Much of Medway sits on London Clay, a dense, impermeable substrate. Unlike sandy or chalky soils, clay absorbs water very slowly. During heavy rain, the ground quickly becomes saturated, leading to rapid surface runoff, flash flooding on roads, and water pooling in low-lying gardens and underpasses.
To understand the drainage, one must understand the land. The Medway catchment covers a vast area of the Weald of Kent and Sussex. Geologically, this is a story of clay and sandstone. Unlike the porous chalk downs of other regions, the Wealden clay holds water, creating a "flashy" hydrological response.
Drainage in Medway is a complex issue that requires a comprehensive and multi-faceted approach. While challenges persist, current initiatives and strategies demonstrate a commitment to improving drainage infrastructure and reducing flood risk. By building on these efforts and embracing future opportunities, Medway can create a more resilient and sustainable drainage system that protects its communities and environment.
The (Leigh Barrier) is the crown jewel of this system. It acts as a massive valve, holding back peak flows to protect the urban sprawl of Tonbridge and downstream communities. However, the review reveals a critical flaw in this strategy: moving the problem.
Southern Water has come under intense scrutiny here. The review finds that the drainage network is effectively acting as a pressure valve for the sewage system. When the drainage capacity is exceeded, raw sewage and stormwater are discharged directly into the Medway. This is not a failure of the river’s natural drainage, but a catastrophic failure of infrastructure capacity. It turns the river from a drainage channel into an open sewer during extreme weather events.
This review looks past the surface—past the reeds and the silt—to examine the efficacy, history, and future viability of the Medway’s drainage infrastructure.