Alternative Water Supply Research Articles

Uso do aplicativo PhotoMetrix no monitoramento da concentração de flúor em sistemas alternativos de abastecimento de água

A ingestão frequente de água contendo concentração de flúor acima do limite estabelecido pela legislação brasileira causa uma doença chamada fluorose dentária. Atualmente, o monitoramento do nível de flúor na água para consumo humano é realizado utilizando métodos potenciométricos, cromatográficos ou colorimétricos, que são relativamente caros e utilizam equipamentos de difícil deslocamento para análises de campo. Portanto, surge a necessidade de desenvolver métodos alternativos, visando rapidez, praticidade, mobilidade e redução do custo das análises. O aplicativo para smartphone PhotoMetrix® é um software livre de análise de imagens digitais utilizando modelos matemáticos univariados e multivariados. A captura de imagens pode ser feita através do próprio smartphone ou com uma câmera USB externa. Assim, o objetivo deste estudo foi avaliar o uso do PhotoMetrix® no monitoramento da concentração de flúor em águas de abastecimento. Dois métodos de referência foram utilizados para comparação dos resultados: o método espectrofotométrico e o eletrodo de íon seletivos. Os resultados indicaram concordância entre os métodos, mostrando um coeficiente de determinação (R2) de 0,995 e erro de predição RMSEP (Root Mean Square Error of Prediction) de aproximadamente 0,05 mg L-1. Então, o PhotoMetrix® é um método satisfatório para a determinação de flúor, podendo se tornar uma alternativa viável para o monitoramento da qualidade da água, especialmente para sistemas alternativos de abastecimento.

An examination of the microbial community and occurrence of potential human pathogens in rainwater harvested from different roofing materials

While harvested rainwater can serve as an alternative water supply, microbial contaminants within the collection system can negatively affect water quality. Here, we investigated the impact of roofing material on the microbial quality of rainwater freshly harvested from pilot-scale roofs (concrete tile, cool, green, Galvalume® metal, and asphalt fiberglass shingle). The microbial quality of freshly harvested rainwater from six rain events over two years was analyzed by high-throughput sequencing and culture-dependent and -independent techniques. The concentrations of total coliform were significantly different among rainwaters harvested from the various roofing materials (p-value >0.05). However, the fecal coliform concentrations and the copy numbers of Enterococcus 23S rRNA genes and total Bacteria 16S rRNA genes did not vary by type of roofing material in a statistically significant way. Potential human pathogens such as Legionella, Escherichia coli O157:H7, Shiga-toxin-producing Escherichia coli, and adenovirus were detected at least once in rainwater harvested from the different roofing materials, even though the lowest occurrence of those potential human pathogens was noted from the metal roof. Also, substantial variation in the microbial communities from the different roofing materials was observed at the family and genus levels. These results demonstrate that the type of roofing material affects the microbial quality of freshly harvested rainwater, indicating that the choice of roofing material could shape the microbial community structure entering a rainwater storage tank. Given that detection of potential pathogens in the freshly harvested rainwater also differed between roofing materials, the type of roofing used to capture rainwater needs to be considered in rainwater harvesting system design, particularly if the water is intended for potable use.

Rainwater Harvesting in Greenhouses Establishments and Use as Irrigation Water

Rainwater collection systems are an alternative water supply method that provides environmental and economic benefits according to traditional water supply methods in arid and semi-arid climates. Rainwater harvested in greenhouse roof by rain gutters can be used to irrigate and grow the plants cultivated in greenhouses. However, rain gutters and storage tanks in greenhouses should be of sufficient size to collect rainwater. Water consumption of plants in the greenhouse should be calculated correctly to determine the storage size in greenhouses. In this study, daily water consumption of tomatoes cultivated in greenhouses not regularly heated in Kumluca district of Antalya province is calculated according to FAO Penman Monteith method. Then, the storage capacity of the remaining part of the falling monthly rainfall used in the greenhouse was determined. As a result of the study, the amount of annual irrigation water harvested from rainfall in Kumluca district where total rainfall is 734.44 l/m2 was determined as 661.00 l/m2 based on rainfall factor of 0.9. In the period between September and June when single crop was grown in the year, the total amount of irrigation water needed by the plants in the not regularly heated greenhouse was calculated as 569.86 l/m2. Accordingly, it was determined that it is possible to meet all of the irrigation water to be provided to the plant with rainwater harvesting. Depending on the amount of rainwater harvest obtained, it was determined that the storage capacity of 0.40 m3/m2 in greenhouse is needed. In the study, it was determined that rainwater harvesting may contribute to the development of agricultural activities in areas suffering from water scarcity. Keywords : Greenhouse, Rainwater harvest, crop water requirement, Collection systems. DOI : 10.7176/JSTR/5-5-01

Peritidal stromatolites as indicators of stepping-stone freshwater resources on the Palaeo-Agulhas Plain landscape

Natural sources of freshwater are a limiting feature to the distribution of terrestrial species that rely on regular hydration, especially in coastal environments. Early modern humans would similarly be restricted by water supply and likely would have congregated or settled in close proximity to permanent water bodies such as beyond the estuarine extent of large rivers. However, along the modern south coast of southern Africa, for example, distances between freshwater from rivers can exceed what would be convenient daily walking limits. In the absence of alternative water supply, or a means of water storage, these distances would preclude human settlement beyond river borders. Recent discovery of living peritidal stromatolites forming along the southern South African coastline suggests a potential alternative water source. These unique ecosystems form only at locations where groundwater rich in calcium carbonate meets periodic marine intrusion along the coastal margin. Calcium carbonate is precipitated by cyanobacteria and sediment is trapped by diatoms, primarily, to form layered deposits that preserve into the fossil record. Critical to the formation and growth of these stromatolites is a fresh, uninterrupted supply of groundwater. During their growth, the peritidal stromatolites accumulate and retain this freshwater through the formation of rimstone dams and barrage pools at the seaward margin of neocoastal geological outcrops. Recognising the presence of permanent water sources other than rivers for early humans is challenging; however, these stromatolites provide a clear signature of an alternative water resource. Here we review the modern prevalence of peritidal stromatolites in this region, of which approximately 540 are known along a 200 km stretch of South Africa's southern coastline featuring only 11 estuaries. This is linked to features (cf. rimstone dams and barrage pools) resembling peritidal stromatolites in the adjacent Palaeo-Agulhas Plain landscape using multibeam echosounder and side-scan sonar data and contextualised as a possible water resource for early modern humans.

Experimental Investigation of Water Quality and Inorganic Solids in Malaysian Urban Lake, Taman Tasik Medan Idaman

AbstractWater scarcity is a persistent crisis during dry weather periods in the Gombak area, Kuala Lumpur, Malaysia. Drinking and household water supply in Gombak is usually based on groundwater sources, with the lack of rainfall in key catchment areas during the dry period causing groundwater levels to decline, temporarily resulting in inability of the water pumping system to supply water. To address this issue, the present study investigated an alternative surface water supply source, namely Tasik Taman Idaman Lake. The study objective was to analyse the physicochemical characteristics of the lake water and determine the water standard for potability. A range of water quality parameters were measured in the present study, many being outside the desired levels, based on the standard “Class I” according to Malaysian EQA (Environmental Quality Act 2009). Of these parameters, only pH, total dissolved solids (TDS), total nitrogen (TN) and total phosphorus (TP) were within drinkable level, while the other parameters would have to undergo purification processes to attain the standard “Class I” status.

Plasma-Derived Graphene-Based Materials for Water Purification and Energy Storage

Several crucial problems, such as rapid population growth and extended demands for food, water and fuels, could lead to a severe lack of clean water and an energy crisis in the coming decade. Therefore, low-cost and highly-efficient technologies related to filtration of alternative water supplies (e.g., purification of wastewater and water-rich liquids) and advanced energy storage (e.g., supercapacitors) could play a crucial role to overcome such challenges. A promising class of solid materials for these purposes is exfoliated graphene, and more specifically, its nanoporous forms that exhibit large specific surface areas and pore volumes. In the current work, two plasma-exfoliated graphene-based materials with distinctive morphological and porosity features, including non-porous and low-specific surface area platelets versus nanoporous and high-specific surface area flakes, were tested as filters for water purification purposes (i.e., decolourization and deacidification) and as electrodes for supercapacitors (i.e., ion electrosorption). The findings of this study suggest that a nanoporous and large specific surface area graphene-based material promotes the water purification behaviour by removing contaminants from water-based solutions as well as the energy storage performance by confining ions of aqueous electrolytes.

Core aspects of international water supply and wastewater disposal with a focus on developing countries in the Asia and Africa region

Abstract Water crises are already stressing societies, economies, and the environment worldwide and especially developing countries. The expected growth in population, urbanization and economic activity, as well as the impact of climate change, will exacerbate the situation in the coming decade. In developed countries, conventional water supply and wastewater disposal systems ensure safe access to drinking water, sanitation and wastewater services. The worldwide application of conventional systems is, however, only possible to a limited extent. The reason for this is that these systems are designed for certain climatic conditions and also do not consider the varying requirements regarding water supply and wastewater disposal typical for developing countries. Although there are alternative water supply and wastewater disposal systems that have proved to be successful throughout the developing world, there are still several barriers to their worldwide adoption. To increase the establishment of these approaches this paper focuses on aspects of particular relevance for developing countries, namely: water reuse (untreated wastewater), alternative sewerage (settled and simplified sewerage), alternative wastewater treatment (waste stabilization ponds, constructed wetlands and up-flow anaerobic sludge blanket reactors) and management of water losses (real and apparent losses).

Monitoring, mapping and health risk assessment of fluoride in drinking water supplies in rural areas of Maku and Poldasht, Iran.

The aim of this study was to investigate and determine fluoride concentrations in drinking water supplies in rural areas of Maku and Poldasht in West Azerbaijan Province, the northwest of Iran. Fluorosis risk assessment and characterization was also investigated. Fluoride concentrations mapping was accomplished by using the GIS system. Totally, 356 water samples, including one sample in each season, were collected from 89 water supplies providing water for 95 and 61 rural areas of Maku and Poldasht, respectively. According to the results, in Maku and Poldasht, 25 and 30 rural areas had contaminated water sources, respectively. Average annual fluoride concentrations ranged from 3.04 to 7.31mg/l in the contaminated villages of Maku, which is about 2-4.8 times higher than the maximum standard level of the Iranian drinking water standard, and 4.52-8.21mg/l in the contaminated areas of Poldasht, which is about 3-5.47 times higher than the maximum standard level. The maximum fluoride level was determined 11.12mg/l and 10.98mg/l in one of villages of Maku and Poldasht Counties in summer, respectively. Neither in Maku nor in Poldasht, water resources showed dental cavity risk, while dental fluorosis risk and skeletal fluorosis risk were very significant in some villages of both cities. Children were at most risk of fluorosis. New alternative water supplies for the contaminated villages if possible, consumption of bottled water and application of reverse osmosis are recommended as remedial actions in the contaminated areas.

A flexible framework for assessing the sustainability of alternative water supply options

Increased water scarcity is driving water utilities to consider alternative water supply options (WSOs). Identifying the most sustainable WSOs that meet environmental, economic, and social objectives is challenging due to the overwhelming number of both assessment criteria and treatment configurations, including a growing number of potable reuse options. Conventional approaches using process-based life cycle assessments are data-intensive and site-specific, and therefore not suitable for the early stages of assessing WSOs. To address this gap, we have combined hybrid multi-regional input-output-based life cycle assessment (MRIO-LCA), social impact analysis, and multi-criteria decision analysis (MCDA) to develop a novel, flexible framework with unit process level resolution for the comprehensive evaluation of WSOs. Here we describe the formulation of the framework along with an application to two US utilities considering alternative WSOs. In both cases, given sufficient levels of community acceptance and optimum system design, the results favoured potable reuse WSOs due to their climatic resilience, cost effectiveness and lower environmental impacts (compared to other non-conventional options such as desalination). The generalised and globally applicable framework developed for this study can be used to assess sustainability trade-offs between diverse WSO configurations, providing valuable insights for decision-making processes at the early planning stage, as a complement to existing urban water supply scenario and optimisation models.

Valuing the water supply: ecosystem-based potable water supply management for the Legedadie-Dire catchments, Central Ethiopia

BackgroundThere is a substantial interest in the values that consumers place on drinking water quality and supply. Financial resources are crucial to improving the urban potable water supply in developing countries that are characterized by low-cost recovery rates and a high and rapidly growing demand for more reliable services. This study examined households’ willingness to pay (WTP) for the improvement of water services by identifying their water choice decisions and the mode of water supply that they prefer the water supply authority to use among several alternative water supply options. Stated-preference data were collected from 322 randomly selected households in Addis Ababa, who were presented with three sets of choices (three alternative bundle choices, including the reference scenario). The data were analyzed using the mixed logit WTP space model. Three approaches to modeling the distribution of WTP (fixed, uncorrelated, and correlated) using mixed logit WTP space models were compared.ResultsThree-quarters of the households agreed to contribute money toward ecosystem-based water supply management (EBWSM) intervention programs on a monthly basis. The average contribution that the respondents were willing to pay was 150.5 Ethiopian Birr (ETB) as a one-off lump sum to kick off the EBWSM activities. Most of the respondents chose a bundle of water supply options that provides risk-free and high-quality water with no months of shortages than moderate water quality that is safe to drink and palatable with 1 month shortages annually. This implies that households would need to be supplied with risk-free, high-quality water without interruption at an appropriate flow pressure. The model with correlations fitted the data well with the highest simulated log-likelihoods at convergence and gave the best estimate of the households’ WTP for water improvement. Nearly 46% of the sampled households were willing to pay more than 33 ETB per month, and 49% of the households were willing to pay between 21 ETB and 33 ETB per month for the monthly water bill. Overall, approximately 95% of the sampled households were willing to pay more than 21 ETB.ConclusionCustomers are willing to pay to avoid most types of water supply restrictions. Moreover, WTP is sensitive to the scope of service improvement, income, affixed price, and elicitation method. In summary, mixed logit WTP-space models can help accurately predict household-level WTP, which can be used to select improvements in drinking water access and services in the Legedadie-Dire catchments.

Design considerations and their effects on the operation and maintenance cost in solar‐powered desalination plants

AbstractThe most critical aspects of any desalination plant are maintenance and operation costs. For solar water desalination, cost reduction and production of superior water quality are still crucial factors that attract researchers. Faults in the design of desalination systems can lead to many maintenance and operational problems in these systems and may lead to increasing water costs and/or decreasing quality of water. This paper offers an analytical study of design considerations and its effects on the operation and maintenance of solar‐powered desalination plants such as plant capacity, location, technology, demands, product water specifications, lifetime, availability, reliability, and input resources. This paper also provides an overview of the factors and components of desalination costs compared with other water supply alternatives and traditional desalination methods; discusses challenges and perceptions; and highlights recent developments in the solar water desalination technology that affect the total cost of water delivery and relationships with operation and maintenance.

Socio-hydrological drivers of agricultural water use in small reservoirs

Millions of small reservoirs built across semi-arid areas present a potential to support agricultural livelihoods of rural smallholders. The scale and geographical dispersion of these multiple lakes restrict the understanding of these coupled human-water systems and the identification of adequate strategies to support riparian farmers. This research developed a multi-scalar interdisciplinary approach to characterise the hydrological and wider drivers of agricultural water use around multiple small reservoirs in semi-arid central Tunisia. The combination of field surveys, quantitative questionnaires and qualitative, semi-structured interviews confirmed minimal withdrawals, but highlighted the diversification of practices, the rise in fruit farming and peripheral benefits generated here by the development of 56 lakes. 48% of lakes provide residual benefits for the occasional watering of on average 300 fruit trees and support to downstream wells exploited for irrigation. A further 13 lakes (23%) provide high levels of benefits (900 fruit trees each), albeit with low equity, supporting essentially established farmers. The analysis of surface water assessments every 8 days from Landsat 5–8 imagery over 1999–2014, provides unprecedented insights into the significant water scarcity and unreliability that impedes agricultural intensification on 86% of small lakes. Limited storage capacities and prolonged droughts highlight the need for small reservoirs in this climatic context to retain a supplementary irrigation objective and not strive to support widespread intensification of irrigated practices. Many farmers lack the capabilities to increase their withdrawals and suffer physical and economic water access difficulties, mismanagement, compounded through limited and short-term government assistance. Individual successes resulted from farmers' economic resilience and means to secure alternate water supplies during dry spells.

Physiological and biochemical responses of two spring wheat genotypes to non-hydraulic root-to-shoot signalling of partial and full root-zone drought stress

Non-hydraulic root-sourced signal (nHRS) is so far affirmed to be a unique positive early-warning response to drying soil, however its physiological and agronomic implications are still unclear. We designed two contrast methods to induce nHRS in two wheat (Triticum aestivum L.) genotypes released in different decades under pot-culture conditions. Partial root-zone stress (PS) was performed using the method of split-root alternative water supply (one half wetting and the other drying) to induce the continuous operation of nHRS, and full root-zone stress (FS) was subjected to whole root system to periodic operation of nHRS. nHRS-mediated signalling increased abscisic acid (ABA) production and triggered ROS (reactive oxygen species) generation, which, thereby, led to up-regulation of antioxidant defense system. Cytokinin synthesis reduced during drought stress while proline and malodialdehyde (MDA) content were increased. Regardless of drought treatment methods and wheat genotype, a significant decrease in grain yield, root biomass and above-ground biomass (p < 0.05) was observed, without significant changes in root-to-shoot ratio. Harvest index was increased, proposing that more energy was allocated to reproductive organs during the action of nHRS. Moreover, higher water use efficiency was witnessed in PS. The data suggest that nHRS triggered ABA accumulation, thereby closing stomata, and reducing water use and also decreases the production of ROS and improves the antioxidant defence enzymes, thus enhancing drought tolerance. This survey of different-decade genotypes suggests that advances in grain yield and drought tolerance would be made by targeted selection for a wheat genetic resource.

The Environmental Impact of Cattle Access to Watercourses: A Review

The degradation of freshwater resources and loss of freshwater biodiversity by anthropogenic activities, including agriculture, are of major global concern. Together with diffuse pollutants, point sources, such as where cattle have direct access to riparian margins and watercourses, can potentially present significant environmental challenges. These can include impacts on stream morphology, increased sedimentation, nutrient additions, microbial contamination, and impacts on aquatic biota. Mitigation measures aimed at reducing these frequently include reducing the amount of time cattle spend in riparian margins and watercourses. This is often accomplished through the provision of an alternative water supply and grazing management, or even cattle exclusion measures. Although a number of studies refer to potential negative impacts, there has been little attempt to review previous research on this topic. The key aim of this paper is to collate and review these disparate studies, as well as those relating to the effectiveness of mitigation measures. Although it is difficult to draw generalizations from studies due to the inherent variability between and within catchments, evidence pertaining to impacts in relation to sedimentation, pathogens, and riparian margin vegetation were strong. Conclusions in relation to impacts on stream morphology and nutrient parameters were less clear, whereas studies on responses of macroinvertebrate communities were particularly variable, with differences due to cattle access difficult to separate from catchment scale effects. A greater understanding of the impact of cattle access on watercourses under varying conditions will help inform policymakers on the cost effectiveness of existing management criteria and will help in revising existing measures.

RAINWATER HARVESTING ON GREENHOUSE ROOF AND USE IN IRRIGATION

Rainwater collection systems are alternative water supply methods providing environmental and economic benefits compared to traditional water supply methods used in arid and semi-arid climates with water shortages. Rainwater harvested in greenhouse roof by rain gutters can be used to irrigate and grow the plants cultivated in greenhouses. However, rain gutters and storage tanks in greenhouses should be of sufficient size to collect rainwater. Water consumption of plants in the greenhouse should be calculated correctly to determine the storage size in greenhouses. The amount of annual irrigation water harvested from rainfall in Kirsehir province where total rainfall is 388.3 l/m2 was determined as 349.57 l/m2 based on rainfall factor of 0.9. Total amount of irrigation water needed by the plants in the unheated greenhouse between April and September for single crop cultivation was 568.33 l/m2. The results revealed that 61.49% of irrigation water needed for plants can be met by rainwater harvesting. In addition, 47.74% of the total water demand of plants in the heated greenhouse where crops are grown throughout a year can be met by rainwater harvesting. The storage capacities needed for unheated and heated greenhouses were determined as 0.21 m3/m2 and 0.30 m3/m2 depending on the amount of rainwater harvested. The results showed that rainwater harvesting may contribute to the improvement of agricultural activities in water-scarce regions.

Pilot study of a horizontal roughing filtration system treating greywater generated from a peri-urban community in Durban, South Africa

Abstract There is a growing pressure on the available freshwater resources in South Africa and many other countries around the world. This has led to a large scale of interest in the application of water reclamation and reuse of wastewater as alternative water supply sources. This is becoming critical to sustain development and economic growth in the southern Africa region. This study investigated the performance of a horizontal roughing filtration system treating greywater generated from a peri-urban settlement in Durban, South Africa. The horizontal roughing filtration system consists of three compartments containing different sizes of gravels that serve as the filter media. The horizontal roughing filter was operated at a filtration rate of 0.3 m/hr for 90 days. The results indicated that at this low filtration rate, effective reduction in turbidity, conductivity, chemical oxygen demand and total solids can be achieved. Overall average removal efficiencies of 90% turbidity, 70% chemical oxygen demand, 86% conductivity, and 84% total solids were obtained for the entire duration of operation of the horizontal roughing filtration system. Thus, it was concluded that the horizontal roughing filtration system is suitable for the treatment of greywater for non-potable reuse applications although further investigation needs to be conducted for the microbial removal during the treatment.

Analyzing the Energy Consumption, GHG Emission, and Cost of Seawater Desalination in China

Seawater desalination is considered a technique with high water supply potential and has become an emerging alternative for freshwater supply in China. The increase of the capacity also increases energy consumption and greenhouse gases (GHG) emissions, which has not been well investigated in studies. This study has analyzed the current development of seawater desalination in China, including the capacity, distribution, processes, as well as the desalted water use. Energy consumption and GHG emissions of overall desalination in China, as well as for the provinces, are calculated covering the period of 2006–2016. The unit product cost of seawater desalination plants specifying processes is also estimated. The results showed that 1) The installed capacity maintained increased from 2006 to 2016, and reverse osmosis is the major process used for seawater desalination in China. 2) The energy consumption increased from 81 MWh/y to 1,561 MWh/y during the 11 years. The overall GHG emission increase from 85 Mt CO2eq/y to 1,628 Mt CO2eq/y. Tianjin had the largest GHG emissions, following are Hebei and Shandong, with emissions of 4.1 Mt CO2eq/y, 2.2 Mt CO2eq/y. and 1.0 Mt CO2eq/y. 3) The unit product cost of seawater desalination is higher than other water supply alternatives, and it differentiates the desalination processes. The average unit product cost of the reverse osmosis process is 0.96 USD and 2.5 USD for the multiple-effect distillation process. The potential for future works should specify different energy forms, e.g. heat and power. Alternatives of process integration should be investigated—e.g. efficiency of using the energy, heat integration, and renewables in water desalination, as well as the utilization of total site heat integration.

Geoelectrical exploration for groundwater in crystalline basement rocks of Gbongudu community, Ibadan, Southwestern Nigeria

Gbongudu community, Ibadan underlain by crystalline rocks of Basement Complex of Southwestern Nigeria has need for alternative water supply due to inadequacies of surface water supply and common occurrences of low yield or dry boreholes coupled with rapid development within the community. Geophysical investigation involving electrical resistivity was carried out with the aim of evaluating the groundwater potential of the community. Thirty-three (33) Vertical Electrical Soundings were acquired across the community adopting Schlumberger electrode configuration with current electrode separation (AB) varying from 2 to 200 m. The acquired field data were interpreted using partial curve matching with suitable auxiliary chart and “RESIST” resistivity sounding interpretation software was also used for iteration. The results revealed two to five geo-electric layers, namely, topsoil, clayey soil, lateritic clay, weathered layer, fractured unit and fresh basement. The weathered and the fractured units form the aquiferous zones in the area investigated. Thematic maps of geoelectric and Dar-Zarrouk parameters produced from the interpreted VES data are aquifer unit (weathered layer) thickness map, aquifer unit (weathered layer) resistivity map, overburden thickness map, basement resistivity map, basement topography map, reflection coefficient map, total longitudinal conductance map, total transverse resistance map and electrical anisotropy (coefficient of anisotropy) map. The thematic maps were combined to form a single component which gives the groundwater potential map of the study area. The groundwater potential map was used to classify the study area into poor, low and good aquifer potential zones. The study reveals that the weathered and fractured zone that occur in the southeastern part of the study area constitute the water bearing zone which can be regarded as good groundwater potential. This study has provided evidence on the hydrogeologic framework and subsurface nature of main aquifer units in the area.KEY WORDS: Groundwater exploration, RESIST, Dar-Zarrouk parameters, Electrical anisotropy, Borehole drilling.

Geophysical appraisal of groundwater potential in the crystalline rock of Kishi area, Southwestern Nigeria

The need for alternative water supply is inevitable in Kishi area, Southwestern Nigeria due to inadequacies of surface water supply and common occurrences of low yield and abortive boreholes coupled with increase in population and developments in the area. Thus, electrical resistivity investigation was deployed to map fracture pattern and orientation, and obtain the geo-electric parameters of the crystalline rock which were used to evaluate the groundwater potential of the area. The result obtained was compared with the borehole yield as well as the geology that underlain the study area. A total of seven Radial Vertical Electrical Soundings (RVES) and ninety-three Vertical Electrical Soundings (VES) were acquired within Kishi area using Schlumberger array with half-current electrode spacing (AB/2) ranging from 1.0 m to 133 m. The RVES was measured as a function of bearing at 0° 45° 90° and 135° about a fixed central point. The acquired data were interpreted and the layer model obtained from the sounding curves revealed three to four geo-electric layers comprising topsoil, lateritic clay (compacted), weathered basement, fractured formation and basement. Thematic maps for overburden thickness, basement relief, bedrock resistivity, aquifer resistivity, aquifer thickness, and reflection coefficient were generated from the geoelectric parameters. Overburden thickness above 20 m were considered thick, basement relief of less than 355 m above sea level were considered as basement depressions, bedrock resistivity of less than 800 Ωm were interpreted as fractured basement, aquifer resistivity of less than 100 Ωm were considered saturated formation, aquifer thickness of above 15 m were considered thick and the reflection coefficient of less than 0.75 were considered as fractured basement. These maps were integrated to generate groundwater potential map of Kishi area and was used to delineate area of good, medium and poor groundwater yielding zone. The groundwater potential map generated for the study area correlates with basement fracturing with area of intense fracturing corresponding to area of high groundwater yield. The correlation observed between the groundwater potential map and the geological map show that area with high groundwater yield and intense basement fracturing fall on quartzite/quartz schist and granite gneiss.

Collaborative, Risk-Informed, Triple Bottom Line, Multi-Criteria Decision Analysis Planning Framework for Integrated Urban Water Management

The historical division of water management into different sectors, with financially and technologically driven decision processes, makes taking a more holistic approach to finding sustainable solutions for urban water management difficult. Here, a planning framework for Integrated Urban Water Management (IUWM) that evolved during a two-year study evaluating alternative strategies for dual water supply within a local government context is described. The planning framework was developed to overcome the obstacles that surfaced over the course of the study. It provides a structured approach to strategic decision making that integrates triple bottom line (TBL), multi-criteria decision analysis (MCDA), uncertainty and sensitivity analyses, and participatory decision making into an exploration of water supply alternatives. TBL assured stakeholders that the decisions considered the financial, social, and environmental performance. MCDA provided visibility into the benefits and trade-offs of the alternatives by providing a quantitative method for comparing alternatives that incorporates incommensurate performance indicators and priorities of multiple stakeholders. Uncertainty and sensitivity analyses addressed concerns regarding decision risk and improved transparency into inputs driving uncertainty in the analysis. Finally, a flexible participatory process helped to circumvent socio-institutional barriers by adapting the methodology and increasing cooperation among stakeholders and multidisciplinary experts. The resulting collaborative, risk-informed, TBL-MCDA (CRTM) planning framework helps to refine the feasible set of alternatives by providing more transparency into the drivers, technologies, and stakeholders influencing the decision. The planning framework increased the number of participants that were involved in the study, increased interaction between participants, changed the structure of the decision problem, increased the number of performance indicators considered, and improved stakeholder cooperation in the decision process.