Perennial Streams Research Articles

Nutritional, medicinal and indigenous use of Nasturtium officinale in Tehsil Thunag of District Mandi, Himachal Pradesh, North Western Himalaya, India

Inhabitants of the hilly regions largely depend on wild herbs for medicine and food supplements. The indigenous knowledge and traditional use of these wild herbs are vanishing fast. Thunag Tehsil is the rich repository of wild medicinal herbs. One among them is Nasturtium officinale (watercress), of the family Brassicaceae, it has been long used as a home remedy or a medicinal plant, edible herb by the local people. The aim of this study was to investigate the traditional use, nutritional, medicinal use of N. officinale in the Tehsil Thunag of District Mandi Himachal Pradesh Western Himalayas. Local inhabitant of valley used to collect this green leafy vegetable from nearby river streams, they used to consume it as (sagg) green leafy vegetable or as a medicine. It is a good source of food, medicine and income for local people in the study area, as this area is surrounded by large number of perennial rivers and streams where this plant is found in abundant. But the young generation is least interested about these traditional herbs and their uses.Its traditional knowledge is declining sharply. So to document this knowledge, the present study was carried in this region.

The Influence of Climate Variability on the Accuracy of NHD Perennial and Nonperennial Stream Classifications

AbstractNational Hydrography Dataset (NHD) stream permanence classifications (SPC; perennial, intermittent, and ephemeral) are widely used for data visualization and applied science, and have implications for resource policy and management. NHD SPC were assigned using a combination of topographic field surveys and interviews with local residents. However, previous studies indicate that non‐NHD, in situ streamflow observations (NNO) frequently disagree with NHD SPC. We hypothesized that differences in annual climate conditions between map creation years and the years NNO were collected contributed to disagreement between NNO and NHD SPC. We compared NHD SPC to 10,055 NNO (classified as “wet” or “dry”) collected in the Pacific Northwest between 1977 and 2015. Annual climate conditions were described with the Palmer Drought Severity Index (PDSI). Stream order was added as a covariate to account for different effects along the stream network. NHD SPC agreed with 80.5% of NNO. “Dry” NNO were five times more likely to disagree with NHD than “wet” NNO (p < 0.0001). Disagreement was greatest on first‐order streams. When NHD SPC were collected during a wetter period than NNO the probability of disagreement increased by a factor of 1.17 (p < 0.0001) per unit difference in PDSI. The influence of climate on disagreements between NNO and NHD SPC provides support for the continued development of dynamic models representing SPC as opposed to static NHD classifications.

Communities in high definition: Spatial and environmental factors shape the micro‐distribution of aquatic invertebrates

Abstract According to metacommunity theories, the structure of natural communities is the result of both environmental filtering and spatial processes, with their relative importance depending on factors including local habitat characteristics, functional features of organisms, and the spatial scale considered. However, few studies have explored environmental and spatial processes in riverine systems at local scales, explicitly incorporating spatial coordinates into multi‐taxa distribution models. To address this gap, we conducted a small‐scale study to discriminate between abiotic and biotic factors affecting the distribution of aquatic macroinvertebrates, applying metacommunity concepts. We studied a mountain section in each of three perennial streams within the Po River Basin (northern Italy). We sampled macroinvertebrates both in summer and winter, using specific in situ 50‐point random sampling grids. Environmental factors, including benthic organic matter (BOM), flow velocity, water depth, and substrate were recorded together with spatial coordinates for each sampling point. The relationships between community metrics (taxon richness, abundance, biomass, biomass–abundance ratio, and functional feeding groups) and explanatory variables (environmental and spatial) were assessed using generalised additive models. The influence of the explanatory variables on community structure was analysed with joint species distribution models. Environmental variables—primarily BOM—were the main drivers affecting community metrics, whereas the effects of spatial variables varied among metrics, streams, and seasons. During summer, community structure was strongly affected by BOM and spatial position within the riverbed, the latter probably being a proxy for mass effects mediated by biotic and stochastic processes. In contrast, community structure was mainly shaped by hydraulic variables in winter. Using macroinvertebrate communities as a model group, our results demonstrate that metacommunity concepts can explain small‐scale variability in community structure. We found that both environmental filtering and biotic processes shape local communities, with the strength of these drivers depending on the season. These insights provide baseline knowledge that informs our understanding of ecological responses to environmental variability in contexts including restoration ecology, habitat suitability modelling, and biomonitoring.

Lessons from the 2018 drought for management of local water supplies in upland areas: A tracer‐based assessment

AbstractClimate change, combined with industrial growth and increasing demand, could result in serious future water shortages and related water quality and temperature issues, especially for upland and humid areas. The extreme 2018 drought that prevailed throughout Europe provided an opportunity to investigate conditions likely to become more frequent in the future. For an upland rural catchment utilised by the distilling industry in North‐East Scotland, a tracer‐based survey combined discharge, electrical conductivity, stable water isotopes and temperature measurements to understand the impacts of drought on dominant stream water and industry water sources, both in terms of water quantity and quality (temperature). Results showed that water types (groundwater, ephemeral stream water, perennial stream water and water from small dams) were spatially distinct and varied more in space than time. With regards to the drought conditions we found that streams were largely maintained by groundwater during low flows. This also buffered stream water temperatures. Water types with high young water fractions were less resilient, resulting in streams with an ephemeral nature. Although our results demonstrated the importance of groundwater for drought resilience, water balance data revealed these storage reserves were being depleted and only recovered towards the end of the following year because of above average rainfall in 2019. Increased storage depletion under continued trends of extreme drought and water abstraction could be addressed via informed (nature based) management strategies which focus on increasing recharge. This may improve resilience to droughts as well as floods, but site specific testing and modelling are required to understand their potential. Results could have implications for management of water volumes and temperature, particularly for the sustainability of an historic industry, balancing requirements of rural communities and the environment.

Assessing water conditions for Heleophryne rosei tadpoles and the conservation relevance

The Table Mountain Ghost Frog (Heleophryne rosei) is endemic to the Table Mountain massif and is Critically Endangered. Other than clear, clean perennial stream flow, the optimal aquatic conditions required by their larvae are unknown. Dissolved oxygen, temperature, pH, electro-conductivity, aspect and permanence of flow are the independent variables measured seasonally at two sampling altitudes at 12 rivers of the massif. Using a logistic regression model we found that a permanence of water flow and lower water temperature were significant predictors of tadpole presence. Streams with mean summer temperature above 17.2 °C, at 300 m – 400 m above sea level, do not have tadpoles. Summer and autumn abstraction should be avoided, while a summer water temperature above an average of 17.2 °C is a threshold of potential concern for management authorities responsible for biodiversity conservation, threat mitigation efforts, and bulk-water supply and abstraction.Conservation implications: The Environmental Water Reserve has not been determined for streams of Table Mountain. The requirements of the Critically Endangered Table Mountain Ghost Frog (Heleophryne rosei) can be adopted as the minimum conditions to support this species and associated communities. Perennial flow, an average January water temperature of 17.2 °C or lower.

Water source utilization under differing surface flow regimes in the riparian species Liquidambar styraciflua, in the southern Appalachian foothills, USA

Studies across the United States and globally have revealed that mature riparian trees often utilize little streamwater, relying on soil moisture and groundwater instead. Contrastingly, riparian plants growing in wetland systems in the southeastern US use greater proportions of swamp water. The purpose of the present study was to determine if plant water uptake was linked to surface flow regime of the riparian system, characterized by stream flow and standing pond water nearby. Water sources of Liquidambar styraciflua growing along Whetstone Creek, a perennial stream in Stoneville, NC, were determined and compared to those of individuals growing along adjacent spring-fed ponds by analyzing stable isotopic compositions of plant water. Plant water status and environmental variables were also monitored due to possible influences on the specific water sources accessed. It was expected that pondside individuals, due to the lower flow rate and increased pond water availability, would utilize a greater amount of surface water than groundwater, which is shallow at the site, compared to streamside trees. However, trees at both sites appeared to rely about equally on shallow soil and surface water, while groundwater contributed only a minor proportion to trees at both sites. There were no meaningful relationships between the water sources measured and environmental factors, and plant water status was consistently high for trees at both sites. The current study is one of the first to demonstrate quantitatively a strong reliance on surface water by mature riparian trees in the southeastern US.

Calibrated Simulation of the Long‐Term Average Surficial Groundwater System and Derived Spatial Distributions of its Characteristics for the Contiguous United States

AbstractWhile the physical processes governing groundwater flow are well understood, and the computational resources now exist for solving the governing equations in three dimensions over continental‐scale domains, there remains substantial uncertainty about the subsurface distribution of the properties that control groundwater flow and transport for much of the contiguous United States (CONUS). The transmissivity of the shallow subsurface is a key parameter for the simulation of water table position, shallow groundwater flow, and base‐flow discharge, but is not well‐characterized at large regional to continental scales. We used a process‐based inversion of CONUS‐extent groundwater information to generate national data sets of (a) the transmissivity of the shallow groundwater system, (b) the depth to the water table, (c) groundwater discharge as base‐flow, and (d) long‐term average water content in the unsaturated zone. CONUS‐extent coverage was developed in the form of 75 subdomain models, with the spatial distribution of long‐term average transmissivity for each subdomain model calibrated against water‐levels derived from U.S. Geological Survey (USGS) observation wells, NHDPlusV2 first‐order perennial streams, and National Wetlands Inventory (NWI) freshwater wetlands. Estimated transmissivities were lower in the western CONUS than the eastern CONUS, and across the CONUS both transmissivity and depth to water correlate with recharge, elevation, and topographic slope. These generated data sets provide spatially distributed, long‐term average estimates of subsurface properties and hydrological states that we anticipate will complement other environmental modeling efforts as explanatory variables, boundary conditions, or transport pathways.

Insights of Forest Dynamics for the Regional Ecological Fragility Assessment

Forest ecosystems play a vital role in sustaining various life forms on the earth. These ecosystems support society through the provision of goods (timber, fuelwood, etc.) and an array of ecological services (carbon sequestration, nutrient cycling, etc.). However, unplanned developmental activities have been affecting the ecological integrity evident from the fragmentation of forests, barren hilltops, conversion of perennial streams to intermittent or seasonal streams, etc. During the past three decades, forests have undergone major transitions with the breaking of contiguous native forests into small parcels of land, restricting the movement of species thereby limiting the potential of species for dispersal and colonization. This paper analyzes the landscape dynamics and spatial patterns of forests fragmentation of Shimoga District, Central Western Ghats and prioritizes ecologically fragile or Ecologically Sensitive regions (ESR) at village levels based on bio-geo-climatic-social variables with the land use dynamics considering temporal remote sensing data. Results revealed that there was a net loss of 10% in forest cover from 43.83% (1973) to 34.02% (2018), primarily caused by the expansion of agriculture, horticulture, and forest plantations. Forest fragmentation has increased, evident from the decline of the interior forest to an extent of 11% from 26% (1973–2018). ESR prioritization at village level in the Shimoga district considering the ecological, geo-climatic and social variables indicate that 11% villages are ESR 1 (highest sensitivity), 30% are in ESR 2 (higher sensitivity), 36% are in ESR 3 (high sensitivity) and the remaining 23% are in ESR 4 or moderate sensitivity category. The analysis illustrates the importance of understanding spatiotemporal patterns of landscape structure for sustainable management of tropical forests.

Landscape evolution and the environmental context of human occupation of the southern pampa del tamarugal, Atacama Desert, Chile

As with most living organisms, human populations respond to climatic, environmental, and population pressures by transforming their range and subsistence strategies over space and time. An understanding of human ecology can be gained when the archaeological record is placed within the context of dynamic landscape changes and alterations in natural resource availability. We reconstructed the landscape evolution of the Quebrada Maní fan complex, situated along the west-facing slope of the Central Andes in the hyperarid core of the Atacama Desert, an area that contains an archaeological record that spans almost 13,000 years. Surficial geologic mapping and dating of three 2–12 km2 study sites, in conjunction with archaeological records and analysis of remotely sensed data for the ∼400 km2 fan complex, was conducted to reconstruct the landscape evolution and the way of life of Paleoindian (ca. 12.8–11.5 ka) and early/late Formative (ca 2.5 to 0.7 ka) social groups.Just prior to any known human occupation, a large pluvial event in the high Andes, regionally referred to as CAPE I, impacted the Quebrada Maní fan complex from ca.18–16.5 ka. During CAPE I, the Maní fan complex was dominated by perennial stream systems that deposited well-sorted conglomerates in the upper reaches of the fan (Unit T2) and perennial wetlands (Unit B1). This pluvial period was followed by the onset of an extreme drought sometime after 15 ka, but before 13 ka, when wetlands desiccated and the distal reaches of the fan deflated. Sand sheets and sand dunes were deposited across broad reaches of the landscape and Quebrada Maní incised 3–5 m into its floodplain. This drought had profound implications for the distribution of natural resources during the subsequent pluvial event (CAPE II) that ensued from ca. 12.5–9.5 ka. Incision along the upper reaches of the fan caused a more restricted floodplain and allowed the deposition of extensive wetlands along the more distal central reaches of the fan where groundwater emerged. Paleoindian residential open-air camps were placed in these areas. Wetlands were replaced by a tree-covered floodplain during the latter portion of this pluvial event (ca. 10.5–9 ka).We found no archaeological evidence for human occupations between ∼8–2.5 ka, suggesting a lack of natural resources and/or very low hunter-gatherer population densities. During this time, Quebrada Maní incised up to 8 m into the floodplain. Mudflow deposition – typical of the present-day fan complex – initiated around 2.5 ka, likely responding to an increase in precipitation. This triggered a re-population of the fan surface by Formative agricultural groups that irrigated and extensively farmed these floodplains. By the end of the Formative, these socio-cultural groups became increasingly vulnerable to climatic changes as cut-and-fill cycles in the drainage necessitated major infrastructure adjustments, until the technologies and social-cultural convention of the epoch could not cope with environmental change and investments were abandoned by ∼0.8 ka.

Evaluating the potential of treated effluent as novel habitats for aquatic invertebrates in arid regions

Increasing anthropogenic demands for freshwater have altered many aquatic systems, including the drying of formerly perennial streams. The discharge of treated effluent has returned perennial flow in some of these streams, especially in arid and semi-arid regions, but the ability of treated effluent to support diverse aquatic communities is poorly understood. We examined the potential of treated effluent to create aquatic invertebrate habitat using the effluent-dependent Santa Cruz River in southern Arizona, USA as a case study. We identified 92 invertebrate taxa across our ten sampling sites and two sampling dates. Community composition was primarily shaped by water quality but also by stream drying (on daily time scales) and benthic substrate. Specifically, Linear Mixed-Effects models revealed a strong positive relationship between dissolved oxygen and taxonomic richness and a strong negative relationship between stream drying and invertebrate density. Although there are unique challenges to biota in effluent-dependent systems, our results suggest that treated wastewater could be managed to augment or recreate aquatic habitats that have been otherwise diminished or lost.

Characterizing benthic macroinvertebrate and algal biological condition gradient models for California wadeable Streams, USA

Abstract The Biological Condition Gradient (BCG) is a conceptual model that describes changes in aquatic communities under increasing levels of anthropogenic stress. The BCG helps decision-makers connect narrative water quality goals (e.g., maintenance of natural structure and function) to quantitative measures of ecological condition by linking index thresholds based on statistical distributions (e.g., percentiles of reference distributions) to expert descriptions of changes in biological condition along disturbance gradients. As a result, the BCG may be more meaningful to managers and the public than indices alone. To develop a BCG model, biological response to stress is divided into 6 levels of condition, represented as changes in biological structure (abundance and diversity of pollution sensitive versus tolerant taxa) and function. We developed benthic macroinvertebrate (BMI) and algal BCG models for California perennial wadeable streams to support interpretation of percentiles of reference-based thresholds for bioassessment indices (i.e., the California Stream Condition Index [CSCI] for BMI and the Algal Stream Condition Index [ASCI] for diatoms and soft-bodied algae). Two panels (one of BMI ecologists and the other of algal ecologists) each calibrated a general BCG model to California wadeable streams by first assigning taxa to specific tolerance and sensitivity attributes, and then independently assigning test samples (264 BMI and 248 algae samples) to BCG Levels 1–6. Consensus on the assignments was developed within each assemblage panel using a modified Delphi method. Panels then developed detailed narratives of changes in BMI and algal taxa that correspond to the 6 BCG levels. Consensus among experts was high, with 81% and 82% expert agreement within 0.5 units of assigned BCG level for BMIs and algae, respectively. According to both BCG models, the 10th percentiles index scores at reference sites corresponded to a BCG Level 3, suggesting that this type of threshold would protect against moderate changes in structure and function while allowing loss of some sensitive taxa. The BCG provides a framework to interpret changes in aquatic biological condition along a gradient of stress. The resulting relationship between index scores and BCG levels and narratives can help decision-makers select thresholds and communicate how these values protect aquatic life use goals.

Thermal Regimes of Perennial Rivers and Streams in the Western United States

AbstractThermal regimes of rivers and streams profoundly affect aquatic ecosystems, but are poorly described and classified in many areas due to the limited availability of annual datasets from extensive and representative monitoring networks. By mining a new temperature database composed of >23,000 site records that spans the western United States (U.S.), we extract annual monitoring records at 578 sites on perennial streams to describe regimes in this diverse region. Records were summarized using 34 metrics that described regime aspects related to magnitude, variation, frequency, duration, and timing. The metrics were used in a multivariate cluster analysis to classify streams into seven distinct regime types and in a principal components analysis (PCA) to examine patterns of redundancy among metrics. The PCA indicated that 2–5 orthogonal PC axes accounted for 74%–89% of the variation in thermal regimes at the monitoring sites. Most of the variation in PC scores that defined the two dominant axes was in turn predictable from a suite of geospatial covariates in multiple linear regressions that included elevation, latitude, riparian canopy density, reach slope, precipitation, lake prevalence, and dam height. Our results have parallels to previous flow regime analyses that describe the utility of small numbers of PCs or allied metrics in regime characterization, and can be used to better understand and parsimoniously represent thermal regimes in the western U.S.

Environmental filtering and limiting similarity as main forces driving diatom community structure in Mediterranean and continental temporary and perennial streams

Climatic extreme events such as droughts (unpredictable), dry periods (predictable) or even flush floods, threaten freshwater ecosystems worldwide. The filtering mechanisms of these events and their strength on communities, however, can be different among regions. While time-for-adaptation theory defines whether or not water scarcity can be considered as disturbance, the stress-dominance theory predicts an increase in importance of environmental filtering and a decrease in the role of biotic interactions in communities with increasing environmental stress. Here, we tested whether environmental filtering (leading to trait convergence) or limiting similarity (leading to trait divergence) is the main assembly rule shaping the structure and trait composition of benthic diatom assemblages in Mediterranean (Portuguese) and continental (Hungarian) temporary and perennial streams. We assumed that the trait composition of diatom assemblages in the two stream types would be less different in the Mediterranean than in the continental region (addressed to time-for-adaptation theory). We also hypothesized that trait composition would be shaped by environmental filtering in the Hungarian streams while by biotic interactions in Portuguese streams (addressed to stress-dominance theory). Our results supported our first hypothesis since traits, which associated primarily to temporary streams were found only in the continental region. Our findings, however, only partially proved the stress-dominance hypothesis. In the continental region, where drying up of streams were induced by unpredictable droughts, biotic interactions were the main assembly rules shaping community structure. In contrast, environmental filtering was nearly as important as limiting similarity in structuring trait composition in the Mediterranean region during the predictable dry phase with no superficial flow. These analyses also highlighted that drought events (both predictable and unpredictable ones) have a complex and strong influence on benthic diatom assemblages resulting even in irreversible changes in trait composition and thereby in ecosystem functioning.

Vegetation dynamics of ephemeral and perennial streams in mountainous headwater catchments

Ephemeral and perennial streams of mountainous catchments in Sabaragamuwa Province of Sri Lanka and Hong Kong of China were studied for two years on vegetation dynamics. Each year, sampling was conducted during a period when ephemeral streams had low surface flows. Sampling was realized contiguously using belt transects. The standing crop biomass (hereafter biomass) of herbaceous vegetation in ephemeral channels was comparatively lower than perennials and so was the herb diversity. Herb diversity showed a peak from 1.5 to 4.5 m from the centerline/thalweg of ephemeral and perennial streams. Out of 24 herbs, only three were common for both. A peak herb biomass zone was observed in perennials in the same region where diversity peaked. In ephemerals, herb biomass increased laterally up to ∼1.5 m, and was constant thereafter. Seedling experiment results tallied with the field diversity observations of both stream types, and suggested that seed dispersion was the main reason for herb colonization. Furthermore, it showed sapling emergence to be significantly higher in perennials than ephemerals. Return period of annual maximum monthly rainfall was a strong indicator of age of trees in ephemeral streams, and elucidated the possibility of hindcasting past flow episodes. Electrical conductivity was significantly high in ephemeral streams among all the water quality parameters. The contents of the water nutrients were approximately the same in both stream types. While recommending further studies on eco-hydrology of ephemerals, we recognize ephemeral streams to be valuable references in climate change studies due to their responsiveness and representativeness in long term hydrological changes.

Ecology of Binwa a Western Himalayan Hill Stream in relation to Water Quality

Binwa is a perennial hill stream of the Western Himalayan region of Himachal Pradesh. During the present investigation, four observation sites based on altitudinal differences were selected, i.e., Kharli(S1), Baijnath (S2), near Chobin (S3), and Triveni (S4) and water samples were analyzed for physico-chemical and biological parameters for one year (Mar.2011-Feb.2012). Water temperature, water current, dissolved oxygen, turbidity, T.D.S., electric conductivity, total Hardness, phosphate, and nitrate had played an essential role in determining the variations in planktonic and macroinvertebrate fauna of the stream.Species diversity indices such as Simpson, Shannon and Wiener, and Margalef’s diversity index of macroinvertebrates were worked out for all the observation sites. Based on the comparison of physico-chemical parameters of water samples with different standards prescribed for drinking water, water quality index for four stations calculated. Similarly, EPT taxa (Ephemeroptera, Plecoptera, Trichoptera) measured, and EPT index computed. The water quality of the stream deteriorates downstream from head to mouth due to different types of anthropogenic interferences. The findings revealed that stream has no pollution at S1, while it is oligotrophic from S2 to S3 and meso-oligotrophic at S4.

Channel mobility drives a diverse stratigraphic architecture in the dryland Mojave River (California, USA)

AbstractThe links between flood frequency and rates of channel migration are poorly defined in the ephemeral rivers typical of arid regions. Exploring these links in desert fluvial landscapes would augment our understanding of watershed biogeochemistry and river morphogenesis on early Earth (i.e. prior to the greening of landmasses). Accordingly, we analyse the Mojave River (California), one of the largest watercourses in the Great Basin of the western United States. We integrate discharge records with channel‐migration rates derived from dynamic time‐warping analysis and chronologically calibrated subsidence rates, thereby constraining the river's formative conditions. Our results reveal a slight downstream decrease in bankfull discharge on the Mojave River, rather than the downstream increase typically exhibited by perennial streams. Yet, the number of days per year during which the channel experiences bankfull or higher stages is roughly maintained along the river's length. Analysis of historical peak flood records suggests that the incidence of channel‐formative events responds to modulation in watershed runoff due to the precipitation in the river's headwaters over decades to centuries. Our integrated analysis finally suggests that, while maintaining hydraulic geometries that are fully comparable with many other rivers worldwide, ephemeral desert rivers akin to the Mojave are capable of generating a surprisingly wide range of depositional geometries in the stratigraphic record. © 2020 John Wiley & Sons, Ltd.

Thinking Upstream: How Do Landowner Attitudes Affect Forested Riparian Buffer Coverage?

Little is known about the conservation of intermittent and ephemeral streams on private lands despite the importance of these waterways for ecosystem and hydrologic outcomes. Our case study of a watershed of central New York State considers landowners' attitudes toward perennial and intermittent streams on their property. We combine social science survey responses with aerial imagery to assess the underlying drivers of landowners' attitudes about their streams, and the extent to which these attitudes shape riparian conservation behaviors on their properties. We find that stream flow regularity directly and positively shapes landowners' stream attitudes, with landowners of perennially flowing streams holding their streams in higher regard than landowners with streams of intermittent flows. Landowners with forest and wetlands as the primary land cover had more riparian buffer coverage on their properties than agricultural landowners. Landowners with a weaker perceived land use efficacy also had greater buffer coverage. Our findings suggest that landowners in headwater regions do not perceive their influence on downstream water quality, and that outreach efforts should emphasize the importance and conservation of headwater streams and associated water quality outcomes.

Impact Assessment of Groundwater Quality using WQI and Geospatial tools: A Case Study of Islamkot, Tharparkar, Pakistan

Groundwater is the only source of fresh water in the Thar Desert which is located in an arid region of Pakistan with dense population and spreads over 19,638km2. Low rainfall, low groundwater recharge, high evaporation and absence of perennial streams are the general reasons for water scarcity. Being the single water source for drinking, domestic and industrial uses, and livestock activities, this source is highly overexploited. Realizing the gravity of the situation, this paper presents a groundwater quality evaluation of Islamkot, Tharparkar, using Water Quality Index (WQI) and Geospatial tools. 40 samples were collected from dug wells. The TDS of 28 samples was found higher than 3000mg/L and 12 samples ranged from 1500 to 3000mg/L. Many (28) samples were not further analyzed due to their very high TDS which made the water unfit for drinking. Twelve samples with TDS ranging from 1500 to 3000 mg/L were further analyzed. The analyzed results revealed the average values of pH, EC, TDS, salinity, chloride, total alkalinity, fluoride, and arsenic. The results did not meet NEQS and WHO guidelines. Pearson correlation analysis was conducted among parameters. Further, groundwater quality was assessed by WQI and indicated that water quality varied from very poor to unsuitable for drinking. The consumption of polluted groundwater has been the main cause of prevalent waterborne diseases and poses a very high risk for public health

Rapid groundwater recharge dynamics determined from hydrogeochemical and isotope data in a small permafrost watershed near Umiujaq (Nunavik, Canada)

Hydrogeochemical data are used to better understand recharge dynamics and to support a hydrogeological conceptual model in a 2-km2 watershed in a discontinuous permafrost zone in Nunavik, Canada. The watershed contains an upper (surficial) and lower aquifer within Quaternary deposits, above and below a marine silt layer containing ice-rich permafrost mounds. The analysis is based on water samples from precipitation, groundwater monitoring wells, ground ice in permafrost mounds, thermokarst lakes and a perennial stream. Groundwater geochemistry in both aquifers reflects young, poorly evolved waters, with mainly Ca-HCO3 water types and low mineralisation ranging from 11 to 158 mg/L total dissolved solids (TDS), implying short pathways and rapid travel times of a year or less. While relatively low, TDS signatures in groundwater and surface water show increasing values downgradient. Groundwater isotope values (δ18OH2O and δ2HH2O) are often strongly influenced by snowmelt, while those of thermokarst lakes show evidence of evaporation. Recharge along the cuesta contributes to a transverse component of groundwater flow within the valley with higher TDS and δ13CDIC values influenced by open-system weathering. Even where permafrost-free, the marine silt unit has a strong confining effect and plays a more important role on recharge dynamics than the discontinuous permafrost. Nevertheless, the vulnerability of these types of hydrogeological aquifer systems is expected to increase due to rapid recharge dynamics associated with the gradual loss of the confining effect of permafrost. This hydrogeochemical data set will be useful as a baseline to document impacts of permafrost degradation on the hydrogeological system.

Ichnology and sedimentology of aeolian and shallow‐marine interactions in the Permian Unayzah Group of central Saudi Arabia: Towards a mechanism for infaunal colonization of coastal dune fields and erg margins

AbstractThis paper documents aeolian and shallow‐marine interactions and describes their ichnofossil suites from the early Permian Tinat Member of the Nuayyim Formation of subsurface Saudi Arabia, thereby confirming marine sedimentation in an interval historically interpreted as being dominated by continental settings wherein aeolian processes prevailed. This paper attempts to characterize in situ animal–sediment interactions in coastal dune fields and erg margins in arid to semiarid settings; where the description of organism–sediment relationships, until now, has been focused on the landward portion including freshwater suites. Sedimentological and ichnological assessments in the Tinat Member allowed the identification of aeolian and marginal‐marine, tidally influenced interactions in two facies associations that are conformably interbedded. Facies Association 1 includes sediment deposition in aeolian and continental, groundwater table‐related environments such as: aeolian dunes (facies 1); dry and damp aeolian interdunes (facies 2 and 3); ephemeral and perennial stream deposits (facies 4 and 5); and palaeosols (facies 6). Facies Association 2 reflects sedimentation in shallow‐marine, tidally influenced environments and includes punctuated occurrences of tidal flats and sheltered shallow bay deposits (facies 7 and 8) displaying a brackish‐water trace fossil assemblage. This suite exhibits a diminutive, highly stressed mixture with structures reflecting an impoverished Skolithos Ichnofacies and Cruziana Ichnofacies associated with tidal flat deposits displaying synaeresis cracks, lenticular bedding, low‐angle and wavy lamination, flaser bedding, reactivation surfaces, carbonaceous double mud drapes, current ripples and tubular tidalites. Aeolian sedimentation and trace fossil associations presented in this paper are significant because they provide evidence for shallow‐marine, tidally influenced and aeolian processes in the Unayzah Group during deposition of the Tinat Member of the Nuayyim Formation. More importantly, documenting marine and aeolian interactions and their resulting ichnofossil suite can be used: (i) to build integrated sedimentological and ichnological facies models; and (ii) to characterize the resulting trace fossil association in this particular interactive setting that can be used to identify similar successions elsewhere in the rock record.