Simulation-Based Solutions Reducing Soil and Groundwater Contamination from Fertilizers in Arid and Semi-Arid Regions: Case Study the Eastern Nile Delta, Egypt

Abstract

Intensive agriculture requires increasing application of fertilizers in order to sustain food production. Improper use of these substances in combination with increasing seawater intrusion results in long-term and nonpoint soil and groundwater contamination. In this work, a 3-D groundwater and solute transport numerical model was created to simulate the effect of excessive fertilizers application along the Bahr El Baqar drain system, in the eastern Nile Delta, Egypt. The geotechnical properties of the soils, hydrologic parameters, and unconfined compressive strength were determined at different sites and used as input parameters for the model. Model results showed that silty clay soils are able to contain the contaminations and preserve the groundwater quality. Nevertheless, sandy soils primarily located at the beginning of the Bahr El Baqar drain allow leakage of fertilizers to the groundwater. Thus, fertilizer application should be properly managed in the top sandy layers to protect the groundwater and soil, as increasing aquifer by excess irrigation water increased the groundwater contamination in confined layers due to the high value of cumulative salt for the current situation while the unconfined zone decreased groundwater and soil contamination. A mass transport 3-D multi-species (MT3D) model was set to identify the optimal measure to tackle soil and groundwater contamination along the Bahr El-Baqar drain system. A potential increase of the abstraction rates in the study area has a positive impact in reducing the transfer of fertilizer contamination to groundwater while it has a negative impact for soil contamination. The scenario analysis further indicated that the installation of a drainage network decreases the groundwater and soil contamination. Both solutions are potentially effective for protection against nonpoint contamination along the Bahr El Baqar drain system. However, a more sustainable management approach of fertilizer application is needed to adequately protect the receptors located further downstream in the Nile Delta.

Investigating and Managing the Impact of Using Untreated Wastewater for Irrigation on the Groundwater Quality in Arid and Semi-Arid Regions

“…The results are consistent with Abd-Elhamid et al [ 19 ] who approved that increasing pumping rates led to increase the aquifer contamination. Additionally, Figure 11 shows the increasing of the wastewater recharge rates ( R ) to 401.5, 438, 474.5, 511, and 547.5 mm/year compare with 365 mm/year at base case led to increase the COD distribution in aquifer to 52.73, 56.02, 59.29, 62.8, and 65.65 ppm at a depth of 25 m and 22.27, 24.6, 27.53, 30.73, and 32.7 ppm at a depth of 50 m. These findings according to Abd-Elaty et al [ 21 ] who studied the effect of increasing fertilizers concentration and combination of pumping rates with fertilizer rates led to increase aquifer contamination. Applying different pumping rates with increasing wastewater recharge rates as in the combination case increased COD in groundwater to 56.60, 65.53, 72.55, 79.48, and 85.70 ppm at a depth of 25 m and reached 24.79, 30.59, 36.51, 44.54, and 56.06 ppm at a depth of 50 m as shown in Figure 11 .…”

“…This results in a lack of direct discharge, and supply of nutrients to water bodies [ 20 ]. Abd-Elaty et al [ 21 ] carried out geotechnical and numerical study for applied solutions to reduce soil and groundwater contamination by fertilizers in arid and semi-arid regions in the Eastern Nile Delta, Egypt. The result showed that silty clay soils are able to contain the contaminations and preserve the groundwater quality, and, more than pumping, has a positive effect for groundwater contamination and negative effect for soil pollution.…”

Assessing the Impact of Lining Polluted Streams on Groundwater Quality: A Case Study of the Eastern Nile Delta Aquifer, Egypt

“…The Eastern Nile Delta Aquifer (ENDA) is located between latitudes 30 • 00 , 31 • 30 north and longitudes 31 • 00 , 32 • 30 east with a total area of 14,000 km 2 . The ENDA has a predominantly agricultural nature with a high density of overlapping irrigation and drainage networks which follow from the south to the north, as shown in Figure 1 [21,26]. The area is bounded by the Damietta branch in the west, Suez Canal in the east, El Manzala Lake in the north, and Ismailia canal in the south.…”

“…The hydraulic conductivity of sand-bentonite mixtures (80% sand and 20% bentonite) has been tested and calculated to be 0.033 m/d [19]. Different numerical simulations have been applied to study protecting groundwater from polluted streams using lining, a cutoff wall, and increasing fresh groundwater [20][21][22].…”

Environmental rethinking of wastewater drains to manage environmental pollution and alleviate water scarcity

“…The findings showed that lowering the conductivities of liner materials lowered the contaminates spread. In the eastern Nile Delta of Egypt, Abd-Elaty et al ( 2020 ) created simulation-based methods to reduce soil and groundwater contamination from fertilizers; the results revealed that installing a drainage network reduces groundwater and soil contamination.…”