Improved Water Supply Research Articles

Willingness to pay for improved water supply service in coastal urban settings: evidence from Khulna, Bangladesh

Abstract The provision of clean water and sanitation has been one of the challenging targets of the Sustainable Development Goals (SDGs) for developing countries like Bangladesh. The southern cities of the country confront the scarcity of fresh and improved water for drinking and sanitation. The study aims to investigate the demand for improved water service among city dwellers and the potential revenue for the water supply authority. The study surveyed 100 households in Khulna city by administering a simple random sampling method. The single-bounded dichotomous choice contingent valuation method revealed that years of schooling, household income, and excessive time in water collection positively affect willingness to pay (WTP) for improved water service. The households are willing to pay US$ 5.05 per month on average for enjoying improved water service, which in turn produces annual revenues of US$ 4.26 million, overriding the current level of revenue by 2.5 times. Additionally, the water supply authority is incurring around US$ 2.14 million of revenue loss annually which can be recovered by supplying improved water to the city households. This study suggests that the government may be able to address the fresh and improved water scarcity in the urban territory by capturing and utilizing the potential revenue efficiently through removing the structural barriers.

Can We Use the Water Budget to Infer Upland Catchment Behavior? The Role of Data Set Error Estimation and Interbasin Groundwater Flow

AbstractWater budgets are essential for characterizing water supplies from snow‐dominated upland catchments where data are sparse, groundwater systems are complex, and measurements are prone to error (ε). One solution is imposing water budget closure (CWB) by ignoring difficult‐to‐measure variables, including inter‐basin groundwater fluxes (G) and ε. However, conventional CWB‐based analyses, which derive evapotranspiration (ET) from precipitation (P) and streamflow (Q) (e.g., the Budyko hypothesis), are limited in their ability to take advantage of recent advances in ET products, physically‐based frameworks for improving inferences about G, or tools to statistically characterize ε (Triple Collocation [TC]); all of which offer promise for improved water supply predictions via open water budgets (OWB). We clarify the value of these advances in upland settings by comparing standard land surface model, Ensemble Mean, and TC‐Merged P and ET products in 114 upland catchments. When compared against a long‐term OWB, we find that the CWB assumptions are unsupported in 75%–100% of our 114 catchments, depending on the product. We then show how applying these CWB assumptions in snowy, steep catchments where ε is large can inflate inferences about streamflow response to climate change by up 9 times more than independent (OWB) estimates of ET using TC. Finally, we demonstrate how advances in OWB analysis reveal that high, arid settings with deep permeable substrate are groundwater exporters while most other basins are groundwater importers. Our results highlight the advantages of OWB analyses that harness new products, tools, and frameworks for characterizing inter‐basin groundwater fluxes in critical upland settings.

Households’ willingness to pay for improved water service in Bonga town, Kaffa zone, Southwestern Ethiopia

This study was initiated to estimate households’ willingness to pay for improved water services and identify its determinants by using the contingent valuation method in Bonga town of Kaffa zone, Southwestern Ethiopia. A cross-sectional data from a total of 212 sampled households’ from two randomly selected kebeles of Bonga town. Contingent valuation survey responses were analyzed through descriptive and econometric analysis using Probit and Bivariate probit model. Double bounded dichotomous choice with open-ended follow-up format was used to elicit the household’s willingness to pay. The descriptive analysis showed that out of the total 205 valid responses indicated that most households’ have perceived the problem of existing water services and were willing to pay for its improvement. Results from the study showed that about 80.98% of the sampled households were willing to pay the initial bid offered for an improvement in their water services scheme. The Probit model regression result shows that the age, daily water use, satisfaction level, fetching time, initial bid, ownership of the house, quality, family size, stay in town, and income were important factors that influenced WTP for improved water service. The study also shows that the maximum willingness to pay for improved water service was calculated to be 57.62 Birr and 30.11 Birr per month from double bounded and open-ended format respectively. The study also reveals that the aggregate welfare gains from the improvement of water supply in the study area were calculated to be 1,176,531 and 614,810 ETB per month from double bounded dichotomous choice and open-ended format respectively. Therefore, the policymakers, as well as project implementers who design solutions to address the problem of water service in the study area, should take account of these factors into their decision. Int. J. Agril. Res. Innov. Tech. 12(1): 105-114, June 2022

Impact of Hydropower Dam on Household Water Security: Evidence from Amerti-Neshe Reservoir in Northwestern Ethiopia

Understanding the impact of hydropower dam construction on adjacent local community water security is critical for identifying factors that influence water security as well as improving water supplies in rural areas. This study analyzes the impact of hydropower dam construction on the water security of households around the Amerti and Neshe dams in Northwestern Ethiopia. A multistage sampling procedure was followed to select 485 households (268 affected and 217 non-affected) for our analysis. A principal component analysis was applied to five dimensions of water security (access, utilization, affordability, quality, and quantity) and then the households water security index (HWSI) was constructed. An endogenous switching regression model was applied to analyze the impact of dam construction on the water security status at the household level in the study area. Our findings revealed that there is a significant mean difference in HWSI between affected and non-affected households regarding water access and quality. The average treatment effect indicates that the construction of the two dams has had a negative impact on household water security, reducing it by 12%. As a result, government and other stakeholders should consider relocating affected households to better areas in order to mitigate such negative effects on household water security.

SiteFinder: A geospatial scoping tool to assist the siting of external water harvesting structures

Water harvesting has a long history, but still plays an important role today by increasing crop productivity, combatting erosion, and improving water supplies. Geographical Information Systems (GIS) are used extensively to assess the suitability of sites for water harvesting but available tools fail to consider the synoptic topography of sites. Here, we report the creation of a novel, automated tool – “SiteFinder” – that evaluates potential locations by automatically calculating site-specific information, including structure parameters (height, length, and volume) and descriptors of the zone affected by the structure (storage capacity and area of influence) and the catchment area. Innovatively, compared to existing tools of this kind, SiteFinder works within a GIS environment. Thus, it allows the possibility of combining its outputs with larger Multi-Criteria Decision-Making processes to consider other bio-physical, socio-economic, and environmental factors. It utilises a Digital Elevation Model (DEM) and automatically analyses thousands of potential sites, computing site characteristics for different barrier heights that are dependent on the surrounding topography. It outputs values of eight parameters to aid planners in assessing the characteristics of sites as to their suitability for water harvesting. We conducted case studies using 30 × 30 m gridded DEMs to automatically evaluate several thousand sites and, by filtering the tool outputs, successfully identified sites with characteristics appropriate for scenarios at three spatial scales: large dams for nationally significant water supply reservoirs (383 sites analysed; 5 filtered sites with barriers up to 30 m in height); large gully erosion control dams for regional-scale interventions (4,586 sites analysed; 6 filtered sites with barriers up to 3.6 m in height); and local, community-based earth embankment projects (801 sites analysed; 6 filtered sites with barriers up to 2 m in height). A higher resolution (1 × 1 m) terrain elevation model, derived from open-source airborne survey data, was used to assess the veracity of these results. Correlations between the barrier length, impounded area and storage volume capacity derived from the two different resolution data sets were all strongly significant (Spearman’s rank correlation, p < 0.001); and normalised root mean square errors were 9%, 15% and 16% for these parameters, respectively.

Adopting a Combination of Labour-Saving Mechanisms for Increasing Rural Women’s Participation in Livelihood Strategies in Busega District in Tanzania

Abstract The paper aims at examining rural women’s adoption of a combination of labour-saving mechanisms such as improved water supplies and harvesting techniques, cooking facilities and means of transport for household chores with its implications in diversifying livelihood strategies in Busega District of Tanzania. The study adopted Diffusion of Innovations Theory to explain the importance of adopting labour-saving mechanisms to reduce rural women’s workload and save time for diversifying livelihood strategies. The study employed cross-sectional research design to collect data from 210 rural women. Household survey, interviews, focus group discussions and non-participant observations were used to collect primary data. Cross-tabulation, One-way ANOVA, five point Likert scale and multiple logistic regression were employed to analyse quantitative data. Content analysis was employed to analyse qualitative data. The study revealed that, 61.43% of rural women were limited to adopt any kind of labour-saving mechanisms. In addition, the multiple logistic regression revealed significant differences at p-value of 0.05 for the likelihood of diversifying livelihood strategies. As such, rural women’s participation in livelihood strategies differed greatly based on the ability to adopt labour-saving mechanisms for reducing the workload of household chores. The study recommends that development stakeholders should implement development programmes centred on increasing prospects of adopting a combination of labour-saving mechanisms for reducing the burden of household chores to save time for diversifying livelihood strategies.

Dilution and Pollution: Assessing the Impacts of Water Reuse and Flow Reduction on Water Quality in the Los Angeles River Basin

Los Angeles (LA), California, USA is one of many population-dense, arid cities whose treated wastewater discharge comprises most of the river flow (up to 70% in the LA River). Like other arid cities, LA plans to improve water supply by reusing treated wastewater and diverting nonstorm stormdrain flows. This study quantifies the impact of these management actions on pollutant loads and concentrations in the LA River. Daily pollutant loads and concentrations for total suspended solids (TSS), total dissolved solids (TDS), copper, zinc, and lead were predicted using EPA SWMM across nine wastewater reuse and nonstorm stormdrain diversion scenarios. Reduced flows generally decreased daily loads for all pollutants, but the impact on daily concentrations varied. Concentrations of TDS, TSS, copper, and lead increased with wastewater reuse, while zinc concentrations increased with the reduction of nonstorm stormdrain flows. Copper, zinc, and TDS water quality objectives were met less frequently with increasing flow reduction. These results elucidate the potential impacts of flow reductions on water quality and will help inform management decisions in effluent-dominated rivers.

Identification of pathways that lead to continuous or intermittent water supply by conducting a qualitative comparative analysis of rural water utilities in China

Abstract Ensuring a continuous water supply (CWS) for households is beneficial for the current global drinking water, sanitation, and hygiene agenda. Despite improvements in water supply, intermittent water supply (IWS) remains prevalent in rural areas. To determine the factors that lead to different water supply modes for villages, we select 38 village-level water utilities covered by the Chinese Safe Drinking Water Project for fuzzy set qualitative comparative analysis to identify causal configurations (‘pathways’) that lead to IWS or CWS across systems. Six configurations of water supply mode are identified on the basis of the outcomes of each case. Among these, three configurations for adopting CWS are determined. Configuration 1 features water utility with government subsidy and bills using a water meter. Configuration 2 features water utility with small population coverage, government subsidy, and villager participation in the management. Configuration 3 features a water utility collectively managed and owned by a rich village and water-saving initiatives. Configurations that lack meter-based bills, government subsidies, and water-saving initiatives are the main paths for IWS. Results highlight the uniqueness of the configurational approach in understanding different water supply patterns across various cases and emphasise the importance of government subsidies, villager participation, water-saving programmes, and water meter-based billing to achieve CWS.

Multi-objective operation of cascade reservoirs based on short-term ensemble streamflow prediction

Ensemble streamflow predictions (ESPs) play an essential role in reservoir operation in terms of flood control, water supply and hydropower generation, etc. However, the working mechanism of dam-regulated ESP is rarely explored even though a large fraction of major waterways is affected by artificial hydraulic infrastructure, let alone its application value in multi-objective multi-reservoir operating system. Here this study develops three-layered hydrologically-relevant long and short-term memory (LSTM) models to implement 1–3 days ahead ESP of cascade reservoirs with the help of numerical weather prediction (NWP), and designs operating policies based on Gaussian radial basis function which can explicitly incorporate ESP information into reservoir operating decision. The framework of our proposed ESP-based operating way is demonstrated on a cascade reservoir system in the upper Hanjiang River basin, China and assessed against two benchmark control ways (i.e., no-forecast and deterministic-forecast operations). Results show that (1) LSTM models have reasonable accuracy in short-term NWP-based ESP of cascade reservoirs, especially for high-flow regimes; (2) compared with the no-forecast operation, our ESP-based operation could harvest additional approximately 36 million kW·h of hydropower generation per year with a slight improvement in water supply over 11 years of operation during the flood season. These findings highlight the application potential of our numerically efficient and skillful NWP-based ESP scheme for multi-objective cascade reservoir operation to address water-energy shortage issues.

Social relations of gender in contexts of precarious water supply and their impacts on women in rural areas

A significant portion of the Brazilian population is excluded from easy access to water, especially in rural areas. Women play a fundamental role in terms of water resources in this context. Given the theoretical gaps on this subject, this study aims to analyse the social construction that determines the unequal division of domestic demands related to water supply between women and men in three rural areas studied for the development of the National Rural Sanitation Programme of Brazil: Barreiro Amarelo and Nova Esperança in the State of Bahia and Pontal do Buriti Settlement in the State of Goiás. The qualitative methodology, based on the principles of grounded theory, applies semi-structured interviews, direct observation, and thematic-categorical content analysis. The results indicate that the unequal dedication to water demands is based on sexist logic, determined by the sexual division of labour and influenced by the patriarchal culture. Thus, activities with less social prestige demanding daily dedication are women’s responsibility. There is evidence that improvements in water supply positively impact women’s lives, especially their health. Moreover, water policies should be interrelated with social and gender policies, reducing inequalities and improving women's quality of life.

Sustainable management of water utility in Samoa through services improvement with Okinawa Water Bureaus

This study examines how Samoa improved the capacity of Samoa Water Authority (SWA) by implementing integrated cooperation with water utilities in Okinawa Prefecture, and hardware and software development to reduce the high non-revenue water (NRW) ratio and improve water supply quality and inadequate water pressure. Standard operation procedures were formulated to enhance the capacity of SWA. The cooperation method adopted continuous on-the-job training with a bottom-up approach. Consequently, the NRW ratio was reduced from 68 per cent to 36 per cent and water supply with proper pressure was achieved in the targeted area. The quality of the tap water, in which many coliform bacteria were detected before the cooperation, achieved 100 per cent compliance with standards. The cooperation evidenced that improving water services can help users’ understanding of tariff payments, although the water tariff increased for most consumers due to a shift from fixed to metered tariff.

The Impact of Better Access to Improved Water Sources on Health, Schooling, and Water Collection of Girls and Boys in Rural Zambia

This paper examines the short-term impact of better access to improved water available at newly built boreholes on children’s health, schooling, and time allocation in rural Zambia. We employed a difference-in-differences estimation using a dataset collected under a quasi-experimental setting. We observed significant effects of better access to improved water sources on the reduced incidence of diarrhea for pre-school children but not for school-age children. We found no significant effect on school attendance. To understand the mechanism behind this pattern, we examined any changes in time use by children who had better access to improved water sources. For girls, particularly those who lived near the boreholes, we found a significant decrease in time spent on schooling and homework and a significant increase in time spent on water-related household chores including fetching water. We did not find any significant changes for boys. Alongside a significant decrease in time spent on water-related chores by female adults, better access to improved water supply shifts the burden of water-related household chores from female adults to girls while the net burden of water collection alone for girls was unchanged.

PROVISION OF THE CITIES OF KYRGYZSTAN WITH ENGINEERING AND TRANSPORT INFRASTRUCTURE AND PROBLEMS OF DEVELOPMENT

The article presents an urban planning analysis of the problems of water supply, sanitation, heat supply, gas supply, garbage disposal and urban improvement in Kyrgyzstan. Provision of Kyrgyz cities with engineering and transport infrastructure is interconnected with their functioning and development. The current state of the engineering and transport infrastructure of the cities of the Kyrgyz Republic reflects the existence of a problem in ensuring comfortable living of the population. The increased number of the population, the high level of motorization, the consolidation of urban development directly affect the level of development of engineering and transport communications.

An IUWM incorporated model to improve water supply reliability in intermittent and no service areas

Water supply reliability is an increasingly important aspect of water system design, especially in regions with unreliable water supply. Most water systems initially designed as continuous supply systems are affected by constraints such as limited freshwater supply, infrastructure inadequacy and insufficient expansion, poor operations and management, contributing to Intermittent Water Supply (IWS) or no services in some regions. IWS is a common condition in developing countries like India. Many approaches have been developed to address water availability and quality challenges, including Integrated Urban Water Management (IUWM). The main principle of IUWM is to incorporate non-conventional water supply sources, such as stormwater, rooftop rainwater and recycled wastewater, to augment water supply and provide fit-for-purpose water. However, in developing countries, IUWM principles have not been sufficiently investigated to understand how they can improve water supply reliability in regions with IWS or no centralized water supply. In this study, an IUWM incorporated model was developed to understand how supply reliability can be improved in areas with IWS or no services, with Bangalore city in India, as a case study. Five different supply configurations to incorporate IUWM principles were analyzed and compared to identify the most efficient way to incorporate non-conventional water sources. The analysis identifies potential supply issues in the area under the current centralized water supply. The results show that the traditional water supply system can not meet the minimum water demand. The reliability can be improved from <50% to 100% with the incorporation of non-conventional water sources.

Modeling Exposure to Fecal Contamination in Drinking Water due to Multiple Water Source Use.

The Joint Monitoring Programme estimated that 71% of people globally had access to “safely managed” drinking water in 2017. However, typical data collection practices focus only on a household’s primary water source, yet some households in low- and middle-income countries (LMICs) engage in multiple water source use, including supplementing improved water supplies with unimproved water throughout the year. Monte Carlo simulations and previously published data were used to simulate exposure to fecal contamination (as measured by E. coli) along a range of supplemental unimproved source use rates (e.g., 0–100% improved water use, with the remainder made up with unimproved water). The model results revealed a statistically significant increase in annual exposure to E. coli when individuals supplement their improved water with unimproved water just 2 days annually. Additionally, our analysis identified scenarios–realistic for the data set study setting–where supplementing with unimproved water counterintuitively decreases exposure to E. coli. These results highlight the need for evaluating the temporal dynamics in water quality and availability of drinking water sources in LMICs as well as capturing the use of multiple water sources for monitoring global access to safe drinking water.

English

To improve water supply services in Port Sudan City (Sudan), a dam with storage capacity of 16 Mm3 was established at the upper gorge of the Khor Arbaat catchment area, which generates runoff that contributes to the sedimentation of the dam at an average rate of about 6% annually. At present (2021), the storage capacity of the dam is reduced by 69% of its original design capacity. Without interventions, the dam is expected to continue silting up reducing its capacity to 94% of the original design capacity by year 2044. Although the dam has reduced the amount of runoff that reaches the alluvium aquifer and has caused groundwater recession downstream, the continuous sedimentation and reduction of the dam&rsquo;s storage capacity mean the amount of water that could flow out would gradually increase.&nbsp; Despite its sedimentation, the dam has provided groundwater recharge 1 km upstream of the dam resulting in a rise of 2 m in groundwater level and enabled irrigation of 85% of the arable land. Comparatively, a drop of 1.8 m was observed in groundwater level at 5 km upstream of the dam, with irrigation of only 33% of the arable land. Also, the interception of the base-flow/underflow by the dam, has contributed to the recession of groundwater downstream. These observations can help optimize the use of this resource; by reducing evaporation losses and maximizing the benefit from the reservoir&rsquo;s available storage through the intensification of pumping during the winter period (October-March) when evaporation is comparatively low and reservoir storage can be replenished by winter runoff. Beyond technical fixes (and in the long term), management of water resources in the Khor Arbaat should consider the catchment area as a whole and in an overall framework of Integrated Water Resources Management (IWRM). Key words: Base-flow, groundwater, integrated water resources management, irrigated land, sedimentation, runoff.

Optimizing Water Supply through Reservoir Conversion and Storage of Return Flow- A Case Study at Joe Pool Lake

Maintaining an adequate water supply is one of the key challenges faced by the Dallas-Fort Worth Metroplex, where increasing population and rising water demand have elevated the vulnerability of the communities to water shortages. In this paper, we conducted a preliminary study exploring the possibility of converting flood storage in the Joe Pool Lake (JPL) as a means to improve water supply reliability and achieve better cost efficiency. This study employs a mixed integer linear programming (MILP) approach that considers the costs of meeting conversion demand and supply requirements over the northern portion of the Trinity River Basin. It includes trade-offs between capturing and storing natural flow versus return flow from the treatment facilities of the Trinity River Authority (TRA). A set of hypothetical prices and demand figures with the record drought of 1940-1996 considered to test the LP model. The optimal strategy yields expansion of JPL and associated storage-diversion on an annual basis. Also, the outcomes of the analyses suggest that, while the conversion would have a positive impact on water availability, storing the return flow might not produce sufficient cost savings; unless higher prices were imposed on the stored-return flow.

Enterotoxins as a molecular marker of water quality

Abstract Safety of improved water supplies using enterotoxins as a molecular marker is evaluated. Water samples were collected from 248 households and tested for enterotoxins using polymerase chain reaction (PCR). The relationships between the presence of at least one enterotoxin and independent variables were investigated using Chi-square (χ2), Fisher's exact test and binary logistic regression. Some 156 enterotoxin biomarkers were detected, 39% of samples had at least one, and 17% had multiple varieties. EAST1 was detected in the highest proportion of samples (33%) and Sta in the lowest (2%). Shallow groundwater sources yielded 18% less enterotoxins than water from piped systems, a statistically significant result (P=0.031). A lower proportion of enterotoxins was detected in relation to those who did not know and use cloth filters than those with knowledge of them, and the negative association is statistically significant (P=0.017). It was shown that water samples in which total coliform (TC) colonies were detected were more likely to contain enterotoxins than those without (P=0.001). It is concluded that enterotoxin molecular markers can be used to monitor water safety.

Association of wash practices with diarrheal diseases among residential and nonresidential school children at Wardha District: A comparative study

Introduction: Sustainable development goals, adopted at the 2015 UN general assembly, aim to significantly boost water and sanitation globally and include two concrete targets for drinking water, sanitation, and hygiene (WASH) as set out in objective 6. Improved water supply and sanitation results in a reduction of 23% and 36% respectively in morbidity due to diarrhea and an increase of around 2 billion school days. The present study was conducted to assess and to compare the WASH practices and its association with diarrheal diseases in residential and nonresidential schools at Wardha district. Methodology: A cross-sectional school-based study conducted using a prestructured and predesigned questionnaire carried out among residential and nonresidential schools in Wardha district. The study participants were the students of 8–13 years of age group or 3rd–7th standard. Data collection tools were prepared using the World Health Organization standards for WASH in Schools in Low-cost Settings and Monitoring Package developed by UNICEF for WASH in Schools which is adaptable in developing countries. Results: In residential school, out of 240 boys 96 (40%) and out of 231 girl students 30 (12.98%) were suffered from diarrheal disease in the past 3 months of interview. While in nonresidential school out of 178 male students 10 and 12 female students gives a history of diarrheal disease in the past 3 months; this association was statistically nonsignificant. When compared by Binomial Logistic Regression found that in residential school variables like Gender, Not Using “Urinals” provided in the school, Not using soap for washing hands found to be statistically significant, with an odds ratio of 0.433, 1.65, and 4.43, respectively. Conclusion: This study shows that male participants from residential schools have a high incidence of diarrheal disease compared with females from the schools, whereas in nonresidential schools females suffered from diarrheal comparatively more than males; improper water handling practices seem to be more in residential schools than that of nonresidential schools this may be the main reason of getting more incidence of diarrheal diseases in residential school.

BRITISH MILITARY CONTRIBUTIONS TO THE GEOLOGY OF MALTA, PART 2: THE SECOND WORLD WAR, 1939–1945

ABSTRACT During the Second World War, the central Mediterranean island of Malta was famously besieged by the Italian navy and intensively bombed by Italian and later German air forces, from June 1940 until Allied victory in North Africa in May 1943 brought an end to the siege. It was then scheduled as a staging post to support the Allied invasion of Sicily from North Africa in July 1943 and of mainland Italy from Sicily in September. From 1941 until 1945, two Tunnelling Companies Royal Engineers, overlapping in succession, excavated underground facilities safe from aerial or naval bombardment. In 1943 and then 1944–1945, two Boring Sections Royal Engineers in succession drilled wells to enhance water supplies, initially for increased troop concentrations. Borehole site selection was guided in 1943 by the Director of the Geological Survey of Great Britain (Edward Battersby Bailey: 1881–1965) and by geologists Captain Frederick William Shotton (1906–1990) and Major Gordon Lyall Paver (1913–1988). In 1944, it was guided by geologist Captain Howard Digby Roberts (1913–1971), leading a detachment from 42nd Geological Section of the South African Engineer Corps that pioneered earth resistivity surveys on the island. Overall, these military studies generated a new but unpublished geological map of the island at 1:31,680-scale and refined knowledge of its geological structure: a much faulted but otherwise near-horizontal Oligo-Miocene sedimentary sequence. Further refinement was achieved as a consequence of the 1944–1945 drilling programme, led principally by geologist Captain Thomas Owen Morris (1904–1989) of the Royal Engineers. By 1945, this had helped to develop an improved water supply system for the island, and plans to develop groundwater abstracted from a perched upper aquifer (in the Upper Coralline Limestone and underlying Greensand formations, above a ‘Blue Clay’) as well as from the main lower aquifer, near sea level (in the Globigerina Limestone and/or underlying Lower Coralline Limestone formations).