Subsurface Hydrological Conditions Research Articles

Assessment of morphometric characteristics and decadal fluctuation of groundwater level of Kali River basin and its link with climate change, West Uttar Pradesh, India Using Geographical Information System

The Kali River is a sixth-order tributary of the Ganga River. It originates near Khatoli town in Muzaffarnagar and confluences with the Ganga River at Kanauj District, Uttar Pradesh. In this study, drainage morphometry, temporal groundwater level observations and precipitation data are used to examine surface and subsurface hydrological conditions. Survey of India topographic maps has been used to identify the basin characteristics based on their 1:50,000 scale. The groundwater and precipitation data were obtained from the Indian Meteorological Department and the Indian Water Resources Society. The basin area was calculated about 11,470 sq. km with an NW-SE sloping. In addition, it is elongated-shaped with a dendritic pattern. The bifurcation ratio (5.06), drainage density (0.65), stream frequency (0.24) and ruggedness number (0.09) show strongly permeable alluvium, low relief, high infiltration rate, least erodible and high permeability. The basin reflects a relationship between spatio-temporal groundwater level and rainfall (~21 years: 1996 to 2017). According to this study, the water level declined at a rate of 124.7 meters per year as a result of excessive groundwater use and climate changes such as a decrease in precipitation rates around the area. Therefore, it is recommended to conservation of groundwater resources in the future.

Estimating anthropogenic effects on a highly-controlled basin with an integrated surface-subsurface model

This study presents a decision support method that can quantify the effects of water management practices on surface water and groundwater systems using a basin-scale fully-integrated model. For improvement to the decision-making process, the integrated model consists of evapotranspiration, surface, and subsurface hydrologic conditions and accounts for anthropogenic water management such as groundwater pumping, and dam and weir operations, which significantly affect the water resources of the Geum River Basin, South Korea. In this study, the fully-integrated model is calibrated based on a step-wise calibration approach. For a reliable decision support model, the calibrated model was further evaluated against five-year monthly transient agricultural pumping and control structure operation data with taking into account the parametric uncertainty of the model. The calibration and evaluation results agree well with various observation datasets including watertable depths, surface flow, reservoir water depths, and dam and weir discharge rates. Simulation results reveal that annual average net precipitation ratio for the simulation period is 0.32 with a range from 0.12 to 0.40, which is a water surplus condition. Within each year, however, negative net precipitation ratios, or water deficit conditions, occur consistently during the dry seasons, indicating that the hydrologic systems in the basin may be vulnerable during the dry seasons. Groundwater pumping within the basin lowers the local groundwater levels an average of 0.52 m over five years. In the downstream area of the basin, groundwater pumping activities affect approximately 30% of the area and result in a reduction of groundwater levels by 0.4 m with an acceptable range of uncertainty. As a decision support method for weir operations, we apply a weir removal scenario to evaluate the changes in surface flow conditions. The simulation results reveal that surface flow rates in weir reservoirs increase by three orders of magnitudes and surface water depths in the reservoirs of the dams and weirs reduce by two to four times compared to a case where all the weirs are in operation. Therefore, appropriate weir removal plans are necessary to minimize the impact on the ecosystem of the Geum River.

Impacts of subsurface hydrologic conditions on sediment selectivity and sediment transport in rills

Sediment size distribution and sediment load are important factors for the estimation of sediment transport processes. Subsurface hydrologic conditions including drainage, saturation, and seepage can affect the sediment selectivity process and sediment transport, given that downward infiltration under drainage and upward exfiltration under seepage can add one more force on surface particles compared to saturation conditions. The aim of this study was to investigate characteristics of sediment selectivity and transport rates under different subsurface hydrologic conditions in small laboratory flume channels. Series of experiments were conducted with an Opal clay soil under four subsurface hydrologic states ranging from free drainage to 10 cm seepage head conditions with water discharge rates from 0.0003 to 0.0008 m2 s−1 at three slope gradients from 4.56% to 12.17%. Results showed that the fraction of coarse-sized particles increased from saturation to 5 cm and 10 cm seepage head conditions. Compared to saturation conditions, the greater proportion of coarse particles leaving in flow in the free drainage experiments may have been caused by infiltration enhancing the deposition processes and regenerating a coarser surface when reaching the dynamic equilibrium. As slope gradients increased, the subsurface hydrologic impacts decreased on the sediment selectivity process. Both the sediment size distribution and the sediment transport rate changed dynamically and spatially before reaching an equilibrium condition. The determination of sediment transport capacity should consider both dynamic and spatial equilibrium conditions. For the Opal soil, the sediment transport capacity values greatly increased from free drainage to saturation conditions, and the differences between these two subsurface hydrologic conditions increased for greater water discharge rates and slope gradients. From saturation to 5 cm and 10 cm seepage head conditions, the sediment transport capacity values increased slightly, and the differences were stable for the slope gradients and water discharge rates studied.

Prediction of rill sediment transport capacity under different subsurface hydrologic conditions

When estimating rill sediment transport capacity for overland flow conditions, almost all widely used models focus on the impacts of surface hydraulic conditions and particle characteristics. However, the subsurface hydrologic impacts on the soil erosion process cannot be ignored. The upward force by exfiltration and the downward force by infiltration give opposite direction forces on the particles, which further influence sediment transport under seepage and drainage conditions. The aim of this research was to investigate the quantitative impacts of subsurface hydrologic conditions on sediment transport capacity in rills and improve the estimation of one existing transport capacity model by considering subsurface hydrologic effects. In this study, 216 rill flow experiments were completed in a 3.0 m long flume which contained four rill channels with slope lengths of 0.5, 1.0, 2.0, and 3.0 m. The experiments were conducted on close to uniform sands with four water discharge rates on 4.56%, 8.75%, and 12.17% slopes under four subsurface hydrologic conditions. The sediment transport rates from 192 of the 216 runs were estimated to have reached the sediment transport capacities for the corresponding condition based on the changes of sediment transport rates along the slope length and the surface elevation changes of the bottom region in the rills. The results indicated that rill sediment transport capacity increased significantly from free drainage to saturation conditions, and these differences increased with greater water discharge rates and greater slope gradients. Small increases in rill sediment transport capacity were observed from saturation to the 10 cm seepage condition with relatively stable differences. The selected sediment transport capacity equation provided good predictions under saturation and seepage conditions. The adjustment of water discharge rates improved the sediment transport capacity predictions with the discrepancy ratio between predictions and observations (P.O0.5–2.0) increasing from 73.0 to 90.5% under the free drainage condition and reaching 100% under the saturation and seepage conditions.

Critical shallow and deep hydrologic conditions associated with widespread landslides during a series of storms between February and April 2018 in Pittsburgh and vicinity, western Pennsylvania, USA

The potential for widespread landslides is generally increased when extraordinary wet periods occur during times of elevated subsurface hydrologic conditions. A series of storms in early 2018 in Pittsburgh, Pennsylvania, overlapped with a period of increased shallow soil moisture and rising bedrock groundwater levels resulting from seasonally diminished evapotranspiration and induced widespread landslides in the region. Most of the landslides were shallow slope failures in colluvium, landslide deposits, and/or fill. However, deep-seated landslide activity also occurred and corresponded with record cumulative precipitation from late February to April and bedrock groundwater levels rising to an annual high. Landslides blocked or damaged roads, adversely affected multiple houses, disrupted electrical service, crushed vehicles, and resulted in considerable economic losses. The initial landslides occurred during or immediately after a rare period of three successive days of heavy rain that began on February 14. Subsequent landslides between late February and April were induced by multiday storms with smaller rainfall totals. As shallow soil moisture at a monitoring site rose above a volumetric water content of 32%, the mean rainfall intensities necessary to induce slope failure in colluvium and other surficial deposits decreased. Deep-seated landslide movement occurred in the region mostly when the groundwater level in a bedrock observation well was shallower than 1.7 m. The availability of hydrologic and landslide movement monitoring data during this extraordinary series of storms highlighted the evolution of the landslide hazard with changing moisture conditions and yielded insights into potential hydrologic criteria for anticipating future widespread landslides in the region.

Impacts of subsurface hydrologic conditions on rill sediment transport capacity

Sediment transport capacity (Tc) is the equilibrium sediment transport value under steady-state flow and channel conditions. Given the difficulties in controlling hydrologic parameters close to steady-state in the field, most previous studies measured transport capacity in the laboratory on either non-erodible beds or erodible beds without drainage. However, infiltration under drainage conditions and exfiltration under seepage conditions cannot be ignored in the real world, and their impacts on soil strength and water discharge may affect transport capacity. The objective of this study was to estimate the effects of subsurface hydrologic conditions on rill sediment transport capacity, and the observations are discussed under both detachment-limited and transport-limited conditions. Series of experiments were carried out with a relatively uniform sand using three water discharges on a 4.56% slope flume with four rills from 0.5 to 3.0 m long under four subsurface hydrologic conditions varying from free drainage to 10 cm seepage head. The determination of equilibrium sediment transport capacity was based on the spatial change of sediment transport as slope lengths increased and the elevation change of the erodible surface in rills. Results from 107 runs indicated that there was only one equilibrium sediment transport value for a given surface and subsurface hydrologic condition, given similar observations were obtained under detachment-limited and transport-limited conditions. For the studied sand, observed critical shear stress decreased around 20% from the drainage to the saturation condition, and decreased slightly from the saturation to the seepage condition. Measured transport capacity increased 13% to 15% from drainage to seepage conditions for the studied water discharges, which was the result of decreased soil strength and increased water discharge. The differences in transport capacities between drainage and saturation increased as water discharge increased, but the differences between saturation and seepage were relatively stable for all studied water discharges.

Fluid transport and reaction processes within a serpentinite mud volcano: South Chamorro Seamount

Natural fluids with a pH (25 °C) up to 12.3 were collected from a sub-seafloor borehole observatory (Ocean Drilling Program (ODP) Hole 1200C) on South Chamorro Seamount, a serpentinite mud volcano in the Mariana forearc. We used systematic differences in the chemical compositions of pore waters from drilling operations during ODP Leg 195 and borehole fluids collected subsequently from Hole 1200C to define two endmember solutions, one of which was a sulfate-rich fluid with a methane concentration of 50 mM that ascends from the subduction channel and the other was a low-sulfate fluid. The sequence of sample collection and fluid compositions constrain subsurface hydrologic conditions. Deep-sourced, sulfate- and methane-rich, sterile fluids from the subduction channel can reach the seafloor unchanged within the central conduit, whereas other fluid pathways likely intersect the pelagic sediment that underlies the serpentinite mud volcano, providing potentially suitable conditions and inoculum for microbial anaerobic oxidation of methane (AOM). These AOM-affected, low-sulfate fluids also make it to the seafloor where they discharge. The source of the sulfate- and methane-rich fluid in the subduction channel is attributed to abiotic methane production fueled by hydrogen production from serpentinization and carbonate dissolution. This methane production includes a mechanism to raise the pH above values from serpentinization alone. Results from South Chamorro Seamount represent an end member along a transect defined by the distance from the trench. Results from this site are applied to other serpentinite mud volcanoes along this transect to speculate on likely chemical conditions within shallower and cooler portions of the subduction channel.

Variation in the vertical zonality of erodibility and critical shear stress of rill erosion in China's Hengduan Mountains

AbstractSoil erodibility is an essential parameter used in soil erosion prediction. This study selected the Liangshan town watershed to quantify variation in the vertical zonality of rill erodibility (kr) in China's ecologically fragile Hengduan Mountains. Soil types comprised of yellow–brown (soil A), purple (soil B), and dry‐red (soil C) in a descending order of occurrence from the summit to the valley, which roughly corresponds to the vertical climate zone (i.e. cool‐high mountain, warm‐low mountain, and dry‐hot valley sections) of the study area. With elevation, vertical soil zonality varied in both soil organic matter (SOM) content and soil particle‐size fractions. A series of rill erosion‐based scour experiments were conducted, using water discharge rates of 100, 200, 300, 400, 500, and 600 mL min‐1. Additionally, detachment rates (Dr) were measured under three hydrological conditions (the drainage, saturation, and seepage treatments). Results show that both Dr and flow shear stress (Ʈ) values increased as discharge increased. As elevation increased, the kr values decreased, while the vertical zonality of critical shear stress (Ʈc) values showed no obvious variation. The highest kr values were observed during the seepage treatment, followed by the saturation treatment then drainage treatment, indicating that variation in vertical hydraulic gradients could significantly alter kr values. This study also found that land‐use types could also alter kr and Ʈc values. Further research, however, is necessary to better quantify the effects of subsurface hydrological conditions and land‐use types on kr under different soil zonalities in China's Hengduan Mountains. © 2018 John Wiley & Sons, Ltd.

Differences in behavior and distribution of permafrost‐related lakes in Central Yakutia and their response to climatic drivers

AbstractThe Central Yakutian permafrost landscape is rapidly being modified by land use and global warming, but small‐scale thermokarst process variability and hydrological conditions are poorly understood. We analyze lake‐area changes and thaw subsidence of young thermokarst lakes on ice‐complex deposits (yedoma lakes) in comparison to residual lakes in alas basins during the last 70 years for a local study site and we record regional lake size and distribution on different ice‐rich permafrost terraces using satellite and historical airborne imagery. Statistical analysis of climatic and ground‐temperature data identified driving factors of yedoma‐ and alas‐lake changes. Overall, lake area is larger today than in 1944 but alas‐lake levels have oscillated greatly over 70 years, with a mean alas‐lake‐radius change rate of 1.6 ± 3.0 m/yr. Anthropogenic disturbance and forest degradation initiated, and climate forced rapid, continuous yedoma‐lake growth. The mean yedoma lake‐radius change rate equals 1.2 ± 1.0 m/yr over the whole observation period. Mean thaw subsidence below yedoma lakes is 6.2 ± 1.4 cm/yr. Multiple regression analysis suggests that winter precipitation, winter temperature, and active‐layer properties are primary controllers of area changes in both lake types; summer weather and permafrost conditions additionally influence yedoma‐lake growth rates. The main controlling factors of alas‐lake changes are unclear due to larger catchment areas and subsurface hydrological conditions. Increasing thermokarst activity is currently linked to older terraces with higher ground‐ice contents, but thermokarst activity will likely stay high and wet conditions will persist within the near future in Central Yakutian alas basins.

Mapping of Hydropedologic Spatial Patterns in a Steep Headwater Catchment

A hydropedologic approach can be used to describe soil units affected by distinct hydrologic regimes. We used field observations of soil morphology and geospatial information technology to map the distribution of five hydropedologic soil units across a 42-ha forested headwater catchment. Soils were described and characterized at 172 locations within Watershed 3, the hydrologic reference catchment for the Hubbard Brook Experimental Forest, New Hampshire. Soil profiles were grouped by presence and thickness of genetic horizons. Topographic and bedrock metrics were used in a logistic regression model to estimate the probability of soil group occurrence. Each soil group occurred under specific settings that influence subsurface hydrologic conditions. The most important metrics for predicting soil groups were Euclidean distance from bedrock outcrop, topographic wetness index, bedrock-weighted upslope accumulated area, and topographic position index. Catchment-scale maps of hydropedologic units highlight regions dominated by lateral eluviation or lateral illuviation and show that only about half the catchment is dominated by podzolization processes occurring under vertical percolation at the pedon scale. A water table map shows the importance of near-stream zones, typically viewed as variable source areas, as well as more distal bedrock-controlled zones to runoff generation. Although the catchment is steep and underlain by soils developed in coarse-textured parent material, patterns of groundwater incursion into the solum indicate that well-drained soils are restricted to deeper soils away from shallow bedrock and the intermittent stream network. Hydropedologic units can be a valuable tool for informing watershed management, soil C accounting, and understanding biogeochemical processes and runoff generation.

Bench- and pilot-scale applications of electrochemical peroxidation: A new remedial concept

Electrochemical peroxidation (ECP) is a proprietary process that utilizes sacrificial iron electrodes and stochiometrically balanced applications of hydrogen peroxide to efficiently destroy aqueous phase contaminants. In laboratory trials it has been successful in reducing, often to non-detectable levels, BTEX, fuel additives, chlorinated solvents, and polychlorinated biphenyls in ground waters. The process has also been found effective in reducing the chemical and biological oxygen demand of industrial waste water. Agency-approved pilot tests will be conducted at two gasoline spill sites during 2000 where traditional pump and treat methods have proven ineffectual because of ground water chemistry or subsurface hydrologic conditions. The ECP process utilizes a tripartite treatment strategy consisting of 1) ex situ chemical oxidation; 2) in situ oxidation by reinjection of treated water with residual oxidants at the head of the plume; and 3) reestablishment of aerobic biodegradation by alteration of subsurface redox conditions. In contrast to other in situ oxidation treatment methods, dissolved iron is derived electrochemically, negating the need for ferrous salt addition. Dilute hydrogen peroxide (3 percent) is incrementally added to maximize oxidation efficiency and eliminate safety and environmental concerns accompanying the use of highly concentrated solutions. Results of laboratory trials and the geological and geochemical considerations of upcoming pilot-scale applications are presented. Other potential applications currently under investigation include combination with other remedial processes (e.g. permeable barriers and hydrogen release compounds) to insure complete and rapid contaminant mineralization.

Application of digital enhancement techniques for groundwater exploration in a hard-rock terrain

Abstract Geomorphological and geological features, namely landforms, rock units and geological structures, have a definite relationship with the occurrence and movement of groundwater in hard-rock crystalline formations. Exploration and exploitation of this sub-surface resource depend upon the understanding of expected subsurface hydrological conditions through surface expressions. The different types of digital enhancement techniques using remotely sensed data help in the extraction of specific features that act as groundwater indicators and ultimately lead to the preparation of maps indicating groundwater prospective zones. In this study, different enhancement techniques, such as linear stretching, band combination, filtering and edge enhancement, have been employed for deriving groundwater-controlling features in typical hard-rock crystalline formations of parts of the Raichur district, Karnataka, India. The qualitative evaluation of each enhanced output for its feature exhibitance has narrowed down th...