying water throughout the sediments. Low SO₄^2- concentrations (less than 0.2 mM) are common in the sediments of Lake Anna that receive acid mine drainage; however, sediment with as much as 20 mM SO₄^2- at about 20cm below the sediment surface is also seen in this section of the lake. A decision tree was proposed to investigate the cause of the high SO₄^2- concentrations at depth (HSD) in the sediment. The first possibility proposed was that an increase in the quantity of groundwater flowing through Lake Anna sediments may increase groundwater advection of SO₄^2- or oxygen which would induce sulphide oxidation. This hypothesis was tested by measuring groundwater flow. HSD profiles were found in a discrete region of the lake; however, stations having these profiles did not have higher groundwater flow than other sites sampled. Alternate explanations for the HSD profiles were that the region in which they occurred had: (1) unusual sediment chemical compositions; (2) a different source of regional groundwater, or (3) a lateral intrusion of high SO₄^2- groundwater. There were no differences in sulphide and organic matter concentrations between the two regions. The area which has HSD in the sediment covers a large area in the middle of the lake, so it is unlikely that it has a unique source of regional groundwater. The third alternative was supported by the fact that in all three sample years, HSD stations were located in the preimpoundment stream channel, which is a likely lateral flow path for groundwater containing high SO₄^2- concentrations.     

Tritium in ground water of the georgia piedmont: Implications for recharge and flow paths

Environmental tritium was measured in 33 natural water samples representative of precipitation, stream runoff, and groundwater (derived principally from production wells) within the Georgia Piedmont Province. Major ion analyses were used to assist in the interpretation of the tritium results. Tritium concentrations were significantly greater within shallow groundwater derived from the regolith (28–34 TU) and stream runoff (25–30 TU) than within recent rainfall (4–17 TU). Based upon the decay-corrected tritium input function, this probably indicates that at least some of the shallow water is stored within the regolith for a period of approximately 25 years. A ‘post-bomb’ component of recharge was present in all groundwater derived from production wells in the study area. Groundwater sampled from the bedrock aquifers was commonly less tritiated than either stream runoff or shallow water stored in the regolith. the lower tritium concentrations May, have resulted from the mixing of ‘pre-bomb’ water stored within the fractures or the transitional zone directly above the bedrock and modern water stored in the shallow regolith. the preponderance of modern water provides evidence that groundwater flow paths are areally restricted within this setting, probably confined to local surface water drainage basins. the residence time of groundwater in the Piedmont is limited by the lack of deep, gravity-driven regional flow and the localized vertical flow induced by pumping. the results of this study indicate that relatively small tritium concentration variations (10-20 TU) May, have regional hydrological significance in the southeastern Piedmont Province and similar settings.     

A simple method of ground water direction measurement in a single bore hole

A simple technique to find both the magnitude and direction of ground water flow in a single bore hole, sited in a pervious water bearing medium, is described. The experiment may be performed with tracers which may not be radioactive (like inactive potassium bromide).     

Estimating the deep seepage component of the hillslope and catchment water balance within a measurement uncertainty framework

Deep seepage is a term in the hillslope and catchment water balance that is rarely measured and usually relegated to a residual in the water balance equation. While recent studies have begun to quantify this important component, we still lack understanding of how deep seepage varies from hillslope to catchment scales and how much uncertainty surrounds its quantification within the overall water balance. Here, we report on a hillslope water balance study from the H. J. Andrews Experimental Forest in Oregon aimed at quantifying the deep seepage component where we irrigated a 172‐m² section of hillslope for 24·4 days at 3·6 ± 3 mm/h. The objective of this experiment was to close the water balance, identifying the relative partitioning of, and uncertainties around deep seepage and the other measured water balance components of evaporation, transpiration, lateral subsurface flow, bedrock return flow and fluxes into and out of soil profile storage. We then used this information to determine how the quantification of individual water balance components improves our understanding of key hillslope processes and how uncertainties in individual measurements propagate through the functional uses of the measurements into water balance components (i.e. meteorological measurements propagated through potential evapotranspiration estimates). Our results show that hillslope scale deep seepage composed of 27 ± 17% of applied water. During and immediately after the irrigation experiment, a significant amount of the irrigation water could not be accounted for. This amount decreased as the measurement time increased, declining from 28 ± 16% at the end of the irrigation to 20 ± 21% after 10 days drainage. This water is attributed to deep seepage at the catchment scale. Copyright © 2010 John Wiley & Sons, Ltd.     

Measuring streambank erosion due to ground water seepage: correlation to bank pore water pressure,precipitation and stream stage

Limited information exists on one of the mechanisms governing sediment input to streams: streambank erosion by ground water seepage. The objective of this research was to demonstrate the importance of streambank composition and stratigraphy in controlling seepage flow and to quantify correlation of seepage flow/erosion with precipitation, stream stage and soil pore water pressure. The streambank site was located in Northern Mississippi in the Goodwin Creek watershed. Soil samples from layers on the streambank face suggested less than an order of magnitude difference in vertical hydraulic conductivity (K_s) with depth, but differences between lateral K_s of a concretion layer and the vertical K_s of the underlying layers contributed to the propensity for lateral flow. Goodwin Creek seeps were not similar to other seeps reported in the literature, in that eroded sediment originated from layers underneath the primary seepage layer. Subsurface flow and sediment load, quantified using 50 cm wide collection pans, were dependent on the type of seep: intermittent low‐flow (LF) seeps (flow rates typically less than 0·05 L min^?1), persistent high‐flow (HF) seeps (average flow rate of 0·39 L min^?1) and buried seeps, which eroded unconsolidated bank material from previous bank failures. The timing of LF seeps correlated to river stage and precipitation. The HF seeps at Goodwin Creek began after rainfall events resulted in the adjacent streambank reaching near saturation (i.e. soil pore water pressures greater than ?5 kPa). Seep discharge from HF seeps reached a maximum of 1·0 L min^?1 and sediment concentrations commonly approached 100 g L^?1. Buried seeps were intermittent but exhibited the most significant erosion rates (738 g min^?1) and sediment concentrations (989 g L^?1). In cases where perched water table conditions exist and persistent HF seeps occur, seepage erosion and bank collapse of streambank sediment may be significant. Copyright © 2007 John Wiley & Sons, Ltd.     

Heterogeneity in ground water–surface water interactions in the hyporheic zone of a salmonid spawning stream

Spatial and temporal variability in ground water–surface water interactions in the hyporheic zone of a salmonid spawning stream was investigated. Four locations in a 150‐m reach of the stream were studied using hydrometric and hydrochemical tracing techniques. A high degree of hydrological connectivity between the riparian hillslope and the stream channel was indicated at two locations, where hydrochemical changes and hydraulic gradients indicated that the hyporheic zone was dominated by upwelling ground water. The chemistry of ground water reflected relatively long residence times and reducing conditions with high levels of alkalinity and conductivity, low dissolved oxygen (DO) and nitrate. At the other locations, connectivity was less evident and, at most times, the hyporheic zone was dominated by downwelling stream water characterized by high DO, low alkalinity and conductivity. Substantial variability in hyporheic chemistry was evident at fine (<10 m) spatial scales and changed rapidly over the course of hydrological events. The nature of the hydrochemical response varied among locations depending on the strength of local ground water influence. It is suggested that greater emphasis on spatial and temporal heterogeneity in ground water–surface water interactions in the hyporheic zone is necessary for a consideration of hydrochemical effects on many aspects of stream ecology. For example, the survival of salmonid eggs in hyporheic gravels varied considerably among the locations studied and was shown to be associated with variation in interstitial chemistry. River restoration schemes and watershed management strategies based only on the surface expression of catchment characteristics risk excluding consideration of potentially critical subsurface processes. Copyright © 2002 John Wiley & Sons, Ltd.     

Surface water–groundwater interactions of Xiluodu Reservoir based on the dynamic evolution of seepage,temperature, and hydrochemistry due to impoundment

Reservoir construction greatly affects the regional ecological environment, particularly surface water–groundwater interactions around the reservoir. Xiluodu Reservoir, a representative large-scale reservoir in China, has had substantial impacts on surface water–groundwater interactions at the dam site since impoundment. This study analysed the dynamic characteristics of surface water–groundwater level, temperature, and hydrochemistry to determine the evolution of surface water–groundwater interaction before and after the impoundment. The levels of groundwater and some surface water rose by more than 100 m after impoundment and the water level of saturated limestone gradually stabilized, whereas basalt saturation in the affected area continued to expand. The groundwater temperature did not decrease significantly, whereas the hydrochemical types and ion contents of both surface water and groundwater experienced significant changes. Calculation of the saturation index indicated spatiotemporal changes in the saturation state of minerals. The replenishment source of each type of water and their mutual relationships were determined using cluster analysis and isotope characteristics. The results confirmed continuous, significant, and variable surface water–groundwater interactions at the dam site, which were partially reversed after impoundment. Changes in surface water–groundwater interactions were due to impoundment, the impact of which decreases with distance from the dam, as well as the unique geological conditions and artificial construction.     

江苏地电台站渗流方位角和极化方位角差异特征分析研究

利用江苏地电台站的地电场和地磁数据,计算各个台站的极化方位角和渗流方位角,其中,渗流方位角分别采用谐波振幅和峰谷值2种方法进行计算,并对计算结果进行分析。结果表明:(1)新沂台和南京台由于台站覆盖层较浅,极化方位角存在线性极化和较多的非线性极化现象;而高邮台和海安台由于覆盖层较厚,极化方位角多数存在非线性极化现象。(2)用峰谷值法与用谐波振幅法计算所得的渗流方位角,两者相差不大,与理想模型间的差距也较小;而极化方位角与模型差距较大。因此,用渗流方位角尝试进行地震映震关系研究是基本可靠的。(3)高邮台的渗流方位角与高邮-宝应M_S4.9地震间具有较好的对应关系。     

地电场水文地质因素及裂隙水 主体渗流方向逐日计算

2007年西昌和天祝地电场观测台阵建立, 随后两年西昌台阵地电场的TGF-A波形明显, 天祝台阵则以TGF-B波形出现. 台阵内各台站间地电场相关性高, 这受地电场潮汐机理的支持; 不同台站或同一台站的不同方向地电场潮汐波峰谷值差异明显, 地电场潮汐机理和场地水文地质资料表明, 这主要与岩石、 裂隙度、 裂隙优势走向、 含水度、 透水率、 水矿化度和裂隙水压力差等因素相关. 潮汐电信号形成于裂隙水或水中电荷周期性移动, 电荷被岩壁吸附或脱离产生噪声, 该信噪比在同一台阵内基本相同, 信噪比值与潮汐电信号产生过程和场地电磁背景关系密切. 应用地电场潮汐谐波振幅计算裂隙水主体渗流方向, 结果与应用潮汐波峰谷值法基本一致, 这消除了峰谷值法取值的偶然误差. 2008年汶川M_S8.0地震前, 两台阵内都存在场地裂隙水主体渗流方向的短临变异现象, 西昌台阵这种变异更明显.     

Fracture control of ground water flow and water chemistry in a rock aquitard

There are few studies on the hydrogeology of sedimentary rock aquitards although they are important controls in regional ground water flow systems. We formulate and test a three-dimensional (3D) conceptual model of ground water flow and hydrochemistry in a fractured sedimentary rock aquitard to show that flow dynamics within the aquitard are more complex than previously believed. Similar conceptual models, based on regional observations and recently emerging principles of mechanical stratigraphy in heterogeneous sedimentary rocks, have previously been applied only to aquifers, but we show that they are potentially applicable to aquitards. The major elements of this conceptual model, which is based on detailed information from two sites in the Maquoketa Formation in southeastern Wisconsin, include orders of magnitude contrast between hydraulic diffusivity (K/S(s)) of fractured zones and relatively intact aquitard rock matrix, laterally extensive bedding-plane fracture zones extending over distances of over 10 km, very low vertical hydraulic conductivity of thick shale-rich intervals of the aquitard, and a vertical hydraulic head profile controlled by a lateral boundary at the aquitard subcrop, where numerous surface water bodies dominate the shallow aquifer system. Results from a 3D numerical flow model based on this conceptual model are consistent with field observations, which did not fit the typical conceptual model of strictly vertical flow through an aquitard. The 3D flow through an aquitard has implications for predicting ground water flow and for planning and protecting water supplies.     

Gravity change and its mechanism after the first water impoundment in Three Gorges Project

Introduction During and before the construction of the Three Gorges Project, the annual observation was continuously undertaken by the Three Gorges gravity observation network established around the head area of the reservoir (the section between Sandouping and Badong). This network has pro-vided substantial high precise data related to seismic activity. However, the annual gravity survey together monitoring of the existed observation stations can hardly effective monitor some potential sei…     

藏南羊卓雍错流域水化学主离子特征及其控制因素

水化学主离子特征是流域湖泊的一个重要特征,对气候以及河流所经地区的环境具有指示作用.本文对藏南羊卓雍错流域水化学主离子组成特征及其控制因素进行分析,结果显示流域内不同水体(湖水、河水、地下水)之间的主离子组成以及水化学类型差异显著.其中,羊卓雍错的水化学类型为SO24--HCO3--Mg2+-Na+,巴纠错为SO24--Mg2+-Na+,沉错为SO24--Na+-Mg2+-Ca2+,普莫雍错为HCO3--SO24--Mg2+-Ca2+,空姆错为HCO3--SO24--Ca2+;流域河水中主要阴离子为HCO3-和SO24-,Ca2+为绝对优势阳离子;流域地下水化学类型则为HCO3--Ca2+.究其原因,流域水体化学组成主要受岩石风化作用控制;除此,羊卓雍错、巴纠错和沉错水化学组成亦受自身蒸发-结晶作用的影响.就入湖河水而言,羊卓雍错入湖河水整体受碳酸盐岩石风化的影响较大,蒸发岩溶解的影响次之;沉错和空姆错入湖河流(卡鲁雄曲)的蒸发岩来源则略大于碳酸盐岩来源;而硅酸盐对流域内河水的水化学性质影响较小.与入湖河水相比,羊卓雍错和沉错湖水的Mg2+、Na+和SO24-含量较高,而Ca2+和HCO3-含量较低.这应该与湖水蒸发强烈使得湖水中Ca2+和HCO3-析出并沉积到湖底有关.而空姆错由于湖泊面积小、入湖河水流量大,致使其湖水与入湖河水的主离子组成差异不显著.     

取样瓶内球胆对水中溶解气测值影响的研究

引言 地下水中溶解气体的观测，在水文地质、水文地球化学、构造地球化学、环境保护等领域的水质调查研究中是一项经常做的项目。近20多年来，作为监测地震前兆的方法，更在国内外较广泛地开展起来，且取得了一些较好震例资料（张炜等，1992；蒋凤亮等，1989），在为各种目的所进行的溶解气体取样方法，多年来基本上都采用大口试剂瓶（内含球胆）作为取样、脱气装置（图1）。我们在实际工作中发现，这种取样装置内用来脱气的球胆对溶解气体总量及其组分等观测结果会有较大的影响。另外，还发现文献（地矿部地下水标准检验方法编写组，1988；…     

Proposing a formula for evaporation measurement from salt water resources

Evaporation involves the change in state of a liquid to a vapour. The evaporation rate from salt‐water resources depends mostly on saturated vapour pressure above its surface. On the other hand, the saturated vapour pressure is affected by the ion activity coefficient, which stems from the chemical salt concentration of water. Thus, an increase in concentration of water results in a reduction of saturated vapour pressure. In order to acquire the actual rate of evaporation from salt‐water resources, a uniform set of evaporation pans with different but specified salt concentrations were used, in a meteorological station under the same conditions. The difference in evaporation rate of each pan can only stem from the difference in chemical salt concentration and, indeed, the molar fraction of water in each saline solution. Therefore, by applying the water molar fraction in the pressure term of fresh‐water evaporation measurement formulas, these equations were developed further for determination of evaporation rate from salt‐water resources. The proposed formulas using very simple terms seem to be suitable for determination of evaporation rate from any water (typically saline, semi‐saline and fresh water) with a satisfactory precision. Copyright © 2007 John Wiley & Sons, Ltd.     

Variability and comparison of hyporheic water temperatures and seepage fluxes in a small Atlantic salmon stream

Ground water discharge is often a significant factor in the quality of fish spawning and rearing habitat and for highly biologically productive streams. In the present study, water temperatures (stream and hyporheic) and seepage fluxes were used to characterize shallow ground water discharge and recharge within thestreambed of Catamaran Brook, a small Atlantic salmon (Salmo salar) stream in central New Brunswick, Canada. Three study sites were instrumented using a total of 10 temperature sensors and 18 seepage meters. Highly variable mean seepage fluxes, ranging from 1.7 x 10(-4) to 2.5 cm3 m(-2) sec(-1), and mean hyporheic water temperatures, ranging from 10.5 degrees to 18.0 degrees C, at depths of 20 to 30 cm in the streambed were dependent on streambed location (left versus right stream bank and site location) and time during the summer sampling season. Temperature data were usefulfor determining if an area of the streambed was under discharge (positive flux), recharge (negative flux), or parallel flow (no flux) conditions and seepage meters were used to directly measure the quantity of water flux. Hyporheic water temperature measurements and specific conductance measurements of the seepage meter sample water, mean values ranging from 68.8 to 157.9 microS/cm, provided additional data for determining flux sources. Three stream banks were consistently under discharge conditions, while the other three stream banks showed reversal from discharge to recharge conditions over the sampling season. Results indicate that the majority of the water collected in the seepage meters was composed of surface water. The data obtained suggests that even though a positive seepage flux is often interpreted as ground water discharge, this discharging water may be of stream water origin that has recently entered the hyporheic zone.The measurement of seepage flux in conjunction with hyporheic water temperature or other indicators of water origin should be considered when attempting to quantify the magnitude of exchange and the source of hyporheic water.     

Identifying spatio-temporal variation and controlling factors of chemistry in groundwater and river water recharged by reclaimed water at Huai River,North China

Reclaimed water is efficiently used to recover the dry river, but river water and groundwater may be impacted considering the water quality. Thus, it is critical to study the factors controlling water chemistry. Samples of reclaimed water, river and groundwater were collected monthly from January to September in 2010, in Huai River (North China). And samples were analyzed for major 15 physio-chemical parameters. Using hierarchical cluster analysis, 9 months are divided into two distinct groups, which show the clear temporal variation. In reclaimed water and river water, one group includes February, while the other includes other months. In shallow and deep groundwater, one group includes months from January to April, while the other encompasses others. Monitoring stations are classified into three groups. Group A with high value of ions and nitrogen (order: NH₄-N > NO₃-N > NO₂-N) includes reclaimed water and river water. Group B with moderate concentration and nitrogen (order: NO₃-N > NH₄-N > NO₂-N) includes all shallow groundwater and one deep groundwater. Group C with the low value and nitrogen (order: NO₃-N > NO₂-N > NH₄-N), includes two deep groundwater. Using multivariate analysis and ionic relationships, river water chemistry is found to be controlled by reclaimed water and evaporation process; chemistry in shallow groundwater and one deep groundwater, with type of Na–Ca(Mg)–HCO₃–Cl, is controlled by dissolution of calcite, carbonate weathering. Additionally, reactions of nitrification, denitrification and cation exchange occur in the infiltration of reclaimed water; chemistry in the other deep groundwater, with type of Ca–Mg–HCO₃–Cl, is controlled by dissolution of calcite, carbonate weathering and denitrification.     

Hydrological processes controlling ground and surface water flow from a hypermaritime forest–peatland complex,Diana Lake Provincial Park,British Columbia,Canada

The proposed harvesting of previously undeveloped forests in north coastal British Columbia requires an understanding of hydrological responses. Hydrometric and isotopic techniques were used to examine the hydrological linkages between meteoric inputs to the surface‐groundwater system and runoff response patterns of a forest‐peatland complex. Quickflow accounted for 72–91% of peak storm discharge. The runoff ratio was lowest for open peatland areas with thick organic horizons (0·02–0·05) due to low topographic gradients and many surface depressions capable of retaining surface water. Runoff ratio increased comparatively for ephemeral surface seep flows (0·06–0·40) and was greatest in steeply sloping forest communities with more permeable soils (0·33–0·69). The dominant mechanism for runoff generation was saturated shallow subsurface flow. Groundwater fluxes from the organic horizon of seeps (1·70–1·72 m³ day^?1 m^?1) were an important component of quickflow. The homogeneous δ²H? δ¹⁸O composition of groundwater indicated attenuation of the seasonal rainfall signal by mixing during recharge. The positive correlation (r² = 0·64 and 0·38, α = 0·05) between slope index and δ¹⁸O values in groundwater suggests that the spatial pattern in the δ¹⁸O composition along the forest‐peatland complex is influenced by topography and provides evidence that topographic indices may be used to predict groundwater residence time. Copyright © 2006 John Wiley & Sons, Ltd.