Hydrogeological Zones Research Articles

Shifting to hydrological boundaries – The politics of implementation in the lower Amu Darya basin

During the time of the Soviet Union, the Central Asian states managed their water resources on the meso level according to administrative rather than hydrological boundaries. It was only in 2003 that Uzbekistan shifted from administrative to hydrological boundaries for water management. Using the example of Khorezm Province in the lower Amu Darya basin, this paper shows that redefining boundaries is a political process, which led in Khorezm to new boundaries which are partly determined by hydraulic, not hydrological, and political considerations. Nevertheless, the new management approach has created more equity amongst the different districts in terms of water supply per irrigated area. However, simple equity in water supply did not take into consideration other issues, such as infrastructure, hydrogeological zones and crop production. In addition, the official data show that the achieved equity was based on an overall increase in water supply to the individual districts and to Khorezm as a whole. When only the increase in water supply to the individual districts is taken into consideration, it appears that the location of the main office and the regional provenance of the main staff influenced water supply to specific districts. Finally, based on the data presented for Khorezm Province the paper goes a stage further and questions the real value of the new water management boundaries implemented in Khorezm.

Groundwater sensitivity mapping in Kentucky using GIS and digitally vectorized geologic quadrangles

Groundwater sensitivity (Ray and O’dell in Environ Geol 22:345–352, 1993a) refers to the inherent ease with which groundwater can be contaminated based on hydrogeologic characteristics. We have developed digital methods for identifying areas of varying groundwater sensitivity for a ten county area of south central Kentucky at a scale of 1:100,000. The study area includes extensive limestone karst sinkhole plains, with groundwater extremely sensitive to contamination. Digitally vectorized geologic quadrangles (DVGQs) were combined with elevation data to identify both hydrogeologic groundwater sensitivity regions and zones of “high risk runoff” where contaminants could be transported in runoff from less sensitive to higher sensitivity (particularly karst) areas. While future work will fine-tune these maps with additional layers of data (soils for example) as digital data have become available, using DVGQs allows a relatively rapid assessment of groundwater sensitivity for Kentucky at a more useful scale than previously available assessment methods, such as DRASTIC and DIVERSITY.

Retrieving self‐potential anomalies in a complex volcanic environment: an SP/elevation gradient approach

The problem of differentiating self‐potential (SP) anomalies from different origins on volcanoes is addressed using the SP/elevation gradient. Surveys on volcanoes classically show the presence of a purely hydrogeological zone on the flanks and a hydrothermal zone in the central area. The hydrogeological zone is characterized by negative SP/elevation gradients, ranging typically between 0 and −2 mV/m, whilst gradients vary in a broader range in the hydrothermal zone. Simple models show how these gradients will be perturbed in the presence of perched water tables, lateral variations of physical properties (e.g. resistivity) or by positive anomalies associated with upward hydrothermal circulations of fluids. The SP/elevation gradient is much more sensitive to the perturbations than the SP and, therefore, it is proposed that the gradient is used to enhance the anomalies. Using digital SP and topographic grids, the gradient can be computed in 2D and a regional SP map of the Piton de la Fournaise volcano (La Réunion, Indian Ocean) is used to illustrate the method. Anomalies are easily identified in the active central area, but are difficult to discern in other areas. Conversely, the anomaly zones are clearly shown on the gradient map as well as the different types of terrain (i.e. with different SP/elevation gradient values) in the hydrogeological zone. In the summit area, where the data coverage is dense, a comparison of the gradient information as a function of the SP map resolution is carried out to illustrate the sensitivity of the method to detect small‐scale structures. As a technique, the gradient approach appears to be very promising for the qualitative interpretation of SP surveys in volcanic areas as well as in other environments.

Application of a resistivity survey and geographical information system (GIS) analysis for hydrogeological zoning of a piedmont area, Himalayan foothill region, India

A Geographical Information System (GIS) has been used for the integration of the results of 70 vertical electrical soundings and hydrogeological data in the piedmont zone of the Himalayan foothills region of Uttaranchal, India. Indian remote sensing (IRS) LISS-III data has been used to prepare thematic maps for the geomorphology and slope maps of the area. The ranges of electrical resistivity values have been assigned to the different formations by calibrating electrical resistivity values with the borehole data. Electrical resistivity, groundwater level monitoring, and borehole and remote sensing data have been integrated in the GIS analysis to delineate the hydrogeological zoning in the study area. Suitable weights were assigned to the different features affecting the groundwater potential. The total score for a particular location is translated in terms of groundwater potential of the area. The results indicate that the southern part of the study area has a very good groundwater potential for meeting the demand of water for irrigation and domestic purposes whereas the steeply sloping area in the northern part, having high relief, has a poor groundwater potential. The resulting delineation of groundwater potential zones are in general agreement with the available yield data of the tube wells.

Spatial geochemical and isotopic characteristics associated with groundwater flow in the North China Plain

AbstractThe North China Plain (NCP) is an important agricultural area in China and has a high population density. Serious water shortages have occurred in this region over the last 20 years. Water transfer from the Yangtze River (the east route) was initiated in the year 2002 to provide water for the major cities of the NCP. This study was carried out before the implementation of the water transfer project, focusing on the spatial integration of the groundwater flow system and geochemical characteristics, which are mainly controlled by tectonics, geomorphology, and lithology. The field survey and the geochemical analyses of the groundwater samples indicated that the groundwater in the NCP has a two‐layer structure, with a boundary at a depth of about 100–150 m. The two layers differ in pH, concentrations of SiO2 and major ions, and isotopes (18O, deuterium and tritium (T)). Chemical components in the upper layer showed a wider range and higher variability than those in the lower layer, indicating the impact of human activity. The flow direction of the groundwater in the upper layer was examined in detail in two profiles, showing that the upper layer flows east towards the Cangzhou–Daming fault, while the groundwater in the lower layer flows northeast towards Tianjin. Three hydrogeological zones are identified: recharge (Zone I), intermediate (Zone II), and discharge (Zone III). The recharge zone was found to be low in chloride (Cl−) but high in T. The discharge zone was found to be high in Cl− and low in T. This may be due to the difference in groundwater age. The discharge zone was subdivided into two sub‐zones, Zone III1 and Zone III2, by considering the effects of human activities. Zone III2 was strongly affected by water diversions from the Yellow River. As groundwater flows from the recharge zone to the intermediate and discharge zones, chemical patterns evolve in the order: Ca‐HCO3 > Mg‐HCO3 > Na‐Cl + SO4. Copyright © 2004 John Wiley & Sons, Ltd.

Characterizing the hydrogeology of a complex clay-rich aquitard system using detailed vertical profiles of the stable isotopes of water

High-resolution 1D profiles of the stable isotopes of porewater (δ2H and δ18O) obtained by direct porewater-equilibration of core samples were used to identify hydrogeologic zones in a thick, complex, till aquitard system in Saskatchewan, Canada. Detailed 1D isotope profiles revealed the presence of three distinct hydrogeological zones: an upper (5–10 m), an intermediate (10–30 m), and a lower (30–62.5 m) till zone. The upper hydrogeological zone was controlled by a sand layer having a high hydraulic conductivity (K). The lack of vertical variability in the stable isotope data in the intermediate zone suggested groundwater flow and solute transport was controlled by a system of interconnected vertical fractures and lateral sand layers. The curved shape of the isotope profile in the lower till zone suggested that solute transport in this zone was controlled mainly by molecular diffusion. We show that high-resolution vertical stable isotope profiles of porewater obtained from core samples and direct equilibration yield cost-effective and invaluable hydrogeologic information on groundwater flow in aquitard systems that cannot be realistically obtained by construction of costly conventional piezometer bundles (i.e. δ2H and δ18O analyses of water samples and K determinations). Further, the direct equilibration approach overcomes the problem of piezometer leakage in low K aquitards.

Characterizing the hydrogeology of a complex clay-rich aquitard system using detailed vertical profiles of the stable isotopes of water

High-resolution 1D profiles of the stable isotopes of porewater (δ 2H and δ 18O) obtained by direct porewater-equilibration of core samples were used to identify hydrogeologic zones in a thick, complex, till aquitard system in Saskatchewan, Canada. Detailed 1D isotope profiles revealed the presence of three distinct hydrogeological zones: an upper (5–10 m), an intermediate (10–30 m), and a lower (30–62.5 m) till zone. The upper hydrogeological zone was controlled by a sand layer having a high hydraulic conductivity ( K). The lack of vertical variability in the stable isotope data in the intermediate zone suggested groundwater flow and solute transport was controlled by a system of interconnected vertical fractures and lateral sand layers. The curved shape of the isotope profile in the lower till zone suggested that solute transport in this zone was controlled mainly by molecular diffusion. We show that high-resolution vertical stable isotope profiles of porewater obtained from core samples and direct equilibration yield cost-effective and invaluable hydrogeologic information on groundwater flow in aquitard systems that cannot be realistically obtained by construction of costly conventional piezometer bundles (i.e. δ 2H and δ 18O analyses of water samples and K determinations). Further, the direct equilibration approach overcomes the problem of piezometer leakage in low K aquitards.

Nitrate pollution from agriculture in different hydrogeological zones of the regional groundwater flow system in the North China Plain

A survey of the quality of groundwater across a broad area of the North China Plain, undertaken in 1998 to 2000, indicates that nitrate pollution is a serious problem affecting the drinking water for a vast population. The use of nitrogen (N)-fertilizer in agriculture has greatly increased over the past 20 years to meet the food needs of the rapidly expanding population. During the study, 295 water samples were collected from wells and springs to determine the water chemistry and the extent of nitrate pollution. High concentrations of nitrate, especially in a recharge area along the western side, but also in the vicinity of Beijing and locally in other parts of the plain, pose a serious problem for the drinking water supply. In places, the nitrate concentration exceeds the maximum for safe drinking water of 45 mg/L. The intense use of N-fertilizer and the widespread use of untreated groundwater for crop irrigation contribute greatly to the problem, but no doubt the disposal of industrial and municipal waste into streams and infiltrating the aquifer also contribute to the problem; however, the lack of data prevents evaluation of those sources. In the recharge area, nitrate is found at depths of as much as 50 m. Near Beijing, relatively high concentrations of nitrate occur at depths of as much as 80 m. In the discharge area, in the vicinity of the Yellow River, high concentrations of nitrate occur at depths of <8 m.

Perfiles paleokarsticos en el techo de la unidad intermedia del mioceno de la cuenca de Madrid

En el techo de la Unidad Intermedia del Mioceno de la Cuenca de Madrid se ha desarrollado un paleokarst temprano, somero y de forma tabular que muestra un marcado control litologico y del dispositivo de facies deposicionales en su genesis. Integrando criterios geomorfologicos, petrograficos y geoquimicos se ha establecido una zonacion hidrogeologica en los perfiles paleokarsticos estudiados, diferenciandose: (i) una zona vadosa caracterizada por la existencia de cavidades alargadas en la vertical tapizadas discontinuamente por espeleotemas y otros cementos vadosos; (ii) una franja de oscilacion del nivel freatico de unos 3-7 metros de espesor, caracterizado por el desarrollo extensivo de cuerpos brechoides estratiformes, la yuxtaposicion de cementos vadosos y freaticos y los contenidos mas bajos en Fe y Mn en el material encajante, y (iii) una zona freatica caracterizada por un aumento en los valores de 813C y el predominio de la cementacion freatica. La correlacion de los perfiles paleokarticos revela una paleogeografia para el techo de la Unidad Intermedia con un paisaje topograficamente descendente de norte a sur en la cuenca para el Vallesiense. [ABSTRACT] An intra-Vallesian (Upper Miocene) paleokarst developed at the top of the Intermediate Miocene Unit in the continental Madrid basin is recognized. This paleokarst is a early shallow, tabular-shaped karst that shows a marked control by the depositional facies pattem and lithologies. By integrating morphological, petrological and geochemical data, three hydrogeological or environmental zones have been established throughout the paleokarstic profiles: (i) a vadose zone, characterized by vertically elongated caves and discontinuous speleothems and vadose cements (ii) a 3-7 m thick water table fringe, characterized by the wide development of stratiform breccia bodies, the superimposition of both vadose and phreatic features, and the lowest Fe and Mn contents in host-rock carbonates; and (iii) a phreatic zone characterized by an increase of 813C values and the predominance of phreatic cementation. The paleogeographic reconstruction for the intra-Vallesian paleokarst using paleokarstic profiles reveals relative topographic highs to the north and topographic lows to the south drawing the paleokarst landscape.

Improving groundwater-flow modeling using optimal zoning methods

Hydraulic conductivity sometimes exhibits complicated spatial variation over a site. A thorough understanding of the spatial distributions of hydraulic conductivity helps to make deterministic models of groundwater more accurate. This study presents a novel procedure that combines simulated annealing algorithms (SA) and the shortest distance method (SD) with the modular three-dimensional groundwater flow model (MODFLOW). The procedure is applied to a hypothetical site with groundwater-monitoring wells to minimize the difference between simulated and observed hydraulic head for optimal zoning of the spatial distribution of hydraulic conductivity. The results of this optimal zoning method indicate that this new procedure not only improves the efficiency of optimization, but also increases the probability of finding the global optimum, minimizing the errors of the hydraulic head simulated by MODFLOW in two scenarios, one with known and the other with unknown hydraulic conductivity. The results also illustrated that the procedure can effectively determine and delineate hydrogeological zones.

Principles of Hydrogeological Zoning by the Conditions of Formation and the Distribution of the Natural Resources of Fresh Groundwater

The principles of hydrogeological zoning of the territory of Russia by the conditions of formation and the distribution of the natural resources of fresh groundwater are discussed. The delineation of the first- and second-order regions is shown to be based on the principles of general hydrogeologic zoning, whereas that of the third and fourth orders is shown to be based on the principles of special hydrogeologic zoning, which can account for the specific structural features of the hydrogeologic section of the zone of intense water exchange, different types of water-bearing rocks, the structure of the unsaturated zone, and, in a number of cases, the climatic and landscape features of the area.

On the Relationship between the Latitudinal Hydrological and Landscape Zones

The closest correspondence between latitudinal hydrogeological and landscape zones is found to exist when the relationship between the heat and moisture received by the land surface is optimal. The lack of heat or moisture eliminates the correlation between the latitudinal hydrogeological and landscape zones. In this case, the major factors that control the area distribution of groundwater are neotectonics, hydrogeological zonality, and permafrost.

Hydrogeological Zoning of the Central Minusinsk Basin by the Conditions of Formation of Fresh Groundwater Resources

A detailed hydrogeological zoning of the central part of the Minusinsk artesian basin is performed. Local basins confined to smaller plicated structures, as well as hydrogeological massifs of local scale, are recognized within large block structures. Direction of subsurface streams and their role in the formation of groundwater resources and composition are discussed. Forecast resources of fresh groundwater are estimated for every recognized structure.

Microbiological groundwater quality and health indicators in Mexico City

Groundwater quality was evaluated in the southern and western zones of Mexico City, using bacterial indicators and pathogens. Water quality from 40 wells was related to rates of diarrheal disease with 995 individuals interviewed. The focus of this first study on environmental health indicators (EHI) was based on population data (e.g., drinking water supplies and basic sanitation) and displayed using a Geographic Information System (GIS). Sixty percent of the wells monitored comply with the Mexican drinking water standards; however, based on other microbial evidence, 95% of the wells did not provide good quality water for human consumption. No significant differences were detected among hydrogeological zones. When analyzing by microbial indicators, the southern area was shown to be statistically different (p < 0.01) from the western area of the city. The highest rates of diarrheal diseases were detected in the south; the lowest rates were observed in the west. Although wells in the western side of the city appeared to be more contaminated (54%) than in the south (40%), no significant association with health indicators was detected. These preliminary findings suggest ways to improve the potential of EHI, by framing epidemiological data and the use of GIS.

Source and Plume Investigation of Chlorinated Compounds in Groundwater at a Chemical Plant: ABSTRACT

ABSTRACT A site assessment was conducted to determine the distribution of chlorinated compounds in soil and groundwater at a chemical plant in Geismar, Louisiana. The assessment first included an investigation of the source(s) of the contaminants using historic aerial photographs, employee interviews and plant records. Next, the stratigraphic framework of the site was defined with a hydrogeological investigation using historic boring logs and cone penetrometer testing (CPT). Finally, a plume investigation was performed to determine the horizontal and vertical extent of the contamination using direct-push methods for the sampling of soil and groundwater. It was determined that chlorinated compounds originated from leaking drums and cleaning operations prior to 1975. Downward migration of these compounds may have been promoted by the installation of uncased 15-meter wooden pilings. The contamination is limited, both vertically and horizontally, to three hydrogeologic zones: (1) the first water-bearing silt zone; (2) an intermediate zone consisting of interlayered silt and clay; and (3) the second water-bearing silt zone. The concentrations of chlorinated compounds are greatest in the intermediate zone. There is some evidence of natural degradation of the chlorinated compounds, particularly in the first water-bearing zone.

Evaluating System for Ground‐Water Contamination Hazards Due to Gas‐Well Drilling on the Glaciated Appalachian Plateau

ABSTRACTRecent drilling for natural gas in the Glaciated Appalachian Plateau area of northwestern Pennsylvania has caused limited, but increasing ground‐water contamination. By evaluating hydrogeologic parameters at a proposed gas well site, such as the ground‐water flow system, permeability of surficial sediments, and the presence of fracture zones, the contamination hazard of the site can be assessed. Three case studies document that the most hazardous sites are generally located on or near valley walls of major drainageways. The relatively steep hydraulic gradient, the frequent presence of highly permeable surficial sediments, and the low to moderate dilution of contaminants along the intermediate‐length flow paths at these sites all contribute to a relatively high pollution hazard. In addition to locating gas wells in high‐hazard hydrogeologic zones, allowing the annulus of gas wells to become pressurized is the other major factor contributing to aquifer contamination.

Karst hydrogeology within a subarctic peatland: Attawapiskat River, Hudson Bay lowland, Canada

The Attawapiskat River has cut through 30 m of mid-Silurian limestone ∼90 km west of James Bay in the Hudson Bay Lowland. Limestone cliffs of 12–15 m provide local relief along the river but inland the terrain is flat, covered by 1.5 m or more of peat. The area emerged from the Tyrrell Sea ∼4400 yr. B.P. Since that time two karst hydrogeological zones have become established. These are: (1) a vadose fluvio-karst zone in the exposed limestone along the river represented by disappearing lakes and streams; and (2) an organo-karst zone represented by sinkholes on or next to limestone bioherms within the peat mantle. They occupy 16% and 13% of the study area, respectively.

The effect of hydrogeology on variations in the electrical conductivity of groundwater fluctuations

A regular monthly inventory of water-level height and water quality of about 100 wells along the coast from Visakhapatnam to Bhimilipatnam was made for a 13-month period during 1974–1975. The electrical conductivity of the waters is found to vary with seasonal water-level fluctuations. It is, however, observed that this variation has two different patterns. The first pattern is that when the water level lowers the electrical conductivity decreases, and the second pattern is that when the water level lowers the electrical conductivity increases. The geological environment is the same for both cases, but the two patterns result from water-table fluctuations in two different hydrogeological zones.

Operating conditions and efficiency of underground drainage systems

The results of theoretical and experimental studies of the operating conditions and efficiency of underground drainage units yielded the principal regularities in the change of the yield of through-flow and deadend drainage units together with the relation between their initial yield and its time-dependence on the one hand and the type of hydrogeological zone concerned on the other, and made it possible to determine the optimum operating conditions and siting of all types of drainage units.

GROUNDWATER ZONING IN WATER RESOURCES MANAGEMENT1

ABSTRACTIn today's society the planned management of groundwater resources has played an increasingly greater role. One means of insuring the protection of groundwater quantity and quality is a regional zoning of groundwater resources. Regional zoning means to classify a given region with regard to hydrogeological characteristics and to evaluate and determine the possible use of each zone. The necessary assumption is the appropriate knowledge of geological structure (compiled in a geological map) and of hydrogeological conditions (compiled in a hydrogeological map). The basis for subdivision is a hydrogeological unit distinguished and delineated on the basis of lithological, stratigraphical, structural, and hydrogeological characteristics. It should have its own distinct hydrological system. The hydrogeological region is the basic unit. Regions may be grouped into larger units: hydrogeological provinces and realms. The subdivision of regions into hydrogeological zones, or subzones when applicable, forms the basis for a groundwater development plan.