Bedrock depth influences spatial patterns of summer baseflow, temperature, and flow disconnection for mountainous headwater streams

In mountain headwater streams the quality and resilience of cold-water habitat is regulated by surface stream channel connectivity and groundwater exchange. These critical hydrologic processes are thought to be influenced by the stream corridor bedrock contact depth (sediment thickness), which is often inferred from sparse hillslope borehole information, piezometer refusal, and remotely sensed data. To investigate how local bedrock depth might control summer stream temperature and channel disconnection (dewatering) patterns, we measured stream corridor bedrock depth by collecting and interpreting 191 passive seismic datasets along eight headwater streams in Shenandoah National Park (Virginia USA). In addition, we used multiyear stream temperature and streamflow records to calculate summer baseflow metrics along and among the study streams. Finally, comprehensive visual surveys of stream channel dewatering were conducted in 2016, 2019, and 2021 during summer baseflow conditions (124 total km of stream length). We found that measured bedrock depths were not well-characterized by soils maps or an existing global-scale geologic dataset, where the latter overpredicted measured depths by 12.2 m (mean), or approximately four times the average bedrock depth of 2.9 m. Half of the eight study stream corridors had an average bedrock depth of less than 2 m. Of the eight study streams, Staunton River had the deepest average bedrock depth (3.4 m), the coldest summer temperature profiles, and substantially higher summer baseflow indices compared to the other study steams. Staunton River also exhibited paired air and water annual temperature signals suggesting deeper groundwater influence, and the stream channel did not dewater in lower sections during any baseflow survey. In contrast, streams Paine Run and Piney River did show pronounced, patchy channel dewatering, with Paine Run having dozens of discrete dry channel sections ranging 1 to greater than 300 m in length. Stream dewatering patterns were apparently influenced by a combination of discrete deep bedrock (20 m+) features and more subtle sediment thickness variation (1–4 m), depending on local stream valley hydrogeology. In combination these unique datasets show the first large-scale empirical support for existing conceptual models of headwater stream disconnection based on underflow capacity and shallow groundwater supply.

Groundwater Impacts and Management under a Drying Climate in Southern Australia

The trend to a hotter and drier climate, with more extended droughts, has been observed in recent decades in southern Australia and is projected to continue under climate change. This paper reviews studies on the projected impacts of climate change on groundwater and associated environmental assets in southern Australia, and describes groundwater planning frameworks and management responses. High-risk areas are spatially patchy due to highly saline groundwater or low-transmissivity aquifers. The proportional reduction in rainfall is amplified in the groundwater recharge and some groundwater discharge fluxes. This leads to issues of deteriorating groundwater-dependent ecosystems, streamflow depletion, reduced submarine discharge, groundwater inundation and intrusion in coastal regions and reduced groundwater supply for extraction. Recent water reforms in Australia support the mitigation of these impacts, but groundwater adaptation is still at its infancy. Risk management is being incorporated in regional water and groundwater management plans to support a shift to a more sustainable level of use and more climate-resilient water resources in affected areas. The emerging strategies of groundwater trade and managed aquifer recharge are described, as is the need for a national water-focused climate change planning process.

GMS-MODFLOW application in the investigation of groundwater potential in Concepcion, Tarlac, Philippines

This study used GMS-Modflow to investigate the ten-year groundwater potential in Concepcion, Tarlac. This region in Central Luzon, Philippines, with limited surface water, depends on groundwater as its primary freshwater source. The water demand projection estimated an increase of 38.5% from 2020 to 2030; hence, higher groundwater abstraction is perceived in the next ten years. To deviate from the risk associated with reliance on groundwater, this study, through GMS-MODFLOW, developed a groundwater model to mimic the aquifer’s current condition and investigated its behavior in response to future spatial and temporal variables. The simulation results generally showed a sustainable groundwater supply in Concepcion, Tarlac, for the next ten years, with no significant decline in hydraulic heads.

High-Resolution Direct Push Sensing in Wetland Geoarchaeology—First Traces of Off-Site Construction Activities at the Fossa Carolina

Wetland environments, with their excellent conservation conditions, provide geoarchaeological archives of past human activities. However, the subsurface soil is difficult to access due to high groundwater tables, unstable sediments, and the high cost of excavation. In this study, we present a ground-based non- and minimal-invasive prospection concept adapted to the conditions of wetlands. We investigated the Fossa Carolina in South Germany, a canal that was intended in 792/793 AD by Charlemagne to bridge the Central European Watershed. Although the resulting Carolingian banks and the fairway with wooden revetments are very imposing, archaeological traces of off-site construction activities have not been identified hitherto. Based on a geophysically surveyed intensive linear magnetic anomaly parallel to the Carolingian canal, we aimed to prove potential off-site traces of Carolingian construction activities. In this context, we built up a high-resolution cross-section using highly depth-accurate direct push sensing and ground-truthing. Our results showed the exact geometry of the canal and the former banks. Thus, the magnetic mass anomaly could be clearly located between the buried organic-rich topsoil and the Carolingian banks. The thermoluminescence dating showed that the position of the magnetic mass anomaly reflected Carolingian activities during the construction phases, specifically due to heat exposure. Moreover, we found hints of the groundwater supply to the 5-metre wide navigable fairway.

Many Oil Wells, One Evil: Potentially toxic metals concentration, seasonal variation and Human Health Risk Assessment in Drinking Water Quality in Ebocha-Obrikom Oil and Gas Area of Rivers State, Nigeria.

Background Oil and natural gas extraction have produced environmental pollution at levels that affect reproductive health of indigenous populations. Accordingly, polluted drinking water from physical, chemical and heavy metals can result in serious health problems, like anemia, kidney failure, immunosuppression, neurological impairments, gastrointestinal as well as respiratory irritation, skeletal system abnormalities, liver inflammation, liver cancer, cardiovascular diseases after chronic exposure and other cancer diseases with negative health effects. These diseases types remain associated to high amounts of heavy metal elements such as lead, chromium, zinc, copper, cadmium, manganese as well as nickel etc. Objectives Compare differences in water quality parameters in the study area (determine the level of pollutions in the different sites). Methodology: The investigation made use of standard analytical procedures. All sampling, conservation, transportation and analysis followed standard procedures described in APHA (2012). To prevent degradation of the organic substances, all obtained samples were transferred to the laboratory, while keeping in an icebox. Results: Result shows that during wet season, the mean values obtained for water quality parameters were significantly lower in site 9 compared with that obtained in other sites (p<0.05) with the exemptions of temperature, DO, BOD, COD, acidity, TH, TDS, K, Mg, Zn, Mn, Cd, Pb, Cu, Cr, NH3, NO2, NO3, Ni though slightly lower in most cases in site 9 were not significantly different (p>0.05) and both alkalinity and SO4 which were significantly higher in site 9 than site 1 (p<0.05). Result obtained during dry season reveals that there is no remarkable difference in pH, acidity, Pb and Ni between the nine sites (p>0.05) while other water quality parameters were significantly lower in site 9 than other sites excluding Cl and Mg which were both significantly higher in site 9 than site 8 (p<0.05). Conclusion: To guarantee quality groundwater supply for various purposes in Nigeria's core Niger Delta region, extra efforts must be taken to fully understand hydrogeochemical features and its suitability. Thus, this study will aid in the development of a quantitative understanding of the effects of diverse causes on groundwater level fluctuations in any aquifer around the world. Also, this analysis reinforces a valuable resource for researchers, activists and public officials seeking to help enhance community awareness, planning and performance. The verdicts would remain a valuable guideline for policymakers, the Ministry of Water Resources and development practitioners, as this highlights the requirement for suitable approaches toward mitigating toxic element of water resources contamination in the core Niger Delta toward safeguarding health of the public from carcinogenic as well as non-carcinogenic risks.

Groundwater in New Valley and kidney disease

Background This study was performed to assess the possible association between groundwater and kidney disease in new valley governorate . Methods This hospital-based cross-sectional observational study was conducted at the Department of Nephrology, Ain Shams University, Cairo, Egypt, during the period from August 2018 to January 2019. After obtaining verbal consent from all participants; the general information of each participant was recorded, full history taken and general examination was done for each participant, then urine samples and serum blood samples taken for urine analysis, serum urea and serum creatinine, then estimated glomulurar filtratin rate (eGFR) was calculated for healthy subjects groups using MDRD Equation; after that three different groundwater samples and Nile water sample collected and analyzed for different solutes and heavy metals contents. Result Our data suggests that rural community as in Eldakhla; which depends on groundwater supply may affected by more risk of CKD than urban community as in Cairo city, which depends on Nile water supply. Conclusion there are increased prevalence of CKD in New Valley governorate and this may be due to groundwater consumption .

Preliminary Identification to Local Coral Bleaching Event in Manjuto Beach, Pesisir Selatan Regency, West Sumatra: Hydro-Oceanographic Perspectives

Highlight ResarchThe cause of local coral bleaching in Manjuto Beash has been addressed.The influence of ebb-tide cycles on salinity mixing and stratification was analyzed.Spatial analysis Digital Shoreline Analysis System (DSASv5) was conducted to determine the coastline changes in Manjuto Beach.Flow model flexible mesh was simulated to determine the flow pattern within Sungai Pinang Bay.AbstractIn October 2019, the local community reported the occurrence of coral bleaching of a colony of Acropora sp. at Manjuto Beach, Pesisir Selatan Regency experienced bleaching. It was published in several local news, becoming a trending topic among local and central government authorities and coastal communities. There were many inaccuracies about the cause of this phenomenon. This study aimed to identify the causes of local coral bleaching in Manjuto Beach based on oceanographic perspectives. The water quality data collected using TOA DKK water quality checker in the surrounding Manjuto Beach were assessed descriptive-statistically. This study also analyzed the spatial changes of the coastline using DSASv5. A time series of tidal data was also used to analyze the tidal range-induced salinity stratification. A flow model with a flexible mesh was also simulated to determine the water mass movement and longshore current patterns in Manjuto Beach. Dissolved oxygen (DO), temperature, and salinity showed anomalies compared to the water quality standard to support marine life. During both flood and ebb tides, it ranged from 5.8-11.2 mg/L, 28-28.3oC, and 25-28 o/oo, respectively. The other parameters measured (pH, conductivity, turbidity, and density) were suitable for marine biota. The findings show that tidal range has a unique influence on salinity stratification. The intrusion of groundwater supply resulted in lowering of salinity, inducing local coral bleaching in Manjuto Beach. Changes in salinity levels were also triggered by tidal current ranging from 0-0.31 m/s resulting in cumulative salinity shock. Currently, Manjuto Beach is experiencing accretion ranging from 2.36-3.17 m/year, altering the water coverage through the flood-ebb cycles. Those states cause cumulative sun rays’ exposures and salinity shock induced by flood-ebb cycles. That is why local coral bleaching event is undoubtedly avoided.

Cost minimization of groundwater supply to a central tank

Minimization of groundwater exploitation cost is examined, considering: (a) Pumping from a system of wells up to a central water tank, including friction losses along the connecting pipe network and (b) amortization of network construction. Assuming that the wells are located symmetrically around the tank and directly connected to it, we derived analytically the distance between tank and wells, which minimizes the total cost. Then we compared the minimum cost of this well layout, with that of placing one well at the location of the tank and the rest symmetrically around it. Finally, we dropped any assumption on well layout, we considered that wells are connected to the tank using a minimum spanning tree and we optimized well locations and flow rates using genetic algorithms. For up to 8 wells, the resulting minimum cost is comparable to that of the symmetrical cases, even when the optimal well layout is quite different. Moreover, the analytical solution, derived for the symmetrical case, can serve to evaluate solutions achieved by sophisticated optimization techniques.

Assessment of Shallow Groundwater Purification Processes after the Construction of a Municipal Sewerage Network

In the present study, the impact of the construction of the sewerage network (2014) on groundwater quality was studied on the example of a middle-sized settlement in the Great Hungarian Plain and changes in water quality were assessed using GIS and multivariate statistical analysis. As a result of the pollution that has been going on for decades, the groundwater supply of the municipality has become heavily polluted. In the period before sewerage (2011–2013), clear spatial differences were shown in the degree of contamination in the area of the settlement: the degree of contamination increased in the direction of local groundwater flow. Based on our results, the construction of the sewerage network resulted in marked changes in the quality of groundwater wells. Our studies showed a clear decrease in the concentrations of inorganic pollutants (NH4+, NO2−, NO3−, PO43−). In the fifth year of the post-sewerage period (2019), the clear spatial difference between wells was eliminated. We have observed a strong descent (1.5 to 2 m) in groundwater levels in the post-sewerage period, the reason for that is clearly due to that wastewater outflow was eliminated. On this basis, it can be declared that the purification processes in the area have started, but at the same time, our results show that pollutants entering environment undergo a number of transformations and remain in the system for a long time.