Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 ENVIRONMENTAL THREATS OF AN ON-SITE SEWAGE DISPOSAL ON GROUNDWATER AT MINIA-ALQAMH, SHARKIA GOVERNORATE, EGYPT Abdel Fattah Morsi Atwa1, Abdelazim Negm2, Asaad M. Armanuos3 1 National Organization for Potable Water & Sanitation Co., General Manager in Sharkia Dep. 2 Chairperson of Environmental Engineering Dept., Egypt-Japan University of Science and Technology E-JUST, New Borg El-Arab, Alexandria, Egypt, E-mail: [email protected], (seconded from Zagazig Uniersity, [email protected]) 3 Ph.D. Student, Environmental Engineering Dept, School of Energy and Environment and Chemical & Petrochemical Engineering, Egypt-Japan University of Science and Technology, E-JUST, Alexandria, Email:[email protected] ABSTRACT All over the world, the urban growth increases the demand of fresh water supply. In some regions the groundwater (GW) is main the sources of fresh water especially when the surface water in not sufficiently available or scarce. This is the case of some places in East of the Nile Delta. In some cases, the GW is polluted be the sewage water causes serious human health problems. Recently, the quality and quantity of the GW has been identified in response to the increased human activities and the deficient in fresh surface water. It was found that the greatest danger of GW pollution is from surface sources such as: sewer, polluted drains, sewage ponds, septic tanks and refuse disposal sites and human sources. The main objectives of this study are to assess the GW in some selected areas in Minia-Alqamh district and to locate the potential sources for GW pollution, based on the available land use data. The study area lies to the eastern part of Nile Delta. The ultimate objective is to improve wastewater treatment in the study area to protect the GW as a fresh water source from being polluted. In order to achieve the goals of this study, the geoelectric resistivity survey were carried out and interpreted in the form of apparent and true resistivity maps, geoelectric cross sections and integrated models. The final models are based on the results of integration of resistivity measurements and data of both hydrogeological and chemical analysis. The extensive analysis of geoelectric resistivity indicated that the quaternary aquifer consists of four layers. The GW level subdivides the second layer into two resistivity facies, the upper facies represented by low values sandy facie and the lower facies represented by silty to sandy facies. The geochemical analysis indicated that a potential pollution from the surface pollution sources are possible and the salinity levels are very high and risky. Therefore, it is recommended that the primary treatment and biological treatment should be included in the water treatment plants to remove BOD and the total suspended solids in addition to The tertiary treatment also to remove impurities from sewage, producing an effluent of almost drinking-water quality. Keywords: Groundwater contamination, Geoelectric resistivity, pollution, treatment, wastewater, landfill waste, Sharika Governorate. 1 INTRODUCTION Urban growth has increased the demands on GW supplies in the area east of the Nile Delta. The problem of GW quality and quantity has been identified during the few years in response to the increased human activities. In this regards, Abdel-Lah and Shamrukh (2001) stated that the Sewage is the main source of pathogenic microbial contamination of ground water as it is in surface water. 127 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Bacteria travel through soil matrix and diverse the microbes within this group. Also, many diseases caused by bacteria such as diarr hoeal, dysentery, cholera, and typhoid fever. The unsafe method of sewage system construction and the shallow depth of water table made the situation of sewage contamination is worsening. In rural areas of Upper Egypt the wastewater is disposed and collected into an underground sewage room and it contact direct with ground water. The results showed that water samples from many hand pumps and deep well s in a Nile Valley village contaminated with pathogenic bacteria. They recommended to prevent the leaching from sewage rooms in Upper Egypt part of Nile Valley aquifer and the depth of hand pumps and wells must be deeper and far away from the sewage tank. Also, Taha et al. (2004) assessed the state of groundwater pollution in the new communities, Southeast Nile Delta, Egypt. Industrial, agricultural and domestic activities were the sources of pollution and cause deterioration of groundwater quality due to the misuse of fertilizers and pesticides. They evaluated the suitability of different water resources in new communities and stated its impacts on human health and plant hazard. Moreover, Gemail et al. (2011) integrated 1D resistivity sounding and 2D resistivity imaging surveys with geological and hydrochemical data to assess the vulnerability and the seawater intrusion in El-Gharbyia main drain, north of Nile Delta, Egypt. Twenty Schlumberger soundings and six 2D dipole–dipole profiles were executed in the western side of the main drain. They assessed the protection of the groundwater aquifer and the potential risk of groundwater pollution depending on results from the results from the resistivity and hydrochemical data. They estimated the integrated electrical conductivity (IEC) by using the inverted resistivity and thicknesses of the layers above the aquifer layer and used if after that for quantification of aquifer vulnerability. The aquifer vulnerability maps indicated that underlying sand aquifer is high vulnerability zone with slightly fresh to brackish groundwater and the subsoil structure around the main drain that is highly affected by waste water. In addition to the above, the resistivity method used in a wide range in geological studies especially in groundwater Nile Delta aquifer. Abdel-Raouf and Abdel-Galil (2013) used electrical resistivity soundings method to investigate groundwater of Wadi El Natrun, Eagypt northwest of the Nile Delta. Also, they studied the stratigraphic sequence of the different aquifers and delineating the factors affecting groundwater potentialities and movements. The results of electrical soundings delineated that there are different water bearing zones with varying thicknesses. The hydrogeological data of the study area related to existence of four main aquifers distributed in the study area. The main aquifer of the study area has been contaminated due to the effect of surface water irrigation. Recently, Armanuos et al. (2015) investigated the factor controlling the groundwater quality western Nile Delta aquifer by using multivariate statistical technique. The results showed that there were four factors account for 77 % of the total variance of hydrochemistry data. The first and second factors related to mineralization, mining and salinity due to saltwater intrusion. The other factors assigned to industrial wastes, domestic wastes and agriculture activities. They recommended that the authorities should take necessary actions to control the different sources of groundwater pollution. Also, Armanuos et al. (2015) assessed the groundwater of western Nile Delta, Egypt for drinking purposes by using water quality index. They used the WHO and Egypt standards (ES) as a reference to determine the suitability of groundwater for drinking purpose. The results showed that about 45.37% and 66.66 % of groundwater wells falls in good drinking water zone according to WHO and Egypt standards. Also, t 37.03 % and 15.07 % fall in the poor drinking water zone according to WHO and ES respectively and 9.25 % and 11.2 % falls in unfit for DW category according to WHO and ES. They concluded that human activities, agriculture activities and other industrial pollutants contribute in the degradation of groundwater quality Nile Delta aquifer. This research presents the results of geohydrochemical - geoelectric resistivity of fresh water aquifer in Minia Alqamh, Sharikia Governorate to answer the question “is the fresh groundwater in the area subject to contamination from the sources of waste water?. To achieve the goals of this study, the geoelectric resistivity survey are carried out and interpreted in the form of apparent and true resistivity maps, geoelectric cross sections and integrated models. The final models are based on the results of integration of resistivity measurements and data of both hydro geological and chemical analysis. 128 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 2 CHARACTERISTICS OF THE STUDY AREA The study area lies to the eastern part of Nile Delta figure (1), where the Quaternary unconsolidated aquifer is separated from the underlying Miocene aquifer by a Pliocene thin clay bed. 31° 15' 31° 30' 31° 15' 32° 00 31° 45' 32° 15' PORT SAID 31° 15' Manzala Lake 31° 00 31° 00 DAKAHLIYA Diarb Nigm 30° 45' Abu Kabir 30° 45' Faqus Hihya 30° 15' 30° 30' A lq a mh El Salhiya Mi na 30° 30 Ismailiya Canal 30° 15' Mashtul El Soak Tenth of Ramadan 30° 00 10 31° 15' 31° 30' 31° 45' Studied area 0 32° 00 10 Km 32° 15' 30° 00 City Location Fig. (1): Location map of the study area 2.1 General Geology Generally, the eastern part of the Nile Delta was investigated by different geological studies, e.g. Bayoumy (1971), Zaghloul et al., (1977), Shata et al., (1979), Said (1981), Korany et al., (1997), Abd El Gawad (1997) Ibrahim et al., (2005), and El Sharkawi (2008). 2.2 Topography The study area ranges between 3m (above sea level) at the northern, to about 15 m at the south of area, with a general slope towards the north (Fig. 2). It is dissected by a complex irrigation system, which has a direct influence on both the GW recharge and movement of the Quaternary aquifer (Shata et al., 1979). 2.3 Surface Geology The surface geology of the study area was studied by several geological studies eg., El Said (1981) and Zaghloul et al., (1990). CONOCO, (1987), According to GPC & the rock units exposed in the area can be mainly classified into Quaternary deposits as follows: 2.3.1 Quaternary deposits Quaternary deposits cover the studied area. It represented by Nile silt, wadi deposits, alluvial fans and sand dunes. According to mode of formation, Quaternary deposits are classified, from bottom to top, into Pleistocene and Recent (Holocene) (Fig. 3). Fig. (2): Topographic map of the studied area (Compiled after Shata et al., 1979). Fig. (3): Geological map of the study area (Compiled after GPC, CONOCO, 1987). 129 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 2.3.2 The Pleistocene sediments; The Pleistocene sediments are considered as the main GW aquifer in the study area. It includes three types of deposits, namely, the old Aeolian deposits or (Mit Ghamr Formation, the old fluviomarine deposits and the old deltaic deposits. 2.3.3 The Holocene deposits They are widespread and divided into the following types: 1) The young deltaic deposits Neonile (Bilqas Formation); which are composed of Nile silt, fine sand and clay. They show gradual increase in thickness (10 m) to the north (Fig.3). 2) The young Aeolian deposits; which are represented by loose fine to coarse sand with variable thickness (Fig. 3). 2.4 Subsurface Geology The subsurface Tertiary rocks in the study area have been subdivided by Shlumberger (1984) from bottom to top into three formations belonging to Miocene and three formations belonging to Pliocene rocks (Fig. 4). 2.4.1 A-Miocene rocks: The Miocene rocks are divided into three formations from bottom to top as follows: Sidi Salem Formation (Middle Miocene, Qawasim Formation Upper Miocene and Rosetta Formation. 2.4.2 B-Pliocene rocks: The Pliocene rocks are divided into three formations from bottom to top as follows Abu Madi Formation (Lower Pliocene , Kafr El Sheikh Formation (Middle Pliocene) and Wastani Formation (Upper Pliocene). The Quaternary subsurface in the studied area are classified into two rock units; Pleistocene rocks (at the bottom) and recent rocks. (Fig. 4). THICNESS(ft) TIME ROCK UNITS 980 DELTAIC FLUVIATILE FLUVIATILE SHALLOW MARINE 4900 SHALLOW MARINE TO KAFR EL-SHEIKH OPEN MARINE ABU MADI 980 HOLOCENE UPPER MIDDLE LOWER EL-WASTANI ROSETTA 160 NEAR SHORE LAGOONAL QAWASIM 2950 UPPER SHALLOW MARINE FLUVIATILE DELTAIC SIDI SALEM 2300 MIDDLE MIOCENE PLIOCENE TERTIOARY CENOZOIC MIT GHAMR 2300 BILQAS RECENT SHALLOW MARINE LOWER MOGHRA Fig. (4): Generalization Litho-stratigraphic column of the studied area (after Schlumberger, 1984). 2.5 Structural setting The structural setting of the study area has been discussed by several researchers, among them are El-Fayoumy (1968), El Diasty (1969), El Shazely et al., (1975), El Dairy (1980), El Ahwani (1982), El 130 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Gamili. (1982), Sallouma (1983) and Khabar (1992).No structures of the study area have been detected. 2.6 Hydrogeology The present section deals with the studying of the GW formation, hydrogeological sitting and the hydrogeological relationship between surface water and GW flow at the study area. 2.6.1 Groundwater Formation: In the study area, the sediments are of hydrogeological importance as it belongs to the Quaternary. The Quaternary aquifer represents the main source of GW in the studied area. It is underlined by the Pliocene plastic clay that acts as an aquiclude, especially in the area of flood plain around Zagazig, Rizzini et al., (1978), El Hefny (1980), Said (1981) and Serag El Din (1989). 2.6.2 Quaternary Aquifer (Nile Delta aquifer) The Quaternary aquifer is the principal reservoir of the GW. It is underlined by the Pliocene plastic clay that acts as an aquiclude, especially in the area of flood plain around Zagazig city. The lateral and vertical variations in the facies of the Quaternary sediments, lead to their classification into a number of distinguishable horizons. Each of these horizons has its own characters such as porosity, hydraulic conductivity, ability for retaining and yielding water, and mode of water occurrence rather than water quality. These horizons are: a) Nile silt, sandy clay and clayey sand (Holocene). b) Fine and medium sands with related sediments (Late Pleistocene). c) Coarse sands and gravels (Early Pliocene). 2.7 Hydrogeological sitting of the study area For studying the lateral and vertical lithological variation and structure elements affecting on the different aquifers in the study area, three hydrogeological cross sections were constructed, covering the whole area Fig. (5), Atwa (2010). Two of them are marked as L2-L2’and V1-V1’. Fig.(5): Hydrological cross section, Atwa (2010) 2.7.1 The hydrogeological cross section (L2-L2’) Figure 6 presents the north-south cross section which shows that the Quaternary aquifer forms the extension of the eastern flood plain of the Nile Delta (Serag El Din, 1983). It is present under semiconfined conditions toward the north of Ismailia Canal, while, it becomes unconfined and in hydraulic contact with the canal at the south. The Quaternary aquifer is underlined directly by the deep aquifer. The Quaternary aquifer is considered as the main source of GW in the study area. 2.7.2 The hydrogeological cross section (V1-V1’) (Fig. 7) 131 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Figure 7 presents the cross section V1-V1’ where it passes the SW-NE direction through wells Abu Hammad and E5 and shows a normal fault structure elements and the presence of two waterbearing formations (Pleistocene and Miocene). The thickness of Pleistocene aquifer in two wells is less variables approximately. L2 RAS EL BAR 1 ___ ___ 0 200 ABU MADI A ___ ___ ___ ___ ___ ___ E V3 4/11 L2' BILQAS FORMATION. ___ ___ ___ ___ S.W BILQAS1 ___ ___ MIT GHAMR 1 7/10 1/11 1/7 5/10 8/7 1/8 17/1 W V3' 2/1 NE Sw E4 Abu Hammad V1 P2 19/1 V1' 10 Water Table Water table ___ ___ 0 Pleistocene -1 0 -400 -2 0 -600 -800 Quaternary aquifer -3 0 MIT GHAMR FORMATION. Miocene ? -1000 -4 0 Pliocene -5 0 20 0 20km 6 -6 0 EL WASTANY FORMATION. -7 0 CONGLOMERATE COARSE SAND FINE SAND ___ ___ CLAY ___ ___ SILT 5 0 0 6 Km 5km -8 0 Sand & gravel Muddy Layer Fine Sand Bentonite Coarce Sand With Gravels Medium Sand YellowCoarse Sand Green Coarce Sand Sands Clays Water table Fault plane Silty clay Fig. (7): Hydrogeologic cross section along profile (V1-V1’) (Compiled after Ibrahem et al. 2005). Fig. (6): Hydrogeologic cross-section in Quaternary aquifer along profile (L2-L2’) Compiled after Serag El Din, 1983). 2.7.3 Recharge and discharge of the aquifer and relationship between surface water and GW: The main GW aquifer (Quaternary aquifer) in the study is considered as free aquifer relating to Pleistocene age and composed of loose quartz sand with pebbles and granules with intercalated thin clayey beds. The aquifer is recharged mainly by three sources, the seepage from the Nile Delta aquifer, seepage from fresh water of Ismailia canal, surface irrigation canals and drains and seepage from agricultural water uses and its fertilizers and Rainfall from desert wadis and from surface run off falling on shed area to the south. The occurrence of GW is highly controlled by the surface water. The relationship between GW and surface water is strongly influenced by the following factors, canal or lake depth, height of the water table relative to the surface and surface water levels, type of sediments forming the bottom and banks of surface water courses, rate of horizontal and vertical hydraulic boundary conditions of the GW system and Hydraulic conductivity of the aquifer. 2.8 Hydrogeochemical Studies 2.8.1 General outlines The hydrogeochemistry at the study area, has been studied by many workers among them Shata & El Fayoumy (1968), El-Shazly et al., (1975), El Hefny (1980), Sallouma (1983), Geriesh (1989), Gad (1995), El Sharkawi (2008) and Atwa (2010). Many ecological changes that occur in water result from human activities includes agricultural, industrial and municipal wastes (Katz et al., 1969). The liquid wastes and sewage are sometimes discharged into the River Nile and other water resources. Generally pollution expected from these sources: seepage from surface polluted irrigation canals , Fig. (8), seepage from agricultural water uses and its fertilizers refuses disposal sites, Fig. (9), sewer, polluted drains Fig. (10), sewage ponds, septic tanks (landfill and open dumpsites) and human sources and rainfall on the area of study from rock wadis and from surface run off falling on shed area to the south. The study of the hydrogeochemical characteristics of GW aims to recognize the water characteristics of the aquifer in the study area, reveal the effect of the geologic setting and the running 132 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 surface water on the GW quality and check the water stability for use for drinking, domestic and irrigation purposes. Fig. (8): Public disposal in Canal. Fig. (9): Public disposal in Drain Fig. (10): Qalubi Drain gaining wastewater 2.8.1 The hydrochemical Pollution Pollution is defined as any change in the physical, chemical, or biological conditions of the environment, which may harmfully affect the quality of human life including effects upon animals and plants. Environmental pollution represents a major problem in both developed and/ or under developed countries. Egypt is one of these countries which suffer from high biosphere pollution (air, soil and water).The water is to be polluted if it contains any chemical constituents in concentration over the maximum permissible level of the Guideline values average daily intake (ADl) of certain pesticides (Table 1). Table (1): The W.H.O. (1983) Guideline values average daily intake (ADl) of certain pesticides. Compound DDT Aldin & Dieldrin Chordane Hexachlorobenzene Lindane 2,4- D 2,4-Dichlorophenoxy acetic acid Guideline value 1.0 0.03 0.3 0.01 3.0 30.0 100.0 ADI – body weight mg/kg 0.005 0.0001 0.001 -0.01 0.1 0.3 2.8.2 Hydrogeochemical Characters of GW It will deals with hydrogeochemical studies at the study area as depth and quality of GW for drinking and domestic uses, quality of GW for livestock and poultry and the hydrochemical pollution. The W.H.O. (1971) and (1983) guidelines values, international and upper limit values for the drinking water quality standards are shown in Table (2). Depth to water table ranges between 3.43 m at WDB30 and 6.3 m at W33, while elevation of water table ranges between 2.6 m at WDB-30 and 7.7 at W 33 (Table 3). The water table in the southern portion of the old deltaic plain, i.e. at Zagazig, occurs at great depth, while it becomes shallower in the northern direction towards the north and east (Sallouma, 1983). Table (2): The W.H.O. (1971) and (1983) guidelines: for the drinking water quality standards. Characteristic constituents PH Chloride (Cl) Magnesium (Mg) Sodium (Na) Sulphate (So4) Calcium (Ca) Total dissolved solids.(TDS) W.H.O.(1983) guide line value 6.5- 8.5 250 ----------------400 --------1000 W.H.O.(1971) international standard 7.5- 8.5 200 ----------------200 75 500 133 Upper limit of concentration 6.5- 9.2 600 150 200 --------200 1500 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Table (3): The results of depth to water table and elevation for selected boreholes located in figure (5). Well No. MES-6 W9 W10 BB-14 MZ-14 Depth to water(m) Elevation of water Table(m) 2.1 4.51 5.08 4.3 3.5 7.9 4.49 2.8 8 7 Well No. W61 W8 WMES-7 W61 W8 Depth to water (m) 4.5 5.26 4.18 4.62 5.26 Elevation Of water Table(m) 4.5 3. 10.8 3.4 3 The direction of GW salinity increasing is from the south (El Nakhas 1070 ppm) towards the south (El Zawamel 400ppm) with gentle gradient. The water salinity with depth reflects that; the seepage is from the lower salt aquifer through a good pervious layer of Pleistocene old deltaic deposits (Table 4). Table (4): Salinity and electric conductivity in aquifer encountered in wells MA-7, MA-61, Mes-6 and Mit Gaber. Depth (m) 10 36 60 80 100 MA-7 T.D.S. E.C. 526 0.85 (ppm) (m.mho) 460 0.82 480 0.82 620 1.05 860 1.38 MA-61 T.D.S. E.C. 810 1.25 (ppm) (m.mho) 400 0.85 470 0.75 540 0.86 680 1.088 Mes-6 T.D.S. E.C. 1005 1.26 (m.mho) 500 0.85 540 0.86 620 1.05 Mit Gaber T.D.S. E.C. 1100 1.76 (ppm) (m.mho) 520 0.85 670 0.8 870 1.6 Groundwater hydrochemistry of the study area is based on the chemical analyses of water samples collected from 14 bore holes distributed through and around the area. The chemical analysis includes the measurement of pH (alkalinity), TDS (total dissolved salts), EC (electrical conductivity), total major cations (Na+, Mg++ and Ca++) and total major anions (Cl-, HCO3- and SO4--). These measurements are carried out at SHAPWASCO, Table (5), Atwa (2010). 7.6 8 0.9 9 MA-7 Mes-6 BB-14 Location 1.66 SO 4 -- .ppm. 6 HCO3-. ppm. 9 78 Cl-. ppm. 400 Ca++ .ppm. 7.5 Mg+ .ppm. TDS. ppm. 0.85 Na+ .ppm. PH 3 S.No. 61 W.n. EC.m mho Table (5): Results of Chemical analysis of water samples at the studied area analyzed by The SHAPWASCO laboratory, Atwa (2010). 24 52 130 230 38.4 Shembara 1070 168 31.2 84 240 340 176 El Nakhas 7.4 584 84 19.2 24 140 140 105.1 Zagazig 1.05 7.5 620 108 4.8 120 180 360 111.6 Bany H|elal 10 0.82 7.5 460 96 33.6 64 160 300 73.6 El Talein 11 0.9 7.5 480 72 14.4 104 120 320 80.4 Minia Alkamh 15 0.65 7.5 490 102 28.8 80 170 400 48 Mashtul Masaken 16 0.95 7.5 500 78 50.4 76 130 300 48 El Sehafa 17 0.65 7.5 360 30 33.6 64 50 300 34 Anshas 134 Eighteenth International Water Technology Conference, IWTC18 14 Sharm ElSheikh, 12-14 March 2015 18 0.8 8.5 512 73 12 66 114 244 49 El Zankaloun 23 0.85 7.5 520 45.6 9.6 40 76 140 85 Shobra El nakhla 24 1.6 7.5 870 180 24 72 300 280 29.6 Mit Gaber 25 0.85 7.4 400 120 19.2 40 200 180 38 El Zawamel 26 1.1 7.5 680 216 31.2 56 360 270 111.8 Awlad Seif 2.8.3 Graphical representation of the chemical analysis and hydrochemical salt combinations: PH Values: The pH values ranges between 7.4 (El Zawamel) and 8.5 (El Zankaloun). Its distribution map figure (10) shows that, the alkalinity increases toward southern and eastern parts with gentile gradient. The water PH lines around canals and drain are irregular and concave in shape which reflect that; the seepage is from canal to the surrounding lands through a good pervious layer of Pleistocene old deltaic deposits of the surrounding region (deltaic deposits), where the GW is more deep and fresh water. The results of chemical analyses show that leaching of salts may cause a change in pH values. 2.8.4 Distribution of Total Dissolved Solids: Total dissolved solids (T.D.S.) comprise dissociated and undissociated substances in water (Korany et al. 1997). The T.D.S. contour map (Fig.11) illustrates that low salinity samples occupied the central and western parts, while the high salinity are concentrated in the northern and the eastern parts. Total dissolved solids (T.D.S.) ranges between 1070 ppm (El Nakhas with freshwater old deltaic deposits) and 400 ppm (El Zawamel). The salinity shows gradual increase with depth and reaching about 1070 ppm at depth 80 shown in table (4). The lines around Ismailia Canal, Moweis canal and Bahr El Bakar drain are irregular and concave in shape which reflect the seepage from the canals and drain to the surrounding lands through a good pervious layer of Pleistocene old deltaic deposits. The used evaluation methods show that the water is generally suitable for drinking, irrigation and industrial usage whereas some samples have concentrations more than the permission by oxidation (weathering) precipitation and infiltration before usage. 31° 15' 31° 15' 32° 15' 31° 45' 32° 15' 31° 45' Manzala Lake Manzala Lake 16 31° 31° 00 31° 00 00 14 31° 00 El Huseiniya 12 Diarb Nigm IbrahimiaAbu Kabir Hihya a mh 10 8 Faqus Abu Hammad El Salhiya A lq 30° 30 30° 30' 30° 30 Ismailiya Canal Faqus Abu Hammad El Salhiya 30° 30' Ismailiya Canal Mi na 6 El Huseiniya Diarb Nigm IbrahimiaAbu Kabir Hihya 4 Mashtul El Soak Tenth of Ramadan 2 30° 0 00 0 31° 15' 2 4 6 31° 45' 8 10 10 Mashtul El Soak 10 Km 0 12 32° 15' 14 Tenth of Ramadan 16 30° 00 30° 00 C.I; 0.2 31° 15' 10 31° 45' 0 10 Km 32° 15' 30° 00 C.I; 1000 ppm Fig. (11): PH Value contour map of the aquifer of the studied area. Fig. (12: Iso Salinity (T.D.S.) contour map of the aquifer of the studied area. 2.8.5 Electrical conductivity Electrical conductivity (E.C) is the ability of substances to conduct an electric current. Specific electrical conductance can be defined as the conductance of a cubic centimeter of water at standard temperature of 25 oC. The ability of the solution to conduct the current is a function of the concentration and change of the ions, and the ability of each dissolved ions. Figure 13 shows the pH values contour map of the aquifer. 135 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Specific conductance, is measured in mmhos/cm, and gives results that are convenient as a general induction of T.D.S. (Todd, 1980). The maximum E.C. (1.66 mmhos / cm) is attained in W-9, while the minimum is obtained in sample (Enshas: 0.65 mmhos /cm). These values reflect the relation between the E.C. and T.D.S., where as the electric conductivity of water increase. Figure Fig. 14 presents the contour map for sodium Na+ of the aquifer in the study area. 31° 15' 32° 15' 31° 45' 31° 15' Manzala Lake 32° 15' 31° 45' Manzala Lake 16 14 31° 00 31° 00 31° 00 El Huseiniya Diarb Nigm IbrahimiaAbu Kabir Hihya 30° 30 Faqus Abu Hammad 31° 00 El Huseiniya 12 Diarb Nigm IbrahimiaAbu Kabir Hihya 10 Faqus 8 El Salhiya 30° 30 30° 30' El Salhiya Abu Hammad Ismailiya Canal 30° 30' Ismailiya Canal 6 Mashtul El Soak 4 Tenth of Ramadan 30° 00 31° 15' 10 0 Mashtul El Soak 10 Km Tenth of Ramadan 10 0 10 Km 2 31° 45' 32° 15' 30° 00 31° 15' 4 30° 00 C.I; 0.5 mmhos / cm Fig. (13): PH Value contour map of the aquifer of the studied area. 6 8 31° 45' 10 12 14 32° 15' 16 30° 00 C.I; 50 ppm. Fig. (14): Iso- Sodium (Na+) contour map of the aquifer of the studied area. 3 FIELD SURVEYING AND INTERPRETATION OF THE MEASURED DATA 3.1 A-Field Surveying And Data Acquisition Geophysical tools are useful in locating and delineating subsurface aquifers. The electrical geophysical techniques including 1-D resistivity sounding and 2-D imaging represent the main tools for mapping subsurface lithofacies and hydrogeochemical conditions and features of the GW aquifer. Description of the field measurements for each method is given in details. The resistivity measurements were carried out using SAS 300C system manufactured by ABEM Co., Fig. (18). The measuring current is selected manually with a maximum of 20 mA. Fig. (18):SAS-300C resistivity meter during sounding 3.2 Measuring of Resistivity Data: measurements. 3.2.1 Measuring of I-D resistivity data: During the last two decades, the curve matching technique become obsolete because of the availability of more computerized techniques (1-D inversion), which are the fastest and more accurate. However, the curve matchingmeathod might still be used in the absence of computation facilities during the tie of survey or derive an approximate model that is required as starting model for one of the iterative modeling techniques. The parameters of a layered sequence can be obtained from the resistivity transform of the field data using linear filtering theory (Koefoed, 1979), or directly from the field observations without using its resistivity transform (Zohdy, 1989). 136 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 3.2.2 Measuring of 2-D resistivity data: Loke and Barker (1995 and 1996) developed the smoothness-constrained least-squares inversion (deGroot-Hedlin and Constable, 1990) and produced a fast computer program (Res2dinv) for inversion of 2-D resistivity and IP data. The procedures of this technique are based on inversion by quasi- Newton method. The inversion technique of Loke and Braker (1996) is used to invert the measured 2-D pseudo sections in the present work and can be summarized as follows. 3.2.2.1 1-D Sounding Survey: A total number of 30 points of 1-D resistivity sounding were executed all over the area. The measurements are carried out along some selected drains, canals and other pollution sources at some selected sites. These sounding are carried out to reflect a regional picture about the subsurface geologic succession and to have an idea about the water bearing formations in the area. The location of the measured points is marked using GPs positioning. The distributions of these sounding points are shown in Fig. (19). The electrical sounding is carried out using Schlumberger configurations with maximum current electrode (AB) spacing of 400 m to explore shallow subsurface conditions. 3.2.2.2 2-D Resistivity Survey: The 2-D resistivity inversion aims to construct an image of the obtained true subsurface resistivity distribution and to map the saltwater intrusion within the area of study. The measured resistivity pseudo sections are 3 profiles at 3 sites located as indicated in Fig. (19). It is inverted using RES2INV inversion software, version 3.4. The inversion procedures used by this program are based on the smoothness-constrained least-squares inversion algorithm. The Sequence of measurements is used to build up a pseudo section in the field (Loke and Barker, 1995); Fig. (20). 31° 30 ' 32° 00 37 41 Manzala Lake 42 31 Aw 31° 00 lad 46 qr Sa 34 68 67 Ka fr Sa 54 61 IB-5 25 AK-1 Abu Kabir 53 72 el et ny Mi mh Qa 64 Hihya 81 52 Bah r B El aq ar Dra in 45 43 40 66 65 74 75 18 76 51 23 3 14 9 Faqus 58 57 HI-1 26 HI-8 24 22 azig17 Zag 16 30° 30 55 56 IHI-8 20 15 19 62 63 27 91 28 96 6 44 El Huseiniya 59 Ibrahimiya 35 48 36 Z4 50 qr 60 13 31° 00 47 69 33 30 12 11 Diarb Nigm29 39 49 73 38 7 5 78 El Salhiya 77 Z26" 30° 30 ' Abu Hammad 82 11 10 8 Mashtul el Soak Ismailiya Canal 70 83 10 71 BB-1 Studied area VES Location 79 88 4 80 89 2 87 90 2-D imaging location 96 Z20" 86 10 85 0 10 Km 84 97 Tenth of Ramadan 30° 00 31° 30 ' E7 32° 00 30° 00 Fig. (20): Sequence of measurements used to build up a pseudo section in the field (after Loke and Barker, 1995). Fig. (19): 1-D sounding points ( V.E.S.es) and 2-D locations 3.3 B-Interpretation of The Measured Data 3.3.1 Interpretation of 1-D Resistivity Sounding: The resistivity sounding data, in the form of apparent resistivity and electrode spacing (AB/2), are interpreted both qualitatively and quantitatively. The results of interpretation have been inspected to determine the litho-stratigraphic boundaries of subsurface layers and to define the possible waterbearing layers in the area as well as to evaluate the depth to save GW for drinking. Quantitative interpretation of the field data is carried out to obtain the true resistivity and thicknesses of subsurface layers using two different techniques, as follows, automatic interpretation technique of Zohdy (1989), the obtained multi-layer model from Zohdy technique is used as preliminary 1-D model for IPI2win software, version2.0 (Bobachev et al., 2001). The obtained results of 1-D modeling are illustrated in columns with the same scales, as geoelectric horizons and correlated with obtained data from drilled boreholes as exemplified in, Figs. (22 and 23). 137 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 To derive a resistivity spectrum of the different subsurface formation and reaching a reliable and acceptable interpretation, the following brief description of the obtained calibration is done: Sounding No. 95 was conducted beside well number 54 (Fig. 23). The inspection of the V.E.S. results corresponding to borehole horizon shows that, the first geoelectrical layer has a specific m and a thickness of 4.2 m. This resistivity is attributed to the near surface clay. The second geoelectrical layer has specific resistivities of 2.61 mand thickness of 5.67 m, this resistivity of 3.6 resistivity may be attributed to clay with seepage water. The third geoelectrical layer has specific mand thickness of 25 m, this resistivity may be attributed to sandy faces. The geoelectrical layer of 56.24 m is correlated with the saturated with freshwater gravelly sand in the resistivities of 23.3 borehole. Therefore, there is a large discrepancy in the V.E.S. results and the lithological log of the borehole, which may be attributed to the fact that this area is subjected to compaction to construct zone of surface water. The increases of compaction and water seepage with depth give low values of resistivities. On the other hand, the deeper layers show good agreement with the borehole data, Atwa (2010). ATO PROGRAM Appar. Resistivity [Ohmm] RMS: 2.5 % Sounding No. 6 RESIST PROGRAM Current Electrode Distance (AB/2) [m] Appar. Resistivity [Ohmm] RMS: 6 % Fig (22): Geoelectrical horizon Sounding No. 6 IPI PROGRAM 1-D modeling sounding results In addition, the interpreted layer parameters of the subsurface layers are listed in Table (6). Current Electrode Distance (AB/2) [m] Table (6): Results of computation of layer electric Resistivities and layer thicknesses for the field measurements. (ρ in ohm.m) (H in meters). V.E.S. NO. 1 3 5 6 9 14 19 72 82 83 88 Type (True Resistivities valuse m) K-A H-A K-A H-A H-A H-A H-A K A-Q A-Q A-K 1 4.96 16.6 13.4 3.52 2.93 7.7 4.429 6.33 3 9.8 9.61 2 9.62 11.6 48.2 2.076 2.07 5.41 2.071 7.42 2.26 3.78 3.63 3 12.6 44.7 41.4 17.02 2.82 11.7 20.82 12 5.09 11 10.8 4 46.4 49.2 56.2 47.4 9.62 383 80.72 120 23 53 111 Thickness of layers (m) 5 6 7 58.4 63.1 22.4 56.2 83.6 72.8 94.2 3.03 2.1 2.1 138 H1 4 0.2 1.26 3.37 0.55 1.82 2.73 2.624 4 6 5.9 H2 11 0.9 4 9.63 4 1.8 1.57 2.284 23 11.9 12 H3 6 3.5 7.9 20.9 3.62 3.24 1.18 17.7 10 20 18 H4 H5 31.5 13.7 2.63 61.8 10.4 20 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 3.3.2 Hydro geophysical Investigation: In hydro geophysical investigation, many geophysical tools are useful in locating and delineating subsurface aquifers. The interpreted layer parameters in the form of resistivity spectrum and lithology of the obtained layers are listed in Table (7). Table (7) Resistivity spectrum and lithology of the obtained layers in the study area. Formation Interpreted Lithology and hydrogeologic conditions Resistivity (Ώm) Thickness (m) Belqas Formation Holocene Surface layer (Agricultural layer) 3- 16.6 1.26-6 deposits Clayey facies 2.26-48.2 0.9-11.9 Clayey to Sandy facies (Cape rock) 5.09-44.7 1.18-20.9 Sand with gravel 31.4- 383 Mit Ghamr Pleistocene deposits Formation 3.3.2.1 Inversion of 2-D Resistivity Data: The 2-D resistivity inversion aims to construct an image of the obtained true subsurface resistivity distribution and to map the saltwater intrusion within the area of study. The measured resistivity pseudo sections (4 profiles at 4 sites) are inverted using RES2INV inversion software, version 3.4. The inversion procedures used by this program are based on the smoothness-constrained least-squares inversion algorithm, which was previously described. The 2-D model used in this program divides the subsurface into a number of rectangular blocks and the resistivity of the blocks are adjusted in an iterative manner to reduce the difference between the measured pseudo section and calculated model, Fig. (24). The resistivities of calculated model are obtained using either the finite-element or finite difference method. Fig. (24): The apparent resistivity pseudo section, calculated model, and 2-D inversion for a Wennar array at Teheimer site. 4 RESULTS AND DISCUSSION From the previous calibration of the resistivities with the corresponding lithofacies and hydrogeochemical conditions, as well as the different geoenvironmental sites in the area of study, it is observed that the resistivity differs for different lithologies according to the their hydrogeochemicl conditions. The study area is characterized by shallow freshwater aquifer trough the following investigations: 1-Hydroresistivity application: 30 sounding points were executed all over the area Fig. (25). The deduced layer parameters were used to construct 10 geoelectric cross- sections correlated with 8 boreholes at different locations as indicated in Fig. (26). 2-Resistivity application; where different geophysical surveys were applied. 139 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Geoelectric resistivity 1-D using vertical sounding (V.E.S.’es) and Schlumberger configurations with maximum current electrode (AB) spacing of 400m has been carried out to explore shallow subsurface condition sand zone of pollution. The interpreted layer parameters in the form of resistivity spectrum and lithology of the obtained layers correlated with boreholes all over the area of study. Hydrogeochemical and geoenvironmental application are listed in (Table 11). 3-True resistivity contour maps are prepared by contouring the values of interpreted true resistivities for different geoelectrical layers, in order to study the lateral and vertical variations of the resistivities with depth. From the tabulated resistivity values Table, (1), three geoelectrical layers are mapped in figures 27, 28, 29, 30, 31 and 32). 4-Three 2-D inverted sections are selected along drains, canals and other pollution sources at some selected sites all over the area of study. (Teheimer, El Nakhas and El Zankaloun) using Wenner array, Fig. (25). The constructed sections are useful in defining the subsurface layer distribution, exploring shallow subsurface conditions and zone of pollution and outlining the extension of the expected aquifer layers. 31° 30 ' 32° 00 31° 30 ' 32° 00 31° 15 ' 37 31° 15 ' 41 Z30" 41 37 Z33 Z31 Manzala Lake 42 31 Sector 2 Z34 46 31° 00 34 31° 00 39 49 47 34 Z23 68 67 50 44 45 El Huseiniya 61 DB-30 13 Ibrahimiya IB-5 35 ZM-17 48 36 91 72 MA-15 MA-7 16 38 El Salhiya 77 Abu Hammad Z26" 72 30° 30 ' T57 Z11 Z1 Z8 Z9' 79 10 DB-14 E3 BB-1 Studied area VES Location Water Smple location Bore Hole location 4 E2 2 P3 90 89 87 Z20" 86 T7 MES-10 MES-7 MES-5 MES-6 88 30° 15 ' 2-D imaging location 79 85 84 0 Z5 7 AH-6 10 Z14" BB-1 E2 87 Z20" T7 T56 Z11" E7 32° 00 Fig. (25):2-D, V.E.S.es and borehole location E5 VES Location Bore Hole location Resistivity Cross-section 30° 15 ' 2-D imaging location T56 Z12 97 Ramadan Z29" 31° 30 ' T57 Ismailiya Canal 89 85 Tenth of Tenth of Ramadan E6 Z26" Z12" Z21" Z35" Sector 396 84 97 30° 00 77 Z15" T25 4 P3 T56 El Salhiya 78 Z24" 2 Z14 E4 38 Z13 86 74 75 Abu Hammad 71 90 30° 45 ' Sector 1 Z27" Z10 7 Z19" E3 Z22" 66 Z18" 76 51 Z28" 80 Z19 10 Km 55 Z28 Z23" Z24 70 DB-14 8 Mashtul el Soak E1 10 Z9 Z4' 10 96 Sector 3 Z29 3 Z6' Z7' 73 5 BB-12 8 FA-1 Z27" 64 65 Z17" Z15 52 11 Z20 Faqus 58 57 AH-3 17 Z3 14 Z2 Z22 MA-27 DB-7 71 80 E1 9 82 83 E5 10 8 ZM-4 MA-15 MA-7 Ismailiya Canal 70 BB-12 8 MES-10 MES-7 MES-5 MES-6 Mashtul el Soak 78 AH-6 7 Z4' 11 88 T56 E4 3 73 DB-7 83 FA-4 Z33" Z25" AK-1 Abu Kabir 53 Z30 Z26 AK-7 56 40 62 Z29" 23 Z34 Z32 45 44 El Huseiniya 63 18 22 17 19 MA-13 Sector 2 50 54 43 HI-5 Z6 6 47 69 68 Z27 61 ZC-9 76 51 AH-3 5 MA-27 74 75 Sector 1 23 Z3 14 9 82 52 18 22 17 ZM-4 30° 30 66 HI-5 Z4 19 30° 45 ' 55 65 39 Z18 49 Z25 67 60 Ibrahimiya Z29 13 IB-5 25 Z16" 35 ZM-19 Z8' ZM-17 IHI-8 27 Z1"91 ZM-2 Z5' 48 Z2' 20 15 HI-1 Z3' Hihya Z10' Z7 ZC-18 26 HI-8 81 24 36 28 FA-1 64 81 24 96 MA-13 Faqus 58 57 Hihya ZC-18 26 HI-8 28 FA-4 AK-1 Abu Kabir 53 HI-1 Z21 11 DB-30 DB-32 AK-7 56 27 20 ZC-9 6 25 Diarb Nigm29 62 63 IHI-8 ZM-2 15 40 Z34" 59 30 Z31" Z16 12 43 60 33 Z17 59 54 DB-32 Sector 2 46 69 33 30 12 11 Diarb Nigm29 Manzala Lake 42 31 Z35 10 0 10 Km E6 30° 00 31° 30 ' E7 32° 00 Fig. (26): cross-sections, V.E.S.es and borehole location 4.1 The Geoelectric Cross-Section (shallow freshwater aquifer): The shallow fresh water aquifer includes the geoelectric cross-sections of Markaz El Zagazig and its surrounding. The aquifer represented by Mit Ghamr Formation. The correlation between 1-D models 30 V. E. S.es, chemical analysis of water samples and 8 boreholes shows resistivity spectrum of the subsurface litho- hydrogeological units in the studied area and characterized by fresh water aquifer area table. Positions of different cross sections are shown in table (8). GW level subdivided the second layer into two resistivity facies, the upper facies represented by low values sandy facie and the lower facies represented by silty to sandy facies. The resistivity ranges for the upper and lower facies are shown in Table (9). Table (8) Positions of different cross sections and corresponding sounding point Number of Cross Position Sounding point included Section 6, 28, 15 and 35 across the borehole Z1-Z1 El Talein, El Nakhas, Frsis and El Setohia). No.9 (Mit Rabiaa, El Zankloun, Gamal Abd El Naser, 9, 19, 21, 95 and 17 across the Z2-Z2 Maokaf El Mansoura and Manzel Haian). borehole No. 33 (Mit Habib, Mit Abu Ali, El Aslogy, El Shobak, El 1, 14, 16, 17, 22 and 24 across the Z3-Z3 Salamoun). borehole No.10 6, 19, 14 and 5 across the borehole Z4-Z4 (El Talein, El Znkloun, Mit Abu Ali, Bourdein). No 14 6, 48, 36 and 35 across the borehole Z8-Z8 (El Talein, Shembara, Deweida and Setohia). No.61 (El Sanagra Bourdein, Mit Hbib, Mit Rabiaa and 7, 5, 1, 9 and 6 across the borehole Z9-Z9 El Talein). No.8 140 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Table (9) The resistivity ranges in the second layer for the upper and lower facies Number of Cross Section Z1-Z1 Z2-Z2 Z3-Z3 Z4-Z4 GW level subdivided the second layer into two resistivity facies The upper facies represented by low The lower facies represented by silty to values sandy facie and resistivity ranged sandy facies and resistivity ranged between between 2.076ohm.m at V.E.S.6 and 7.36ohm.m 13.1ohm.m at V.E.S. 15 and 17.02ohm.m at V.E.S.15, at V.E.S.6. 2.07ohm.m at V.E.S. 9 and 3.85ohm.m 9.62ohm.m at V.E.S.9 to 20.82ohm.m at at V.E.S.85, V.E.S.19. 1.69ohm.m at V.E.S.24 and 42ohm.m at 4.64hm.m at V.E.S.16 to 11.7ohm.m at V.E.S V.E.S.16 V.E.S.14. 2.07ohm.m at V.E.S.14 and 48.2 ohm.m 11.7 ohm.m at V.E.S.14 and 41.4 ohm.m at at V.E.S.5, V.E.S.5. There was variety of resistivity values in the four layers for each cross section. Table (10) shows the depths of the four layers and the range of resistivity values in each cross section. The deduced layer parameters are used to construct 10 geoelectric cross- sections at different locations and directions as indicated in Fig. (26) to Fig (32).Correlation between salinity distribution in the layer and the variation of salinity are shown in Table (11). 141 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Table (10) specific resistivity and layers thickness for different cross section Number of cross section Range in Thickness Z1Z1 Specific Resistivity Range in Thickness Z2Z2 Specific Resistivity Range in Thickness Z3Z3 Specific Resistivity Range in Thickness Z4Z4 Specific Resistivity Range in Thickness Z8Z8 Specific Resistivity Range in Thickness Z9Z9 Specific Resistivity Layer 1 Holocene riverine dry clay to clayey silt and sand range 0.298 m at V.E.S. 35 and 2.51 m at V.E.S. 28 3.526 ohm.m at V.E.S.6 and 9.26 ohm.m at V.E.S.15. 0.595 m at V.E.S. 21 and 2.73 m at V.E.S. 2.49ohm.m at V.E.S.9 and 86.1ohm.m at V.E.S.21 1.8 m at V.E.S. 16 and 5.5 m at V.E.S. 1. 2.01ohm.m at V.E.S. 24 and 42ohm.m at V.E.S.16. 1.26 m at V.E.S.5 and 2.442 m at V.E.S. 19. 3.526ohm.m at V.E.S.6 and 13.4 ohm.m at V. E. S.5. 0.298 m. at V.E.S. 35 and 2.89 m. at V.E.S. 48. 3.52 ohm.m at V.E.S. 6 and 7.66 ohm.m. at V.E.S. 48. 0.554 m at V.E.S. 9 and 5.5 m at V.E.S. 1. 2.93 ohm.m at V.E.S. 9 and 13.4 ohm.m. at V.E.S. 5. Layer 2 Holocene Riverine (Nile ) clay, silty clay and silt 2 m. at V.E.S.28 and 4.05 m at V.E.S.35. 2.076 ohm.m at V.E.S.6 to 7.36 ohm.m at V.E.S.15. 1.57 m at V.E.S. 19 to 3.37 m at V.E.S. 85 1.57 ohm.m at V.E.S.19 to 6.24 ohm.m at V.E.S.21. ------------------------- 4.64 ohm.m at V.E.S.16 and 9.62 ohm.m at V.E.S.1. Layer 3 Pleistocene sands Layer 4 Pleistocene gravely and coarse sand -------------- ------------------- ohm.m at V.E.S.6. 13.1ohm.m and 17.4 ohm.m ----------------- 47.4 ohm.m at V.E.S. 6 and 197 ohm.m at V.E.S.28. ---------------- 7.08 ohm.m at V.E.S. 27 to 20.82 ohm.m at V.E.S.19. 8.91 ohm.m at V.E.S.16 and 35.4ohm.m at V.E.S.24. 8.91 ohm.m to 9.3 ohm.m 46.4 ohm.m at V.E.S. 27 to 94.8 ohm.m at V.E.S. 21. ------------------ 2.435 m at V.E.S.19 and 2.8 m at V.E.S. 14 ---------------- 31.6ohm.m at V.E.S.16 and 383 ohm.m at V.E.S.14 -------------------- 2.07 ohm.m at V.E.S.19 and 5.41ohm.m at V.E.S.14. 1.69 m. at V.E.S. 36 and 3.14 m. at V.E.S. 35. 11.9 ohm.m atV.E.S.5 to 22.9 ohm.m at V.E.S.6, ----------------- 47.4ohm.m at V.E.S.6 and 383 ohm.m at V.E.S. 14. --------------------- 2 ohm.m at V.E.S. 16 and 6.81 ohm.m at V.E.S. 35. 13.6 at V.E.S. 35 and 35.6 ohm.m at V.E.S. 6. 2.63m at V.E.S. 9 and 22.99m at V.E.S. 6. 50.1 ohm.m at V.E.S. 35 and 147 ohm.m at V.E.S. 48. ------------------- 12.6 ohm.m at V.E.S. 1 and 48.2 ohm.m at V.E.S. 32.5 ohm.m at V.E.S. 7 and 63.1 ohm.m at V.E.S. 9. 1.64 m. at V.E.S. 7 and 25.541 m at V.E.S. 6. 2.82 ohm.m at V.E.S. 9 and 48.2 ohm.m at V.E.S. 5. 142 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Fig. ( 30): The Geoelectric Cross-Section Z4-Z4". Fig. ( 28): The Geoelectric Cross-Section Z2-Z2". Fig. ( 31): The Geoelectric Cross-Section Z8-Z8". 1 Eighteenth International Water Technology Conference, IWTC18 Fig. ( 29): The Geoelectric Cross-Section Z3-Z3". Sharm ElSheikh, 12-14 March 2015 Fig. ( 32): The Geoelectric Cross-Section Z9-Z9" Table (11) correlation between specific resistivity and salinity distribution in different cross section No. of Section Z2-Z2 Z3-Z3 Z4-Z4 Correlation between resistivity and TDS confirmed that the Pleistocene sands represents the upper aquifer of underground water and the static water level measured at depth of 3.9 m. the expected connection between drain water zone and clay zone. the Pleistocene sands represents the upper aquifer of underground water and the static water level measured at depth of 4.62 m. 2 Eighteenth International Water Technology Conference, IWTC18 Z8-Z8 Sharm ElSheikh, 12-14 March 2015 a connection between seabage water and underground water (increasing resistivity from 2.56 ohm.m for upper facies to 6.81 ohm.m . 3 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 4.2 True Resistivity Contour Maps True resistivity maps are prepared by contouring the values of interpreted true resistivities for different geoelectrical layers, in order to study the lateral and vertical variations of the resistivities with depth. From the tabulated resistivity values Table, (1), four geoelectrical layers are mapped in figures 33, 34, 35 and 36). Consideration of these maps shows that; 1-The north and eastern parts Zagazig , of the studied area is graded from low resistivity values of clays and sandy clays to medium values of moisture to partially saturated sands, while some localities of dry surface layers due to presence of drains is represented by high resistivity values as El Aslogy. The developed low resistivity anomaly may be due to decreasing in the percent of gravels in this local part. 2-The southern part is occupied by high resistivity values at layer 1 of dry sand, which is shifted toward the west at layer 2. This anomaly is graded to medium values at layer 4 of saturated gravelly sands. 3- Depth 1m. is represented by high resistivity values at layer 1 of dry sand and presence of drains , which is shifted toward the west. This anomaly is decreased at depth 5m Fig. (33) as the effect of seepage water and fertilizers. This anomaly is graded to medium values at 10m Fig. (34) of saturated gravelly sands. The developed low resistivity anomaly may be due to decreasing in the percent of gravels in this local part of buried channels. 4- Groundwater resistivity is characterized by depths 36m and 46m which low grade variation in values Figs. (35 and 36). The anomaly graded to medium values towards north and east is in well agreement with T.D.S. contour map Fig. (12). 31° 15' 31° 15' 32° 15' 31° 45' 32° 15' 31° 45' Manzala Lake Manzala Lake 16 14 31° 00 31° 00 31° 00 12 31° 00 El Huseiniya El Huseiniya Diarb Nigm IbrahimiaAbu Kabir Hihya 10 Diarb Nigm IbrahimiaAbu Kabir Hihya Faqus Faqus 8 30° 30 6 Abu Hammad El Salhiya 30° 30' 30° 30 Ismailiya Canal Abu Hammad El Salhiya 30° 30' Ismailiya Canal 4 Mashtul El Soak 2 Tenth of Ramadan 30° 0 00 31° 15' 0 2 4 6 10 31° 45' 8 10 Mashtul El Soak 10 Km 0 32° 15' 12 14 Tenth of Ramadan 16 30° 00 30° 00 31° 15' C.I; 10 Ohm.m 0 10 Km 32° 15' 31° 45' Fig. (34): True resistivity Contour Map at Depth 10 m. 31° 15' 32° 15' 31° 45' 32° 15' 31° 45' Manzala Lake Manzala Lake 31° 00 31° 00 31° 00 31° 00 El Huseiniya El Huseiniya Diarb Nigm IbrahimiaAbu Kabir Hihya 30° 30 Diarb Nigm IbrahimiaAbu Kabir Hihya Faqus Abu Hammad El Salhiya 30° 30 30° 30' Faqus Abu Hammad El Salhiya Mashtul El Soak Mashtul El Soak Tenth of Ramadan 31° 15' 30° 30' Ismailiya Canal Ismailiya Canal 30° 00 30° 00 C.I; 10 Ohm.m Fig. (33 ): True resistivity Contour Map at Depth 5 m. 31° 15' 10 10 0 31° 45' Tenth of Ramadan 10 Km 32° 15' 30° 00 30° 00 31° 15' 31° 45' 10 0 10 Km 32° 15' 30° 00 C.I; 20 Ohm.m C.I; 20 Ohm.m Fig. (35):True resistivity Contour Map at Depth 36 m. Fig. (36):True resistivity Contour Map at Depth 46 m. 4.3 2-D resistivity imaging: Four 2-D inverted sections are obtained along the selected locations using Wenner array. 1 Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 Site 1 is located eastern side of El Qaliubia drain at Teheimer village sector 1 Fig. (37). Along the profile, a well defined low resistivity zone of 0.865 to1.91 ohm.m is observed at a depth of 6.38 m and corresponds to the fresh and brackish water as indicated by the drilled borehole. The lower aquifer boundary defined by a layer continuing less saline water. The depth to fresh water and saline water boundary is increased in the western part (drain direction passing with) to reach maximum value of 12.4 m at spacing 25 m to reflect more thickness of polluted water at that place. It should be noticed that the dry zone near drain of increasing resistivity is in well agreement with 1-D sounding 16. Fig. (37 ): 2-D Wenner inverted image eastern side of El Qaliubi Drain at Teheimer village. Site 2 is located in El Nakhas village sector 1, Fig. (38). Along the profile, a well defined low resistivity zone of 0.958 to15 ohm.m is noticed at a depth of 6.38 m and corresponds to the fresh and brackish water as indicated by the drilled borehole. The lower aquifer boundary is defined by a layer continuing less saline water. The depth to fresh water and saline water boundary is increased with depth to reach maximum of 12.4 m at spacing 25 m and 120 to reflect more thickness of polluted water at that places. It should be noticed that the lower fresh water aquifer zone of increasing resistivity is in well agreement with 1-D sounding 28. Fig. (38): 2-DWenner inverted section inside of El Nakhas village area Site 3 is located in El Zankaloun village sector 1, Fig. (39). Along the profile, a well defined low resistivity zone of 0.958 to59.6 ohm.m can be noticed that depth of 6.38 m and corresponds to the fresh and brackish water as indicated by the drilled boreholes. The lower aquifer boundary is defined by a layer containing less saline water. The depth to fresh water and saline water boundary is increased with depth to reach maximum value of 12.4 m at spacing 25 m and 120 m to reflect more thickness of polluted water at that places. It is observed that the lower fresh water aquifer zone of increasing resistivity is in well agreement with 1-D sounding 19. Fig. (27): 2-DWenner inverted section inside of El Znkaloun village. 2 Fig. (39): 2-DWenner inverted section inside of El Nakhas village area Eighteenth International Water Technology Conference, IWTC18 Sharm ElSheikh, 12-14 March 2015 4.5 PROPOSED TREATMENT METHODS The results of the resistivity maps in the one and two dimensions indicated that the salinity values is very high so the primary treatment should be taken into account to reduce the BOD of the incoming wastewater. The experience of the first author with this treatment method proved that the use of the primary treatment method reduces the BOD by 20-30% and the reduces the total suspended solids by some 50-60% . The use of the secondary (biological) treatment is important to remove the suspended solids. It is removal efficiency is about 85% of the suspended solids. The BOD can be also removed by a well running plant with secondary treatment. Also, the tertiary treatment can remove more than 99 percent of all the impurities from sewage, producing an effluent of almost drinking-water quality as shown in Table (12). The additional costs due to use of Tertiary treatment for different types of station are tabulated in Table (13). Table (12). Chemical analysis of effluents and permitted to freshwater. Type Analysis TDS T. S. S. C.O.D. H2S B.O.D T.C.F/100ml Raw water Analysis 1092 440 640 10 410 20000 Primary Effluent 987 105 280 3 183 12000 Secondary Effluent 797 18 24 0.4 16 4200 Tertiary Effluent 677 2 0 0 0 1000 Table (13). Original cost of some treated stations and suggesting adding values for tertiary treating at Minia Alqamh, Sharkia Governorate, Egypt. Treated water station Shalshalamoun Algodeida Shembara Atallein Original Cost pounds 710000000 67000000 71000000 26000000 Designal Productive quantity m3/day Suggesting adding value for tertiary treating 20000 15000 15000 5000 2000000 1800000 1800000 1000000 5 SUMMARY AND CONCLOSION The study area of the present paper lies to the eastern part of Nile Delta. The present study assesses the GW in some selected areas in Minia-Alqamh district and locates the potential sources for GW pollution, based on the available land use data and by using, the geoelectric resistivity survey. The geoelectric resistivity are carried out and interpreted in the form of apparent and true resistivity maps, geoelectric cross sections and integrated models. The final models are based on the results of integration of resistivity measurements and data of both hydro-geological and chemical analysis. The results of the six geological cross sections showed that the quaternary aquifer consists of four layers. The first layer presented by Holocene riverine dry clay to clayey silt and sand range (3- 16.6 Ώm), the second layer presented by Holocene Riverine (Nile) clay, silty clay and silt(2.26-48Ώm). The third layer presented by Pleistocene sands (5.09-44.7Ώm) while the fourth layer presented by Pleistocene gravely and coarse sand (31.4- 383Ώm). The GW level subdivides the second layer into two resistivity facies, the upper facies is represented by low values sandy facie (Belqas Formation Holocene deposits ) and the lower facies is represented by silty to sandy facies. (Mit Ghamr Formation). The results of the present research indicate that; - Very high conductive anomalies in the top 4-12 m of the subsurface. 3 Eighteenth International Water Technology Conference, IWTC18 - - Sharm ElSheikh, 12-14 March 2015 The groundwater in the study area is subject to a potential pollution from the surface waste from surface pollution sources such as: sewer, polluted drains, sewage ponds, septic tanks and refuse disposal sites and human sources. The values of the BOD and the total suspended solids are very high and exceeding the allowable values, so the primary treatment and biological treatment should be included in the water treatment plants to reduce their concentration in the wasted water before it finds its way to the drain and after that to the groundwater. 6 RECOMMENDATIONS - - Improper land waste disposal within the drains has negative impacts on the quality of the groundwater at the studied area. 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