Why Have We Wrecked Our Estuaries? Perpetrators & Can We Learn How To Manage Waterways Sustainably Instead?

Wednesday 2 October 2019 - 14:00 to 15:00
NOC Liverpool - Nicholson Lecture Theatre (University of Liverpool).
Dr Bob Kirby (NOC)

Mainland Europe is drained by eight major muddy commercial estuaries. In recent years several have had their geomorphological configuration rigorously documented. Whilst these exhibit natural variations, each has suffered severe degradation of function. The Loire, Ems Elbe, Scheldt,& Weser have been shifted into hyper-turbid, flood-dominated regimes, also forfeiting their marginal “accommodation space”. The “culprit” driving all this has been over-dredging to accept our “Goose That Laid The Golden Egg”, the deep-draughted trading vessel, the engine of our maritime economies. Early, faltering, attempts to reverse this degradation will be outlined. Already clear that this will require a prolonged timescale & great expense. Meanwhile, British estuaries?

 Related to this, from almost 50 years ago, the speaker & others have developed, proved & are now having accepted, five so-called “Generic Sediment Management Systems”. Each solves a site- specific mud siltation problem occurring repeatedly around the world:- Semi-enclosed Basins, Impounded Docks, Lock Entrances, Fairways etc. The total & partial solutions devised involve Current Deflecting Walls, Trickle Auto-flushing Systems, Passive (PND) & Active Nautical Depth (AND). This latter, AND, has two distinct components & two contrasting consequences. One permits vessels to sail through mud in controlled conditions, the other hinges on in-situ bio-degradation of adsorbed contaminants. All are KSIS technologies-“Keep Sediment In the System”.

 Procedural, cost & environmental implications are all major & favourable. Traditional surveying & maintenance dredging have long dominated port operations, but these emerging  modern mud management techniques have shifted mud from an expensive, intractable, oft –contaminated waste to being a precious resource with a beneficial use. This is new, though not for all of us. The “ocean sciences”, until now an unfamiliar area, have been harnessed to underpin this vital industry. This is the future. Examples will be set out. Through these methods, too, by leaving mud in-situ, the technologies impinge on geomorphological consequences of deep-draughted vessel trade & dredging.

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