Surface Water Channels Research Articles

Water, sanitation, and hygiene–specific risk factors of recent diarrheal episodes in children aged under 5 years: analysis of secondary data from the multiple indicator cluster survey (MICS 2019)

ObjectivesAccess to safe drinking water, sanitation, and hygiene, collectively called WASH, is a fundamental human right and a cornerstone of public health. However, inadequate WASH practices and environments significantly contribute to the global burden of diarrheal diseases, particularly, in children aged under 5 years. Inadequate WASH conditions are the primary drivers of various infectious diseases, including cholera, dysentery, hepatitis A, typhoid, and polio. MethodsWe conducted secondary data analysis using the 2019 Zimbabwe Multiple Indicator Cluster Survey to investigate the specific WASH risk factors associated with recent diarrheal episodes in children aged under 5 years. ResultsA total of 853 (14%) of 6092 children were reported to have experienced an episode of diarrhea in the last 2 weeks preceding the survey. Having insufficient water in the household was associated with 17.0% diarrhea episodes compared with 13.6% in those who did not face this problem. The availability of soap or detergents to wash hands was associated with a risk of diarrhea, with an odds ratio and 95% confidence interval of 1.19 (1.01-1.40), P = 0.033. The use of surface water, including rivers, dams, lakes, ponds, streams, canals, and irrigation channels, was associated with differences in diarrheal episodes, although this was of borderline significance, P = 0.082. Of the children who had a recent episode of diarrhea, 41.0% had their parents or caregivers seeking medical attention. ConclusionsThere is need for an improvement in safe water supply to households and an improvement in health education on the importance of using soap after using the toilet to avoid contamination of food and water.

Impact of Conditioning Agent Addition Sequence on Dewatering Performance of Advanced Anaerobic Digested Sludge

The advanced anaerobic digestion process enhances sludge resource utilization. However, thermal hydrolysis pretreatment of anaerobically digested sludge reduces dewatering efficiency due to excessive organic matter decomposition. This necessitates significant time and effort for sludge conditioning in wastewater treatment plants. Using conditioning agents can achieve high dewatering efficiency. This study investigates how the order of adding coagulants and flocculants impacts the dewatering performance of digested sludge. The results indicate that, compared to the flocculation–coagulation process with the same dosage, the coagulation–flocculation process leads to a 15–20% increase in the average particle size of digested sludge. The content of polysaccharides and proteins in S-EPS decreases by 28.8–30.8% and 10.1–11.3%, respectively. The filter cake solids content increases by 8.5%, and there is an increase in surface water channels within the flocs. This is because initially adding coagulants efficiently adsorbs small particles, forming larger aggregates that settle effectively. This promotes the breakdown of extracellular polymeric substances, releasing more bound water. Adding flocculants later bridges the aggregates, further enhancing settling and filtration performance, thereby improving sludge dewatering efficiency. These research findings contribute to a better understanding of the mechanisms of coagulant and flocculant co-conditioning for digested sludge and provide recommendations for optimizing sludge conditioning steps.

Comprehensive assessment of the degree of contamination in surface water channels

The problems of clean water and the protection of aquatic ecosystems are becoming more acute, constantly getting worse and reaching such levels of pollution when the use of water for various purposes is severely limited or water can be harmful to humans. The article is devoted to the problems of pollution of water resources with harmful chemicals that affect human health. The analysis of a comprehensive assessment of the degree of contamination of surface waters is carried out, cases of high and extremely high pollution of surface waters on the territory of the Kurgan region are considered, ways of solving these problems are proposed.

SAR-based Subsidence Monitoring and Assessment of the Factors Involved in the Occurrence of Subsidence, Lahore City

The judicious use and management of natural resources is vital to achieve sustainable development. Land and water are prime natural resources, and their depletion and degradation can lead to serious threats like land subsidence. Land subsidence is a phenomenon of the alteration of elevation at a point on the earth through the sinking of the surface. It occurs when the earth's surface loses its support. The major causes of land subsidence include groundwater extraction, mining, construction overload, and other similar factors that increase pressure on the surface and eventually subsidize the land. Urban centers with excessive groundwater extraction and infrastructure development are at a high risk of subsidence. Lahore, the second-largest city in Pakistan, is undergoing an enormous increase in population density, uncontrolled urbanization with very large-scale construction projects, and intensive groundwater extraction which are responsible for subsidence directly or indirectly. Therefore, studies on groundwater status and unplanned urban appraisals have seriously urged monitoring of the subsidence in Lahore. Herein, we used freely available Sentinel-1 data for one year (from August 2018 to August 2019), with a high spatial and temporal resolution, to monitor subsidence in Lahore. The data were processed using the SNAP/StaMPS approach for Persistent Scatterer Interferometric Synthetic Aperture Radar (PSI) analysis, which is an advanced InSAR technique. The displacement velocity map from InSAR processing shows a significant land deformation in the area with values ranging from –114 to 15 mm yr–1. Along with the Sentinel-1 data, we also used supplementary data obtained from various government agencies of Pakistan to study the land cover map, transportation network and waterways of Lahore, soil types, population density, and field points for assessing the results and understanding the roles of various factors in the occurrence of uplift or subsidence. A strong correlation was established between subsidence and various parameters such as groundwater extraction and lowering of the water table, soil type variations, land cover changes, surface water channels, and population density. The deformation map confirms the greatest subsidence in the central part of Lahore, while the uplift is observed in the less populated and rural areas situated near Ravi River. The land subsidence and uplift could be attributed to groundwater extraction and recharge through the canal system and the river, respectively.

Antimicrobial resistance genes are enriched in aerosols near impacted urban surface waters in La Paz, Bolivia

Antibiotic resistance poses a major global health threat. Understanding emergence and dissemination of antibiotic resistance in environmental media is critical to the design of control strategies. Because antibiotic resistance genes (ARGs) may be aerosolized from contaminated point sources and disseminated more widely in localized environments, we assessed ARGs in aerosols in urban La Paz, Bolivia, where wastewater flows in engineered surface water channels through the densely populated urban core. We quantified key ARGs and a mobile integron (MI) via ddPCR and E. coli spp. as a fecal indicator by culture over two years during both the rainy and dry seasons in sites near wastewater flows. ARG targets represented major antibiotic groups—tetracyclines (tetA), fluoroquinolines (qnrB), and beta-lactams (blaTEM)—and an MI (intI1) represented the potential for mobility of genetic material. Most air samples (82%) had detectable targets above the experimentally determined LOD: most commonly blaTEM and intI1 (68% and 47% respectively) followed by tetA and qnrB (17% and 11% respectively). ARG and MI densities in positive air samples ranged from 1.3 × 101 to 6.6 × 104 gene copies/m3 air. Additionally, we detected culturable E. coli in the air (52% of samples <1 km from impacted surface waters) with an average density of 11 CFU/m3 in positive samples. We observed decreasing density of blaTEM with increasing distance up to 150 m from impacted surface waters. To our knowledge this is the first study conducting absolute quantification and a spatial analysis of ARGs and MIs in ambient urban air of a city with contaminated surface waters. Environments in close proximity to urban wastewater flows in this setting may experience locally elevated concentrations of ARGs, a possible concern for the emergence and dissemination of antimicrobial resistance in cities with poor sanitation.

Carbon quantum dots (CQDs) nanofiltration membranes towards efficient biogas slurry valorization

In this article, novel nanofiltration (NF) membranes with highly selective surface and fast water and ion transport channels were fabricated for the valorization of biogas slurry. Unlike conventional thin film composite (TFC) membranes, the novel NF membranes compose hydrophilic carbon quantum dots (CQDs) as the interlayer. The carboxyl groups from CQDs react with the polyethyleneimine (PEI), leading to the lower cross-linking degree in the interfacial polymerization layer of NF membranes. Besides, the presence of the hydrophilic CQDs can create fast water and ion transport channels in the NF membranes. The water permeability of membranes is therefore enhanced significantly from 3.6 to 9.7 LMH·bar−1. The NF membranes were used to concentrate the amino acids from biogas slurry; it achieved rejection rates above 90% towards model amino acids such as lysine, glutamic acid and leucine, due to its highly positive electrical properties, while allowing most of the unwanted salt ions to permeate through. The excellent selectivity between amino acids and salt ions demonstrates the great potential application of the NF membranes in biogas slurry valorization.

Using geochemistry to discern the patterns and timescales of groundwater recharge and mixing on floodplains in semi-arid regions

Floodplains may alternate between discharge zones for regional groundwater and areas of recharge from river water during high-flow events. Understanding the mechanisms and timescales of recharge on floodplains is important for their management and for the protection of fragile ecosystems. The floodplains of the River Murray host important ecosystems, particularly remnant eucalypt forests that are vulnerable to changes in inundation, rising regional water tables, and salt accumulation. This study addresses floodplain recharge and groundwater mixing on the Pike and Katarapko floodplains of South Australia. At Pike, 3H activities of groundwater in the low hydraulic conductivity Coonambidgal Formation that crops out on the floodplain are ∼0.25 TU. 3H activities of groundwater in the underlying higher hydraulic conductivity Monoman Formation decrease from ∼1 TU near the contact with the Coonambidgal Formation to <0.02 TU at >15 m depth. Groundwater 14C activities are between 40 and 95 pMC but are less well correlated with depth. The 3H or 14C activities do not vary systematically with distance from the surface water channels on the floodplains. These observations imply that groundwater recharge at Pike is dominantly through the floodplain rather than through the channel banks. In contrast to the regional groundwater where total dissolved solids (TDS) concentrations are commonly >35,000 mg/L, the TDS of groundwater on the floodplain is locally <500 mg/L. A correlation between 3H activities and TDS and the presence of groundwater with relatively low 14C activities but above detection 3H activities implies that recently recharged waters have mixed with regional groundwater in the floodplain sediments. The 3H activities in these mixed waters implies that mixing occurs over a few years. By contrast, at Katarapko, the highest 3H activities in the Monoman Formation groundwater (up to 2.35 TU) are closer to the Murray River, implying that recharge through the bank may occur. These contrasting patterns of recharge probably reflect local topographic controls. Understanding the recharge-discharge relationships are vital for managing proposed floodplain inundation programs aimed at improving ecosystem health.

Technogenic effect of liquidation of coal mines on earth’s entrails: hydrogeochemical aspect

The authors of the paper have established the geochemical features of the composition of underground waters and regularities of their formation in the areas of the liquidated coal mines of Russia and Ukraine. It is shown that the mine flood resulted in the formation of technogenic waters which geochemical specificity originates in the feeding field and is transformed in the direction of the filtration flow. It depends on the geological structure of sedimentary basins and the presence in the coal and supra-coal beds of the marine, salt-bearing and freshwater groups of geological formations. The water types are distinguished characterizing the conditions and processes of their formation that may be the regional markers in the hydrochemical and geological constructions. The technogenic waters influenced the safety of the underground waters, sources of water supply of the regions, and surface water channels. The pollutions are of local character in space.

Comprehensive Groundwater Balance Development to Characterize Selenium Loading to Surface Water Channels in Orange County, California

Selenium concentrations are elevated above water quality criteria in several tributaries of Newport Bay. A watershed-scale hydrogeologic study was performed to identify processes driving selenium transport in the former “Swamp of the Frogs” area (cities of Santa Ana, Irvine, and Tustin). The former Swamp of the Frogs area was a depositional environment that historically received regional surface water runoff and accumulated naturally occurring selenium-bearing sediments from the larger watershed. Development beginning in the early 20th century included surface water channel installation that lowered the water table and drained the wetland, mobilizing selenium. A comprehensive groundwater/surface water balance was conducted in order to constrain hydrologic processes that continue to drive selenium mobilization into the surface water channels. The groundwater budget included precipitation and irrigation percolation modeling and groundwater flow mapping from thousands of publicly-available groundwater level measurements. Groundwater balance results indicated that lateral groundwater flow from upgradient alluvial-fan recharge areas accounts for most of the groundwater input to the former wetland area with additional input supplied by deep percolation of precipitation within the former wetland area itself, deep percolation of irrigation, and sewer/water line leakage. Overlaying selenium concentration data from groundwater wells and surface water sampling locations confirmed that selenium concentrations are similar in groundwater and nearby groundwater-to-surface water discharge points (e.g., weepholes). Results supported a Best Management Practice (BMP) Strategic Plan developed in compliance with a regulatory order prescribing numeric limitations on groundwater-related discharges of selenium in the watershed.

Distinguishing wetland vegetation and channel features with object-based image segmentation

Mapping landscape features within wetlands using remote-sensing imagery is a persistent challenge due to the fine scale of wetland pattern variation and the low spectral contrast among plant species. Object-based image analysis (OBIA) is a promising approach for distinguishing wetland features, but systematic guidance for this use of OBIA is not presently available. A sensitivity analysis was tested using OBIA to distinguish vegetation zones, vegetation patches, and surface water channels in two intertidal salt marshes in southern San Francisco Bay. Optimal imagery sources and OBIA segmentation settings were determined from 348 sensitivity tests using the eCognition multiresolution segmentation algorithm. The optimal high-resolution (≤1 m) imagery choices were colour infrared (CIR) imagery to distinguish vegetation zones, CIR or red, green, blue (RGB) imagery to distinguish vegetation patches depending on species and season, and RGB imagery to distinguish surface water channels. High-resolution (1 m) lidar data did not help distinguish small surface water channels or other features. Optimal segmentation varied according to segmentation setting choices. Small vegetation patches and narrow channels were more recognizable using small scale parameter settings and coarse vegetation zones using larger scale parameter settings. The scale parameter served as a de facto lower bound to median segmented object size. Object smoothness/compactness weight settings had little effect. Wetland features were more recognizable using high colour/low shape weight settings. However, an experiment on a synthetic non-wetland image demonstrated that, colour information notwithstanding, segmentation results are still strongly affected by the selected image resolution, OBIA settings, and shape of the analysis region. Future wetland OBIA studies may benefit from strategically making imagery and segmentation setting choices based on these results; such systemization of future wetland OBIA approaches may also enhance study comparability.

Point sources of emerging contaminants along the Colorado River Basin: Source water for the arid Southwestern United States

Emerging contaminants (ECs) (e.g., pharmaceuticals, illicit drugs, personal care products) have been detected in waters across the United States. The objective of this study was to evaluate point sources of ECs along the Colorado River, from the headwaters in Colorado to the Gulf of California. At selected locations in the Colorado River Basin (sites in Colorado, Utah, Nevada, Arizona, and California), waste stream tributaries and receiving surface waters were sampled using either grab sampling or polar organic chemical integrative samplers (POCIS). The grab samples were extracted using solid-phase cartridge extraction (SPE), and the POCIS sorbents were transferred into empty SPEs and eluted with methanol. All extracts were prepared for, and analyzed by, liquid chromatography–electrospray-ion trap mass spectrometry (LC–ESI-ITMS). Log DOW values were calculated for all ECs in the study and compared to the empirical data collected. POCIS extracts were screened for the presence of estrogenic chemicals using the yeast estrogen screen (YES) assay. Extracts from the 2008 POCIS deployment in the Las Vegas Wash showed the second highest estrogenicity response. In the grab samples, azithromycin (an antibiotic) was detected in all but one urban waste stream, with concentrations ranging from 30ng/L to 2800ng/L. Concentration levels of azithromycin, methamphetamine and pseudoephedrine showed temporal variation from the Tucson WWTP. Those ECs that were detected in the main surface water channels (those that are diverted for urban use and irrigation along the Colorado River) were in the region of the limit-of-detection (e.g., 10ng/L), but most were below detection limits.

Geochemical and isotopic constraints on groundwater–surface water interactions in a highly anthropized site. The Wolfen/Bitterfeld megasite (Mulde subcatchment, Germany)

The Bitterfeld/Wolfen region is a megasite with multiple contaminant sources from more than a century of industrial activity, which have a considerable impact on the environment. At present, the contaminated groundwater covers an area of about 25 km 2 and poses a threat for the surrounding aquifers and the Mulde River. This study focuses on the Schachtgraben, a man-made channel in the Mulde Floodplain that collects the effluents of the industrial area. It aims to characterise the relationship between surface water (channels, rivers) and the groundwater in the shallow Quaternary aquifer. Waters are Ca-SO 4 type with TDS reaching 3.8 g L −1 in the industrial area. Stable isotopes ( δ 18O, δ 2H) show that two of the rivers are recharged mainly by groundwater that can be divided into two groups. Strontium isotopes ( 87Sr/ 86Sr) designate different geochemical end-members and enable the identification of mixing between natural and anthropogenic surface and groundwater.

Storm water runoff concentration matrix for urban areas

The infrastructure (roads, sidewalk, commercial and residential structures) added during the land development and urbanisation process is designed to collect precipitation and convey it out of the watershed, typically in existing surface water channels, such as streams and rivers. The quality of surface water, seepage water and ground water is influenced by pollutants that collect on impervious surfaces and that are carried by urban storm water runoff. Heavy metals, e.g. lead (Pb), zinc (Zn), copper (Cu), cadmium (Cd), polycyclic aromatic hydrocarbons (PAH), mineral oil hydrocarbons (MOH) and readily soluble salts in runoff, contribute to the degradation of water. An intensive literature search on the distribution and concentration of the surface-dependent runoff water has been compiled. Concentration variations of several pollutants derived from different surfaces have been averaged. More than 300 references providing about 1300 data for different pollutants culminate in a representative concentration matrix consisting of medians and extreme values. This matrix can be applied to long-term valuations and numerical modelling of storm water treatment facilities.

Comparison of management scenarii in a regional groundwater system

The groundwater system in the Milan area represents the main water supply for civil and industrial uses. Since the 1950s its natural equilibrium has been conditioned by notable water table fluctuations; in particular during the last decade a remarkable rise in the groundwater level has led to a real state of emergency. Many buildings and subsurface structures were constructed in the 1970s, and they were not designed to coexist with groundwater: at present the foundation and the underground structures of many important constructions (hospitals, parking, subways) are under the water table affecting their durability and security. A complete understanding of the dynamics of the aquifer system is the first step to manage the emergency and to plan opportune interventions. To achieve this purpose, a 3D finite element model is developed for an area bounded by the rivers Po, Ticino, Adda and the pre‐Alps. A reliable model of this groundwater system requires current and historical data on a number of key parameters: geology (deep and surface), topography, surface water rivers and channels and their hydraulic characteristics, groundwater levels, recharge from rainfall, pumping from aquifer for civil and industrial uses. The numerical scheme is applied in both the saturated and in the unsaturated zone. The numerical model is calibrated in both steady and unsteady state flow. Different scenarios are performed to simulate the response of groundwater system to various stresses: an increasing of water pumping in the city of Milan, a particularly rainy season, the reopening or the obstruction of spring lines located in South Milan. The results of the model can be a useful tool to optimize intervention, thereby reducing costs of management.

Evaluation of the use of reach transmissivity to quantify exchange between groundwater and surface water

A method to quantify the exchange of water between surface water channels and the groundwater aquifer based on the concept of reach transmissivity was evaluated for use under transient conditions and incorporated into a numerical model. This method provides significant benefits relative to the common existing method of calculating leakage, which assumes flow of water through a discrete, low permeability layer at the bed of the surface water channel. The reach transmissivity leakage relationship employs input parameters that are more commonly available from published sources, which reduces the effort required for model calibration; also, the calibrated values of the reach transmissivity relationship input parameters are less dependent on model grid spacing. Furthermore, the reach transmissivity relationship allows calculation of flow to each side of the surface water channel, rather than calculating only the net exchange between the surface water and groundwater systems. The reach transmissivity leakage relationship is based on the assumption of steady state conditions; a method was developed to estimate the error associated with its use to simulate transient conditions. The reach transmissivity relationship was further evaluated through its use in analytical and numerical models to simulate conditions in a field study area.

Evaluation of the use of reach transmissivity to quantify exchange between groundwater and surface water

A method to quantify the exchange of water between surface water channels and the groundwater aquifer based on the concept of reach transmissivity was evaluated for use under transient conditions and incorporated into a numerical model. This method provides significant benefits relative to the common existing method of calculating leakage, which assumes flow of water through a discrete, low permeability layer at the bed of the surface water channel. The reach transmissivity leakage relationship employs input parameters that are more commonly available from published sources, which reduces the effort required for model calibration; also, the calibrated values of the reach transmissivity relationship input parameters are less dependent on model grid spacing. Furthermore, the reach transmissivity relationship allows calculation of flow to each side of the surface water channel, rather than calculating only the net exchange between the surface water and groundwater systems. The reach transmissivity leakage relationship is based on the assumption of steady state conditions; a method was developed to estimate the error associated with its use to simulate transient conditions. The reach transmissivity relationship was further evaluated through its use in analytical and numerical models to simulate conditions in a field study area.