River Water Supply Research Articles

지방정부의 댐 하천관리의 물공급에 관한 사례분석: 유지유량 관리를 중심으로

The purpose of this study was to find solutions for local government dam river management and water supply for maintenance flow. For this purpose, based on data collected and organized on items to be included in the system related to the environment around Unmun Dam and Dongchang Stream, a comparative review of the policy status of other local governments and environmental facilities was conducted, and case analysis was conducted focusing on domestic and international cases. The local government's maintenance flow management plan for water supply in dam river management is, first, to manage the river flow in a stable manner throughout the year in order to perform the smooth function of the river, and second, to pump water to maintain the basic flow rate of the river. A reverse pumping method that sends water from downstream to upstream, and third, artificial supply of soil through flooding or flushing discharge to improve the environment of the river downstream of the dam were proposed. As a result, we tracked changes in the natural ecological environment of Dongchang Stream after the construction of Unmun Dam and proposed dam operation plans and flood control policies to derive implications such as ecological environment restoration, flood prevention measures in downstream areas, and local economy revitalization measures.

Multiple barriers as an efficient treatment for removing pesticides aiming direct potable reuse: A pilot scale study

Water reuse for potable purposes can represent a realistic source supply of drinking water in areas with water scarcity. Therefore, combining conventional wastewater treatment technologies with advanced technologies is necessary to remove contaminants and obtain high-quality and safe water. In this study, the pesticides and degradation products, atrazine (ATZ), hydroxyatrazine (ATZOH), deethylatrazine (DEA), deisopropylatrazine (DIA), simazine (SMZ), ametryn (AMT), diuron (DIU), 2,4-D, fipronil (FIP), fipronil sulfide (FIP-SF) and fipronil sulfone (FIP-SN) were evaluated in effluent after membrane bioreactor (MBR), effluent after advanced treatment by multiple barriers (MBR, reverse osmosis, UV/H2O2 and activated carbon), in tap water collected in the urban region of Campinas and in the Atibaia River (water supply source from city of Campinas). The pesticide concentrations in the Atibaia River and the post-MBR effluent ranged between 1 and 434 ng L−1 and 1 and 470 ng L−1, respectively. Therefore, the Atibaia River and the post-MBR effluent had the same magnitude pesticide concentrations. In the production of potable water reuse, after the multiple barriers processes, only fipronil (1 ng L−1) and atrazine (3 ng L−1) were quantified in some of the samples. In tap water from Campinas, atrazine, ATZOH, DEA, diuron, and 2,4-D were quantified in concentrations ranging between 3 and 425 ng L−1. Therefore, when comparing drinking water obtained from conventional treatment with potable water reuse, according to the pesticides studied, it is possible to conclude that the advanced treatment used on a pilot scale is promising for use in a potable water reuse plant. However, studies involving more microbiological and chemical parameters should be conducted to classify potable water reuse as drinking water.

Stormwater characterisation and modelling for Sungai Air Hitam in Selangor, Malaysia using model for urban stormwater improvement conceptualisation (music)

The aim of this study is to evaluate the current water quality status of one of the urban rivers in Malaysia, called Sungai Air Hitam. The river's water supply is not only unsuitable for the inhabitants but also hazardous to the aquatic species that depend on it. In order to simulate the water quality formulation of the river, the Model for Urban Stormwater Improvement Conceptualization (MUSIC) was used. The effects of various best management practices (BMPs) components have been examined to improve the river's water quality. This study also investigated different scenarios of the expected future changes in the land cover and the quality of the river. As the proportion of impervious surfaces increases, the urban hydrology cycle can be significantly altered, resulting in an increase in volumes and peak flows, and a decrease in storage, infiltration, and interception. The MUSIC results have shown significant reductions in biochemical oxygen demand (BOD), total suspended solids (TSS), total phosphorus (TP), and total nitrogen (TN) after introducing BMPs. It was also noticed that the prediction of pollutants falls within the acceptable range set by the Urban Stormwater Management Manual for Malaysia (MSMA) 2nd edition. For the land cover, it was found that the total reduction of BOD, TSS, TP, and TN for existing land use is 92.5 %, 94.5 %, 90.7 % and 91.9 %. Meanwhile, the total reduction in future land use is 81.6 % for BOD, 86.2 % for TSS, 80.9 % for TP and 80.8 % for TN. From the simulation results, it was observed that the application of BMPs has successfully reduced the observed mean BOD concentration from 92.38 mg/L (Class V) to 6.93 mg/L (Class IV) of the national water quality standards, NWQS, water quality index. As a result, the water quality index of the overall catchment has improved from Class IV to Class III (WQ1, WQ3, and WQ4) and from Class V to IV (WQ2) with the application of the BMPs. This assessment aims to raise awareness within the Sungai Air Hitam community regarding the importance of preserving river cleanliness and understanding the long-term environmental impact of water quality. These findings underscore the importance of an integrated system in managing urban water systems, which can offer valuable insight to the decision-makers.

Cross-contamination and ecological risk assessment of antibiotics between rivers and surrounding open aquaculture ponds

Antibiotics are causing widespread concern as one of the emerging contaminants. There is the abuse of antibiotics in high-density open aquaculture, and the tailwater is often discharged into surrounding rivers. At the same time, the water replenishment of open aquaculture ponds from nearby rivers containing antibiotic contamination from different sources may result in cross-contamination. However, it is still unclear which pollution intensity is greater in rivers or in open aquaculture. So in this paper, the levels of 20 antibiotics (i.e., Fluoroquinolones (FQs), Sulfonamides (SAs), Tetracyclines (TCs), Macrolides (MLs) and Lincosamides (LCs)) in rivers and high-density open aquaculture ponds were investigated in the Baini River basin in the suburbs of Guangzhou, China. The results showed that norfloxacin (NFX) was the predominant antibiotic in river and aquaculture water, with concentrations ranging from 6.12 to 156.04 ng/L and from 7.47 to 82.62 ng/L in both aquatic systems, respectively. As for the pollution intensity of antibiotics, the annual pollution contribution (28.64 kg/a) of the river water supply to open aquaculture is higher than that (10.81 kg/a) of open aquaculture to the river, which means river pollution has a greater impact on aquaculture ponds. The risk quotient (RQ) showed that the ecological risk of lincomycin (LIN), erythromycin (ERY), sulfamethoxazole (SMX), norfloxacin (NFX), ciprofloxacin (CFX) and chlortetracycline (CTC) in rivers and aquaculture environments had high ecological risks from 1.21 to 1.81. Water interactions with contaminated rivers will result in a corresponding increase in the ecological risk of antibiotics in the aquaculture environment. Overall, according to the results, the risk of polluted rivers to open aquaculture cannot be ignored, and it is recommended that open aquaculture should use these water sources with caution, and that the water quality evaluation of aquaculture water should be increased with monitoring indicators for emerging contaminants such as antibiotics.

Recombinant Organophosphorus acid anhydrolase (OPAA) enzyme-carbon quantum dot (CQDs)-immobilized thin film biosensors for the specific detection of Ethyl Paraoxon and Methyl Parathion in water resources

Organophosphates pesticide (OP) toxicity through water resources is a large concern globally among all the emerging pollutants. Detection of OPs is a challenge which needs to be addressed considering the hazardous effects on the health of human beings. In the current research thin film biosensors of recombinant, Organophosphorus acid anhydrolase (OPAA) enzyme along with carbon quantum dots (CQDs) immobilized in thin films were developed. OPAA-CQDs thin film biosensors were used for the specific detection of two OPs Ethyl Paraoxon (EP) and Methyl Parathion (MP) in river water and household water supply. Recombinant OPAA enzyme was expressed in E. Coli, purified and immobilized on the CQD containing chitosan thin films. The CQDs used for this purpose were developed by a one-pot hydrothermal method from phthalic acid and Tri ethylene diamine. The properties of CQDs, OPAA and thin films were characterized using techniques like XPS, TEM, XRD, enzyme activity and CLSM measurements. Biosensing studies of EP and MP were performed by taking fluorescence measurements using a fiber optic spectrometer. The analytical parameters of biosensing were compared against an estimation carried out using the HPLC method. The biosensing performance indicates that the OPAA-CQDs thin film-based biosensors were able to detect both EP and MP in a range of 0–100 μM having a detection limit of 0.18 ppm/0.69 ppm for EP/MP, respectively with a response time of 5 min. The accuracy of estimation of EP/MP when spiked in water resources lie in the range of ∼100–102% which clearly indicates the OPAA-CQD based thin film biosensors can function as a point-of-use method for the detection of OP pesticides in complex water resources.

Study on the Optimization of Multi-Objective Water Resources Allocation in the Henan Yellow River Water Supply Zone

With the continuous growth in the global population, rapid socioeconomic development, and the impacts of factors like climate change, we are facing increasingly severe challenges regarding water scarcity. The scientific and rational allocation of water resources has become a key factor in ensuring sustainable development. The Henan Yellow River water supply zone occupies a crucial position in the socioeconomic development of Henan Province. Currently, there is a shortage of water resources with relatively low utilization rates. To alleviate the contradiction between water supply and demand, a study on the optimization of water resources (with p = 90%) for the years 2025 and 2030 was conducted. In this study, we constructed a multi-objective optimization model with the objectives of maximizing economic benefits, minimizing total water shortage, and maximizing water use efficiency. The second-generation non-dominated sorting genetic algorithm (NSGA-II) was utilized to solve this model. The results indicate that by 2025, the optimized allocation of water resources will correspond to 17.663 billion m3, reducing the average water shortage rate in the research area to 9.69%. By 2030, the optimized allocation of water resources will further increase to 18.363 billion m3, bringing down the average water shortage rate to 8.34%. Concurrently, the supply structure of the research area will significantly improve after optimization. This is manifested through an increase in the proportion of surface water supply and a substantial rise in the proportion of supply from other water sources, while the proportion of groundwater supply noticeably decreases. These research findings can serve as a reference for the rational utilization and distribution of water resources in the future and can also offer insights for optimizing water resource allocation in other regions.

Study on the propagation law of meteorological drought to hydrological drought under variable time Scale: An example from the Yellow River Water Supply Area in Henan

To study the propagation law of meteorological droughts to hydrological droughts under variable time scales, and to reveal the synchronisation gap and lag time of hydrological droughts compared to meteorological droughts, and the lag degree of hydrological drought is quantitatively studied. In this paper, the Yellow River Water Supply Area in Henan is taken as the research area, and the propagation time of meteorological drought to hydrological drought under variable time scale is mainly studied. The calculation of drought propagation time is set as two states: interval scale and continuous scale. The Standardized Precipitation Index (SPI) sequence and Standardized Runoff Index (SRI) sequence (1)with interval and continuous scales were obtained by multi-scale standardization of precipitation and runoff, which were used to characterize meteorological drought and hydrological drought respectively. The Mann-Kendall (M−K) test method was used to analyze the evolution of SPI sequence and SRI sequence at monthly scale, and to study the lag time of hydrological drought in four seasons compared with meteorological drought. Combining the Grey Correlation Method and Pearson correlation coefficient methods, the time interval for the propagation of meteorological droughts to hydrological droughts was determined based on the strongest correlation of different combinations of sequences. Finally, the propagation time series is divided into sliding windows to analyse the M−K dynamic trend of propagation time from a seasonal scale perspective. It provides a strong basis for the study of drought propagation based on multi-scale.

Optimizing environmental flow based on a new optimization model in balancing objectives among river ecology, water supply and power generation in a high-latitude river

Environmental flow plays an important role in maintaining the health of river ecosystems and aquatic habitats. Although ecological regulation of environmental flow has attracted the attention of scientists, managing the world's reservoir-regulated rivers to better meet the needs of human being and ecosystems is a complex social challenge. To address the above issues, we constructed a model for optimizing reservoir operation based on a balance in achieving multi objectives among environmental flow, water supply and power generation (EWP). The model was solved using an intelligent multi-objective optimization algorithm (ARNSGA-III). The developed model was demonstrated in a large reservoir, Laolongkou Reservoir in the Tumen River. The results showed that the reservoir altered environmental flows mainly in terms of flow magnitude, peak, times, duration and frequency, which result in a sharp decrease in spawning fish, and degradation and replacement of vegetation along the channels. In addition, the mutual feedback relationship between the objectives of environmental flows, water supply and power generation is not static, but varies over time and space. The constructed model based on Indicators of Hydrologic Alteration (IHAs) can effectively guarantee the environmental flow at daily scale. In detail, the river ecological benefit increased by 64% in wet year, 68% in normal year, 68% in dry year after optimizing regulation of reservoir, respectively. This study will provide a scientific reference for the optimizing of the management in other rivers affected by dams.

A Survey of the Bureau of Reclamation’s Decree Accounting Reports in the Lower Colorado River Basin

From the Rocky Mountains in the US to the Sea of Cortez in Mexico, the Colorado River is one of the most managed and monitored rivers in the world. As decreasing river flows from drought and climate change continue to impact the Colorado River Basin, the US federal government, seven US states, and Mexico have signed agreements that would reduce deliveries, including a Drought Contingency Plan (DCP), an agreement among the US states and the Bureau of Reclamation, and Minute 323 (a treaty agreement between the US and Mexico). As part of the DCP, the US Bureau of Reclamation (Reclamation) committed to increasing conservation efforts to augment storage in Lake Mead. This paper presents an analysis of Reclamation’s Decree Accounting Reports that record water deliveries and conservation savings from 1964 to 2019. Overall, this analysis illustrates that (1) the agency has implemented significant conservation actions over the last three decades, (2) the agency has responded to increased accounting needs as dictated by national and international management agreements, (3) some actions have resulted in environmental costs, and (4) future actions could be designed to avoid environmental harms while also augmenting Lake Mead levels. As climate change continues to constrain Colorado River water supply, detailed accounting may help reveal areas for potential efficiencies or demonstrate where the greatest levels of savings have been reached while ensuring that environmental and social benefits are preserved.

Research on High-Quality Development Evaluation and Regulation Model: A Case Study of the Yellow River Water Supply Area in Henan Province

Unbalanced and inadequate development has led to challenges such as resource shortage, ecological fragility, and economic backwardness in the water-receiving area of Henan Province, which has hindered the high-quality development of the region. This research aims to construct a high-quality development regulation model. The single-indicator quantification–multi-indicator synthesis–multicriteria integration (SMI-P) method was used to evaluate the level of regional development; using the method of embedded system dynamics, the regulation model was constructed and applied. The results show that (1) from 2011 to 2020, the degree of regional high-quality development showed an increasing trend, rising from a low level (0.34) to a medium level (0.57), an increase of one level, but the level of high-quality development still has a lot of room for improvement and faces great challenges; (2) the development of a resource–ecology–economy–social system was in a state of non-harmonious balance, and the proportion of contributions of each system was very different, but the system was developing towards a state of harmony and balance; (3) based on the constructed high-quality development regulation model, the key constraints affecting the high-quality development of the Yellow River water supply area in Henan Province are per capita water consumption, per capita energy consumption, carbon emissions per capita, GDP per capita, etc. The model constructed in this paper can improve the quality development level through the application of examples. The high-quality development degree of the study area was increased from 0.57 to 0.8.

HYDRO-ECOLOGICAI CONDITION OF LAKE LYMAN (DVS RP "LYMANSKE" OF KHARKIV REGION)

A comparative analysis of the hydro-ecological state of Lake Lyman (DVSRP "Lymanske" of the Kharkiv region) of the cooling reservoir of the Zmiyivska TPP (Siverski Dinets basin) was carried out for the study of ecological and genetic features of white (Hypophthalmichthys molitrix) and variegated (Aristichthys nobilis) carp using ISSR DNA markers during 2019-2020. The ecological state of water bodies is presented, the species composition of the biota, the natural fodder base and the factors influencing the environment on the conditions of aquaculture are defined; the ecological conditions of growing a population of different age groups of variegated (Aristichthys nobilis) and white carp (Hypophthalmichthys molitrix) in the conditions of the Lymanske DVSRP of the Kharkiv region were studied in 2019. The studied phytoplankton shows a rather significant increase in biomass compared to previous research results (1984-2010). A significant increase in the number of phytoplankton is also evidenced by the fixation of floating masses of phytoplankton in the reservoir with a layer of up to 2-3 cm, among which blue-green algae (Cyanophyta), dinophyta (Dinophyta), and diamond algae (Bacillariophyta) predominated in number. The zooplankton of Lake Lyman was represented by rather widespread forms of three main groups: Rotifera, Cladocera, Copepoda. The ichthyofauna of the cooling pond of the Zmiivskaya TPP, which now includes 28 species of fish from 8 families, was studied. The main factors in the formation of the composition of fish in the cooling reservoir are the thermal load of the station, fishing activity and regular supply of river water to the reservoir. Changes in the composition of the fish fauna in recent years are due to the massive spread of evribiont fish-intervenors (needle fish, stickleback), a decrease in the power plant's working capacity (chub fish, gustera, or whitefish), as well as the release of fish from cages when the latter are broken.

Ecological and economic significance of the Middle Don sand arenas

The research purpose is a comprehensive assessment of the Middle part of the Don river sand massifs soil and hydrological conditions. The research objects are the sandy massifs of the Middle Don on an area of 527 thousand hectares. The sand arenas water balance dynamics for the period from November to March and for the period from April to October has been revealed. It has been established that atmospheric precipitation is the main source of river water supply. The basis of river systems flood filling are clay soils that form an intra-soil runoff. The low water period level is supported by sandy soils. A decrease in the density of plant formations contributes to an increase in groundwater supply. The total underground runoff reaches 599 million m3 from the sandy massifs of the Middle Don. The volume and dynamics of the moisture movement in the soil depend on the system of sandy areas use. Therefore, the load on sandy arenas should be regulated. Pasture farming should remain the dominant form of sand use. An effective method of sandy arenas afforestation is the planting of pine plantations according to the savanna type.

Geospatial analysis of patients' social determinants of health for health systems science and disparity research.

Geospatial analysis of patients' social determinants of health for health systems science and disparity research.

The energy, water supply, and ecology coordination for middle-long-term reservoirs scheduling with different connection modes using an elite mutation strategy-based NMOSFLA

Abstract Conventional reservoir operation emphasizes power generation (PG) with ignoring downstream river ecosystem and water supply benefits for sustainable development. Compared with the model defining water supply and ecological flow requirements as constraints, a novel long-term multi-objective scheduling model in complex parallel reservoir system (LTMOSCPRS) is developed to assess and achieve win–win and sustainable development for energy, water supply, and ecological benefits. The suitable and ideal ecological water requirements are calculated based on the requirement level index. Afterward, the novel multi-objective shuffled frog leaping algorithm (NMOSFLA) including renewed frog grouping, local search, and external elite frog set mutation strategies is proposed. Results indicate that three optimization objectives expose a mutual competing relationship. The benefit of the river ecosystem will increase at a loss of PG and water supply guarantee rate (WSGR). Therefore, the parallel reservoir system should be adjusted to improve the benefits of WSGR and ecological water spill and shortage (EWSS) with minimizing the loss of PG, simultaneously. Finally, the NMOSFLA is verified to outperform other compared methods at the solution diversity and convergence which is evaluated by multiple indicators. Overall, the NMOSFLA provides efficient reservoir operation schemes for decision-makers to select optimal trade-off schemes and feasible ways to solve the LTMOSCPRS.

Mining Scheme for Small Rivers near Water Sources—A Case Study of Liuan River in Linquan County, China

During dry seasons or years, the runoff processes from small rivers influence the safety of riverside groundwater source fields. Water source exploitation has a considerable effect on river runoff. In this study, the riverside source field of the Liuan River in the Linquan County, Anhui Province, was analyzed. The effect of mining on the ecological flow of the river under river runoff conditions in different typical dry years was quantified. This was undertaken using numerical simulations of the groundwater flow to provide guidance for the establishment of mining schemes for riverside source fields. In 95% of typical dry years, the water supply of small rivers is insufficient. The improved 7Q10 method used to calculate the ecological flow in different dry years revealed that mining water had little effect on the ecological flow. However, during the pumping process, the groundwater level of the water source area decreased greatly. The establishment of riverside source fields can aid in reducing excessive development and use of deep groundwater. The planning, construction, and implementation of the “Divert water from the Yangtze River to the Huaihe River” project can effectively reduce the economic losses that have occurred due to severe drought in the local area.

Study of the Lateral Bearing Capacity and Optimization Reinforcement Scheme of an Open Caisson with Consideration of Soil Disturbance

The bearing capacity of an open caisson under lateral loads is a key factor affecting the normal operation of an open caisson. It will inevitably have a disturbing effect on the surrounding soil layers during the sinking process of the caisson; that is, a disturbance ring will develop around the caisson. Based on the Jurong Yangtze River water supply project, the lateral bearing characteristics of the open caisson are analyzed by the numerical method with due consideration to soil disturbance, and the reinforcement scheme is optimized. The numerical results show that when the thickness of the disturbance ring is less than 0.5 m the disturbance ring has little effect on the lateral bearing capacity of the open caisson. An arc-shaped cement–soil reinforcement at the loading area can effectively improve the lateral bearing performance of the caisson. The optimized reinforcement thickness is 2 times that of the disturbance ring, and the reinforcement angle is approximately 60°.

Response Surface Models Using the Wavelet Technique for Reservoir Inflow Prediction

Reliable streamflow prediction is vital to improving river operations, flood avoidance, water supply, and water resources management. Recently, response surface models have been launched in reservoir inflow prediction due to their potential to model composite nonlinear behaviour. Authors develop a hybrid model, wavelet quadratic response surface for reservoir inflow prediction in Chenab river basin, Pakistan. Wavelet transform has extensive applications in the field biomedical, engineering, and hydrology. Discrete wavelet transform technique discloses the structure of nonstationary signals. A proper and careful selection of mother wavelet ensure the best performance of wavelet transform. The choice of a suitable wavelet function participates in implementing the wavelet function used in response surface based models for reliable prediction. The performance of the proposed model is checked on different performance indices for model evaluation. The new developed model, wavelet quadratic response surface, depicts excellent results than other studied models.

Critical streamflow for water supply safety based on the withdrawal avoiding saltwater model in coastal areas-taking the water supply for Zhuhai and Macao in the Guangdong-Hong Kong-Macao Greater Bay Area as a case

枯水期咸潮入侵已经严重威胁到了感潮河流区域供水安全.本文通过构建避咸蓄淡供水模型，耦合了咸度预测、河库联合供水调度和供水安全分析模块，为依赖感潮河流为水源地的区域供水安全管理提供了一种整体思路和决策方法.以面向粤港澳大湾区珠海东部及澳门的珠江三角洲磨刀门水道取供水为例，基于潮汐、径流和风等因子及咸度实测数据，较好地拟合了基于BP神经网络的咸度预测模型，及含氯度与超标时间的曲线函数，建立了上游来水和咸度超标时间之间的联系，得到了避咸蓄淡取水时机.咸度预测与当地河库联合供水调度相结合，得到了上游枯水期来水过程的当地区域供需平衡状况.枯水期不考虑水库调蓄的资源性缺水临界需水量为3.22亿m³，水库参与调蓄的工程性缺水临界需水量为3.75亿m³.通过供水安全分析模块，基于设定的风险阈值和临界阈值识别出了不同需水规模的上游来水临界流量特征.对于当地规划的需水规模4.23亿m³，期望上游枯水期临界流量均值约为3372 m³/s.整体上来说，需水规模越大，对上游来水期望的临界流量越大，但同时还与枯水期流量分布有关.;Salt-tide invasion in the dry season seriously threatens regional water supply in a tidal river area. In this paper, a new model, the withdrawal avoiding saltwater model (WASM), which combines salinity prediction, joint water supply of rivers and reservoirs, and security of water supply analysis, was developed. The model provides an overall idea and decision-making method for security analysis of regional water supply, depending on the withdrawal from tidal river. The water supply for Zhuhai and Macao of the Guangdong-Hong Kong-Macao Greater Bay Area from the Modaomen waterway in the Pearl River Delta was considered as an example. Data of tide, streamflow, and wind factors as well as those of salinity were used. The BP-ANN model for salinity prediction and the function between daily average chlorine and the time exceeding its standard value were well fitted. Upstream streamflow and the time of excessive salinity in the waterway were connected, and the time of withdrawal avoiding saltwater for the streamflow was obtained. The joint water supply of rivers and reservoirs associated with salinity prediction, regional water supply, and demand facing any upstream streamflow during the dry season was analyzed. If only the capacity of withdrawal from the river was considered, the critical demand for the resource supply accounted for 322 million m³ in the dry season. When the regulation of reservoirs was also taken into consideration, the critical demand for the engineering supply accounted for 375 million m³ in the dry season. Then, water supply security was further analyzed, and critical upstream streamflow for various scenarios of water demand in the dry season was identified for given thresholds of risk and critical. The critical streamflow in the dry season accounted for 3372 m³/s when the demand increased to 423 million m³ of local planning water demand. Overall, the larger the demand was, the greater the expected critical streamflow in upstream was. However, the security of water supply is associated with the distribution of upstream streamflow in the dry season.

Upper Gila, Salt, and Verde Rivers: Arid Land Rivers in a Changing Climate

Abstract The major tributary of the lower Colorado River, the Gila River, is a critical source of water for human and natural environments in the southwestern United States. Warmer and drier than the upper Colorado River basin, with less snow and a bimodal precipitation regime, the Gila River is controlled by a set of climatic conditions that is different from the controls on upper Colorado River flow. Unlike the Colorado River at Lees Ferry in Arizona, the upper Gila River and major Gila River tributaries, the Salt and Verde Rivers, do not yet reflect significant declines in annual streamflow, despite warming trends. Annual streamflow is dominated by cool-season precipitation, but the monsoon influence is discernable as well, variable across the basin and complicated by an inverse relationship with cool-season precipitation in the Salt and Verde River basins. Major multiyear streamflow droughts in these two basins have frequently been accompanied by wet monsoons, suggesting that monsoon precipitation may partially offset the impacts of a dry cool season. While statistically significant trends in annual streamflow are not evident, decreases in autumn and spring streamflow reflect warming temperatures and some decreases in spring precipitation. Because climatic controls vary with topography and the influence of the monsoon, the impact of warming on streamflow in the three subbasins is somewhat variable. However, given relationships between climate and streamflow, current trends in hydroclimate, and projections for the future, it would be prudent to expect declines in Gila River water supplies in the coming decades. Significance Statement This research investigates the climatic controls on the Gila River and its major tributaries, the Verde and Salt Rivers, to gain insights on how trends in climate may impact future water supply. The Gila River is the major tributary of the lower Colorado River, but, unlike the situation for the upper Colorado River, no significant decreasing trends in annual streamflow are evident despite warming temperatures. Climate–streamflow relationships are more complex in this part of the Colorado River basin, and several factors may be buffering streamflow to the impact of warming. However, given the key climatic controls on streamflow, current and emerging trends in climate, and projections for the future, declines in streamflow should be expected in the future.

Assessment of Coagulation–Flocculation Process Efficiency for the Natural Organic Matter Removal in Drinking Water Treatment

Natural organic matter (NOM) represents a range of heterogeneous hydrophobic and hydrophilic components naturally occurring in the water source and, due to the fact that they can act as precursors for the disinfection, by-products may have a considerable impact on drinking water quality. Coagulation–flocculation (C/F) is among the most applied processes for NOM removal from water sources (especially rivers). In this study, C/F efficiency for a river water supply was investigated in cold and warm conditions, by varying the coagulant dose and mixing conditions. In this study, polyhydroxy aluminum chloride PAX XL 60, and polyacrylamide FloPam AN 910 SEP were used as coagulant and flocculant, respectively. Multiple water quality indicators were determined, such as turbidity, chemical oxygen demand (COD), dissolved organic carbon (DOC), and residual aluminum concentration. Some unconventional parameters relevant for NOM removal were also considered, like absorbance at 254 nm (A254), at 280 nm (A280), and at 365 nm (A365), as well as the ratios A254/DOC, A254/280, and A254/A365. After coagulation–flocculation, turbidity was completely removed in all the studied conditions. The DOC content was reduced by up to 22.65% at a low temperature and by up to 31.81% at a high temperature. After the addition of polyelectrolyte in cold conditions, the efficiency in terms of A254 increased by up to 37.4%, while the specific absorbance decreased. The high molecular weight NOM increased after C/F, based on the A254/A365 ratio. Chemometric analysis was employed in order to determine the effect of the coagulant dose on the process efficiency. The optimum coagulation–flocculation conditions were corroborated by means of the principal component analysis.