Soil loss plagues Hawke’s Bay, and arguably represents the region’s most severe environmental problem … a bigger problem than drought.
HBRC has estimated the loss at roughly 3 million tonnes per year. And major rainfalls deliver the most severe run-off, as you see in crossing any local bridge, and as these recent dramatic satellite photos of Hawke Bay clearly show.
Not only does this sediment disrupt and destroy our stream and river ecosystems, it clogs our vital estuaries that should nurture our aquatic life … and then spills over into the Bay marine environment as well.
Our scientists have been measuring and largely understand the impact on waterways and estuaries; but at this point have only scant knowledge of the impact on the marine environment. But we can no longer assume once at sea this sediment simply dissolves away with no adverse effects.
And the effects on water and waterways is just half the story.
Consider the loss of all this soil from an agricultural perspective. This is an asset that nature has taken thousands of years to create. It is the asset – effectively irreplaceable – upon which our entire farming and food production enterprise rests.
Commendably, the Regional Council has in the last couple of terms brought fresh focus and very substantial funding to protecting our soils, particularly our most vulnerable hill country land. The approach it touts involves tree planting on fragile slopes (as opposed to grazing or leaving hillsides bare), as well as riparian planting to help ‘catch’ and hold eroding soil and stock exclusion to protect stream banks.
All well and good, but not good enough. It’s the ambulance at the bottom of the cliff.
All this soil is not coming merely from stream banks. Most of it is coming from poorly managed and grazed hill country … from land that too many farmers allow to be chewed down to the nub, eliminating – along with soil compaction – any chance of rainwater being absorbed and stored in the soil in the first place. Where nature intended it to be.
There is no question that well-managed soil/land has hugely more water retention capacity.
And this is a cardinal tenet of so-called ‘regenerative farming’, which stresses year-round diverse ground cover, deep roots and alternative stock grazing methods. These are the farmers who don’t suffer nearly as much – many not at all – during ‘droughts’ and they are the true stewards of the soil … confounding ‘conventional wisdom’.
The Regional Council needs to get firmly behind these farmers, and not just apply band-aids over poor farming practices.
The worst soil erosion comes from logging. Why is this always ignored?
Also do not ignore what comes from the mountain parks. The Mohaka river is often well laden when it passes us whilst our farm streams are all running clear in the same rainfall event.
Soil erosion is a natural process…that is how we get flood plains. Was there much erosion in the last event? I have seen a few “biggies” in my time, and suspect this event wasn’t one of those. As Malcom says, don’t ignore what is happening in the ranges!
Come on the whole of the heretaunga plains is built from erosion this is nothing new
I’m not saying that humans haven’t made it worse but you scare mongering bull crap is out of control and it’s about time you loose your ponytail grow up and become something productive
And would you say measured loss of this magnitude — much of it from poor land management — can just continue forever? Prudent land management can keep much of this soil in place, where it might be productively used. Why would we not want to do that? There’s ‘natural’ and there’s ‘dumb’.
Even though the author has a point, it gets really frustrating from a scientific point of view when someone targets a specific area/practice. There are many reasons for getting sediment in streams/rivers during floods or a period of high rainfall.
I would love the author to find any river in the world that would run clean after a long dry period followed by a sudden increase of runoff. Even full bush etc will have a massive sediment buildup after 6 months of no rain.
Also dont forget about the natural organic breakdown in any stream or river from fish, birds and insects etc. That carbon breakdown has to go somehwere otherwise our rivers would just be a dirty swamp land that everyone would start moaning about (not to mention the inability to sustain insect/invertebrate life due to anaerobic conditions of such water ways).
Dont get me wrong there are terrible practices such as pine tree being planted on very marginal land, a small proportion of farmers doing brainless things and useless urban/city living townies sitting behind their computers moaning abouts others before looking out their own windows. But for a hb councilor to post this total one side argument is just pathetic.
Precisely BECAUSE I was a regional councillor I had six years on the TANK stakeholder group to see and weigh — with all the other participants — the hard data on soil loss in that particular catchment (plus the opportunity to look at comparable data from the Tukituki). It was clearly understood by all that substantial ‘natural’ soil loss does occur, and various estimates of that were made. However the group clearly recognised that significant amount of soil loss could be mitigated by sounder land use practices. And consequently a great deal of effort was made to explore those, including their costs and expected benefits. One key area of concern, for example, was the accelerated silting of the Waitangi Estuary, which frankly is in danger of becoming a mud pit if we don’t do something about the soil erosion we CAN control. Seems like a no-brainer to me, but then I’ve had the benefit of absorbing a great deal of pertinent data and science on the matter.
The Heretaunga Plains was a flood plain, but the rivers are no longer able to flood and spread silt and nutrients all over the place. Human intervention ie stopbanks on all the major rivers has controlled the flooding process. This is for very good reason of course, so we can live here and use it effectively. In order to continue doing this we need to do the best we can to work with nature and ensure that what we do is the best compromise we can come up with. Manage the soil use, minimize the soil runoff, but a large proportion of the silt and shingle in the rivers must have always ended up in the bay as the Heretaunga Plains were formed.