Aquifer recharge vs surface water storage

A109 Light Utility Helicopter flight with mayor Gisborne City from the air in November 2023.

Opinion

Re: Waiting for a meaningful plan, November 7 column.

While it is great to have ideas put forward, it does make me wonder if Mr Bibby has taken the time to review published material regarding freshwater management for the region and the associated documentation regarding the Managed Aquifer Recharge project.

Gisborne is blessed with many things but suitable locations for large surface water storage is not something we have in abundance. This was identified in the MAR project when alternatives were considered.

Also, if a storage reservoir was built there is a lot of additional infrastructure to be installed to distribute water from where it is stored to where it gets used.

This was a significant part of the MAR proposal, as it allows water to be distributed for free under a large proportion of the Flats.

The freshwater management plan is a ground-breaking publication which outlined many strategies for the improved management of our water resource, and methods to ensure that resource is available for people and industry for now and in the future.

NO need to wonder any more Mr Bannister.

Actually, I am the first to commend all those involved with the testing of the managed aquifer recharge project.

They appear to have proved that the theory can work in practice.

Unfortunately, what they can’t and will never be able to prove is the simple “pub test” of reliability under all extreme climatic conditions.

That doesn’t mean that it can’t be a valued part of the total freshwater delivery system. Just that no engineer worthy of the name would be prepared to recommend Government stump up the cash for a reticulation system hooked up to such an unreliable source that could not be guaranteed to meet the demand in every instance. That is because nobody is or will be able to guarantee that the recharge water will be available in the quantities we need when we want it.

There are a number of reasons why this limiting factor will remain as such, but the most obvious one is that we have no way of knowing whether the source of the recharge water will be sufficiently unpolluted or available in the quantities we require to satisfy the needs of all users from both urban and rural sectors.

Why else do you think that every East Coast region (except us) is either looking at or is in the process of building a system of supply based on massive freshwater storage capacity, when every one of them could have taken the option to use the aquifers they have (like us) under their arable plains? It is all about reliability and quality of supply.

And yes, we do have options for water storage sites, either by enlarging the capacity of existing dams that are not earthquake-prone like the Puninga complex or in the Motu catchment that’s probably the best option on a reliable rainfall basis.