Groundwater Management in the Esna City , Upper Egypt : An Application of Remote Sensing and Numerical Modeling

The major issues concerning water development and management include water conservation and the efficiency of water use, cost recovery, social and environmental factors. So continuous monitoring is essential to evaluate the reclamation impacts on the groundwater potentiality such as Esna Area. The main objective of this work is to determine the new development areas in Esna during the period from 1984 to 2011 using remote sensing technique. The impacts of the present and future development have been evaluated by using the two-dimensional numerical groundwater flow Simulation Package (visual modflow 4.2). The package is used to construct and calibrate a numerical model that can be used to simulate the response of the aquifer in the study area under implementing different management alternatives in the form of changes in piezometric levels and salinity. From land use maps of the study area in the year 2011, a lot of changes in development areas especially out the border of the old land were observed. The change in land reclaimed area was estimated with 44% in the period from year 1984 to 2011. This development accompanied with draw down about 2.5 meters through this period of time. The authors recommend applying different kinds of change detection technique on the study area. Comparing between results, continuous monitoring of the development area is highly recommended.


INTRODUCTION
aquifer as shown in Figure (1).The government Remote Sensing, with its advantages of spatial, area but farmer is still suffering from shortage of surface spectral and temporal availability of data covering large water, therefore groundwater wells are used to cover and inaccessible areas within short time, has become a demands.Due to extensive abstraction from public and very effective tool in assessing, monitoring and private wells (about.68BCM), the water level in the well conserving groundwater resources [1].Satellite data fields declined significantly [2].To avoid the deterioration provides quick and useful baseline information on the of the aquifer system and control side effects of the parameters controlling the occurrence and movement of development in this area, an efficient integrated and groundwater such as geology/lithology, land use/ land sustainable planning and monitoring are needed.Also cover and hydrological parameters.These parameters predict the effects of this development on the have to be integrated to assess groundwater.However, groundwater conditions through numerical modeling.the conventional techniques have the limitation to study these parameters together because of the non-availability The main objectives of the present study are as follows: of data, integration tools and modelling techniques.
Esna is an important area in Egypt, which has limited Producing two land use maps for the study area water resources although it lies on the upper part of Nile hydrogeological settings (geology, aquifer system,

MATERIALS AND METHODS parameters, groundwater flow pattern and
Water resources management is a complex process Two landsat TM images for the Esna city obtained at that requires a multi-disciplinary team in order to take all 1984 and 2011 are analyzed to produce landuse maps its facets into consideration.The integrated water (1984,2011) then change detecion map which resources management approach combines different illustrates the new the reclaimed areas using Erdase aspects under one system that balances between water Imagine Software.supplies and water demands taking into account the The final results of the new reclaimed areas that preserve of water quality.To study the impacts of obtained from the change detection map are used to implementing the developing policy on the groundwater feed the numerical groundwater flow model to potentiality, a groundwater simulation package used to simulate the response of the aquifer under the simulate the behavior of groundwater aquifer and its implementation of the present and future water interaction with surface water within the study area.
resources policy.The simulation process will be The package is fed with the hydrogeological information executed by using the Numerical Groundwater about the groundwater aquifer system and the surface Simulation Package Visual Modflow 4.2) was used.water bodies, constructing a numerical model for the Esna aquifer.The model is calibrated against the historical Land-Cover Maps and Change Detection Maps: Esna is an observation records of the groundwater piezometric heads important area in Egypt, which has limited water resources under the steady state condition.Then it is invoked to although it lies on the upper part of Nile aquifer and test many management scenarios of water resources farmers are suffering from shortage of surface water, policy and predict the aquifer response in forms of therefore groundwater wells are used to cover piezometric levels and water quality.forming an essentially impermeable base.The total cultivated area based on groundwater reach Bedrock in the vicinity of the graben consists of to about 1000 fed., and located in the north and south of marine sediments of Cretaceous to Eocene age, including the western fringes as shown in the change detection carbonates, marls and shales.These units act.asmap.
aquitards, except for the deeper Cretaceous Nubian The numerical groundwater flow simulation package Sandstone (Kn), which forms a regional aquifer modflow was used to predict the expected drawdown and beneath much of Egypt.The Nubian Sand lies several water balance in the future as a result of groundwater hundred meters below the Nile valley floor in the study development in the area.The study concluded that the area (Figure 7).Research wells penetrating the Nubian most critical areas which have been affected by Sand show artesian pressure along most of the Nile valley remarkable lowering in the groundwater level especially in [2] and salinity above 1000 ppm.Some leakage is the new cultivate land postulated from the Nubian Sand aquifer upward along Hydrogeology: Two principal groundwater aquifers are Groundwater flow is primarily toward the river from present in the study area, the Quaternary aquifer of the the valley walls, with a slight northward (downriver) Nile Valley, and the Cretaceous Nubian Sandstone gradient present (Figure 8).A barrage, or low-head-dam found near the surface 50 km or more away from the built across the Nile at Esna in 1960 causes the steeper valley.The Quaternary aquifer consists of gravel, sand gradients just downstream.The profile line used for and silt deposited by the River Nile in a structural low modeling below is essentially perpendicular to isopach formed during OHgo-Miocene rifting related to the lines, and therefore two-dimensional cross-sectional opening of the Red Sea [5].Egyptian geologists have modeling along this line is a valid approximation of the interpreted the depression to be a fault graben in the Esna system.area [2].The bedrock walls of the graben are comprised of Cretaceous to Eocene marine shales, carbonate and Ground Water Flow Model: The numerical modeling is a sandstone.
powerful and helpful tool for the analytical solution, The distribution of hydrostratigraphic units in the especially when the area of model has variability and study area has been investigated through geophysical complicated in the hydrogeological conditions as surveys and borehole studies [2].The graben fill is of acquired in the study area.In addition, it is used for greatest importance to this study, and the RIGW studies forcasting the effect of development proposed scenarios indicate a deeper sand-clay zone ("Plio-Pleistocene on the groundwater levels after 50 years.To satisfy this aquifer" or Qi on Figure 7) overlain by gravel-sand objective the latest version of numerical modeling ("Quaternary aquifer" or Q ).These are the principal software (Visual Modflow 4.2) was used.respectively.

Geometry of Modeling Area and Input Data:
The regional Calibration Results: Results of the model is considered groundwater model covers west Esna map sheet with satisfactory where the difference between the computed longitudinal length 75km.The modeled area was divided and measured heads from hydrogeological map of west into 82 cell in north south direction and 50cell in east west direction, each cell cover area 900km.The model includes two layers (one semi-confined aquifer).The first layer is consist of clay its thickness varies from 0 to 8m, and the second layer is the quaternary aquifer which consists of sand and gravel with some intercalation of clay, its thickness varies from 100m to 150m.development.The total amount of discharge distributed all over the area through grouped sinks; 4)Topography; 5) the hydraulic parameters of the River and main canals and drains (water level, wetted perimeters, and resistance).

Boundary Conditions and Conceptual Model:
The boundaries of the regional model are selected to coincide with natural hydrogeological conditions.The boundary conditions are defined as follows: 1) River Nile is considered river boundary; 2) the western boundary coincides with a general head boundary for the pizometric level -81m (with respect to m.s.l)(Figure 9).

Calibration:
The calibration process is executed through 2 phases, first phase: steady state conditions at 1990 using the existing pizometric head contour map [2].
The second phase: unsteady state condition for regional model during the period from 1990 to 2011 accoding to The calibration process has been done through

Fig. 8 :
Fig. 8: surface in the vicinity of Esna increased to about 2.719×10 m3/year at 2011 due to new Data: The input data of the model based on: 1) Geometry of the aquifer system including the top layer; 2) Hydraulic Parameters of the Aquifer System (Transmisivity, Storativity, Vertical and Horizontal hydraulic conductivity); 3) The average rate of hydraulic conductivity of the clay layer reach to 0.05m/day, while it varies between 60-100m/day for quifer layer area [6].The average rate of recharge is ranging between 0.0001 -0.0005 m/day in flood plain, whereas the main discharge in the model area, is groundwater extraction for various uses which reach to about 2.14×10 m3/day at 1990 [7], while it 9 9