Human-induced sedimentological changes in Manzala Lagoon, Nile Delta, Egypt

Abstract

The Manzala Lagoon in Egypt's Nile ' »el-ta has become a sediment sink of reduced area and depth, with increased contaminant levels. Loss of much-needed fresh to brackish water reserves and decreased fish catches have serious ramifications. Herein, maps of temporal and regional sediment distributions in Manzala incorporate petrological and statistical analyses of 200 surficial and short core samples. These provide baseline information needed to help implement protection measures for this vital wetland. Four periods are considered: 1920s, 1940s, ~ 1965, and 1990. Important depositional changes between 1940s and ~ 1965 resulted from anthropogenic effects on this quasi-closed lagoon system, including industrial buildup, wetland conversion to agricultural land, and irrigation waterway development. Further modification from ~ 1965 to 1990 is associated with closure of the Aswan High Dam, continued construction of waterways that discharge waste water into lagoon margins, and marine incursion into the northern lagoon. If current practices continue, the lagoon could be reduced to about one-third of its present area by 2050 AD.

Environmental characteristics, landscape history and pressures on three coastal lagoons in the Southern Mediterranean Region: Merja Zerga (Morocco), Ghar El Melh (Tunisia) and Lake Manzala (Egypt)

“…Within the lake are hundreds of islands which vary in size and shape. Some in the north, which often have a long axis parallel with the coast, have been attributed to former coastal sand ridges while, further south, islands which are less elongated or trend south-north may reflect deposition along former branches of the Nile (Sestini, 1976;Abdel-Kader, 1982;Randazzo et al, 1998). Most islands are surrounded by emergent vegetation, predominantly Phragmites and Typha, and the largest are occupied by small fishing communities.…”

“…Sand bars (up to 2 km wide, 1-2 m high) separate Manzala from the Mediterranean except where they have been artificially cut. Marshes dominated by Phragmites and Typha fringe much of the other three lake margins (Randazzo et al, 1998;Ramdani et al, 2001). Beyond these marshes land use is characteristic of the intensively cultivated Nile Delta.…”

“…The lake's longest (northwest-southeast) axis is parallel to the Mediterranean and is about 50 km long. Its widest point (northeastsouthwest) is about 30 km (Randazzo et al, 1998). Sand bars (up to 2 km wide, 1-2 m high) separate Manzala from the Mediterranean except where they have been artificially cut.…”

“…It is the largest of the delta lakes; others include Burullus, Edku and Maryut , with a current area of c. 700 km 2 . The lake is a shallow, rhombohedral-shaped wetland (Randazzo et al, 1998) within the actively subsiding delta plain (Stanley, 1988(Stanley, , 1990. The lake's longest (northwest-southeast) axis is parallel to the Mediterranean and is about 50 km long.…”

An overview of integrated hydro-ecological studies in the MELMARINA Project: monitoring and modelling coastal lagoons—making management tools for aquatic resources in North Africa

“…At Lake Manzala, however, regulation of the Nile provided by upstream impoundments, most notably the High Aswan Dam, and the development of perennial irrigation in the Nile Delta have greatly diminished the seasonality of freshwater inflows (e.g. Stanley & Warne, 1993;Randazzo et al, 1998). The balance of freshwater inflows and tidal cycles largely regulates the salinities of each lagoon so that summer water levels are maintained by seawater at Merja Zerga and Ghar El Melh.…”