Murphys Creek Update 18 September 2013
Work continues on stormwater management proposals for the Murphys Creek stormwater catchment.
July 30 2013 has been a pivotal date. A group representative of residents met with Mayor Alistair Sowman, Councillor Peter Jerram and two senior staff to discuss the issues they had with what Council was proposing and put forward other possibilities for consideration.
The outcome from that meeting changed the timing and direction of the scope of the project.
The current state and direction of the project is summarised in the Mayor's comments to the resident's group, as indicated below:
The approach adopted by the Mayor and expressed to the residents was for him to listen, and to take further technical advice from staff before putting a number of options back to Councillors for discussion and decision.
In other words, the current proposal, while still on the table, was effectively on hold pending Council's consideration of it alongside other options.
Meantime investigation work would continue as would evaluation of these other options.
Mayor Sowman said he would wait until after the elections (in October) and have the new Council debate the options.
Water quality concerns were to be addressed at that time as well.
The following sections provide insight to the work that is being carried out as part of a wider investigation into stormwater management for the Murphys Creek catchment:
Record from a staff workshop - 14 August 2013
Council staff on the Murphys Creek project met on 14 August to brief one another on their areas of work.
A record from that workshop is included.
Included is an account of the residents' meeting with Mayor Sowman on 30 July.
Review of flood events in Murphys Creek and the Taylor River
Brin Williman (staff) has carried a major review of factors affecting flood levels in Murphys Creek. Brin's report on this work is entitled Review of Design Parameters for Murphys Creek Flood Levels'.
It is in-depth and comprehensive and the most recent and most the complete analysis of these factors in this location.
The full report is not reproduced in full here but two key sections are.
These are:
(i) The probability of Murphys Creek floods coinciding with Taylor River floods
(ii) Flood photographs from 1994 and 2008
The probability of Murphys Creek floods coinciding with Taylor River floods
This section of Brin's full report examines the existing flood record and discerns that there are three categories of event as far as the coincidence of flood flows in the Taylor River and Murphys Creek are concerned.
An outcome of this work has been to identify nine additional scenarios to be run through the hydraulic model of Murphys Creek that has been used to predict flow levels during stormwater events. This modelling work is almost complete at time of post.
Coupled with survey work (currently being undertaken) to ascertain floor levels, the results from these additional model runs will enable likely flood levels for different scenarios to be explained to property owners at each house site in the lower reaches of Murphys Creek.
Flood photographs from 1994 and 2008
See links below for a series of flood photographs near the confluence of Murphys Creek with the Taylor River during events in 1994 (1) and 2008 (2). These were taken from the air.
Of particular note are:
(i) The timing of the flood in relation to peak flows
(ii) The appearance of Murphys Creek, ie; clear water
Water quality - some additional information
This includes some additional slides on water quality; notably how Murphys Creek rates on a water quality index relative to other waterways in Marlborough.
Web map - a work in progress
Council's IT section are working at getting a web map for Murphys Creek up and running and available for viewing via this web page. This link gives a flavour of what you might see when it comes available. There will be layers of information that you can turn on or off and as you drill down (magnify) more detail will becomes visible.
