Surface Water Discharge Research Articles

Climatic Characteristics and Their Impact on the Amount of Surface Water Discharge in the Province of Najaf

Geographical studies are interested in analyzing most of the different aspects of life in order to put the problem and the appropriate solutions to it spatially according to a geographical distribution that shows the relevant authorities how to develop and alleviate the burdens of population societies that have a growing need to meet all human consumptions, including water, because without it, life and control over the various economic aspects is not possible. The population is exposed to a decrease in the levels of water and its discharge quantities as a result of many reasons, including the climate, especially the amount of solar radiation, temperature, wind speed and relative humidity, which as a whole affect directly or indirectly the decrease in the quantities of surface water, especially the Kufa and Abbasiya beaches, which we are in the process of studying and presenting all its details. Linking the statistical relations between them and the prevailing climatic characteristics in the study area according to a climatic station, which is the Najaf climatic station for the period 1990-2020. The same is the case with regard to the hydrological characteristics 1990-2020, through which statistical relations are found and through modern statistical programs, so that the results are represented according to modern maps as well.

Per- and polyfluoroalkyl substances (PFAS) contamination in a microtidal urban estuary: Sources and sinks

This study evaluates PFAS contamination and determines the major drainage sources to a temperate microtidal estuary, the Swan Canning Estuary, in Perth Western Australia. We describe how variability in these sources influences PFAS concentrations within this urban estuary. Surface water samples were collected from 20 estuary sites and 32 catchment sites in June and December from 2016 to 2018. Modelled catchment discharge was used to estimate PFAS load over the study period. Three major catchment sources of elevated PFAS were identified with contamination likely resulting from historical AFFF use on a commercial airport and defence base. Estuary PFAS concentration and composition varied significantly with season and spatially with the two different estuary arms responding differently to winter and summer conditions. This study has found that the influence of multiple PFAS sources on an estuary depend on the historical usage timeframe, groundwater interactions and surface water discharge.

Evaluation of Wastewater Quality Treated by the Step of the City of Errachidia (Morocco)

The objective of this study is the physico-chemical and bacteriological characterisation of raw and purified wastewater from the WWTP of the city of Errachidia, Morocco, during the year 2020, in order to evaluate the effectiveness of wastewater treatment. of the wastewater treatment plant, of the aerated lagoon type, and see their reuse in irrigation. The average monthly results of the physico-chemical analyses of treated wastewater carried out from January to December 2020 are as follows: BOD5 = 94.45 mgo2/l; COD = 339.32 mgo2/l; SS = 87.67 mg/L. The results show compliance with the general limit values for the discharge of Moroccan surface water, which protects the environment. Thus, the bacteriological results show the presence of various germs with average annual values where faecal coliforms (CF) are 680 CFU/100 ml; total coliforms (CT) are 2810 UFC/100 and faecal streptococci are 46 UFC/100 ml, which remain below the limit values recommended by Moroccan irrigation standards (CF < 1000 UFC/100 ml), which allows their exploitation and their reuse in irrigation.

Modeling multi-year phosphorus dynamics in a bioretention cell: Phosphorus partitioning, accumulation, and export

Phosphorus (P) export from urban areas via stormwater runoff contributes to eutrophication of downstream aquatic ecosystems. Bioretention cells are a Low Impact Development (LID) technology promoted as a green solution to attenuate urban peak flow discharge, as well as the export of excess nutrients and other contaminants. Despite their rapidly growing implementation worldwide, a predictive understanding of the efficiency of bioretention cells in reducing urban P loadings remains limited. Here, we present a reaction-transport model to simulate the fate and transport of P in a bioretention cell facility in the greater Toronto metropolitan area. The model incorporates a representation of the biogeochemical reaction network that controls P cycling within the cell. We used the model as a diagnostic tool to determine the relative importance of processes immobilizing P in the bioretention cell. The model predictions were compared to multi-year observational data on 1) the outflow loads of total P (TP) and soluble reactive P (SRP) during the 2012–2017 period, 2) TP depth profiles collected at 4 time points during the 2012–2019 period, and 3) sequential chemical P extractions performed on core samples from the filter media layer obtained in 2019. Results indicate that exfiltration to underlying native soil was principally responsible for decreasing the surface water discharge from the bioretention cell (63 % runoff reduction). From 2012 to 2017, the cumulative outflow export loads of TP and SRP only accounted for 1 % and 2 % of the corresponding inflow loads, respectively, hence demonstrating the extremely high P reduction efficiency of this bioretention cell. Accumulation in the filter media layer was the predominant mechanism responsible for the reduction in P outflow loading (57 % retention of TP inflow load) followed by plant uptake (21 % TP retention). Of the P retained within the filter media layer, 48 % occurred in stable, 41 % in potentially mobilizable, and 11 % in easily mobilizable forms. There were no signs that the P retention capacity of the bioretention cell was approaching saturation after 7 years of operation. The reactive transport modeling approach developed here can in principle be transferred and adapted to fit other bioretention cell designs and hydrological regimes to estimate P surface loading reductions at a range of temporal scales, from a single precipitation event to long-term (i.e., multi-year) operation.

Cascadia Earthquake-Triggered Rockslide Burial of Beeswax Galleon Wreck Timbers in a Sea Cliff Wave-Cut Platform Site, North Smuggler Cove, Oregon, USA

Shipwreck timbers (n=27) from the Spanish galleon Santo Cristo de Burgos, also known as the Beeswax Wreck (lost in 1693), are examined for origins of multiple, simultaneous rockslide burials that protected and preserved the timbers on an intertidal wave-cut platform in the small Smuggler Cove in the Northern Oregon coast. The rockslides (n=3–4) that buried the shipwreck timbers are compared to nearby historic rockslide analogs to better establish the mechanisms of boulder distributions on the wave-cut platform. Large boulders (n=20), generally ≥1.0 m intermediate diameter, in the North Smuggler Cove (NSC) timber burial site were measured for estimated mass (1–41 t) and alongshore distribution below small gullies that routed the boulders to the wave-cut platform from overlying short (~100 m distance) but steep hillslopes (40–60% gradient). The multiple independent rockslides in the NSC site, dated to ~300 years by the buried Beeswax Wreck timbers, showed catastrophic, simultaneous activation by a widespread trigger. Anomalous rainfall and/or storm wave attack are unlikely mechanisms for these rockslide activations due to 1) hillslope protections from extended-upslope surface water discharge and 2) sea cliff protection from direct storm wave impacts. The most likely widespread trigger for rockslide activation in the NSC site is seismic ground shaking from an earthquake in the Central Cascadia subduction zone. Modern storm wind velocities (>10 s-1 sustained velocity and 170–225° bearing) and storm surge generated rip currents (≥0.5 km offshore distance) indicate that Beeswax Wreck timbers could have been transported north (1–10 km) to Smuggler Cove, within several winter seasons after the breakup of the Santo Cristo de Burgos. The most likely seismic trigger that could have activated the multiple rockslides in the NSC site, shortly after the brief accumulation of shipwreck timbers on the narrow, intertidal wave-cut platform in Smuggler Cove, is the 1700 Cascadia great earthquake (Mw~9.0). Additional sea cliff rockslide sites (n=8) in the central Cascadia margin are suggested for further investigations of seismically activated slope failures by the 1700 Cascadia great earthquake.

Spatially distributed water quality responses to freshwater discharge in a tropical estuary, Hilo Bay, Hawai'i.

Hilo Bay, Hawai'i, is an estuary of great importance to its neighboring coastal community, but it is threatened by impaired water quality indicated by excessive turbidity and chlorophyll a associated with river discharges of sediments and nutrients. The Wailuku River in the western half of the bay is the primary source of freshwater discharge, hypothesized here to form a surface water-dominant half of the bay with different water quality traits than the groundwater-dominant, eastern half of the bay where the spring-fed Wailoa River discharges. The water quality of both halves of the bay over different flow conditions of the Wailuku River is examined in this study using spatially distributed water quality sampling which collects hundreds of samples in either half of the bay at a distance of about every 40m. The dense sample shows significant differences between the two halves of the bay, with greater salinity dilution and turbidity in the surface water-dominant area. Both salinity and turbidity have a predictable relation to discharge, with salinity decreasing and turbidity increasing in higher flow conditions. Chlorophyll a, however, has a more complex relation to discharge, as chlorophyll a concentrations are greatest in high-flow conditions, but this may be because the water quality samples were collected in different seasons. Furthermore, significantly greater chlorophyll a concentrations in the groundwater-dominant half of the bay in low-flow conditions show that discharge may be spuriously correlated to chlorophyll a, and further studies of the effects of surface water discharge on chlorophyll a concentrations are warranted.

Nitrogen migration and transformation in a saline-alkali paddy ecosystem with application of different nitrogen fertilizers.

With the increasing transformation of saline-alkali land into paddy, the nitrogen (N) loss in saline-alkali paddy fields becomes an urgent agricultural-environmental problem. However, N migration and transformation following the application of different N fertilizers in saline-alkali paddy fields remains unclear. In this study, four types of N fertilizers were tested to explore the N migration and transformation among water-soil-gas-plant media in saline-alkali paddy ecosystems. Based on the structural equation models, N fertilizer types can change the effects of electrical conductivity (EC), pH, and ammonia-N (NH4+-N) of surface water and/or soil on ammonia (NH3) volatilization and nitrous oxide (N2O) emission. Compared with urea (U), the application of urea with urease-nitrification inhibitors (UI) can reduce the potential risk of NH4+-N and nitrate-N (NO3--N) loss via runoff, and significantly (p < 0.05) reduce the N2O emission. However, the expected effectiveness of UI on NH3 volatilization control and total N (TN) uptake capacity of rice was not achieved. For organic-inorganic compound fertilizer (OCF) and carbon-based slow-release fertilizer (CSF), the average TN concentrations in surface water at panicle initiation fertilizer (PIF) stage were reduced by 45.97% and 38.63%, respectively, and the TN contents in aboveground crops were increased by 15.62% and 23.91%. The cumulative N2O emissions by the end of the entire rice-growing season were also decreased by 103.62% and 36.69%, respectively. Overall, both OCF and CSF are beneficial for controlling N2O emission and the potential risks of N loss via runoff caused by surface water discharge, and improving the TN uptake capacity of rice in saline-alkali paddy fields.

Reuse of Produced Water from the Petroleum Industry: Case Studies from the Intermountain-West Region, USA

The produced water (PW) volume in the Intermountain-West (I-WEST) region is about 600 million m3 in 2021. More than one-third of the PW is injected for disposal, which can be a waste of water, considering the water scarcity in the I-WEST region. In this work, we analyzed the potential for the reuse of PW in the I-WEST region. The PW composition and volume in different basins in the I-WEST region were analyzed. The regulations for drinking water, domestic use, irrigation, livestock watering, aquatic, surface water discharge, groundwater discharge, hydraulic fracture, and hydrogen (H2) production were summarized. We identified the appropriate treatments depending on the PW composition and water standards. We also analyzed each PW treatment’s water recovery, energy demand, and cost. We selected the samples of PW from the Raton Basin, San Juan Basin, and Permian Basin to assess the potential reuse of PW in the I-WEST region. The comparison between PW composition and water standards shows that the regulations are not designed for the reuse of PW because the constituents in water regulations do not match the constituents in PW. The low-salinity PW can be treated for agricultural use with relatively low cost and high water recovery, while the high-salinity PW is more suitable for hydraulic fracturing. The treatment cost (including operation, maintenance, energy, labor, and disposal cost) ranges from $0.11/bbl to $1.01/bbl, depending on the PW composition and targeted water standards. The reuse of PW for H2 production is a promising usage purpose. Due to the high demand for fresh water in H2 production, the reuse of PW can alleviate the stress of water scarcity in the I-WEST region. This work provides guidance for the reuse of PW in the I-WEST region.

Retention potential of a drained wetland in the Lusatian lignite mining district, Briesener Niedermoor, Germany, Europe

Acid mine drainage (AMD) is one of the most important global causes for polluted water. It occurs in mining areas due to oxidation of sulfide minerals. Depending on hydrological conditions, wetlands are considered suitable for passive treatment of AMD. The aim of the study was to characterize the long-term retention performance of a drained wetland, Briesener Niedermoor, in an iron and sulfate contaminated catchment area. The site is located in the Lusatian lignite mining district, Germany. Hydrological and hydrochemical measurements as well as time series of groundwater and surface water were evaluated and saturation conditions of iron species were determined using Phreeqc Interactive and EH–pH diagrams for the Fe–S–K–O–H system. Progressing peat degradation due to drainage leads to a hydraulic behaviour of the wetland that is more comparable to a rain bog than a fen, and thus to more pronounced oxic conditions. Groundwater feeds the wetland with significant loads of iron and sulfate, which are temporally stored in the wetland. At low surface water discharge, iron is removed and weak acidic pH is buffered by the dominant phase of schwertmannite (Fe8O8(OH)6SO4), usually during summer months. In winter, greater water availability initializes a high source strength from the wetland, that cannot be retarded. Thus, only during summer, there is a retention potential; in winter, the retention potential is not strong enough to prevent an inflow of iron and sulfate. Only a significant rewetting of the wetland may result in a restoration of the retention potential of the wetland Briesener Niedermoor.

Assessment of River-Aquifer Interaction and Nitrogen Contamination in an Agricultural Zone Located in the Guarani Aquifer System Outcrop Area.

The excessive use of nitrogen fertilizers is responsible for an increase in nitrate concentrations in water bodies, which in the future could led to an irreversible contamination compromising the water resource quality. In this way, understand the water movement within a watershed and evaluate the impacts related to agricultural practices is relevant for water management, especially in an environmental fragile region, such as the outcrop area of the Guarani Aquifer. Water samples from a small watershed located at the Guarani Aquifer region in São Paulo state, representing surface water and groundwater discharge in riverbeds from two creeks, as well as groundwater (springs and wells) were collected for isotopic ratios (δ18O e δ2H) and nitrate determination. The results indicated that the river flow is mostly supplied by groundwater discharge, and despite the observed concentrations of nitrate in groundwater reaching the creeks, the current scenario indicate contamination in the surface water, above the regulatory levels. Therefore, the expansion in sugarcane production increases the possibility that the released nitrate reaches high levels in the future in this watershed.

Characterization of Reverse Osmosis Reject Wastewater Generated from Sulaibiya Wastewater Treatment Plant

Sulaibiya Wastewater Treatment Plant (Kuwait) is considered as one of the largest wastewater treatment plants that use Reverse Osmosis (RO) membranes in their processes to reclaim water from municipal wastewaters for indirect potable water reuse. This result in considerable wastewater treatment brine which needs to be further investigated before discharge. Samples were collected on daily basis from the RO reject wastewater (brine wastewater) for one month and analyzed in situ and in the laboratory. The results obtained showed that the brine wastewater met the requirements of the Kuwait Environment Public Authority with the exception of biochemical oxygen demand, total dissolved solids, and total phosphate. In Kuwait, the brine wastewater is either used for deep-well injection or is discharged to the seawater. Based on the monitoring results, potential reuse options of wastewater brine include surface water discharge, sewer disposal, deep-well injection, and land application. Treatment options via evaporation ponds using membrane filters will further enhance the quality of the brine wastewater.

Seasonal Variation in Physico-chemical Properties of Effluent Generated at a Sewage Treatment Plant in Varanasi and It’s Suitability for Irrigation

The current investigation was carried out to ascertain the suitability of the influent and effluent of Varanasi's Bhagwanpur sewage treatment plant for irrigation as well as variations in its physicochemical properties throughout the year 2018. The suitability of the water for irrigation was evaluated by taking water samples from the plant's inlet, aerator, and outlet tanks. Then, these samples were examined for heavy metals as well as parameters like pH, EC, TDS, BOD, COD, and dominant anions and cations.The plant's effluent is suitable for irrigating agricultural fields because parameters like pH, nitrate, phosphate, and other cations are below the permissible limit and will provide the necessary nutrients for crops. However, higher concentrations of some heavy metals were a notable concern that will need close attention and ongoing monitoring in the near future if effluent water is to be used for irrigation. The treatment process significantly lowers the effluent water's COD, sulphates, and other ions to levels that allow for surface water discharge, but it leaves the BOD, nitrate, and phosphate content just above levels which are recommended, making it unsuitable for discharge into the holy Ganges since it will cause eutrophication.

Groundwater Artificial Recharge Potentiality in Al-Qilt Catchment Jericho – West Bank – Palestine

The main research objective is to highlight the potentiality of artificial groundwater recharge in Al-Qilt catchment- Jericho – Palestine regarding the water shortage in the groundwater-supplied areas. Artificial recharge can be a possible option in increasing the storability of the underground aquifer, which will add values to the Palestinian strategy to optimize the total accessibility of groundwater resources. The increase of water demands and the scarcity of water resources in the Jordan Rift areas are putting challenges for the water managers and planners to improve the water supplies in order to reach the best ways for the integrated water resources management. In Al-Qilt catchment, the surface water discharge flowing into the wadies in huge amounts had no noticeable significant benefits. A hydrological model was built for the Qilt basin using HEC-HMS software system and it was considered as an essential tool for better understanding of the basin hydrological situation and its hydrogeological characteristics. The surface runoff water speed was measured to be 3.2 m/s (27&lt;sup&gt;th&lt;/sup&gt; of February, 2019) with a cross section width of 9.2 m and 0.75 m hight with water leading to a flow of 18.77 m&lt;sup&gt;3&lt;/sup&gt;/s and the total flow of approximately 67565 m&lt;sup&gt;3&lt;/sup&gt;/hr. The estimated model simulations reavealed of 18.5 m&lt;sup&gt;3&lt;/sup&gt;/s and 66600 m&lt;sup&gt;3&lt;/sup&gt;/hr for the speed flow and the total flow respectively and matched with the measured ones. The results were used for improving the aquifer-integrated management in Al-Qilt area and determining of the aquifer potentiality for artificial recharge. The built model results gave guiding to the hydrologists and the decision makers for selecting the appropriate techniques and sites for artificial recharge. The model indicated of good simulation tools to be used for other West Bank catchments.

Reducing uncertainty of karst aquifer modeling with complementary hydrological observations for the sustainable management of groundwater resources

• We propose a lumped model to simulate a strategic karst aquifer under management. • Parameter estimation is conducted on multiple surface and groundwater data types using a Monte-Carlo procedure. • Parametric uncertainty is greatly reduced when hydrological surface discharge observations are introduced in the parameter estimation process. • We estimate a tipping point between sustainable and unsustainable management as a decision key for stakeholders. A quantitative estimation of the sustainability of groundwater resources is a challenge for water supply in most regions of the world. Sustainability can be estimated through numerical simulation, but uncertainty of models somehow limits the reliability of models’ predictions. To overcome this limitation, we explore how parametric and predictive uncertainties is reduced by adding complementary groundwater and surface water dynamics data to a lumped parameter model. This is illustrated with the example of a Mediterranean karst hydrosystem pumped at high flow rate (∼1 m 3 s −1 ) to supply water to about 350,000 habitants. A lumped parameter model was set up to simulate spring discharge, water table levels and surface water discharge measured within this karst hydrosystem over a 40 year period. Then, a parameter estimation and uncertainty quantification, based on groundwater discharge, water table levels and surface water discharge observations, was conducted with a Bayesian approach. Our study illustrates how the consideration of complementary hydrological data allows reducing parametric and predictive uncertainty and improving model performance. The model is then applied to assess the impact of an increasing groundwater abstraction according to different prospective scenarios, with a focus on the storage and dynamic of flux between the different compartments of the karst hydrosystem. Based on simulation results and related predictive uncertainty, a groundwater abstraction threshold, which must not be exceeded for a sustainable management of the groundwater resource, is determined.

Wastewater toxicity removal: Integrated chemical and effect-based monitoring of full-scale conventional activated sludge and membrane bioreactor plants

The literature is currently lacking effect-based monitoring studies targeted at evaluating the performance of full-scale membrane bioreactor plants. In this research, a monitoring campaign was performed at a full-scale wastewater treatment facility with two parallel lines (traditional activated sludge and membrane bioreactor). Beside the standard parameters (COD, nitrogen, phosphorus, and metals), 6 polynuclear aromatic hydrocarbons, 29 insecticides, 2 herbicides, and 3 endocrine disrupting compounds were measured. A multi-tiered battery of bioassays complemented the investigation, targeting different toxic modes of action and employing various biological systems (uni/multicellular, prokaryotes/eukaryotes, trophic level occupation). A traffic light scoring approach was proposed to quickly visualize the impact of treatment on overall toxicity that occurred after the exposure to raw and concentrated wastewater. Analysis of the effluents of the CAS and MBR lines show very good performance of the two systems for removal of organic micropollutants and metals. The most noticeable differences between CAS and MBR occurred in the concentration of suspended solids; chemical analyses did not show major differences. On the other hand, bioassays demonstrated better performance for the MBR. Both treatment lines complied with the Italian law's “ecotoxicity standard for effluent discharge in surface water”. Yet, residual biological activity was still detected, demonstrating the adequacy and sensitivity of the toxicological tools, which, by their inherent nature, allow the overall effects of complex mixtures to be taken into account.

Projecting the hydrochemical trajectory of a constructed fen watershed: Implications for long-term wetland function

Surface mining operations for bitumen have fundamentally altered large areas of boreal forest and fen peatland in the Athabasca Oil Sands Region (AOSR) of Alberta, Canada. Pilot projects intended to assess the feasibility of fen construction as a reclamation option have been designed, built, and are currently undergoing monitoring. Initial assessments of ecohydrologic function have been conducted for these systems but offer limited insight into their evolution and likely successional pathway. Thus, this study projects the hydrologic and geochemical behaviour of a constructed fen watershed to understand whether the system will be capable of supporting peatland processes into the future. A numerical groundwater flow and sodium transport model was calibrated and validated with 7 years of hydraulic head, water flux, and water chemistry data. Based on Monte Carlo simulations, the projected fen water table would be stable and remain close to the surface (<15 cm), indicating that the design of the system can generate sufficient water quantity to meet evaporative demand and maintain surface water discharge. However, water quality was more sensitive to climatic variability, which induced a large range in potential sodium concentrations at the fen surface (450–850 mg L−1). Evapoconcentration of salts across the surface of the fen will likely limit moss establishment for decades following construction. Yet stress-thresholds of salt-tolerant vegetation like sedges will not be exceeded. Ultimately, these projections support the original design principles and philosophy that guided the creation of the watershed. Nonetheless, this work indicates that increasing the area of the fen relative to the upland would not have a detrimental impact on the ability of the system to maintain a high water table. This could allow for the proportion of peatlands on the reclamation landscape to reflect the pre-disturbance environment more faithfully.

Surface Water and Groundwater Recharge Modeling in Sunsari District using Integrated SWAT-MODFLOW Model

This study employs an integrated groundwater-surface water (GW-SW) model, using SWAT-MODFLOW, to assess groundwater recharge and withdrawals at a regional scale in eastern Nepal. The model components were calibrated and validated using monthly river flow and hydraulic head data for the 1979-2017 period. Our results demonstrate that the average annual groundwater discharge is 2.43 m3/s. Seasonally, the average groundwater discharge is 2.73 m3/s during Summer and is 2.13 m3/s during winter. We observe that the maximum (6.9 m3/s) and minimum (0.036 m3/s) rates occurred in September-October and March-April, respectively. We also find that the average runoff fraction (i.e., runoff/ precipitation) varied from 0.34 to 0.72, and the ET component varied from 0.24 to 0.547 of the total precipitation within the SWAT model. The yearly fluctuation in TWS varied from ± 9.9% to ± 58% of the total precipitation. The Aquifer thickness varies from 16m to 57 m, and the specific yield in the Sunsari district varied from 0.12 lps to 890 lps. In the southern part, we see the water level declines from 2-4 m from July to August, where the bottom water slowly declines in September. The recharge of 1380 l/sec is observed in the Sapta Koshi area in the Bhabar zone. There is substantial underflow from hills simultaneously, resulting in the total recharge in the Sunsari district of 1.98 MCM/yr. At the same time, the total discharge, including surface, sub-surface, and spring water discharge, is nearly 29.2 MCM/yr. This study shows that the Sunsari district’s water resources have many groundwater and surface water, properly managed for future use.

Optimization of mobile oil and gas produced water treatment unit deployment logistics to achieve economic feasibility

• Techno-economic assessment of on-site produced water desalination . • The concept of capacity factor is applied to desalination where demand is variable. • Systems level optimization of mobile desalination module deployment. • Multi-objective optimization considering economics and water reclamation . Development of unconventional oil and gas wells has resulted in large volumes of wastewater that require careful handling to minimize environmental risks. Common practice is to truck the wastewater from well sites to Environmental Protection Agency Class II underground injection control wells. Recently, on-site wastewater treatment followed by surface water discharge for downstream reuse has emerged as being viable. This work applies the concept of capacity factor to on-site oil and gas wastewater treatment. By accounting for intermittent wastewater treatment demands at individual well sites, the attributes of optimal on-site packaged treatment unit deployment logistics for oil and gas wastewater management are determined. The attributes considered are packaged unit capacity, deployment length, and the number of units deployed. This work explores different deployment logistics in Weld County, Colorado, United States to determine a set of Pareto optimal logistics from a techno-economic and environmental perspective. Ultimately, there exists a Pareto frontier because the marginal cost of water treatment increases as reuse increases beyond a critical threshold, in Weld County where the cost of business as usual operation (injection) is constant at $7.68 per m 3 produced. Generally, optimal deployment logistics, when accounting for capacity factor, utilize packaged wastewater treatment units sized at 100 m 3 per day capacity with deployment location reevaluated monthly. This article focuses on the importance of capacity factors at on-site treatment units and presents limitations of the study and the opportunity for the application of the presented methods to other case studies through utilization of the open-source model produced in this work.

Evaluation of 1,4-dioxane attenuation processes at the Gelman Site, Michigan, USA

1,4-Dioxane released at the Gelman Site in Washtenaw County, Michigan, produced a series of contaminant plumes migrating up to 3 km through a heterogenous glacial aquifer system. An analysis of 1,4-dioxane concentrations in the Eastern Area of the Gelman Site between 2011 and 2017 documented a mass balance deficit of 2200 kg in excess of 2100 kg of 1,4-dioxane removed via remediation. Five mechanisms were evaluated to account for the mass deficiency: sorption, matrix diffusion, biodegradation, surface discharge, and bypass of the existing monitoring well network.The mass of 1,4-dioxane sorbed to aquifer and aquitard materials and the mass of 1,4-dioxane diffused into low permeability zones were estimated. However, decreasing aqueous concentrations across most of the contaminated area between 2011 and 2017 are expected to induce desorption and back diffusion during this period. Surface water discharge to a storm drain in the downgradient portion of the site was analyzed using concentration measurements and stream gage data. Results suggest that 1,4-dioxane mass entering the drain during the period between 2011 and 2017 was insufficient to account for the mass deficiency.Although available geochemical measurements indicate predominantly anaerobic aquifer conditions at the Gelman Site, biodegradation of 1,4-dioxane was estimated using first order decay rate constants from other sites where conditions may be more favorable. Results suggest that biodegradation could explain some but not all of the missing mass.Bypass of the downgradient monitoring well network is the most parsimonious explanation for the 1,4-dioxane mass deficit. This conclusion is supported by documented flow path complexity through the aquifer system and the sparse density of monitoring wells in the downgradient Eastern Area. These findings underscore the importance of characterizing aquifer heterogeneity when modeling and remediating persistent groundwater contaminants such as 1,4-dioxane.

Predicting the dust events frequency around a degraded ecosystem and determining the contribution of their controlling factors using gradient boosting-based approaches and game theory.

This study was aimed to evaluate the performance of gradient boosting machine (GBM) and extreme gradient boosting (XGB) models with linear, tree, and DART boosters to predict monthly dust events frequency (MDEF) around a degraded wetland in southwestern Iran. The monthly required data for a long-term period from 1988 to 2018 were obtained through ground stations and satellite imageries. The best predictors were selected among the eighteen climatic, terrestrial, and hydrological variables based on the multicollinearity (MC) test and the Boruta algorithm. The models' performance was evaluated using the Taylor diagram. Game theory (i.e., SHAP values: SHV) was used to determine the contribution of factors controlling MDEF in different seasons. Mean wind speed, maximum wind speed, rainfall, standardized precipitation evapotranspiration index (SPEI), soil moisture, erosive winds frequency, vapor pressure, vegetation area, water body area, and dried bed area of the wetland were confirmed as the best variables for predicting the MDEF around the studied wetland. The XGB-linear and XGB-tree showed a higher capability in predicting the MDEF variations in the summer and spring seasons. However, the XGB-Dart yielded better than XGB-linear and XGB-tree models in predicting the MDEF during the autumn and winter seasons. Rainfall (SHV = 1.6), surface water discharge (SHV = 2.4), mean wind speed (SHV = 10.1), and erosive winds frequency (SHV = 1.6) had the highest contribution in predicting the target variable in winter, spring, summer, and autumn, respectively. These findings demonstrate the effectiveness of the gradient boosting-based approaches and game theory in determining the factors affecting MDEF around a destroyed international wetland in southwestern Iran and the findings may be used to diminish their impacts on residents of this region of Iran.