Hydrological Setting Research Articles

Laboratory Experiments to Evaluate the Effectiveness of Persulfate to Oxidize BTEX in Saline Environment and at Elevated Temperature Using Stable Isotopes

In this study, batch experiments were carried out to investigate the effectiveness of persulfate (PS) as an oxidant agent to remediate benzene, toluene, ethylbenzene, and xylenes (BTEX) in saline environments and at high water temperatures (30 °C). This hydrological setting is quite common in contaminated groundwater aquifers in Middle Eastern countries. In general, increasing the system temperature from 10 to 30 °C greatly enhanced the effectiveness of PS, and resulted in a faster oxidation rate for the target contaminants. When PS was added to the reactor at 30 °C, the targeted contaminants were almost completely oxidized over a 98-day reaction period. During the chemical oxidation of the BTEX, carbon and hydrogen isotope fractionations were monitored and utilized as potential proof of contaminant degradation. The calculated carbon-enrichment values were −1.9‰ for benzene, −1.5‰ for ethylbenzene and toluene, −0.4‰ for ρ,m-xylene, and −1.4‰ for o-xylene, while the hydrogen enrichment values were −9.5‰, −6.8‰, −2.1‰, −6.9‰, and −9.1‰, respectively. In comparison with other processes, the hydrogen and carbon isotope fractionations during the chemical oxidation by PS were smaller than the isotope fractionations resulting from sulfate reduction and denitrification. This observation demonstrates the differences in the transformation pathways and isotope fractionations when compounds undergo chemical oxidation or biodegradation. The distinct trend observed on the dual isotope plot (Δδ13C vs. Δδ2H) suggests that compound-specific isotope analysis can be utilized to monitor the chemical oxidation of BTEX by PS, and to distinguish treatment zones where PS and biodegradation technologies are applied simultaneously.

Urban Flood Risk Assessment and Development of Urban Flood Resilient Spatial Plan for Bhubaneswar

Urban flooding is growing as a serious development challenge for cities. Urbanization demands the conversion of pervious land to impervious land by pushing the transformation of water bodies, flood plains, wetlands and green spaces into built-up spaces. This affects the hydrological setting of the city’s geographic area. Bhubaneswar, one of the first planned cities of independent India, has expanded rapidly with an increase in the settlement land use cover from 41 km2 to 81 km2 in the last two decades. Non-consideration of disaster risk assessment in the land use plan has placed the city at high disaster risk. Hence, this article explores various avenues for making a flood resilient city through spatial planning. To understand the flood and its consequences, a flood hazard and vulnerability map was prepared by overlaying the existing social and infrastructure networks, and flood risk zones were generated through analytical spatial modelling in GIS. This accounts for the areas in which flood hazards are expected to occur, as well as the area whose socio-economic and infrastructure susceptibility to the disaster is more. The key outcome is to ensure urban development that can work concurrently with nature by integrating disaster risk reduction strategies into land use planning.

Zonation of protistan plankton in a productive area of the Patagonian shelf: Potential implications for the anchovy distribution

In the southwestern Atlantic Shelf, in northern Patagonia, the coastal-inner shelf area of El Rincón (38°-41°S) is relevant due to retention processes and the occurrence of a mid-shelf front (MSF), which provide favorable habitat for the anchovy Engraulis anchoita, from which other commercial species feed on. Here, we assess the protistan plankton (>5 μm) composition and biomass during spring and summer of different years to explore the community structure at the base of the food web and its potential relation with the heterogenic spatial distribution of the anchovy's life stages previously reported in the literature. Our in situ data together with analyses of surface circulation patterns and satellite chlorophyll a denote a marked zonation of phytoplankton. We find that diatoms are the largest carbon contributors in the coastal sector and dinoflagellates near the MSF, where large copepods and mainly juveniles and adults of E. anchoita are found. In turn, transient small-scale eddies develop in the low chlorophyll central area dominated by nanoflagellates and ciliates, where small copepods and eggs and larvae of the anchovy dominate. Our results provide insights of the potential link between plankton assemblages, hydrological settings and developing stages of a highly exploited fish. Moreover, we contribute to biodiversity records used in global assessments of possible shifts at the population and community levels that might have cascading effects on marine ecosystems' productivity.

Environmental Drivers of the Seasonal Prevalence of Enteropathogenic Bacteria in the Gulf Ecosystem of Gujarat, India: Unravelling Its Diarrheal Enigma

Recurrent episodes of water borne diarrheal outbreaks is the pressing public health crisis in the Gulf of Khambat (GoK), Gujarat and its adjoining area. We aimed to identify seasonality of environmental signatures associated with the dynamics of Gulf enteropathogens and related health implications. A yearlong sampling data has been generated from the five sites across the GoK of high anthropogenic burden and contrasting hydrological settings. Hydro-chemical characteristics of water samples and bacteriological indices were analysed on field and laboratory condition respectively and robust statistics was applied to assess their interrelationship and associated health risks. Annual variation of hydro-chemical indices viz. temperature 26.4oC–36.7oC, pH 7.51–8.44, salinity 28.3–36.7 mS/cm, turbidity 3.6–995 NTU and Dissolved Oxygen (DO) was recorded in the water samples. Extremely high turbidity (70.5-995) along with high salinity (28.3-34.8) is found to be the unique characteristic feature of Gulf water, which facilitates the abundance of various enteropathogenic bacterial species, specially the clinically important ones like V. cholerae, V. alginolyticus and E. coli. Surprisingly, an explosive annual preponderance of V. alginolyticus could be observed throughout all the study sites and existence of V. cholerae is restricted only in the high turbid water (>500NTU) of Gulf. Detection of E. coli is also a significant report from this high saline habitat, indicating faecal contamination. Seasonality of Vibrios and coliforms are highly influenced by precipitation rate and turbidity of water (p<0.05). DO level is found to be another crucial marker which regulates distribution of enteropathogens across the Gulf water as well as indicates the pollution level of Gulf attributed to environmental health risk. This is the first report of a longitudinal study of enteropathogenic load in GoK and its direct relationship with diarrheal incidence profile, which adds valuable knowledge for the formulation of ‘bio-environmental tool’ for effective water quality monitoring and disease prevention.

Projected changes of regional lake hydrologic characteristics in response to 21st century climate change

ABSTRACT Inland lakes are socially and ecologically important components of many regional landscapes. Exploring lake responses to plausible future climate scenarios can provide important information needed to inform stakeholders of likely effects of hydrologic changes on these waterbodies in coming decades. To assess potential climate effects on lake hydrology, we combined a previously published spatially explicit, processed-based hydrologic modeling framework implemented over the lake-rich landscape of the Northern Highlands Lake District within the United States with an ensemble of climate change scenarios for the 2050s (2041–2070) and 2080s (2071–2100). Model results quantify the effects of climate change on water budgets and lake stage elevations for 3692 lakes and highlight the importance of landscape and hydrologic setting for the response of specific lake types to climate change. All future climate projections resulted in loss of ice cover and snowpack as well as increased evaporation, but variability in climate projections (warmer conditions, wet winters combined with wet or dry summers) interacted with lake characteristics and landscape position to produce variable lake hydrologic changes. Water levels for drainage lakes (lakes with substantial surface water inflows and outflows) showed nearly no change, whereas minimum water levels for seepage lakes (minimal surface water fluxes) decreased by an average of up to 2.64 m by the end of the 21st century. Our physically based modeling approach is parsimonious and computationally efficient and can be applied to other lake-rich regions to investigate interregional variability in lake hydrologic response to future climate scenarios.

Contrasting fates of terrestrial organic carbon pools in marginal sea sediments

Burial of terrestrial organic carbon (OCterr) in marginal sea sediments is a key component of the carbon cycle, exerting long-term influence on atmospheric CO2 and climate. Assessment of the burial efficiency of OCterr is of key importance, yet remains poorly constrained due to current gaps in our knowledge of mechanistic controls, including the influence of organic matter composition and age on the fate of OCterr in marine sediments. We measured bulk characteristics (δ13C and Δ14C of OC; mineral surface area, SA; grain size; n = 98 samples) and biomarker carbon isotopic compositions (fatty acid δ13C and Δ14C; n = 11) of a suite of surface sediment samples from the Bohai Sea and Yellow Sea (BS-YS). Combining with published results, bulk OC (n = 234) and biomarker (n = 19) carbon isotopic data are used to examine spatial variability in the sources and ages of OCterr in this shallow marginal sea system. Biomarker carbon isotopic values are used to constrain endmember values, and a dual carbon isotope mixing model was applied to all bulk samples to develop a spatially explicit assessment of contributions of different pools of OCterr. Although highly spatially variable, pre-aged OC (OCpre-aged) and fossil OC (OCfossil) when combined (i.e., “non-modern OC”) on average accounted for 51 ± 10% of the OC in BS-YS surface sediments. This was equivalent to the proportion of OCterr (ave., 51 ± 14%) estimated from a δ13COC binary mixing model, suggesting OCterr in the mixed layer of BS-YS sediments is predominantly composed of millennial-aged OC. The burial potential of pool-specific OCterr was then evaluated through comparison of corresponding mineral SA-normalized loadings of surface sediments with those of Yellow River suspended particulate matter. Both the regression slope and the arithmetic mean value approaches reveal high burial potential for all terrestrial OC pools delivered by Yellow River, which is attributed to the aged and refractory nature of OC exported from the Yellow River. However, differing relationships of pool-specific OCterr loadings between BS-YS and Yellow River sediments imply contrasting fates. In particular, we find that the burial potential of OCpre-aged is consistently greater than that of OCfossil. This surprising observation suggests either enhanced degradation of OCfossil during lateral transport (possibly as a consequence of different mineral associations and hydrodynamic sorting effects), or additional sources for OCpre-aged, such as from small rivers or aerosol deposition. Overall, OC age, mineralogical composition and hydrological settings contribute to the complex patterns of OC residing in northern China marginal sea surface sediments. This novel molecular-isotopic approach reveals significant spatial variability in proportions, contents and burial potential among terrestrial OC pools, and underlines the importance of considering organic matter age and composition in understanding and constraining the fate of OCterr in marine sedimentary environments.

Time-series temperature analyses indicate conduction and diffusion are dominant heat-transfer processes in fine sediment, low-flow streams

Stream-groundwater exchange has been investigated in a wide range of hydrologic settings, though very few studies have focused on fine-sediment streambeds. Well-established thermal methods (i.e., analytical and numerical solution of time-series temperature depth-profiles) in combination with Darcy's and electrical resistivity (ER) evaluations were implemented to improve understanding of processes dominating flow and transport in a low permeability and low-flow coastal stream such as Oso Creek, Texas. The seasonal-trend decomposition using Loess (STL) is tested as a potential means to differentiate between advection and conduction and is validated against groundwater fluxes derived from the other well-established thermal methods. The numerical and analytical solutions indicate groundwater upward discharge was 9 mm d−1 for summer and 3.5 mm d−1 for winter, corresponding to the region's extreme drought conditions. These types of low flow conditions are usually accompanied by hyporheic flow, limiting the vertical flow assumption. While the numerical and analytical methods provide good insight into streambed hydrology for a low-permeability and low-flow stream in a semiarid coastal area, there are limitations associated with the STL method. The analytical and numerical thermal methods employed herein confirm that conduction and diffusion are the dominant processes of heat and solute transfer in fine-sediment streambeds, providing an improved understanding of process-based groundwater-stream interaction and water resources in this type of settings.

Sustainable Power Purchase Contracts for Local Industries from Floating Solar & Pumped Hydro Integration

This paper analyses the technical and business cases for a hybrid floating solar and pumped hydro facility to provide secure, sustainable baseload power to local industrial and commercial users through bilateral PPA contracting and private wire connections. Based upon a realistic hydrological setting with a range of assumptions for both the floating solar and the pumped hydro installations, daily optimisation of operations to provide different levels of secure baseload PPA contracts are optimised. The research shows how the premium for baseload contracts depends upon the size of the contracts and the size of the solar installation. The premia are the opportunity costs to the hydro operators from potential sales to the wholesale market. We find that the premia are affordable to local users and that the combination of solar and pumped storage thereby enables a hydro operator to offer higher levels of secure baseload power throughout the year to local industries where the national power resources are otherwise unreliable.

Characterising hillslope–stream connectivity with a joint event analysis of stream and groundwater levels

Abstract. Hillslope–stream connectivity controls runoff generation, during events and during baseflow conditions. However, assessing subsurface connectivity is a challenging task, as it occurs in the hidden subsurface domain where water flow can not be easily observed. We therefore investigated if the results of a joint analysis of rainfall event responses of near-stream groundwater levels and stream water levels could serve as a viable proxy for hillslope–stream connectivity. The analysis focuses on the extent of response, correlations, lag times and synchronicity. As a first step, a new data analysis scheme was developed, separating the aspects of (a) response timing and (b) extent of water level change. This provides new perspectives on the relationship between groundwater and stream responses. In a second step we investigated if this analysis can give an indication of hillslope–stream connectivity at the catchment scale. Stream water levels and groundwater levels were measured at five different hillslopes over 5 to 6 years. Using a new detection algorithm, we extracted 706 rainfall response events for subsequent analysis. Carrying out this analysis in two different geological regions (schist and marls) allowed us to test the usefulness of the proxy under different hydrological settings while also providing insight into the geologically driven differences in response behaviour. For rainfall events with low initial groundwater level, groundwater level responses often lag behind the stream with respect to the start of rise and the time of peak. This lag disappears at high antecedent groundwater levels. At low groundwater levels the relationship between groundwater and stream water level responses to rainfall are highly variable, while at high groundwater levels, above a certain threshold, this relationship tends to become more uniform. The same threshold was able to predict increased likelihood for high runoff coefficients, indicating a strong increase in connectivity once the groundwater level threshold was surpassed. The joint analysis of shallow near-stream groundwater and stream water levels provided information on the presence or absence and to a certain extent also on the degree of subsurface hillslope–stream connectivity. The underlying threshold processes were interpreted as transmissivity feedback in the marls and fill-and-spill in the schist. The value of these measurements is high; however, time series of several years and a large number of events are necessary to produce representative results. We also find that locally measured thresholds in groundwater levels can provide insight into the connectivity and event response of the corresponding headwater catchments. If the location of the well is chosen wisely, a single time series of shallow groundwater can indicate if the catchment is in a state of high or low connectivity.

Towards the Understanding of Hydrogeochemical Seismic Responses in Karst Aquifers: A Retrospective Meta-Analysis Focused on the Apennines (Italy)

Earthquakes are known to affect groundwater properties, yet the mechanisms causing chemical and physical aquifer changes are still unclear. The Apennines mountain belt in Italy presents a rich literature of case studies documenting hydrogeochemical response to seismicity, due to the high frequency of seismic events and the presence of different regional aquifers in the area. In this study, we synthesize published data from the last 30 years in the Apennine region in order to shed light on the main mechanisms causing earthquake induced water changes. The results suggest the geologic and hydrologic setting specific to a given spring play an important role in spring response, as well as the timing of the observed response. In contrast to setting, the main focal mechanisms of earthquake and the distance between epicenter and the analyzed springs seems to present a minor role in defining the response. The analysis of different response variables, moreover, indicates that an important driver of change is the degassing of CO2, especially in thermal springs, whereas a rapid increase in solute concentration due to permeability enhancement is observable in different cold and shallow springs. These findings also leave open the debate regarding whether earthquake precursors can be recognized beyond site-specific responses. Such responses can be understood more comprehensively through the establishment of a regional long-term monitoring system and continuous harmonization of data and sampling strategies, achievable in the Apennine region through the set-up of a monitoring network.

Magnetic Properties of Late Holocene Dead Sea Sediments as a Monitor of Regional Hydroclimate

AbstractDiagenetic processes in anoxic sedimentary environments influence sediment magnetic properties mainly through dissolution of detrital magnetite and precipitation of authigenic greigite. Recently exposed late Holocene Dead Sea sediments provide an opportunity to study the processes governing greigite formation and preservation, and their relation to different hydrological settings. Magnetic data and pore‐fluid compositions were obtained from three Holocene sections along a N‐S transect on the western Dead Sea shore: Og, Ein‐Feshkha (EF), and Ein‐Gedi. The northern sections are closer to the major freshwater source to the Dead Sea‐the Jordan River. Detrital titanomagnetite is present at all sections, but greigite is the dominant magnetic phase at Og and EF. Bulk rock magnetic data vary between and within the sections by over 3 orders of magnitude, where higher values indicate higher greigite concentrations. At the three sites, pore fluids have similar or lower salinity than the modern and Holocene Dead Sea brine, with variable and dissolved iron (Fe2+) and sulfate (SO42−). Magnetic property changes are reflected by iron and/or sulfate microbial reduction that controlled sedimentary greigite formation. We propose that the N‐S greigite decrease suggests that anoxic microbial activity was controlled by labile organic matter and/or reactive iron brought by, or formed as a result of, freshwater influx from the Jordan River. Hence, greigite concentration changes depended on past freshwater input to the hypersaline lake and proximity to the freshwater source. The apparent relationship between hydrological conditions and magnetic properties provides a new method to trace past hydrological changes in the Dead Sea.

Fluoride contamination in and around selected geothermal sites in Odisha, Eastern India: assessment of ionic relations, fluoride exposure and remediation.

Fluoride contamination in groundwater is a major problem throughout the world as well as in India. High-fluoride content was reported in the hot springs of Atri and Tarbalo sites in Odisha, India, and residents of nearby villages showed the manifestations of fluorosis. Around 39% of the groundwater samples showed fluoride concentration > 1 mg/l, higher than the desirable limit specified by the WHO. The dominant chemical facies of groundwaters were ions of Ca-Mg-HCO3 and Ca-Na-Cl, which infers the lithological control over the hydrochemistry of this area. A strong correlation between fluoride and other major ions could not be found, suggesting that multiple processes are responsible for the enriched fluoride concentration observed in the study area. The major geochemical processes include dissolution of fluoride-bearing minerals from the rocks, evapotranspiration, agricultural input and mixing of cold groundwater with hot spring water containing high fluoride. The maximum fluoride exposure doses through drinking water from fluoride-contaminated tube wells were estimated to be 0.07 mg/kg/d for infants, 0.125 mg/kg/d for children and 0.06 mg/kg/d for adults, which are higher than the minimum risk level (0.05 mg/kg/d). Exposure doses of fluoride indicate that exposure risk is doubled for children in comparison to infants and adults, which might cause severe dental fluorosis and other ailments. Considering the environmental and hydrological set up of the study area, membrane defluoridation process can be suggested as the best remediation method. Nalgonda technique, dilution of fluoride-rich groundwater and better nutrition containing calcium and vitamin C are other possible options that can be included for early mitigation of fluoride contamination.

Footprints of Atlantification in the vertical distribution and diversity of gelatinous zooplankton in the Fram Strait (Arctic Ocean)

Gelatinous zooplankton (GZ), here understood as pelagic cnidarians and ctenophores, are an important component of marine ecosystems. Their diversity and distribution reflect local hydrological settings especially well, thus allowing the development of biotic indices for studying climate-mediated changes in the world’s oceans. The effects of global warming are most pronounced in the Arctic Ocean and have been further accelerated by the strengthening inflow of relatively warm Atlantic waters (AtW) via the Fram Strait, referred to as Atlantification. Here, we use the GZ distribution to describe the current state of Atlantic water inflow into the Arctic Ocean and to discuss the future of this fragile ecosystem. For this purpose, we characterized the abundance, diversity, and demography of the GZ identified from vertically stratified samples (down to 1000 m) collected in the Fram Strait along two latitudinally parallel transects of varying influence of AtW. Overall, we identified 17 taxa, with Aglantha digitale, Dimophyes arctica and Mertensia ovum being the most abundant. We then contrasted our jellyfish and ctenophore data with both biotic and environmental ecosystem characteristics and analysed the associations between the GZ community and water mass distribution. We showed that the more abundant GZ community was found along the southern transect; that the sampling depth and bathymetric zone played the most important roles in structuring the GZ diversity; that water mass distribution affected GZ demography; and that AtW was dominated by A. digitale, that constituted 66% of the total GZ abundance. Our results, although temporarily limited, suggest that the Atlantification will promote the expansion of boreal species into the Arctic, and could lead to a less diverse, but more abundant GZ community in the future. In addition, we compare in detail the GZ community found in different water masses, at different depths, and in different bathymetric zones, and supported with literature data, discuss the future of the European Arctic under the scenario of increasing inflow of Atlantic water.

Towards harmonisation of image velocimetry techniques for river surface velocity observations

Abstract. Since the turn of the 21st century, image-based velocimetry techniques have become an increasingly popular approach for determining open-channel flow in a range of hydrological settings across Europe and beyond. Simultaneously, a range of large-scale image velocimetry algorithms have been developed that are equipped with differing image pre-processing and analytical capabilities. Yet in operational hydrometry, these techniques are utilised by few competent authorities. Therefore, imagery collected for image velocimetry analysis (along with reference data) is required both to enable inter-comparisons between these differing approaches and to test their overall efficacy. Through benchmarking exercises, it will be possible to assess which approaches are best suited for a range of fluvial settings, and to focus future software developments. Here we collate and describe datasets acquired from seven countries across Europe and North America, consisting of videos that have been subjected to a range of pre-processing and image velocimetry analyses (Perks et al., 2020, https://doi.org/10.4121/uuid:014d56f7-06dd-49ad-a48c-2282ab10428e). Reference data are available for 12 of the 13 case studies presented, enabling these data to be used for reference and accuracy assessment.

Hydrogeochemical and environmental water quality standards in the overlap between high mountainous natural protected areas and copper mining activities (Mapocho river upper basin, Santiago, Chile)

Natural hydrogeochemical backgrounds or signatures from rivers around the world show great differences depending on the geological and hydrological settings where the specific watershed is placed. This fact is especially relevant and notorious, when the metallic content of waters draining hydrothermally-altered high-mountainous regions is considered. The present study offers a hydrogeochemical perspective to improve the generation of Environmental Water Quality Standards (EWQS) in mineralized high mountain regions comprised by rivers unaffected and affected by acid rock drainage (ARD). To this end, the complex and versatile reality at the Mapocho river upper basin (comprised by a natural ARD affected sub-basin, a mining intervened sub-basin and a third sub-basin with Andean unaffected waters) was used to evaluate the effect of seasonal and long-term climatic variations on hydrothermally-altered high-mountainous regions.In addition, 22 different environmental water quality standards (EWQS) from different countries around the globe were analyzed. This information was used to define what could be understood as “an acceptable water quality for environmental use”. Also, the obtained elemental concentration and physicochemical ranges were compared with the results obtained at the Mapocho upper basin to assess the importance of regional and local geochemical backgrounds on the generation of EWQS. As a result of this information generation, compilation, analyses and intercomparison, several recommendations to consider during the generation of EWQS at heterogenous high mountainous watersheds comprised by both ARD affected and unaffected sub basins were made. Special attention was paid to the incorporation of seasonal variations and long-term effects (climate change) on the generation of more realistic and useful EWQS.

Reach‐scale bankfull channel types can exist independently of catchment hydrology

AbstractReach‐scale morphological channel classifications are underpinned by the theory that each channel type is related to an assemblage of reach‐ and catchment‐scale hydrologic, topographic, and sediment supply drivers. However, the relative importance of each driver on reach morphology is unclear, as is the possibility that different driver assemblages yield the same reach morphology. Reach‐scale classifications have never needed to be predicated on hydrology, yet hydrology controls discharge and thus sediment transport capacity. The scientific question is: do two or more regions with quantifiable differences in hydrologic setting end up with different reach‐scale channel types, or do channel types transcend hydrologic setting because hydrologic setting is not a dominant control at the reach scale? This study answered this question by isolating hydrologic metrics as potential dominant controls of channel type. Three steps were applied in a large test basin with diverse hydrologic settings (Sacramento River, California) to: (1) create a reach‐scale channel classification based on local site surveys, (2) categorize sites by flood magnitude, dimensionless flood magnitude, and annual hydrologic regime type, and (3) statistically analyze two hydrogeomorphic linkages. Statistical tests assessed the spatial distribution of channel types and the dependence of channel type morphological attributes by hydrologic setting. Results yielded 10 channel types. Nearly all types existed across all hydrologic settings, which is perhaps a surprising development for hydrogeomorphology. Downstream hydraulic geometry relationships were statistically significant. In addition, cobble‐dominated uniform streams showed a consistent inverse relationship between slope and dimensionless flood magnitude, an indication of dynamic equilibrium between transport capacity and sediment supply. However, most morphological attributes showed no sorting by hydrologic setting. This study suggests that median hydraulic geometry relations persist across basins and within channel types, but hydrologic influence on geomorphic variability is likely due to local influences rather than catchment‐scale drivers. © 2020 John Wiley & Sons, Ltd.

Assessing groundwater pollution and potential remediation processes in a multi-layer aquifer system

Pumping-induced leakage across aquitards may induce a deterioration of water quality in multi-layer aquifer systems. It is critical to understand long-term trends of water quality parameters when assessing the sustainability of groundwater abstraction. Daily drinking water needs of 2.2 million people in Yinchuan region of northwest China are solely met by groundwater resources, but long-term groundwater withdrawal has created an extensive cone of depression (294 km2 in area) in confined aquifer causing increased vertical recharge. In this study, a model was established and calibrated with head data, then was incorporated with field tracer tests to provide key information on the hydro-dispersive characteristics of the contaminant for assessing both the current and future state of the aquifer system. The results confirmed a close association between water quality deterioration and high downward fluxes of high chloride groundwater, most notably near the center of the cone of depression. On a temporal scale, water quality degradation remains slow, largely due to the high, pre-existing storage of good quality water. Modeling suggests that the water quality in the upper confined aquifer will lose its potability over a 25 km2 and 50 km2 area within 200 years under the current and intensified pumping conditions, respectively. Elevated chloride values were also detected toward the east of the cone, highlighting the impact of hydrological settings on the vertical groundwater flow. Modeling of potential aquifer remediation shows an even slower response with a further 250 years or more required for potability to be restored in affected areas. The findings can provide valuable guidance to for decision makers and support the sustainable management of aquifer exploitation.

Groundwater dynamic response mechanism and quantity vulnerability assessment under the influence of human activities.

Groundwater depletion becomes a prominent issue due to the fast-growing water demand in semiarid and arid regions, which poses serious hydrogeological problems and restrains regional sustainable development. Groundwater dynamic response mechanism analysis and quantity vulnerability assessment are useful methods for groundwater protection and management. This paper analyzed the spatial and temporal variation of groundwater level in Xi'an, and studied the response characteristic of groundwater dynamic to its driving forces in different periods under the influence of human activities. Considering both hydrological settings and human disturbances, a modified evaluation system based on fuzzy comprehensive evaluation method and DRYTECL model was proposed to assess groundwater quantity vulnerability. In order to make the results more reasonable and in line with actual situation of the study area, a weighting system that builds on subjective and objective weights was put forward as well. The results show that groundwater level sharply dropped in the last few decades, and the spatial autocorrelation of groundwater level has gotten weaker, suggesting that the contribution of natural factors to groundwater-level variation decreased. Land use, exploitation, and other human activities had a great influence on groundwater dynamic by changing the discharge and recharge condition of groundwater, and the response characteristic of groundwater level to precipitation, runoff, and exploitation varied with time and hydrogeological conditions. Groundwater quantity vulnerability map showed 63.8% of the study area fell within moderate-to-high quantity risk, which indicated that groundwater depletion mainly occurred in highly urbanized areas. The single-parameter sensitivity analysis showed that the exploitation is the most sensitive factor to groundwater quantity vulnerability, the real effects of land use on groundwater quantity risk are greater than its theoretical effects, and net recharge is important to groundwater recovery.

Monthly Entomological Inoculation Rate Data for Studying the Seasonality of Malaria Transmission in Africa

A comprehensive literature review was conducted to create a new database of 197 field surveys of monthly malaria Entomological Inoculation Rates (EIR), a metric of malaria transmission intensity. All field studies provide data at a monthly temporal resolution and have a duration of at least one year in order to study the seasonality of the disease. For inclusion, data collection methodologies adhered to a specific standard and the location and timing of the measurements were documented. Auxiliary information on the population and hydrological setting were also included. The database includes measurements that cover West and Central Africa and the period from 1945 to 2011, and hence facilitates analysis of interannual transmission variability over broad regions.

Experimental study of road deicing by using the urban groundwater under the climatic condition of Nuremberg city, Germany

Traffic accidents caused by heavy icing and snowing kept increasing in Germany in recent years, and many deicing methods were therefore developed. These methods either harm the environment (deicing salt) or damage roads (snowplows). As an alternative, the heating of roads using electricity or heated water has been proposed. This study considers the direct use of groundwater for road deicing in urban centers. The climatic and hydrological setting of Nuremberg city is referenced for a testing setup inside a cooling chamber using concrete slabs to test inlet water temperatures under different ambient temperatures. They were designed with 100 mm and 200 mm coil distance and both with an installation depth of around 40 mm. Additionally, an outside test field in a similar fashion is built to validate the measurements inside a chamber. The experiments indicated that a groundwater temperature of 10 °C is sufficient to keep the surface ice-free in typical winter days in the study area. Furthermore, the snow did not accumulate on the outside test field during snowfall events. The usability of this heating method could, therefore, be recommended for road deicing under such climatic condition.