Alternative Water Supply Sources Research Articles

Characterizing the relationship between urban sprawl and water demand in Dodoma Urban District, Tanzania: 1992–2029

ABSTRACT Rapid urban growth is making the planning of water resources increasingly uncertain, highlighting the need for plausible forecasts of water demand to achieve optimum allocation among competing uses. This study applies a population balance model and statistical modelling to investigate the relationship between water demand and urban sprawl in Dodoma Urban District in Tanzania. The findings revealed a positive but complex and non-linear relationship that is best characterized by a quadratic model: Predicted water demand (in million m3) = −1.206 + 0.285*(Urban growth in km2) – 0.002*(Urban growth in km2)squared. The model is a first step in characterizing the determinants of water demand for better planning and management of scarce water resources in a data-constrained but rapidly urbanizing region. We recommend striking a balance between desired future urban growth and projected water demand and prioritizing financial investments to develop alternative water supply sources.

Impact of wastewater treatment plants on microbiological contamination for evaluating the risks of wastewater reuse

BackgroundWastewater reuse represents a promising alternative source of water supply considering the water scarcity related to climate change. However, if not adequately treated, wastewater represents a source of microbiological health risk. The purpose of this work was to investigate the role of wastewater treatment on microbiological contamination by evaluating the possible risks associated with wastewater effluent reuse, taking into account new EU legislation (2020/741) on minimum requirements for water reuse. E. coli that produce Shiga toxins (STEC) and thermotolerant Campylobacter were monitored using an enrichment step associated with specific PCR, while Salmonella spp. and Legionella were detected with both cultural and molecular methods (PCR and q-PCR, respectively). Culture method was also used for the enumeration of different microbial indicators. The bacteria detection was compared in different wastewater plants with membrane bioreactor (MBR) system or with disinfection step with chlorine dioxide (ClO2). Moreover a comparison between molecular and culture methods was discussed.ResultsThe results obtained showed good abatement performance for WWTPs equipped with MBR. The high concentrations of E. coli (range between 0.88 and 5.21 Log MPN/100 mL) and contamination by Salmonella spp. in effluent disinfected with ClO2 (17% of samples) showed the need to control the quality of this effluent. In addition, despite the absence of Legionella spp. with the culture method required by EU regulation, high concentrations of Legionella spp. (range between 2 and 7 log GU/L) and the presence of Leg. pneumophila with qPCR (15% of samples) highlight the need to carry out further investigations for reuse associated with aerosol formation (e.g. spray irrigation in agriculture).ConclusionsThe results obtained underline that the MBR technology can be suitable for wastewater reuse applications allowing to achieve the requirement proposed by the new European legislation. More attention should be given to wastewater reuse of effluents treated with ClO2. The use of the molecular methods for pathogens detection in wastewater could allow a more precautionary risks estimation associated with reuse. The overall results highlight that an evaluation of the effectiveness of the wastewater treatments is required for the prevention of a possible risk to public health.

Clinico-epidemiological study of an outbreak of typhoid in North India.

Typhoid fever is endemic in India. There have been various outbreaks of typhoid fever reported from different parts of India. Considering the outbreak potential of typhoid, the present study was undertaken wherein an outbreak of typhoid occurred in a city in northern India. The study design used was a cross-sectional descriptive study. Detailed information was obtained from each reported case. Active case finding surveys were conducted. Case definitions for suspect, probable, and confirmed case taken for our study, have already been validated by the World health organisation (WHO). All patients were subjected to requisite investigations. A sanitary survey was carried out to locate defects in water supply and sewage disposal. Record of bacteriological survey of water samples from the area was scrutinized. Descriptive epidemiology of cases was carried out. Attack rate was 16.1% and 17.4% among men and women, respectively. Fever was present in 52 (69.3%) cases. The epidemic curve displayed a sudden peak and an abrupt fall of cases. This is suggestive of a common point source outbreak. There were no fatalities. Sanitary survey teams found a sewage leak in the locality where maximum cases were reported. Lab reports tested positive for salmonella species in water. The outbreak was promptly controlled after repair of the leaking sewage pipeline; and provision of alternative source of water supply. This study reemphasises the requirement of a basic public health measure and infrastructure, that is, water quality monitoring by concerned authorities to break the chain of transmission of typhoid fever.

Assessment of effects of a Cemetery leachate on Groundwater Quality using an Integrated Approach

The dependency of residents in the vicinity of cemeteries on groundwater from hand-dug wells as an alternative source of water supply for their domestic use without cognisance of the quality of such water has been a concern. So, this research assesses the effects of a cemetery on groundwater quality using an integrated approach in Edunabon, South-western Nigeria. Thirty groundwater samples from available hand-dug wells were collected and analysed for various physicochemical parameters. GIS cloud data collection server and Mobile Data Collector (MDC) were used to obtain these hand-dug wells' locations and spatial distributions. The determination in variation in physicochemical concentration parameters was obtained using the curve fitting technique of ARCVIEW GIS software and digital map. Physicochemical results were used to calculate Water Quality Index (WQI) of each sample. Two Schlumberger Vertical Electrical Soundings (VES) of 130.0m long were conducted at 10.0m intervals to the wall and the next VES, on each side of the cemetery. Current spacing (AB/2) and apparent resistivity (ρa) data were plotted on a double logarithm paper, curved matched and iterated using IPI2Win software for qualitative and quantitative interpretation. WQI results ranged from (107.37–173.64), (76.60–93.37), (54.94–71.53), (31.29–48.01), and (10.84–25.31) for fourteen, seven, three, four and two hand-dug wells respectively, an indication that the water from these wells was unfit for drinking, very poor, poor, good, and excellent respectively. VES results revealed that first, second and third layers were mainly clayey topsoil (46.7–96.8Ωm), lateritic soil (169.0–551.3Ωm), and weathered layer (3.21–27.4Ωm), which favourably enhances the migration of leachate from the cemetery to the surrounding soils and groundwater. The lowest resistivity values recorded in the second and third layers indicated leachate presence at these hand-dug wells. The integration of GIS and electrical resistivity methods would be useful tools to assess groundwater quality around cemeteries. Keywords: Groundwater quality, Mobile Data Collection, unfit for drinking, Vertical Electrical Sounding, Water Quality index

RECLAMO: Unlocking the potential of wastewater reuse for agricultural irrigation in Spain

Increasing water scarcity is encouraging the use of unconventional water resources. In recent years, the European Union has launched numerous initiatives to promote and facilitate water reuse for agricultural irrigation. Today, the use of reclaimed water for agriculture has become an alternative, reliable and safe source of water supply and an indispensable water planning tool, especially in the area of southern Europe. However, water reuse for irrigation is currently far below its potential. Numerous barriers prevent its development and call for a detailed analysis of the different aspects affecting reclaimed water reuse, through an integrated and multidisciplinary approach. A multidisciplinary research team from Universidad Politécnica de Madrid, consisting of agronomists, hydrologists, chemists and agricultural economists, will work on the RECLAMO Project (https://blogs.upm.es/reclamo/), with the aim of providing solutions and recommendations aimed at promoting the full development and use of reclaimed water for irrigation in areas of Spain with marked water stress. For this purpose, project activities will be developed in two selected case studies (the Segura Basin, leader in water reuse in Spain and the Guadiana Basin, with success stories, but low levels of water reuse) and organised according to five axes: 1) development of a comprehensive knowledge-base covering the regulatory, technical, socio-economic and environmental aspects of reclaimed water reuse in agriculture; 2) participatory development of future scenarios exploring possible strategies, barriers and opportunities, in relation to the expansion of the use of reclaimed water for irrigation; 3) impact analysis of the strategies identified at different scales (crop, farm, (sub-)basin), through the development of an integrated modelling platform (hydrologic-agronomic-economic models); 4) Development of a roadmap and policy recommendations to achieve the full development and use of reclaimed water reuse for irrigation; 5) Dissemination of knowledge and promotion of science-policy-society dialogue. To this end, RECLAMO will collaborate closely with experts and stakeholder groups that will play a key role in the project in co-creating the scenarios and modelling tools and validating the results. The project will also seek for synergies and complementarities with other similar projects and explore new ways of collaborating with companies and research groups that allow research to continue and expand beyond the spatial and temporal limits of the project. RECLAMO’s results will promote an integrated approach to the sustainable management of water resources in water-stressed areas, including reclaimed water management. The integrated modelling platform developed in the project will allow policy-makers and water users to benefit from an improved understanding of the interactions between the social, economic and environmental aspects of water systems, in the context of climate and socio-economic change that will lead to better informed decision-making to address future water challenges. In addition, RECLAMO is expected to contribute to raising awareness about the use of reclaimed water reuse in agriculture as a safe and sustainable practice and to improve its social acceptance by producing science-based knowledge that provide evidence on the benefits derived from its use.

Assessing fog water collection in the coastal mountain range of Antofagasta, Chile

Fog water collection can be an alternative source of water supply in areas with limited water resources. Fog water is usually collected with plastic meshes mounted on wooden or metal frames arranged perpendicular to winds carrying fog. This study assessed fog water collection at the coastal mountain range of Antofagasta, Chile, with the purpose of analyzing the relationship between collected water and local meteorological conditions. For this, four standard 1-m2 fog collectors with meteorological instrumentation were located at different places in the study area. From August 2019 to February 2020, the collectors recorded data on collected water and atmospheric variables, including wind speed, wind direction, relative humidity, and ambient temperature. The results indicate that fog water collection ranged between 0.16 ± 0.02 and 0.37 ± 0.05 L m−2 day−1 averaged over the entire period. The collection was notably reduced in summer, with values generally <0.09 L m−2 day−1, due to fewer days with fog collection events. More than half of the collected water was obtained in less than 8% of the study days. The frequency of foggy days and orientation of the collectors were among the main factors explaining the differences in yield between the collectors.

GIS-based modelling of climate variability impacts on groundwater quality: Cape Flats aquifer, Cape Town, South Africa

The need to improve groundwater security remains critical, especially in urban areas where demand for groundwater as an alternative source of water supply is increasing following unprecedented population growth. Climate change continues to threaten groundwater resources in such areas. This study assessed and analysed data from a variety of sources that required holistic analytical tools to demonstrate the impacts of climate change on groundwater quality at the local level. We evaluated how climate conditions affect groundwater quality using a hydrological model (WaterWorld model) in a GIS context. The Cape Flats Aquifer in the city of Cape Town in South Africa was chosen as a case study. The WaterWorld model was used to calculate hydrologic scenarios based on climate change factors and groundwater quality parameters for the period 1950–2000. Mean annual precipitation and temperature were simulated using the multi-model mean and Representative Concentration Pathway 8.5 for the years 2041–2060. Simulation results showed that annual precipitation will increase until 2041 and then decrease until 2060. A significant temperature increase of 1.9 °C–2.3 °C was predicted. Water balance simulations showed a decrease of about 8.6% per year under the future dry climate. ArcGIS 10.3 was used to combine geospatial data and develop a groundwater vulnerability map. Modelling analysis based on GIS showed that the southern and central suburbs of the study area are more susceptible to groundwater contamination and have high surface runoff and higher average temperatures. The groundwater vulnerability index and electrical conductivity concentrations showed a strong positive correlation when the model was validated using linear regression analysis (R2 = 0.99, P < 0.05). In this article, we recommend the use of the WaterWorld model in a GIS environment to simulate hydrologic scenarios on climate change and groundwater quality parameters to provide practical and feasible insights for actions to improve groundwater management.

Spatial Prediction of Groundwater Potentiality in Large Semi-Arid and Karstic Mountainous Region Using Machine Learning Models

The drinking and irrigation water scarcity is a major global issue, particularly in arid and semi-arid zones. In rural areas, groundwater could be used as an alternative and additional water supply source in order to reduce human suffering in terms of water scarcity. In this context, the purpose of the present study is to facilitate groundwater potentiality mapping via spatial-modelling techniques, individual and ensemble machine-learning models. Random forest (RF), logistic regression (LR), decision tree (DT) and artificial neural networks (ANNs) are the main algorithms used in this study. The preparation of groundwater potentiality maps was assembled into 11 ensembles of models. Overall, about 374 groundwater springs was identified and inventoried in the mountain area. The spring inventory data was randomly divided into training (75%) and testing (25%) datasets. Twenty-four groundwater influencing factors (GIFs) were selected based on a multicollinearity test and the information gain calculation. The results of the groundwater potentiality mapping were validated using statistical measures and the receiver operating characteristic curve (ROC) method. Finally, a ranking of the 15 models was achieved with the prioritization rank method using the compound factor (CF) method. The ensembles of models are the most stable and suitable for groundwater potentiality mapping in mountainous aquifers compared to individual models based on success and prediction rate. The most efficient model using the area under the curve validation method is the RF-LR-DT-ANN ensemble of models. Moreover, the results of the prioritization rank indicate that the best models are the RF-DT and RF-LR-DT ensembles of models.

The use of alternative water sources as a means of adaptation to water shortages in Nsimeyong, Yaounde city: a quality assessment

Nsimeyong (Damas), one of the residential areas of Yaounde, Capital city of Cameroon experiences water shortages making residents rely on other sources of water including streams, springs, boreholes and wells. Water samples were aseptically collected from the processing plants and from five sites of Nsimeyong area. This study was aimed at assessing suspected heavy metals and coliforms of water collected from fifteen alternative water supply sources in this area. Heavy metals (Pb and Cd) were determined using an Atomic Absorption Spectrophotometer. The International Organization for Standardization (ISO) 9308-2:1990b last reviewed and confirmed in 2017 was used to determine the Most Probable Number (MPN) of total coliforms by the five-tube MPN table. The presence of presumptive E. coli was confirmed on Sugar, Indole, and Motility (SIM) media at 44⁰C and by the addition of Kovac's reagent to tryptone water. Water samples showed higher concentrations of Pb beyond the maximum permissible level (0.1mg/l). With the exception of processed tap water at home, all other alternative sources of water used in Damas registered Cd above the World Health Organization recommendation (0.03mg/l). Unlike Cd (p = 0.0001), the difference among Pb content of water samples at the collection sites was not statistically significant (p = 0.1416). More than 66% of water samples (of which closed to 39% were open wells) had MPN value for total coliform beyond the permissible level (<10) in drinking water. Moreover, E.coli and Klebsiella spp were detected in 16.7% and 11.1% of water samples from alternative sources, respectively. Additional household treatment such as filtration, to remove heavy metals and boiling before use of such water is necessary to achieve the standard bacteriological quality for human consumption thereby reducing risk of exposure to waterborne diseases. This study constitutes the baseline information to guide the policy makers in the development and implementation of the water safety plan in Nsimeyong area.

WaterROUTE: A model for cost optimization of industrial water supply networks when using water resources with varying salinity

Water users can reduce their impact on scarce freshwater resources by using more abundant regional brackish or saline groundwater resources. Decentralized water supply networks (WSN) can connect these regional groundwater resources with water users. Here, we present WaterROUTE (Water Route Optimization Utility Tool & Evaluation), a model which optimizes water supply network configurations based on infrastructure investment costs while considering the water quality (salinity) requirements of the user. We present an example simulation in which we determine the optimal WSN for different values of the maximum allowed salinity at the demand location while supplying 2.5 million m3 year-1 with regional groundwater. The example simulation is based on data from Zeeuws-Vlaanderen, the Netherlands. The optimal WSN configurations for the years 2030, 2045 and 2110 are generated based on the simulated salinity of the regional groundwater resources. The simulation results show that small changes in the maximum salinity at the demand location have significant effects on the WSN configuration and therefore on regional planning. For the example simulation, the WSN costs can differ by up to 68% based on the required salinity at the demand site. WaterROUTE can be used to design water supply networks which incorporate alternative water supply sources such as local brackish groundwater (this study), effluent, or rainwater.

Dynamic modelling of rainwater harvesting with green roofs in university buildings

University buildings may contribute significantly to the urban demand of potable water, particularly in small and medium communities with large universities. In this regard, alternative sources of water supply contribute to minimizing the pressure on natural resources. This paper investigates the applicability of rainwater harvesting (RWH) systems to partially compensate the daily non-potable water demand in university buildings. The traditional daily water balance model was improved to enhance the accuracy of the performance analysis and design optimization of the RWH system by accounting for consumption and runoff variability. The novel algorithm was tested using real daily water consumption data for two university buildings located in Portugal. In addition, different scenarios were evaluated combing RWH systems with extensive green roofs and different runoff distributions over time. The findings indicate that the use of real daily water consumption data instead of average values influences the final results, especially in buildings with fluctuating water consumption patterns over time up to 11%. Regarding the runoff coefficient, it was verified that variable values are recommended compared to the average values. Runoff variability associated with the installation of green roofs was found to decrease RWH system performance due to reduced stormwater runoff. However, the scenario with 50% of the catchment area covered by extensive green roofs showed promising results, decreasing the potential water saving less than 6% and increasing the volume of retained water by almost 15%.

On the use of a beam infiltration water intake structure for water supply purposes

The object of research in this work is the under-channel waters of the Irtysh River, considered as an alternative source of water supply, necessary for the sustainable provision of high-quality drinking water to the population of cities in emergency situations. In bacteriological and sanitary-hygienic terms, studies have shown that infiltration waters are quite safe. According to the results of the analyzes carried out, infiltration waters are mainly fresh with a salinity of 0.5 to 1 g / l. The most rational scheme from a technical and economic point of view in relation to local conditions are beam water intake structures, which is due to the relatively low thickness of water-bearing rocks. At the same time, infiltration-type water intake structures in the Irtysh river valley should be located at a distance of up to 130 m from the river channel (taking into account the value of hydraulic resistance ∆lн). The distance between wells in a linear row should be taken up to 50 m.

The effect of roof surface area on the quality and quantity of rainwater runoff in the rainwater harvesting system

Rainwater harvesting system is one of the alternative sources of clean water supply to be used during the dry season. The purpose of this research was to analyze the effect of roof area on the quality and quantity of rainwater runoff and determine the potential of rainwater runoff based on quality standards. The observation was conducted 2 different times and collected 23 samples of rainwater runoff from 11 different roof areas. Daily rainfall intensity data during the observation period were analyzed to estimate the quantity of rainwater runoff discharges from the rooftop catchment area. The results showed that parameters that meet the clean water quality standard are turbidity, iron, manganese, nitrate, and nitrite in both observation time. While the color, pH, TDS, and E. coli exceeds the clean water quality standard. The highest rainwater runoff volume was 20.59 m3 for the first week and the second week was 14.06 m3. In conclusion, the rooftop catchment area significantly affects the quantity and quality of rainwater runoff, and potentially be used as a clean water supply through a simple water treatment unit.

Using reclaimed water in dual pressurized water distribution networks. Cost analysis

Reclaimed water can be used for non-potable applications to reduce water consumption from freshwater sources. In several regions, the full potential of reusing treated wastewater has not yet been exploited. Establishing a circular economy could promote the acceptance of reclaimed water as an alternative water supply source. This study investigates the feasibility of constructing a treatment plant to supply reclaimed water for non-potable applications using a dual water distribution network, from an engineering cost standpoint.

Cross-Subsidies between Water Users in Spain: the Guadalquivir River Basin Case

The European Commission highlighted that in Spain: “there is a lack of adequate incentives for efficient use of the resource and the adequate contribution to the recovery from different users is not guaranteed” and recommended to “present transparently subsidies and cross-subsidies”. This paper develops a robust hydro-economic methodological approach that provides transparency in the water cost contribution calculations and helps to assess the economic efficiency of the water resources allocation strategy for a particular water system. The Upper Genil River (a sub-basin of the Guadalquivir River Basin in southern Spain) presents an interesting context of study given its intricate multi-source supply system to meet multi-sectorial water demands, along with conflicts (especially during critical drought events) over historical water rights and the priority of water use. The simulation results demonstrated that, despite the additional average annual cost paid by the household water user for having the theoretical priority of water use (€ 6863 per cubic hectometre of water consumed) compared to the agricultural water user, in practice, that extra cost does not translate into a significant increase in the guarantee of water supply. In fact, the priority of water use would only be patent in very extreme drought events (200-year return period) and when all alternative water supply sources are exhausted. Therefore, competent authorities should ensure that a greater emphasis is placed on transparent water cost recovery assessments to achieve sound water pricing policies and efficient water allocation strategies, which can help to successfully address the major challenge of water scarcity.

Assessing future scenarios of water availability using cmpi5 high resolution climate models – case study of the alto tietê basin

Global climate change and extreme climate variability directly affect the hydrological cycle and rainfall variability, which highlights the importance of studying climatic conditions as a support for water resource management in regions with low water availability, such as the Upper Tietê River Basin (Bacia Hidrográfica do Alto Tietê – BHAT). This study aims to present a diagnosis for BHAT water availability conditions in future climate scenarios, based on the high-resolution models CMCC-CM, MIROC4h, ETA-MIROC5, and ETAHADGEM2- ES, for the time slices 2020-2040, 2041-2070, and 2071-2099, in order to provide climate information for BHAT’s management. The main results showed a clear upward trend in the average annual temperatures. For the RCP8.5 scenario, the average annual increase was 0.5°C from 2006 to 2099. Precipitation showed high interannual variability without a specific defined trend. The average annual flow showed a slight positive trend in the period 2006–2099. However, it also presented a decrease in the monthly average flow in the wet period (13%) and an increase in the dry period (9.7%), compared to the historical data simulated for the time slice 2020–2040 of the RCP8.5 scenario. However, the annual increase in BHAT water availability at future scenarios should not be sufficient to meet the growing demand for water in the region. Therefore, it is necessary to evaluate water availability based on other high-resolution climate models, in order to evaluate uncertainties, and in other regions with different supply systems that provide water to the São Paulo Metropolitan Region, identifying alternative water supply sources.

A combined simulation-optimisation modelling framework for assessing the energy use of urban water systems

Reliance on new and alternative water supply sources is a desirable option for upgrading existing and ageing urban water system infrastructure that is no longer able to cater for steadily increasing water demand. This transformation will increasingly involve the use of decentralised, more complex and energy intensive urban water systems. Modelling capability that takes a holistic systems approach to optimize the dynamic interactions between water and energy is needed to evaluate the performance of fit-for-purpose water supply systems for the urban sector. This paper presents a simulation-optimisation model to concurrently simulate and optimize an urban water supply system based on minimum energy use when water of alternative quality is supplied to different users on a ‘fit-for-purpose’ basis. The model uses a System Dynamics approach to simulate the energy use of different water supply systems in the form of stocks and flows combined with a Genetic Algorithm (GA) technique to optimize energy use while satisfying all the water demands. The comprehensive model framework is built on a Matlab/Simulink® platform. Life Cycle Energy Assessment (LCEA) is used to generate the embodied energy use variables which are input to the simulation-optimisation model. The model is sufficiently flexible to accommodate water supply systems of variable spatial scales and analyse water and energy use at variable time scales. The application of the modelling framework on the Aurora urban development estate, Australia, shows that the model produces essential information about the water supply and energy use intensity according to specified criteria.

Dynamics of change monitoring of sanitary and chemical indicators of water quality in springs in the subarid region by the model of Saratov region

Springs on the right Bank of the Saratov region can be considered as a predictive model of changes in the chemical composition of spring water in a warming climate. The 14 sources most demanded by the population were identified. The probable causes of the detected deviations in the investigated sanitaryhygienic indicators are also described. The research period is 2016–2019. The sources are located on the territory of the right Bank of the Saratov region, including the city of Saratov. We determined the flow rate and type of sources, the water temperature in them, the presence of captage and sanitary protection zones, the chemical composition of water in terms of smell, taste, color, turbidity, pH, total hardness, total mineralization, Cl, SO4 2-, NO3 , NO2 , NH3 , Pb2+, Cd2+, Fecom, Mncom, Crcom, Ascom. We found that 35 % of samples do not meet the requirements of sanitary standards. Deviations were detected in terms of color, turbidity, total hardness, manganese, chlorides, nitrates, and cadmium. The dynamics of changes in chemical indicators of water quality in all surveyed sources was studied. In 6 of them, from 2016 to 2019, an increase in the level of hardness and total mineralization was revealed. The highest concentrations of the studied substances were recorded in the spring period (flood). An increase in the concentration of manganese was observed in 6 sources. In one of them, in March 2017, the critical value of this indicator was recorded (22 MPC). The necessity of using springs by the population as alternative sources of water supply for drinking purposes is analyzed. To identify the demand for springs in the city of Saratov, a survey of 535 people was conducted directly at the sampling sites. The conducted survey of the population indicates the confidence of the population in the quality of spring water. The probable causes of the detected excess are described. A comparison of our results with available data from 2009–2016 indicates a deterioration in the water quality of the surveyed sources.

Addressing the Scarcity of Traditional Water Sources through Investments in Alternative Water Supplies: Case Study from Florida

This paper examines the capital costs for alternative water supply projects in Florida, the third most populous state in the United States. The increasing scarcity of fresh groundwater in Florida has led to investments in alternative water supply sources, including brackish groundwater, surface water capture and storage, reclaimed water, and stormwater. Expenditures to meet the growing water demand for the 20-year planning horizon are estimated using water demand projections and existing supply estimates from Florida’s five water management districts. In the regions where demand projections exceed the existing supply, the districts are required to identify project options to meet the growing water demand while protecting the natural systems. This study uses the database of 645 projects implemented in the past or considered for the future. The Ordinary Least Squares regression model shows that project implementation costs depend on project capacity, type, implementation status, and implementation region. Given the most common project types and project sizes, the total investments to meet the state’s future water demand could reach almost $2 billion in the next 20 years. The expenditures necessitate more cost-effective options (such as expanding stormwater use and water conservation).

Potential health risk and levels of heavy metals in water resources of lead\u2013zinc mining communities of Abakaliki, southeast Nigeria

Heavy metals are potential health risk, especially in mining sites where they deteriorate from sulfide-rich ore bodies. Lead, cadmium, arsenic and mercury are very carcinogenic, while others are toxic. The assessment of the levels of these metals in water resources of the lead–zinc mining communities of Enyigba, Mkpuma Akpatakpa, Ameka, Amorie, Amanchara and Alibaruhu was carried out, and the potential health risk has been investigated. These areas make up the main mining communities of Abakaliki, where active and abandoned mines are located. One hundred and six water samples were analyzed in two seasons using atomic absorption spectrophotometric and ultra-violet/visible spectroscopy. Result indicates levels of Pb2+ > Hg2+ > As2+ > Cd2+ > Mn2+ > Ag2+ > Se2+ > Ni2+ > Cr2+ > Cu2+ in water sources. High levels of Mn2+(63.45 mg/L), Pb2+(11.42 mg/L), Cr3+(14.60 mg/L), Ni2+(1.260), Cd2+(15.67 mg/L), Ag+(6.06 mg/L), Hg2+(2.60 mg/L), As(4.13 mg/L), Se2+(2.68 mg/L), Zn2+(10.53 mg/L) and Co2+(0.9 mg/L) above the WHO recommended standard for drinking water were observed. Only Cu2+ recorded safe concentrations in 100% samples analyzed. Levels of associated metals including Pb2+, As, Hg2+, Se2+ and Cd2+ are higher in groundwater especially in areas close to the active mines; this is due to mineralization in the area. Seasonal analysis shows a decreased concentration of chemical constituents in the rainy season relative to the dry season. Potential health risk is associated with accumulation of toxic heavy metals in tissues including Parkinson disease, arsenicosis, acrodynia, selenoises, Alzheimer’s disease, hair loss, mental imbalance and abortion in women abound in the areas. Alternative water supply sources and sensitization on the potential health risk are highly advocated in these communities.