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Perfluorinated surfactants (PFSs) in groundwater were analyzed to reveal their distribution and sources. Sixteen groundwater and spring samples were collected from the Tokyo metropolitan area, and nine PFSs, including perfluorooctane-sulfonate (PFOS) and perfluorooctanoate (PFOA), were analyzed by liquid chromatography-tandem mass spectrometry. A column test using artificial street runoff was also performed to study their behavior. PFSs were detected in all groundwater samples, some at concentrations comparable to those in wastewater and street runoff, suggesting widespread contamination of groundwater by PFSs. In particular, PFOS -was more abundant in groundwater than in rivers, wastewater, and street runoff. This was attributed to its production from the degradation of its precursors, as supported by the column test. The occurrence of short-chain perfluorocarboxylates (PFCAs) in groundwater was also consistent with the results of the column test, showing that limited amounts of short-chain PFCAs were removed by soil, as the efficiency of removal increased with the chain length. We evaluated the contributions of PFCAs from wastewater and surface runoff to groundwater by using two indicators, the long/(short + long) ratio and the even(even + odd) ratio. Both ratios showed good agreement in their calculated contributions in heavily contaminated groundwater where breakthroughs likely occurred. Wastewater and surface runoff contributed to 54-86% and 16-46% of PFCAs, respectively, in groundwater.

The economy of Northeast Thailand is mainly based on agriculture. The transformation of forestlands to agricultural areas and the encroachment of riverbanks within the Phong watershed have caused severe soil erosion. Strong storms in rainy season exacerbate the problem of soil erosion. Difficulty in getting water drives people in the upstream region to live on riverbanks. Soil erosion affects water utility by increasing the turbidity in the Phong River and also by decreasing the water storage capacity of small reservoirs for the upstream residents, as well as that of the Ubolratana Dam. The rate of siltation in the Ubolratana Dam was estimated to be 1.5 million tons/year during 1965-1990. The main source of water supply is surface water in the Phong watershed, and fluctuating turbidity makes water treatment difficult. The maximum turbidity in the upstream Phong River exceeds 5000 NTU, whereas it is reduced to be about 300 NTU at the intake point of Khon Kaen Municipal Water Treatment Plant because the Ubolratana Dam works as a huge clarifier. Khon Kaen Municipal Waterworks has a daily water supply of 72,960 m3/day. The average amounts of alum used in the wet (May-October) and dry (November-April) periods are 42.33 g/m3 and 28.46 g/m3, respectively. The average costs of the amounts of alum used are 0.213 and 0.143 Bahts/m3 during the wet and dry periods, respectively. Fluctuation of turbidity in raw water makes it difficult to adjust alum dose, resulting in treated water quality unstable, and handling of sludge disposal difficult.

Globally, scale deposition in water supply pipelines is one of the major problems faced by water utilities. This research aimed to determine the causes and effects of scale deposition in the water supply pipelines in Surakarta City, Indonesia. The total dissolved solids (TDS), hardness, manganese, and alkalinity in groundwater were higher than those in the surface water and spring water; thus, the supply areas from groundwater were identified using TDS at the taps. The three scaling indicators, i.e., the Langelier saturation index (LSI), the Ryznar stability index (RSI), and the Puckorius scaling index (PSI), indicated moderate calcium carbonate scaling. However, elemental analysis of eight scale samples using X-ray fluorescence (XRF) revealed that the major components of scale were either manganese (50.1–80.8%) or iron (45.6–63.8%), whereas calcium (3.0–7.8%) was a minor component. Because only five of twenty groundwater sources were chlorinated before distribution, it is estimated that dissolved manganese is oxidized by manganese-oxidizing bacteria. The manganese deposition rate in the networks was estimated to be 1660 kg/year using the manganese concentration at groundwater sources and in customers' taps. These results suggest the importance of the elemental analysis of scale and avoidance of overreliance on scale indicators. [ABSTRACT FROM AUTHOR]

Although the special region of Jakarta Province (DKI Jakarta), Indonesia, has a large population of 10.9 million, piped water coverage remains at only 64%. Therefore, excessive groundwater abstraction has caused serious land subsidence over the last few decades. This study proposed the priority areas for piped water supply extension to alleviate the adverse effects of groundwater over-abstraction in DKI Jakarta. Water consumption and multilayer analyses (e.g., geology, groundwater abstraction, groundwater level, piped water coverage, and groundwater quality) were carried out to determine the priority areas for piped water development. Based on three parameters, namely the water demand–supply gap, land subsidence, and groundwater quality, the northern and western regions of Jakarta were selected as the priority areas for piped water development, followed by the southern and eastern regions. The demand for piped water by the population in the abovementioned priority areas is estimated to be 462,211 m3/d, while the total water demand of Jakarta is 1,878,899 m3/d, which is greater than the supply capacity of 1,747,440 m3/d from the existing water treatment plants. Therefore, the areas for controlled groundwater abstraction were also selected to augment the shortfall of the piped water supply capacity. [ABSTRACT FROM AUTHOR]

A slum upgrading program has provided communal boreholes (KOTAKU boreholes) to improve water supply in slums of Indonesia. However, the achievement of the program was only estimated by the number of households served with the boreholes. We evaluated the water supply improvement by comparing actual water consumption, quality, and expenditure and household satisfaction of existing water sources in a slum of Bandung City, Indonesia. A high iron concentration and microbial contamination were observed in some KOTAKU boreholes, but the quality was better than that in the previous sources of the current KOTAKU borehole users. Twenty percent of the users spend more than 4% of their income on water due to bottled water and vended water for drinking and cooking. However, KOTAKU boreholes replaced that water for drinking and/or cooking, resulting in less water expenditure in low-income households. The average consumption was 134 L per capita per day (LPCD), which was higher than the target (60 LPCD) of the program. However, it was found that a highly intermittent water supply was the reason for household dissatisfaction rather than the amount of consumption. The program improved water supply; however, this study revealed the limitations of the water supply, namely, a lack of attention to continuous water supply and water quality. [ABSTRACT FROM AUTHOR]

Private water supply operators (PWSOs) play an important role in extending piped water services in small cities in Cambodia. However, the connection rates to PWSOs are highly varied. Therefore, this study aimed to find the reasons for the low connection rates of PWSOs and to propose ways to increase the connection rates. The three PWSOs selected for this study supply water continuously, with sufficiently high pressure and good water quality except for the low concentration of residual chlorine, while the per capita supply volume varies significantly. Households with alternative water sources, namely rainwater and well water, consume less piped water than those without alternative water sources. Scattered service areas far away from water treatment plants had coverage rates that were lower than in compact service areas. The present connection costs and water tariffs are higher than those that non-connected households are willing to pay, though they pay high costs for bottled water. Due to the high variation in household income, connection fees and water tariffs are a financial burden for low-income households. Because the operating rates of the PWSOs are 21–47%, it is advised that PWSOs reduce their connection fees and water tariffs to obtain more connected households in their service areas. [ABSTRACT FROM AUTHOR]

Okinawa Island is located in the southern region of Japan and has a population of 1.22 million. Okinawa Prefectural Enterprise Bureau (OPEB) supplies 410,000m³/d of water to 24 municipalities. Although OPEB uses multiple water resources including dam reservoirs and groundwater, increased water demand resulted in occasional water shortages until a seawater desalination plant (40,000m³/d) started operations in 1997. In this study, a model was developed to simulate the water supply system of Okinawa Island using precipitation and OPEB operational data from 2009 to evaluate the role of the desalination plant in reducing risks associated with drought and power consumption of the plant. The simulation results indicate that without the desalination plant, the dam reservoir storage falls below 50% for 70 days, whereas with the desalination plant, storage remains above 50%. If the plant was operated at full capacity, the dam reservoir storage increased by 17.2% after 1 year of simulation time. However, the desalination plant consumes 4.5-14.7 times more electricity per unit volume of water than other water resources. Although the desalination plant plays an important role in avoiding water shortage in Okinawa Island, operational protocols to minimize power consumption need to be developed further using simulation models such as the one developed in this study. [ABSTRACT FROM AUTHOR]

High concentrations of manganese and iron in the Saigon River are major problems for the water supply in Ho Chi Minh City (HCMC), Viet Nam. To identify their sources and leaching processes, we surveyed water quality along the Saigon River and ran batch leaching tests using soil and sediment samples. Two important leaching processes were identified: acidic leaching from acid sulfate soil (ASS) in the middle reaches of the river, and Mn dissolution and Fe reduction from sediments in the downstream reaches. Low pH caused the concurrent release of Fe and Mn from the ASS. In contrast, anoxia caused the release of Fe but not Mn from the sediments, whereas low pH facilitated Mn dissolution. Sediments are a more important source of Mn because of their higher Mn contents (10 times) and release rates (14 times) than those from ASS. [ABSTRACT FROM AUTHOR]

In Yangon City, chlorination commenced in January 2020 to supply drinkable water; therefore, there is as yet no information on chlorine decay and DBP formation in the water supply system. This study aimed to find methods to optimize chlorine dosage in Yangon City. Onsite sampling and laboratory analyses of residual chlorine and trihalomethane (THM) formation, as well as water quality simulations, were conducted to find the chlorine decay and THM formation kinetics. Due to a high chlorine dose of 2 mg/L for both pre- and post-chlorination, disinfection was effective despite the low removal efficiency of turbidity. However, THMs were found in high levels in both treated and tap water due to the high THM formation potential of raw water. The re-contamination and/or transformation of dissolved organic matter were found in the distribution network by increases in specific ultraviolet absorption (SUVA) values and excitation-emission matrix (EEM) fluorophores, which brought about variations of THMs in the networks. The EPANET models were run assuming there to be no water leakages; it was found that the chlorine dose could be decreased to 0.8 mg/L to meet the guidelines for THMs and residual chlorine. The methods employed in this study could be also applied in other water supply systems in tropical developing countries with limited water quality monitoring data. [ABSTRACT FROM AUTHOR]

In Nepal, there are three types of water service providers; two types of government-managed service providers covering urban and municipal areas, and community-managed service providers called Water Users and Sanitation Associations (WUSAs). This study aims to assess the current water supply service levels and water supply inequalities of WUSAs in terms of water consumption, supply hours, and customer satisfaction. Among the three types of water service providers, WUSAs offered the best performance in terms of their low non-revenue water (NRW) rates and production costs, high bill collection rates, and long supply hours. During the COVID-19 lockdown, water consumption increased, but bill payment notably decreased, possibly due to restricted movement and hesitation by customers to make payments. The multiple-year water consumption variations illustrated the uneven water consumption behavior of customers. Despite the variation in water supply hours, Lorenz curves, Gini coefficients (G), and water consumption analysis depicted low inequalities (G ≈ 0.20–0.28) and adequate water consumption among WUSAs even in 2019–2020. In the three WUSAs, more than 90%, 74%, and 38% of customers consumed water above the basic, medium, and high levels, respectively. Thus, maintaining high service levels of WUSAs is instrumental in achieving Goal 6 of the Sustainable Development Goals (SDGs) in Nepal. [ABSTRACT FROM AUTHOR]

Although planned and regulated conjunctive use of surface water and groundwater could help alleviate water shortages in developing countries, unregulated conjunctive use is common due to the lack of water consumption data and management plans. This study aimed to establish planning methods for conjunctive use of urban water resources in Yangon City, Myanmar, for which only limited data on water resources and consumption are available. To obtain accurate operational times for groundwater pumps, vibration loggers were attached to discharge pipes of the groundwater pumps owned by Yangon City Development Committee and households, and the water consumption of residents without piped water supply was estimated based on their housing types. Subsequently, the groundwater consumption by residential and commercial users was estimated from the water mass balance for Yangon City. It was found that the actual groundwater abstraction and consumption in Yangon City is far greater than the amounts reported in the Water Supply Master Plan of 2014. Groundwater abstraction per area (APA) was proposed as an index to prevent land subsidence, and the calculated values of APA for each township of Yangon City were very high compared with those of other Asian cities that have experienced land subsidence. Based on the APAs estimated for three future scenarios with two future water demands, this study calls for immediate regulation of industrial water to minimize the risk of land subsidence in Yangon City. The planning methods for conjunctive use proposed herein could be useful for other cities in developing countries where unplanned conjunctive use is prevalent. [Display omitted] • Novel planning methods of conjunctive water use for cities in developing countries. • Urban water balance model to estimate water consumption and water loss. • Mobile vibration data loggers to obtain operation times of groundwater pumps. • Abstraction per-area proposed as an index to assess the risk of land subsidence. • Phased regulations for groundwater abstraction to avert environmental impacts. [ABSTRACT FROM AUTHOR]

Abstract: In recent decades, soil erosion by water has become a worldwide problem, especially with climate change and progressive declines in the ratio of natural resources to human populations. Changes in future climate will influence soil erosion, particularly suspended sediment (SS) yield, and alter the effectiveness of water resources management strategies from a water quality perspective. We qualitatively assessed future changes in SS yield in Japan. We focused on the impacts of future hydrological changes projected by two models, the Model for Interdisciplinary Research on Climate (MIROC) and the Meteorological Research Institute Atmospheric General Circulation Model (MRI-GCM), whose results have produced monthly data sets for the whole of Japan. The impacts of future climate changes on SS in Japan depend on the balance between changes in climatic and geologic factors. Methods for assessing impact using the catchment simulator were expanded to estimate the SS yield for the whole of Japan. The results indicated that SS generation will increase by the 2090s, with an 8% increase predicted using MRI-GCM data and a 24% increase using MIROC data, compared to present-day values measured by the Automated Meteorological Data Acquisition System (AMEDAS) of the Japan Meteorological Agency. Analysis by month showed the largest increases in SS in September, related to the frequency of extreme events such as typhoons. Increased SS can have negative effects on both society and the environment, including reduced crop productivity, worsened water quality, lower effective reservoir water levels, flooding and habitat destruction. Prediction of the impacts of future climate change on SS generation is crucial for effective environmental planning and management. [Copyright &y& Elsevier]