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Home , Beheira Governorate, Kafr El Sheikh, Rosetta, Talkha

Freshwater Contamination (Proceedings of Rabat Symposium S4, April-May 1997). IAHS Publ. no. 243, 1997 255

Hydrogeological and water quality characteristics of the saturated zone beneath the various land uses in the Delta region,

ISMAIL MAHMOUD EL RAMLY PO Box 5118, Heliopolis West, , Egypt Abstract The saturated zone lies beneath several land uses which reflect variations in the aquifer characteristics within the delta basin. The present study investigates the scattered rural and urban areas and their environmental impacts on the water quality of the underlying semi-confined and unconfined aquifer systems. The agricultural and industrial activities also affect the groundwater quality located close to the agricultural lands and the various industrial sites, which have started to expand during the last three decades.

INTRODUCTION

It is believed that the population increase and its direct relation to the expansion of the rural and urban areas in Egypt during the last 30 years has affected the demand for additional water supplies to cover the need of the inhabitants in both areas, which in turn has many consequences for aquifer pollution through the effects of municipal wastewater effluent. The construction of the High Dam caused agricultural expansion by changing the basin irrigation system into a perennial irrigation system. Increase in the application of fertilizers and pesticides has caused the pollution of the surface water bodies which are connected with the aquifer systems in the Nile Delta basin. Industrial activities have much affected the groundwater system below the Nile Delta region due to the increase of the industrial waste effluent dumped into the river without any treatment. Factories involved in sugar, fertilizer, paper, textile and chemical manufacturing, and in food production and steel and iron and wood processing, and oil refineries among other works dump all their hazardous wastes into the river and irrigation canals. The Ministry of Public Works and Water Resources with its specialized institutions is conducting a very comprehensive programme for monitoring water quality in both surface and subsurface water bodies, which is indicating the environmental impact of the different wastes from point and non point sources, especially in the Nile Delta basin.

MORPHOSTRUCTURE OF THE NILE DELTA

The Nile and its Pliocene-Quaternary predecessors accumulated a very large alluvial sequence of deltas, coastal deposits, shelf and slope aprons and deep-sea fans. The present delta, formed since the stabilization of the Holocene sea level some 6000 years ago, covers a triangular area of 22 000 km2. The Nile Delta extends 175 km 256 Ismail Mahmoud El Ramly from base to apex and 220 km along its base. The thickness of the Neogene- Quatemary sediments in the delta exceeded 4 km in the Kafr El-Sheikh borehole. The Pliocene-Quaternary prism of the Nile River was deposited on top of the Upper Miocene erosional surface of the shallow marine zone, and on the contemporaneous evaporite series in the marine environment. In the present study reference is made to the Prenile (600 000 to 125 000 BP) and the Neonile (125 000 BP to 30 000 BP). The Prenile river was the largest and most effective one in forming the modern valley, the delta and the coastline and had a delta twice the surface area of the modern one. The Prenile/Neonile interval extended from the waning of the Prenile 125 000 BP to the breakthrough of the Neonile at 30 000 BP and was characterized initially by a pluvial period during which large quantities of gravel derived from the Eastern Desert were brought down to the Mediterranean and deposited unconformably on top of the Prenile sands and silts. During the following arid period, the valley and lands were eroded by wind and cyclonic rains to nearly their present form. The Neonile, with a regime similar to the modern one, commenced in Egypt 30 000 years ago, and the regime of the present river was established about 9000 years ago. Initially the distributaries of the delta were numerous and extended as far eastward as the old Pelusiac branch which emptied into the Bay of Tineh (east of ) and seven branches were known in historical times, five of which since have silted up. Only

Fig. 1 The study area. Hydwgeology and water quality of the saturated zone in the Nile Delta, Egypt 257 two, and , are active at present (Fig. 1), but with limited flow because of the building of the Dam. About 20 km north of Cairo the Nile divides into two branches which meander across the Nile Delta before entering into the Mediterranean at Rosetta and Damietta. The western terminus of the delta is in the vicinity of and its eastern terminus is just east of the Canal at the bay of Tineh where the now abandoned Pelusiac branch entered the Mediterranean.

STRATO-SEDIMENTOLOGICAL CHARACTERISTICS OF THE NILE DELTA

Prior to the extensive on exploration activities in the Nile Delta, it was somewhat difficult to predict the several sedimentological cycles which have occurred in the delta region. Several authors came to the conclusion that there were cycles of sedimentation in the Nile Delta region, viz. the Miocene, the Plio-Pleistocene and the Holocene cycles. Eight geologic formations were identified in the Nile Delta basin. These thicknesses of these formations from base to top are: (>700 m), Qawasim (700 m), Rosetta (80 m), Abu Madi (300 m), Kafr El-Sheikh (1500 m), El- Wastani (300 m), (700 m) and Bilqas (50 m). The Neogene-Holocene section is composed of shales with interbedded dolomite- marl, sandstones, siltstones, clays, and silts and gravels, with anhydrites and conglomerates. The eastern and southern sides of the Nile Delta are characterized by a sand section with lenses of gravels. Towards the north, the gravels gradually change into sand interbedded with clay layers. The centre of deposition was located to the northeast, and distinct topographic variations occur in the northwest. There is a strong possibility that sediments have been transported from the Red Sea hills (Eastern Desert) and also from the east (Sinai side). The contribution of the basement rocks and the abundance of stable and less stable minerals has been interpreted as due to progressive denudation and unroofing of tectonically active provinces with igneous and metamorphic rocks. This was identified in sediments of the Kafr El-Sheikh, Sidi- Salem and Abu-Madi Formations.

THE NILE DELTA AQUIFER SYSTEMS

The aquifer systems are recharged from deep percolation of subsurface drainage water and seepage from the main irrigation canals crossing the Nile Delta region. The average rate of recharge from the excess irrigation water varies between 0.25 and 1.1 mm day"1. The groundwater aquifer system in the Nile Delta is divided into two major aquifers, viz. the semi-confined aquifer and the unconfined aquifer. Figure 2 shows the distribution of these two aquifers within the delta itself and its fringes (eastern and western). Water samples collected for chemical analyses from shallow depths (nearly 40 m below the ground surface) showed a wide variation in their salt content. Examples from five governorates indicated that the total dissolved solids (TDS) concentration in the El- ranges between 430 and 16 150 mg l"1. In the Kafr-El- Sheikh governorate the TDS ranges between 890 and 10 715 mg l"1. The TDS in the 258 Ismail Mahmoud El Ramly

Fig. 2 General map of the Nile Delta groundwater reservoirs.

groundwater of the El-Monoufia governorate range between 415 and 850 mg l"1. In the El-Sharkia governorate the TDS range between 590 and 2205 mg l"1. The El- Dakahlia groundwater showed a range of TDS from 620 to 19 730 mg l"1. The nitrate content in the groundwater varies from one governorate to another, and ranges between 66.45 and 265.8 mg l"1. The highest concentration of nitrates are found in the El-Beheira and Kafr El-Sheikh governorates. The nitrate content in the Nile water at Cairo is 57.6 mg l"1. The nitrate content in the groundwater is higher than that of the drainage water and the River Nile. The very mobile nature of nitrate ions facilitates their downward migration from the surface to the groundwater in the saturated zone. It should be noted that intrusion of seawater from the Mediterranean has increased the salinity of the groundwater in the aquifers of the northern delta area (El-Dakahlia, Kafr-El-Sheikh, and El-Beheira governorates) and has rendered it unsuitable for any use because of the high TDS and nitrate content.

IMPACT OF AGRICULTURAL AND MUNICIPAL ACTIVITIES

Groundwater levels are generally high in most of the agricultural irrigated lands, but are most acute in the Nile Delta area. Although seasonal fluctuations in aquifer water levels have been reduced since the advent of the High Dam, due to the absence of the annual Nile floods, data from continuous water level recorders reveal a trend towards higher groundwater levels during the summer months as a result of increased application of irrigation waters. Subsurface disposal of village wastewaters, which drain through the sediments underlying the surface, is a factor additional to the increase in irrigation waters. The land surrounding the delta villages are largely used for irrigated agriculture where subsurface drainage is being widely promoted through Hydrogeology and water quality of the saturated zone in the Nile Delta, Egypt 259 the use of tile drain systems discharging to drainage ditches which ultimately carry their flows to the . These subdrain systems do provide some relief from the problems of the high groundwater levels in the agricultural fields and may have some limited effects extending to village areas in some cases. However, in the villages, the problems of high groundwaters and subsurface drainage are seriously compounded by the increasing disposal of wastewaters into the ground through various seepage methods. With the increasing development of village water supply systems and through increase in the income of villagers, water usage and the associated subsurface disposal discharge have significantly increased during the last two decades. Consequently, the drainage capacity of the surface clay deposits has been exceeded, the subsurface soils simply are saturated and drainage rates are inadequate. This situation resulted in the formation of groundwater mounds below the village areas. Figure 3 shows the average salinity of drainage water in the Nile Delta in 1991 expressed as g m3. Accordingly, many difficulties with groundwater have started to appear such as emerging surface pools of septic waters, gross groundwater contamination, deterioration of buildings and structures due to moisture absorption and several other relevant problems. Furthermore, in certain areas where large irrigation canals exist, the flow in the canal is at a level above the altitude of the village and an hydraulic gradient of seepage through the dikes toward the village is created. In the Nile Delta region, a minor percentage of the rural population has access to sanitary waste disposal systems and few villages have complete sewer systems. It

(MEDITERRANEAN SEA

Fig. 3 Average salinity (g m"3) of drainage water in the Nile Delta in 1991. 260 Ismail Mahmoud El Ramly

should be pointed out that although collective treatment of excreta disposal and wastewaters is not extensively practised in Egyptian villages, it is receiving attention as an urgent environmental problem by the authorities through legislation and control action. Pollutants from agricultural activities include salts, nitrogen, organic matter, phosphorus, organochlorine pesticides, etc. With increased generation and discharge of human wastes, the potential for con­ tamination of surface and groundwaters by harmful micro-organisms is rising. Faecal pollution can introduce a variety of internal (enteric) pathogenic bacteria, viruses and parasites. Their presence is linked to microbial diseases. These are considered to be one of Egypt's most serious water quality hazards, and present the greatest threat to the health and life of the Egyptian people, and therefore merit close study.

IMPACT OF INDUSTRIAL ACTIVITIES

Industrial societies use large quantities of metal, which would not be readily available for solution in water. Sources of pollution by trace metals have been attributed to improper management and disposal of industrial wastes. Industries responsible for occurrence of heavy metals are generally those in the heavy engineering, electroplating, tanneries, or chemical categories. At the southern tip of the Nile Delta, in the Shoubra El-Kheima area, the industrial activities include metal production, food processing, detergent and soap manufacturing, textile finishing and paper production. Huge volumes of untreated wastewater are discharged into the agricultural drains daily. In a recent study, 89 industries were identified as being major sources of water pollution in the area. The metal industry, which represents only 15% of the total number, discharges almost 50% of total waste water. High concentrations of trace metals have been found at Qualiub, Al-Mehalla El-Koubra, Kafr El-Zayat, El-Mansoura, , , Kafr El-Dawar and Idfina. In addition to the aforementioned industries, the thermal power stations and oil refineries in the Nile Delta region are other sources of pollution. Bottom mud samples collected from El-Mahmoudiya canal was found to contain the highest levels of cadmium, lead and mercury. The northern sector of this canal (south of the city of Alexandria) exhibited the worst condition. This area receives untreated effluents from various industries and atmospheric fallout from industries and vehicles. The southern sector of the Rosetta Branch also had high concentrations of trace metals. This was most likely a result of the inflow of wastewater from the El-Rahawy Drain, which receives the municipal wastes from the area. Controlling environmental pollution from industrial sources is best achieved by controlling pollutant emission and discharge at the source. Experience gained during the last two decades suggests that in many circumstances it is more efficient and less expensive to incorporate pollution preventive techniques than corrective techniques. Consequently, the immediate institution of improved housekeeping measures and operations and maintenance procedures could potentially reduce environmental risks significantly. Simple environmental management practices such as cleaning oil traps, controlling leakage, and separating cooling water from other process water, as well as waste neutralization are recommended. Hydrogeology and water quality of the saturated zone in the Nile Delta, Egypt 261

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