Fog collection as a source of fresh water supply in the Kingdom of Saudi Arabia

In order to harvest water contained in fog, the topographical features and the climatic conditions of 27 cities in the Kingdom of Saudi Arabia were studied. The topography, altitude and orientation are some of the factors that determined the selection of the site. It was identified that the southwest of the region in the kingdom was the most suitable location for the fog‐collection process. In order to evaluate the effectiveness of fog water collection and the site, three identical standard fog collectors (SFCs) with two different local collection materials were designed and manufactured. Experiments were conducted at two different locations in the area close to Abha, namely Soodha. The maximum amount of water collected was 22.9 L/m² in a day and 7.25 L/m² in a 2‐h period. It was found that there was a high probability of fog when the relative humidity was higher than 95%. The results from the chemical analyses of eight sets of fog water samples collected were compared with World Health Organization drinking water standards. It was found that the level of heavy metals was negligible and the level of Fe was marginally high for the first flush only. The study indicates that in terms of both quality and magnitude of yield, fog is a viable source of water and can be successfully used to supplement water supplies in the fog‐prone regions of the kingdom.     

Investigation of humidity harvest as an alternative water source in the Kingdom of Saudi Arabia

In order to harvest water present in a humid atmosphere, a suitable absorber/desorber was designed. Experiments were conducted in Dhahran to measure the water absorption rate in the nighttime and the water desorption rate in the daytime. It was found that the water absorption rate was 2.11 L/m²/day and the water desorption rate was 1.15 L/m²/day depending on the desiccant flow rate. In order to assess the feasibility of the system, the unit was tested continuously in the nighttime as well as in the daytime and the results are reported in this paper. The chemical characteristics of a set of water samples collected were analysed and the water collected was found to meet most of the World Health Organization drinking water standards. The problem associated with this technology is the mixing of dust and dirt with the desiccant solution, and the fact that a small pump is required to circulate the solution.     

Evaluation of Fog Collection in Jordan

Water-supply augmentation along with supply and demand management in Jordan have been considered to meet the water demand. This paper evaluates the feasibility of fog collection in Jordan using various low-cost materials. Experiments were conducted using four standard fog collectors with different local materials. An analysis of fog-collection effectiveness was carried out and compared with international experience, and showed that local sacking material was the most effective. Recommendations for applying this technique are outlined.     

Electrostatic dust collectors compared to inhalable samplers for measuring endotoxin concentrations in farm homes

Paired electrostatic dust collectors (EDCs) and daily, inhalable button samplers (BS) were used concurrently to sample endotoxin in 10 farm homes during 7‐day periods in summer and winter. Winter sampling included an optical particle counter (OPC) to measure PM_2.5 and PM_2.5–10. Electrostatic dust collectors and BS filters were analyzed for endotoxin using the kinetic chromogenic Limulus amebocyte lysate assay. Optical particle counter particulate matter (PM) data were divided into two PM categories. In summer, geometric mean (geometric standard deviation) endotoxin concentrations were 0.82 EU/m³ (2.7) measured with the BS and 737 EU/m² (1.9) measured with the EDC. Winter values were 0.52 EU/m³ (3.1) for BS and 538 EU/m² (3.0) for EDCs. Seven‐day endotoxin values of EDCs were highly correlated with the 7‐day BS sampling averages (r = 0.70; P < 0.001). Analysis of variance indicated a 2.4‐fold increase in EDC endotoxin concentrations for each unit increase of the ratio of PM_2.5 to PM_2.5–10. There was also a significant correlation between BS and EDCs endotoxin concentrations for winter (r = 0.67; P < 0.05) and summer (r = 0.75; P < 0.05). Thus, EDCs sample comparable endotoxin concentrations to BS, making EDCs a feasible, easy to use alternative to BS for endotoxin sampling.     

Carbonaceous characteristics of atmospheric particulate matter in Hong Kong

To determine the characteristic of carbonaceous species in atmospheric particles in Hong Kong, PM₁₀ and PM_2.5 samples were collected using high volume (hi-vol.) air samplers from November 2000 to February 2001. The organic carbon (OC) and elemental carbon (EC) were analyzed by the selective thermal manganese dioxide oxidation (TMO) method. The ratios of PM_2.5/PM₁₀ mass ratios were 0.61, 0.78 and 0.53 for particulate matter collected at PolyU station (PolyU, near a major traffic corridor), Kwun Tong station (KT, mixed residential/commercial/industrial) and the Hok Tsui background station (HT), respectively. These results indicate that the PM_2.5 concentrations constitute the majority of the PM₁₀ concentrations, especially in urban and industrial areas of Hong Kong. The average concentrations at the three sites ranged from 73.11 to 83.52 μg/m³ for PM₁₀ and from 42.37 to 57.38 μg/m³ for PM_2.5. The highest daily mass concentrations of PM₁₀ and PM_2.5 were 125.89 μg/m³ and 116.89 μg/m³ at KT, respectively. The correlation between PM₁₀ and PM_2.5 was high at KT and HT (r>0.9, P<0.01). This means that the sources of PM₁₀ and PM_2.5 may be the same at both sites. The highest mean concentration of OC (12.02 μg/m³) and EC (6.86 μg/m³) in PM₁₀ was found at the PolyU among the three sites. For PM_2.5, the highest mean concentration of OC (10.16 μg/m³) was at KT while the highest mean concentration of EC (7.95 μg/m³) was at PolyU. However, the background concentrations at HT were higher than another background area, Kosan, Korea. Transportation of pollutants from the Asian continent may be responsible for the elevations of EC+OC at the remote site. More than 74% of the EC and more than 79% of the OC were found in the PM_2.5 fraction at the three sampling locations. At PolyU station, PM_2.5 consisted of 18.18% OC and 11.16% EC while 17.70% OC and 8.81% EC were found in KT station. Thus OC and EC are major constituents of aerosols in Hong Kong. OC/EC ratios for PM₁₀ and PM_2.5 were less than 2 at PolyU and KT stations while the ratio exceeded 3 at HT background station. This indicates that OC measured in the urban area may be emitted directly as a primary aerosol.     

Die umweltfaktoren, die die verbreitung und entwicklung von Chalcalburnus tarichi (PALL. 1881) (Pisces: Cyprinidae) in Burdur-See begrenzen

Burdur Lake, an entirely closed and brackish water lake, having an area of 190 km² and 76 m depth, is located in the “Lakes Region” of Anatolia, 4 km from the west of Burdur city.There have been made many attempts to breed an economically important fish population but all attempts were unsuccessful. During 1946–1948 some hydrobiological investigations were carried out. According to these investigations, hydrobiological conditions of the lake were found to be suitable for Chalcalburnus tarichi (PALL. 1881) (Pisces: Cyprinidae), a fish which is endemic to the Lake Van in eastern Anatolia. Since 1966 an attempt has been made to breed Chalcalburnus tarichi artificially. This attempt was successful, but the economic productivity was not in the estimated level. These fish live in all the depth of the lake, but during the breeding season, they go into fresh water streams flowing into the lake.To find out the reasons of the productivity losses, new hydrobiological investigations have been going on since 1969. Two research stations have been chosen (Fig. 1), where water, plankton and bottom samplings have been collected for hydrobiological research. Nansen bottles were used to take the water samples, in 10 m intervals, from the surface of water towards the bottom. The chemical analysis of water have been done according to the standard methods given in Welcher (1963). The Winkler method is used to find out the amount of dissolved oxygen (Welcher, 1963).Plankton was collected in 10 m intervals by usual type Closing net (20 cm dia, mesh size of 0.05 mm). The amount of plankton per m³ has been calculated according to the Settling methods of Welch (1948).Bottom samples were collected by Ekman's Dredge at four different regions marked (a), (b), (c), (d), on Fig. 1. Samples were wet sieved through four graded sieves (mesh sizes 0.5–2.0 mm). The number of the collected bottom animals per m² were calculated.Observations showed that, the direct flow of waste waters having organic materials from the Burdur Sugar Mill, Milk-Cheese factories and Attar of Rose industries and Hemp (Cannabis sativa) maceration remnants go to the bottom of the lake, therefore, unoxygenated and thereby a hydrogensulphonized water layer is formed by the above mentioned waste products. The unoxygenated water layer level increases 2–2.5 m per year towards the surface. This pollution has caused this unexpected loss of productivity of fish, for this water layer harms the bottom feeding and planktonic organisms and restricts the spreading and development of the adopted Chalcalburnus tarichi (PALL. 1881). It is also clear that this situation is a threat to the future of the lake and its environment.     

Treatment of chromium‐bearing wastewaters with constructed wetlands

Chromium can have detrimental effects on most organisms, including humans. The present study focused on the effect of treating chromium‐bearing, organic‐rich wastewater on constructed wetland performance. Eight laboratory‐scale systems were used to study organic matter and chromium removals, with three features tested in duplicate: media with proven chromium sorption capacity, vegetation presence and intermittent influent loading. A set of two wetlands acted as the base design. Average BOD₅ and chromium removal rates were 13.4 g/m² day and 135 mg Cr/m² day, respectively. From an influent chromium concentration of 5 mg/L, <0.5 mg/L could be detected at the outlet during the study in all systems. Chromium removal efficiencies were statistically different for all systems (P<0.01), except when comparing the base design against the intermittent feed systems (P>0.05). Overall treatment performance of all systems was remarkably good in spite of significant chromium content and salinity.     

Improving building fabric energy efficiency in hot-humid climates using dynamic insulation

New effective technologies and materials that have the potential to reduce energy demand with excellent energy efficiency and low environmental impact are urgently required in the Gulf Region. Dynamic insulation, which functions by recycling fabric heat loss back to the building, has been established theoretically and proven in pilot projects. It sets the green, low carbon benchmark for thermal insulation in buildings. This paper presents details of the Eco-Villa, its construction, how the performance of the villa was monitored, and the findings from the initial monitoring phase and the dynamic simulation model (DSM). The villa was tested in two modes, bypass (static) and dynamic. The static U value of the external envelop wall was estimated at 0.24 W/(m²·K) in bypass mode. The theoretical dynamic U value changed from 0.24 to 0.05 W/(m²·K) when the ventilation airflow was varied from 0 to 0.001 m³/(s·m²) (0 to 1 L/(s·m²)), with a further small reduction occurring when the flow rate increased beyond 0.001 m³/(s·m²) (1 L/(s·m²)). The design ventilation rate for the Eco-Villa was 0.0008 m³/(s·m²) (0.8 L/(s·m²)), which yielded a theoretical dynamic U value of 0.063 W/(m²·K) compared to a measured U value of 0.125 W/(m²·K). The reduction in the fabric conduction gain was found to be 41% whereas the estimate from the DSM was 38%. The results demonstrate the fabric energy efficiency improvements that can be achieved through the use of dynamic insulation.     

Daily measurements of atmospheric sulfates in Paris

Sulfate concentration measurements were made from June 1977 through March 1981 at a sampling site located in the center of Paris. The fiftieth percentile for sulfate was approximately 10μg/m³ and the mean value 12 μg/m³.Relationships of sulfates with meteorological and chemical quantities were studied. Correlations with SO₂ and fine suspended particulates were higher in winter (October to March inclusive) than in summer (April to September inclusive). The highest concentrations were observed especially in winter, when wind speed was less than 2 m/s and/or fog or important morning haze occured, but for these days SO₄/SO₂ ratios were not higher than for the other days. On the other hand, in summer SO₄/SO₂ ratios were abnormally strong for preferential wind directions. Measurements at suburbs sampling sites proved that the sulfate concentrations were at the same time very homogeneous in the Paris metropolitan aerosol ; a station exposed to diesel exhaust did not show significant increase in sulfates.     

Hydrogeological and Hydrochemical Study of the Al-Shagaya Field-F, Kuwait

The study area, Al-Shagaya Field-F, is located at the south western part of Kuwait and includes twenty-seven production water wells, tapping the Kuwait Group aquifer. The main objectives of this study were to identify the aquifer type, determine its properties, outline the geological factors and the hydrochemical processes that control the quality of the groundwater of the study area, and to assess the water quality of the Kuwait Group aquifer. Analyses of aquifer test data revealed that the Kuwait Group aquifer acts as a semi-confined to confined aquifer, with a range of transmissivity values between 103 and 1,198 m²/day. The initial water level ranges from 70 to 146 m (M.S.L). The estimated quantity of groundwater entering the study area is about 12,950 m³/day. The chemical analyses show that the groundwater of the study area is a brackish water type, with total dissolved solids ranging from 3,586 to 5,334 mg/l. The aquifer salinity increases in the direction of regional flow towards the NE. The average pH value is 7.7 and the average electrical conductivity is 5,349 s/cm. Groundwater is highly concentrated with Na⁺, Ca²⁺, Cl^- and SO₄^2- and is depleted in HCO₃^- and Mg²⁺ ions. It is characterized by secondary salinity, where the alkaline earths exceed the alkalies and strong acids exceed weak acids. Three groundwater chemical types are recognized: NaCl, Na₂SO₄ and CaCl₂. The NaCl water type is the most abundant in the study area. The main genetic types of water are: MgCl₂ and Na₂SO₄. It is found that the groundwater is oversaturated with respect to aragonite and calcite and undersaturated with respect to anhydrite, gypsum, halite and dolomite. A comparison of the hydrochemical coefficients of Na⁺/Cl^-, SO₄^2-/Cl^- and Ca²⁺/Mg²⁺ in the study area with those of seawater and river water shows that the groundwater of the study area is a mixture of marine and continental water.     

The significance of atmospheric deposition of heavy metals in four Danish lakes

The atmospheric deposition rate of heavy metals was determined throughout a seventeen month period at four lakes and a control station across Mid-Jutland, Denmark, and its significance was assessed in relation to the concentrations of Zn, Cu, Pb, and Cd in water, sediment and aquatic macrophytes (Phragmites australis (Cav.) Trin, Littorella uniflora (L.) Ashers., Isoetes lacustris L. and Juncus bulbosus L.) from Lake Hampen, Lake Meldgaard, Lake Sortesø, and Lake Gødstrup. Mean annual deposition rates of 1.81–2.77 mg Cu m^?2, 4.09–8.73 mg Pb m^?2, and 0.21–0.37 mg Cd m^?2 were determined. For Zn a mean deposition rate of 15 mg Zn m^?2 year^?1 was used (Hovmand, 1979). The atmospheric deposition per m² of Zn and Cu amounts to 0.2–37%, 0.05–4.3% and 3.4–107% of the contents present in the water column of the lakes, the upper 10 cm of the littoral sediment and in dense vegetation of aquatic macrophytes, respectively. Equivalent figures for Pb and Cd are 1.8–649%, 0.8–30.6%, and 16.8–951%. In the profundal sediments of the oligotrophic Lake Hampen, post-war atmospheric deposition has increased the heavy metal concentration and content up to 180 times. The Pb concentrations in sediments from different depths were significantly correlated with the post-war consumption of gasoline in Denmark. It is concluded that atmospheric deposition of heavy metals results in a significant contamination of lakes, especially oligotrophic lakes for which aerial fallout is the major source. It is further concluded that lake sediments uncontaminated with heavy metals are probably no longer found in Denmark.     

An analytical method for the analysis of trihalomethanes in ambient air using solid‐phase microextraction gas chromatography‐mass spectrometry: An application to indoor swimming pool complexes

A simple method for the collection and analysis of the four brominated and chlorinated trihalomethanes (THMs) in air samples is described. Ambient air samples were collected in pre‐prepared glass vials, with THM analysis performed using solid‐phase microextraction gas chromatography‐mass spectrometry, where the need for chemical reagents is minimized. Analytical parameters, including oven temperature program, solvent volume, incubation time, vial agitation, extraction time and temperature, as well as desorption time and temperature, were evaluated to ensure optimal method performance. The developed method allows for point‐in‐time quantification (compared to an average concentration measured over extended periods of time), with detection limits between 0.7 to 2.6 µg/m³. Excellent linearity (r² > 0.99), repeatability (3% to 11% RSD), and reproducibility (3% to 16% RSD) were demonstrated over a concentration range from 2 to 5000 µg/m³. The method was validated for the analysis of THMs in indoor swimming pool air and was used to investigate the occurrence of THMs in the air above 15 indoor swimming pools. This is the first study to report the occurrence of THMs in swimming pool air in Australia, and concentrations higher than those previously reported in other countries were measured.     

How should urban water be priced? – An empirical analysis for the city of Mekelle,Ethiopia

Urban water utilities have focused on setting water prices to cover average costs, usually using increasing block rate designs. In an attempt to contribute to the use of efficient, equitable, and revenue-sufficient pricing, this paper estimates the long-run marginal and average social costs of water supply in Mekelle city using a multi-product translog cost function that incorporates the shadow price of natural water. Findings show that the marginal social costs of providing one m³ of residential and non-residential water are Birr 5.33 and 7.71 (Birr = Ethiopian currency: 1 Euro ≈ 23 Birr), respectively, while the average current prices are Birr 4.46 and 6.10/m³. On the other hand, the average social costs of residential and non-residential water are estimated at Birr 14.34 and 16.36/m³, respectively, implying that marginal social cost-based prices would still lead to a revenue deficit of approximately Birr 9/m³.     

Surface coating of polyamide reverse osmosis membranes with zwitterionic 3‐(3,4‐dihydroxyphenyl)‐l‐alanine (l‐DOPA) for forward osmosis

To overcome low permeability and fouling problems of membranes used in FO processes, modification is needed to improve the hydrophilicity, permeability and selectivity of membranes. In this work, thin film composite (TFC) commercial polyamide RO membranes (BW30‐LE, SW30‐HR, AG and AC) were functionalized with zwitterionic l ‐DOPA. The effect of l ‐DOPA on the morphology of membranes was determined via SEM, FT‐IR, AFM and contact angle analysis. The l ‐DOPA modified BW30‐LE membrane showed excellent properties with 46° contact angle and 3.8 L/m²hbar water permeability and 0.83 L/m²h salt permeability. Although, l ‐DOPA modified BW30‐LE membrane had the highest water flux and hydrophilicity, l ‐DOPA modified SW30‐HR membrane showed higher FO flux with 9.38 L/m²h than BW 30 membrane with 3.5 L/m²h at 50 g/L NaCl draw solution. Introducing hydroxyl and carboxyl ionic groups on the membrane surface with l ‐DOPA coating enhanced the FO performance and water permeability which provide a new insight in FO applications.     

Solar integrated energy system for a green building

Shanghai is characteristic of subtropical monsoonal climate with the mean annual temperature of 17.6 °C, and receives annual total radiation above 4470 MJ/m² with approximately 2000 h of sunshine. A solar energy system capable of heating, cooling, natural ventilation and hot water supply has been built in Shanghai Research Institute of Building Science. The system mainly contains 150 m² solar collector arrays, two adsorption chillers, floor radiation heating pipes, finned tube heat exchangers and a hot water storage tank of 2.5 m³ in volume. It is used for heating in winter, cooling in summer, natural ventilation in spring and autumn, hot water supply in all the year for 460 m² building area. The whole system is controlled by an industrial control computer and operates automatically. Under typical weather condition of Shanghai, it is found that the average heating capacity is up to 25.04 kW in winter, the average refrigerating output reaches 15.31 kW in summer and the solar-enhanced natural ventilation air flow rate doubles in transitional seasons. The experimental investigation validated the practical effective operation of the adsorption cooling-based air-conditioning system. After 1-year operation, it is confirmed that the solar system contributes 70% total energy of the involved space for the weather conditions of Shanghai.     

Water management — A tool for methane mitigation from irrigated paddy fields

Water drainage is considered to be one of the important practices that reduce the CH₄ efflux from paddy fields. In this study, four different drainage systems (continuous flooding, tillering stage drainage, mid-season drainage and multiple drainage) were compared to find out the best one, for attenuation of CH₄ emission from rice fields. Except for continuous flooding, from all the other three drainage systems, irrigation water from the paddy fields was drained out at the different stages of the crop cycle. Highest efflux of the methane was recorded from continuously flooded plots (346.6 mg/m²/day), followed by 9% less CH₄ efflux from tillering stage drainage (315.1 mg/m²/day), 36.7% less efflux from mid-season drainage (219.3 mg/m²/day) and the least 41% CH₄ efflux from multiple drainage plots (204.7 mg/m²/day). Among all the four different drainage systems applied, mid-season drainage and multiple drainage were found to be highly effective in mitigating methane efflux. Redox potential of the soil of the drainage system was found to be inversely proportional to the methane efflux from all the treatments.     

Comparative studies on the performance of a roadheader,impact hammer and drilling and blasting method in the excavation of metro station tunnels in Istanbul

Drilling and blasting is the most widely used excavation method in mining and tunnelling especially in hard rock conditions. But in recent years, the application of roadheaders and impact hammers in hard rock, especially in fractured geological formations has increased considerably. However, it is strongly emphasized that the prediction of the machine performance plays an important role in the time scheduling and in the economy of tunnelling projects and accumulated data will serve a sound basis for performance prediction models.This paper presents information on Istanbul Kadikoy–Kartal metro tunnels which are planned to be constructed in two stages, the first one which is in Kozyatagi–Kadikoy direction and the second in Kozyatagi–Kartal direction. The construction method of the Kozyatagi–Kadikoy station tunnels is first summarized and later, the performance of a roadheader, impact hammer and the results of drilling and blasting methods are compared.The results of this study show that machine utilization time is 28.2% for roadheader and 14.2% for impact hammers. Average net cutting rates (NCR) are 32.26 m³/h for roadheader (218.3 m³/day), net breaking rate (NBR) 13.1 m³/h (45 m³/day) for impact hammers and production rate with drill and blast method (D&B) is found to be 187 m³/day.     

Combined biological treatment of high‐sulphate wastewater from yeast production

The wastewater from baker's yeast production contains above‐average concentrations of organic pollutants (25 000 mg/L total chemical oxygen demand, TCOD), nutrients (1500 mg/L N_tot, 100 mg/L P_tot) and sulphate (2900 mg/L SO₄^2?). Baker's yeast wastewater with a flow rate of 190 m³/day was treated in a mesophilic anaerobic/anoxic continuous stirred tank reactor (CSTR) system. At the expense of the reduction of trimethylglycine (or betaine‐component of sugar‐beet molasses) to other nitrogen‐containing compounds, it was possible to re‐oxidize the sulphides to elemental sulphur, remove them from the wastewater and increase biogas production. Therefore, the average removal efficiency in the anaerobic/anoxic system was 79% by TCOD, 100% by SO₄^2? in which the concentration of sulphides in the effluent did not exceed 50 mg/L. The application of this combined anaerobic/anoxic system to a full‐scale treatment plant supported biogas production up to 1300 m³/day, and the purification of wastewater was feasible without the use of granular sludge.     

Aquatic insect diversity and biomass in a stream marginally polluted by acid strip mine drainage

Upper Three Runs receives a point source of acid mine drainage from a small acid feeder stream and the pH of the main stream falls from above 6 to about 4.5. Over the 1.2 km study section below the introduction of acid drainage, the pH rises to 5.0. This moderate degree of mine acid pollution has severely affected aquatic insect populations. The acid feeder itself (pH near 3.2) was inhabited only by a chironomid, a megalopteran (Sialis), and the caddisfly Ptilostomis. Biomass was very low (140 mg dry weight/m²). The drainage of the acid feeder into the stream caused a drop in the Shannon-Weiner diversity index from 3.10 to 1.95, and a drop in biomass from 6.5 g/m² to 2.2 g/m². At the two stations further downstream, the diversity index remained relatively constant and the biomass leveled off at about 1.2 g/m². The number of taxa declined steadily from 30 at the control station to 13 at the lowest site. Populations of Coleoptera, Ephemeroptera and Trichoptera showed little or no recovery as the acid pollution ameliorated slightly. Representatives of the orders Diptera and Plecoptera (especially Nemoura) showed a decided recovery and increase in numbers near pH 5.0. If fish were able to survive in acid mine polluted waters of pH's between 4.5 and 5.0 they should find sufficient insect food for maintenance of a limited population.     

Fog drip and its relation to groundwater in the tropical seasonal rain forest of Xishuangbanna, Southwest China: a preliminary study

Rain, fog drip, shallow soil water and groundwater were collected for two years (2002-2003) for stable isotopic analysis, at a tropical seasonal rain forest site in Xshuangbanna, Southwest China. The fog drip water ranged from -30 to +27 per thousand in deltaD and -6.2 to +1.9 per thousand in delta(18)O, conforms to the equation deltaD=7.64delta(18)O+14.32, and was thought to contain water that has been evaporated and recycled terrestrial meteoric water. The rain was isotopically more depleted, and ranged from -94 to -45 per thousand in deltaD, and -13.2 to -6.8 per thousand in delta(18)O. The shallow soil water had a composition usually between those of the rain and fog drip, and was assumed to be a mixture of the two waters. However, the soil water collected in dry season appeared to contain more fog drip water than that collected in rainy season. The groundwater in both seasons had an isotopic composition similar to rainwater, suggesting that fog drip water does not play a significant role as a source of recharge for the groundwater. This groundwater was thought to be recharged solely by rainwater.