Dredging Lake Manzala
Introduction Lake Manzala, in northern Egypt, has long served as a natural buffer and biodiversity hotspot along the Mediterranean. Historically covering 1,709 km², it has shrunk due to land encroachment, aquaculture, and untreated wastewater. In 2017, dredging began to remove pollutant-rich sediments and restore the lake’s water capacity.
Background and Dredging Impacts Data show that the lake’s volume increased from 378.67 MCM in 2016 to 903.64 MCM in 2022—a 138% gain. However, dredging triggered major ecological shifts:
- Chemical Changes: Salinity rose by 73% (2015–2022); transparency shifted from 10–60 cm to 20–65 cm.
- Biological Shifts: Zooplankton dynamics altered; saline species increased from 7 to 12, while freshwater species declined.
- Water Quality: Dissolved oxygen in the north increased slightly (from 12.22 to 12.7 mg/L) but high biological oxygen demand persists near wastewater inflows.
Integrating Models, Theories, and Laws
- Ecological Thresholds & Resilience Theory: Ecosystems have tipping points. Manzala appears to have passed a threshold, making recovery challenging.
- Law of Unintended Consequences: Although dredging clears sediments, it unintentionally releases trapped pollutants and disrupts delicate balances.
- Technocentric vs. Environmental Determinism: Heavy dredging and large-scale treatment plants offer short-term fixes yet fail to address root pollution issues.
- Integrated Watershed Management: Viewing Manzala as part of a broader hydrologic network stresses coordinated policies for wastewater discharge, land use, and coastal dynamics.
Policy Implications and Conclusion
Experts argue that dredging alone is insufficient. Pollution control is essential for long-term recovery. Combining dredging with non-invasive measures—such as constructed wetlands, bioremediation, and robust wastewater treatment—offers a holistic solution. Lake Manzala’s experience underscores the importance of integrating technological interventions with environmental safeguards to maintain ecological balance and ensure sustainable water management.
