About

The land where the Arboretum is being created was originally a marsh. Local folk law has it that in the late 1800’s a single plough line was dragged through the marsh to begin the process of draining it for agricultural land. As is common in much of Australia, that original drainage line quickly began to erode, and then kept on eroding. By the early 2000’s the original plough line had turned into a badly eroded creek chocked with weeds, forming an approximately 10m deep 40m wide scar running through the landscape.

 

The Creek Design

Undertaking the rehabilitation of the waterway that had replaced the marsh was to prove particularly difficult.  The main reason for this was that the waterway more closely resembled eroded drain than any type of waterway that had existed prior to white settlement.  Some of the key elements that define a damaged waterway like this include: 

  • Greatly increased water velocities

  • Aggressive ongoing erosion both of the bed and the banks 

  • Significant levels of incision below pre-existing ground level

  • Elevated nutrient and sediment inputs

  • Weed infestation

  • Degraded water quality

Due to the depth of new waterway it has become impossible, without catchment wide remediation, to recreate a true marsh to replace the new creek. Without an existing, natural, template which could be followed, it became necessary to envisage a new type of waterway.  One which would aim to replicate as many of the attributes of a marsh as possible, while at the same time making allowance for the combination of conditions, especially the now high velocity water flow, that now exist.

The name I have chosen for this new type of waterway is a “Running Marsh”.  The aim of a Running Marsh is to accept some of the realities of the new creek while maximising attempts to slow water speed, minimize erosion, trap sediment, filter water etc.  

In short, the creek project has involved trialling a combination of contemporary best practice techniques selected both from the theory of creek and marsh rehabilitation.  The result of this combination of techniques would seem to offer the best chance of creating a new type of stable, sustainable, biodiversity rich waterway, in short a Running Marsh.