Dry Season Groundwater Research Articles

Groundwater quality index as a hydrochemical tool for monitoring saltwater intrusion into coastal freshwater aquifer of Eastern Dahomey Basin, Southwestern Nigeria

Saltwater intrusion into coastal freshwater aquifers is a threat to groundwater quality globally. This study aims to determine the extent of saltwater intrusion into the coastal freshwater aquifer of the Eastern Dahomey Basin (EDB), Nigeria. Groundwater chemistry was sampled and analysed for ionic ratios and interpreted using a hydrochemical facie evolution diagram (HFE-D), the saltwater mixing index (SMI) and the Groundwater quality index for saltwater intrusion (GQIswi). High EC and TDS and the concentration of dissolved ions showed increased salinity as a result of seawater intrusion in wells located around communities in Seme, Lekki, Eleko, Okun-Ajah, Ode-Mahin and Igbokoda. Correlation of ions in the wet season also suggests higher salinities which originate partly from industrial and municipal effluents especially from wells which are close to river channels, while dry season groundwater shows the dominant influence of seawater intrusion. HFE-D revealed that mixed groundwater of Na + Ca–HCO3, Na–Cl and Ca–Cl dominate the area due to gravity-driven flow leading to groundwater freshening inland from the coastline towards the northern part of the basin. The groundwater quality index from SMI and GQIswi shows areas within 3 km from the coastline that are more sensitive to saltwater intrusion based on abstraction rate and depth of the wells. The present study provides information of value to planners and policy-makers for the sustainable management and protection of coastal groundwater resources in the Eastern Dahomey Basin.

Icing - Renewable Water Source and Resource

The icing phenomena occurs in Mongolia every winter, same places where groundwater overflow on ice on surface waterbed, create next ice sheet and create extended ice storage. This phenomenon is important parameters in hydrological cycle and surface water regime for semi-arid, cold regions. The highly continental, semi-arid and cold region has a high variability in river discharge depending on precipitation, with a general tendency towards decreasing water availability due to increasing air temperatures and thus rising potential evaporation. In this study considered understanding natural process of creating icing, due to keep water source as in ice form on surface in dry season. From March to May icing meltwater recharge groundwater and river flow while river is non-flow condition. Some year’s in April riverbed dry without ice in valley under highly mountains, but upper side is cold and water source is still in snow and ice form. Therefore, icing in river valley could recharge surface water by melting where is cold on top mountains river origin but under valley riverbed no snow, ice cover. In this paper written icing process code by MATLAB using energy change between water, air and ice. When we are promoting naturally ice storing or build icing then winter coldness creates ice storage thus artificially recharge surface water resources in dry season like April. The ice storage amount and simulation results shown that recharge groundwater in dry season is icing method one of the possibilities which creates and build huge ice storages in winter. That is new technology keep water in ice form through winter and recharge surface and groundwater in dry season.

Source identification and management of perennial contaminated groundwater seepage in the highly industrial watershed, south India.

Perennial contaminated groundwater seepage is threatening the downstream ecosystem of the Kazipally Pharmaceutical industrial area located in South India. The sources of seepage are unknown for the last three decades that challenging the regulatory authorities and industries. In general, water quality monitoring and geophysical techniques are applied to identify the sources. However, these techniques may lead to ambiguous results and fail to identify the seepage sources, especially when the area is urbanized/paved, and groundwater is already contaminated with other leakage sources that have similar chemical compounds. In the present study, a novel and multidisciplinary approach were adopted that includes satellite-based Land Surface Temperature (LST) observations, field-based Electrical Resistivity Tomography (ERT), continuous Soil Electrical Conductivity (SEC) and Volumetric Soil Moisture (VSM%) measurements along with groundwater levels monitoring to identify the sources and to control the seepage. The integrated results identified that the locations with the Standard Thermal Anomaly (STA) in the range of-0.5 to -1°C, VSM% >50%, SEC>1.5mS/cm, bulk resistivity<12Ωm with shallow groundwater levels<3m below ground level (bgl) are potentially contaminated perennial seepage sources. Impermeable sheet piles have been installed across the groundwater flow direction to control the seepage up to 1.5m bgl, where groundwater frequently intercepts land surface. The quantity of dry season groundwater seepage has been declined by 79.2% after these interventions, which in turn minimized the treatment cost of 1,96,283 USD/year and improved the downstream ecosystem.

Hydrogeochemical characterization and quality assessment of groundwater using self-organizing maps in the Hangjinqi gasfield area, Ordos Basin, NW China

Water resources are scarce in arid or semiarid areas, which not only limits economic development, but also threatens the survival of mankind. The local communities around the Hangjinqi gasfield depend on groundwater sources for water supply. A clear understanding of the groundwater hydrogeochemical characteristics and the groundwater quality and its seasonal cycle is invaluable and indispensable for groundwater protection and management. In this study, self- organizing maps were used in combination with the quantization and topographic errors and K-means clustering method to investigate groundwater chemistry datasets. The Piper and Gibbs diagrams and saturation index were systematically applied to investigate the hydrogeochemical characteristics of groundwater from both rainy and dry seasons. Further, the entropy-weighted theory was used to characterize groundwater quality and assess its seasonal variability and suitability for drinking purposes. Our hydrochemical groundwater dataset, consisting of 10 parameters measured during both dry and rainy seasons, was classified into 6 clusters, and the Piper diagram revealed three hydrochemical facies: Cl-Na type (clusters 1, 2 and 3), mixed type (clusters 4 and 5), and HCO3-Ca type (cluster 6). The Gibbs diagram and saturation index suggested that weathering of rock-forming minerals were the primary process controlling groundwater chemical composition and validated the credibility and practicality of the clustering results. Two-thirds of 45 groundwater samples were categorized as excellent- or good-quality and were suitable as drinking water. Cluster changes within the same and different clusters from the dry season to the rainy season were detected in approximately 78% of the collected samples. The main factors affecting the groundwater quality were hydrogeochemical characteristics, and dry season groundwater quality was better than rainy season groundwater quality. Based on this work, such results can be used to investigate the seasonal variation of hydrogeochemical characteristics and assess water quality accurately in the others similar area.

Evaluation for Irrigation Water Purposes of Groundwater Quality in the Vicinity of Sivas City Centre (Turkey) by Using Gis and an Irrigation Water Quality Index

AbstractIn this study, the physical and chemical characteristics of wet and dry season groundwater quality parameters of 35 wells within the provincial boundaries of Sivas were used for calculations such as sodium adsorption ratio (SAR), Kelly's ratio (KR), sodium percentage (Na%), permeability index (PI), residual sodium carbonate (RSC) and magnesium hazard (MH), which are used in irrigation water quality ratings. Also, the irrigation water quality index (IWQI) was calculated for all groundwater sources within the study area. Groundwater quality parameters and the spatial distribution of the parameters calculated throughout the study were mapped using GIS, and irrigation water quality evaluation was performed in accordance with USA Salinity Laboratory diagram and irrigation water quality standards. The correlations between the irrigation water quality parameters were determined using Pearson correlation analysis. IWQI values showed that the majority of groundwater samples (45.7%) are in the ‘weak' (MR: medium rating) category for the dry season, whereas 42.9% of groundwater samples fall within the ‘very weak' (HR: high restriction) category for the wet season. © 2019 John Wiley &amp; Sons, Ltd.

Icing phenomena for managed aquifer recharge (MAR) and it’s feflow simulation result

Ulaanbaatar, the capital of Mongolia, shows a highly dynamic urban and industrial development, with a strong increase of population. Thus, water demand is continuously rising while water availability is in general low and less reliable. The semi-arid and cold environment shows a high variability in precipitation and river discharge, with a general tendency towards decreasing water availability due to increasing air temperatures and thus rising potential evaporation. In parallel with the city’s development, the extended groundwater aquifer shows a clear decline, and the groundwater levels drop significantly. Therefore, a groundwater management system based on managed aquifer recharge is proposed and a strategy to implement these measures in the Tuul valley is presented. In this study considered enhancement of natural recharge rates during the early winter cold period, an increase of groundwater recharge through creating ice storages, due to keep water source as in ice form on surface. In dry season March to May ice storage recharge surface and groundwater by melting where Tuul River is non-flow condition. In this paper also written matlab icing code in water supply wells location, limited and unlimited area. The study of icing was processed in feflow simulation scenarios for artificially recharging groundwater resources.In this study considered feflow simulation scenarios for artificially recharging groundwater resources like enhancement of natural recharge rates during the early winter cold period, an increase of groundwater recharge through creating ice storages, due to keep water source as in ice form on surface, drainage canal recharging aquifer from opposite side, constructing underground dam that accumulates groundwater behind. The result shown that one of the possibilities recharge groundwater in dry season is icing method which creates ice sheets over ice and build ice storages in winter, keep water in ice form.

Seasonal and regional limits to growth of water-intensive crop farming in Bangladesh

Irrigation-led expansion of crop farming raised demand for groundwater in Bangladesh. This study aimed to reconcile cropped areas compatible to future water demand using secondary data on cropped area, crop yield, food intake, water footprint, rainfall, river-flow, etc. Yearly and seasonal time series were used in forecasting of areas and yields for all categories of crops. Out of total 76.5 bm3 water consumption for crop farming in the early 2010s, 34.1 bm3 was supplied through irrigation of which 79.8% was from groundwater and that would reach at 100.5, 46.6 and 88.2%, respectively in 2029–30. However, pulses, oilseeds, vegetables and potato were identified as feasible crops on the basis of groundwater demand, dietary-balanced self-sufficiency and domestic resource cost ratio. Any reduction of cereal and sugarcane areas over projections and its adjustment with feasible crops would save about one and a half billion m3 of groundwater in dry season. The demand for diversification effort index justified the necessity of initiating special crop diversification projects for the country’s Eastern Hills, North Central and North East regions. Moreover, any initiatives for building water reservoirs might facilitate for sustainable groundwater management in the long run.

Groundwater dependence of coastal lagoons: The case of La Pletera salt marshes (NE Catalonia)

Coastal wetlands are among the most productive ecosystems of the world, playing an important role in coastal defense and wildlife conservation. These ecosystems, however, are usually affected by human activities, which may cause a loss and degradation of their ecological status, a decline of their biodiversity, an alteration of their ecological functioning, and a limitation of their ecosystem services. La Pletera salt marshes (NE Spain) are located in a region mainly dominated by agriculture and tourism activities. Part of these wetlands and lagoons has been affected by an incomplete construction of an urban development and in this moment is the focus of a Life+ project, whose aim is to restore this protected area. Several studies have analyzed the role of hydrological regime in nutrients, phytoplankton and zooplankton in this area, however, the role of groundwater was never considered as a relevant factor in the lagoon dynamics, and its influence is still unknown. In this study, the hydrogeological dynamics in La Pletera salt marshes has been analyzed, as a basis to set sustainable management guidelines for this area. In order to determine their dependence on groundwater resources, monthly hydrochemical (with major ions and nutrients) and isotopic (δ18OH2O and δD) campaigns have been conducted, from November 2014 to October 2015. In particular, groundwater from six wells, surface water from two nearby streams and three permanent lagoons, and sea water was considered in these surveys. Taking into account the meteorological data and the water levels in the lagoons, the General Lake Model has been conducted to determine, not only evaporation and rainfall occurring in the lagoons, but also the total inflows and outflows. In addition, the Gonfiantini isotopic model, together with equilibrium chemical-speciation/mass transfer models, has been used to analyze the evaporation and the physicochemical processes affecting the lagoons. Results show that during the dry season groundwater inputs may account for 15–80% of the water in La Pletera lagoons. Besides, water salinity depends on two main processes: 1) mixing of fresh and sea water occurring within the lagoons or in the aquifer; and 2) evaporation. According to the obtained results, the goal of preserving La Pletera lagoons and their salinity conditions implies maintaining groundwater fluxes towards the ocean, and also the hydraulic connectivity of these lagoons with the aquifer.

Hydrochemical characteristic and interaction process of surface and groundwater in mid-lower reach of Hanjiang River, China

Hanjiang River, the largest tributary of Yangtze, faces environmental pressures from South-to-North Water Transfer project and anthropogenic influences. In order to reveal the chemical characteristics of river and contribution of groundwater to the river along mid-lower reaches of Hanjiang River, field works have been conducted in wet and dry seasons. The major ion compositions are characterized by the dominance of Ca2+, and HCO3 − in surface water and groundwater. As a result, calcite weathering is a dominant process for surface water and groundwater. Additionally, dolomite weathering also contributes to hydrochemical evolution in the groundwater of the basin. Stable isotopes (δ18O, δD) show that both surface and groundwater most probably originate from present-day precipitation. Isotopic of both surface water and groundwater can provide greater confidence in identifying the weathering and extent of interaction processes. It was found that river water was mainly recharged by tributaries in wet season while recharged by groundwater in dry season. Dissolved solute flux from tributaries and groundwater to the river was estimated by water balance budget model and environmental tracer mass balance approach. Tributaries and groundwater contribute to mid-lower reach of Hanjiang River in wet season and dry season, respectively. From section H1 to H9, there were 455.4 kg/s of total dissolved solute (TDS) transferred from tributaries to the main channel and 99.8 kg/s of TDS fluxed from groundwater to river water in dry season.

Salinity, groundwater, and water uptake depth of plants in coastal uplands of Everglades National Park (Florida, USA)

AbstractWe examine salinity, ground water depth, and water uptake of common plant species in coastal upland communities: buttonwood hammocks, hardwood hammocks, and buttonwood prairies of Everglades National Park. We show that the elevation gradient is gentle with a mean gradient of 0.12 m North American Vertical Datum of 1988 from buttonwood prairie to hardwood hammocks, but the species composition and canopy cover among communities are different. Plant communities differ significantly in groundwater salinity. Hardwood hammocks have brackish groundwater [14–27 parts per thousand (PPT)], buttonwood hammocks have brackish to saline groundwater (23–35 PPT), and buttonwood prairies have saline groundwater (30–44 PPT). The depth to water table is greater for plants in hardwood and buttonwood hammocks than in buttonwood prairies, which makes the freshwater recharge capacity of vadose zone larger in hammocks than in buttonwood prairies. The majority of species accessed water from deep soil (5–30 cm) and groundwater in dry season and switched to using shallow soil water (0–5 cm) in wet season. Exception to this pattern is herbaceous Chromolaena frustrata, endemic to buttonwood hammocks of South Florida, which accessed shallow soil water in dry season and deep soil water in wet season. Our study assesses susceptibility of coastal upland species to sea level rise (SLR)‐driven changes in water table and salinity; the results of which can be incorporated into planning for adaptation to SLR. Copyright © 2014 John Wiley &amp; Sons, Ltd.

Watershed‐scale modeling of streamflow change in incised montane meadows

AbstractLand use practices have caused stream channel incision and water table decline in many montane meadows of the Western United States. Incision changes the magnitude and timing of streamflow in water supply source watersheds, a concern to resource managers and downstream water users. The hydrology of montane meadows under natural and incised conditions was investigated using watershed simulation for a range of hydrologic conditions. The results illustrate the interdependence between: watershed and meadow hydrology; bedrock and meadow aquifers; and surface and groundwater flow through the meadow for the modeled scenarios. During the wet season, stream incision resulted in less overland flow and interflow and more meadow recharge causing a net decrease in streamflow and increase in groundwater storage relative to natural meadow conditions. During the dry season, incision resulted in less meadow evapotranspiration and more groundwater discharge to the stream causing a net increase in streamflow and a decrease in groundwater storage relative to natural meadow conditions. In general, for a given meadow setting, the magnitude of change in summer streamflow and long‐term change in watershed groundwater storage due to incision will depend on the combined effect of: reduced evapotranspiration in the eroded meadow; induced groundwater recharge; replenishment of dry season groundwater storage depletion in meadow and bedrock aquifers by precipitation during wet years; and groundwater storage depletion that is not replenished by precipitation during wet years.

Hydrology of a forested riparian zone in an agricultural landscape of the humid tropics

Forested riparian zones are known to reduce movement of nitrogen from farms into streams in temperate areas, but predictive models of nitrogen transport and transformations rely on hydrological understanding, which is limited in the humid tropics. As a first step to understanding nitrogen cycling in the forested riparian zone of a lowland humid tropical agricultural landscape, we studied the hydrology of a riparian site in northeast Australia. The site has undulating topography and a 150-m wide strip of relatively undisturbed forest between sugarcane fields and the perennial stream. Riparian hydrology was dynamic in the wet season with frequent interactions between ground and surface water. Vertical and lateral fluxes of water through the variably saturated zone were high during the wet season due to intense rainfall, permeable soils and a variable discharge zone. However, complete saturation was never observed in the variably saturated zone. During the dry season groundwater movement was slow and the water table was several metres deep throughout most of the site. Uptake of groundwater by vegetation was a significant component of the water balance during the dry season and groundwater discharge to the creek is likely to be negligible at this time. During the wet season, uptake was small relative to other fluxes and the transpiration requirements of the trees could be met by the topsoil for much of the time. The hydrological conditions encountered are likely to exert large and variable influences on the transport and transformations of nitrogen in this part of the landscape. Contrary to the common understanding of riparian zone function, it appears that riparian zones of humid tropical lowlands are likely to be ineffective at removing nitrogen from groundwater. This will have implications for downstream water quality and ultimately on the quality of water discharging into the Great Barrier Reef lagoon, a sensitive and vulnerable marine environment.

A synthesis of long-term research by the Florida Coastal Everglades LTER Program

This paper synthesizes research conducted dusring the first 5–6 years of the Florida Coastal Everglades Long-Term Ecological Research Program (FCE LTER). My objectives are to review our research to date, and to present a new central theme and conceptual approach for future research. Our research has focused on understanding how dissolved organic matter (DOM) from upstream oligotrophic marshes interacted with a marine source of the limiting nutrient, phosphorus (P), to control productivity in the oligohaline estuarine ecotone. We have been working along freshwater to marine transects in two drainage basins located in Everglades National Park (ENP). The Shark River Slough transect (SRS) has a direct connection to the Gulf of Mexico, providing this estuarine ecotone with a source of marine P. The oligohaline ecotone along our southern Everglades transect (TS/Ph), however, is separated from this marine P source by the Florida Bay estuary. We originally hypothesized an ecosystem productivity peak in the SRS ecotone, driven by the interaction of marine P and Everglades DOM, but no such productivity peak in the TS/Ph ecotone because of this lack of marine P. Our research to date has tended to show the opposite pattern, however, with many ecosystem components showing enhanced productivity in the TS/Ph ecotone, but not in the SRS ecotone. Water column P concentrations followed a similar pattern, with unexpectedly high P in the TS/Ph ecotone during the dry season. Our organic geochemical research has shown that Everglades DOM is more refractory than originally hypothesized. We have also begun to understand the importance of detrital organic matter production and transport to ecotone dynamics and as the base of aquatic food webs. Our future research will build on this substantial body of knowledge about these oligotrophic estuaries. We will direct our efforts more strongly on biophysical dynamics in the oligohaline ecotone regions. Specifically, we will be focusing on inputs to these regions from four primary water sources: freshwater Everglades runoff, net precipitation, marine inputs, and groundwater. We are hypothesizing that dry season groundwater inputs of P will be particularly important to TS/Ph ecotone dynamics because of longer water residence times in this area. Our organic geochemical, biogeochemical, and ecosystem energetics work will focus more strongly on the importance of detrital organics and will take advantage of a key Everglades Restoration project, scheduled for 2008 or 2009, that will increase freshwater inputs to our SRS transect only. Finally, we will also begin to investigate the human dimensions of restoration, and of a growing population in south Florida that will become increasingly dependent on the Everglades for critical ecosystem services (including fresh water) even as its growth presents challenges to Everglades sustainability.