Rivers losing their healthy look
Healthy rivers have good water quality and consistent flows (that naturally fluctuate with the seasons and rainfall), but they also have a particular healthy look. They should have pools, rapids, and runs, lots of plants growing alongside and shading them, bits of wood and branches in them, stony bottoms (at least in most streams), and they shouldn’t be lined with stopbanks or concrete walls.
This diversity of physical characteristics provides important habitat for the fish and macroinvertebrates that live in the rivers. If a river is clean and full of water, but lacks good physical character (i.e. habitat), it has limited ability to support macroinvertebrates, fish, and birds.
Unfortunately, river management in Aotearoa led to a lot of our rivers being channelised and effectively turned into drains. They’ve become disconnected from their floodplains, the native trees that once lined their banks are gone, and the natural sequence of riffles, runs, and pools has been engineered away. This was beneficial from a flood management perspective – get water out to sea as quickly as possibly – but it devastated our rivers and the landscapes they’re connected to.
Natural river management
Fortunately, people are starting to realise the harm that the old-school management approach has done to our rivers and are adopting a modern approach to river management. This approach has become known as providing ‘room for the river’ (e.g. ³, ⁴, ⁵, ⁶) and aligns well with concepts like Te Mana o te Wai that have been given increased importance through recent law reform.
Providing room for a river means giving a river room to move and be itself. Room to jump from one channel to another (avulse) during high flow, to overtop its lower banks during a flood, and to erode and form new channels, among many other things. While it might seem this would make a river unstable, it’s actually a lot more stable than trying to control a river with stopbanks, because the river is provided with the room it needs to accommodate high flood-flows and can spread the energy of floodwaters over a large area (rather than bursting through or overtopping a bank at high energy and damaging houses or hurting people).⁷
The river can reach a state of stable equilibrium with the environment around it. It also means the river can maintain a healthy physical condition and provide plenty of habitat for fish, birds, and plants to thrive.
Benefits aren’t always obvious
Unfortunately communicating the benefit of providing room for the river can be difficult when those benefits are not immediately tangible – most of the time, rivers appear to have ample room, stopbanks are not overwhelmed, and many people already see their local river as relatively natural (even if it has been extensively engineered).
This isn’t helped by the approach of many councils and decision-makers to immediately push a river back into its assigned channel as quickly as possible after a flood (often at considerable cost), which preserves the status quo and sense of stability, even if that stability is somewhat unfounded. Telling people those stopbanks and other river reinforcements might be phased out in favour of providing room for the river is a challenge and often taken as a statement that river managers are going to allow peoples’ land to be flooded or washed away downstream through erosion.
Visualising river health
Recently, I’ve been attempting to overcome these responses by visually communicating the value of providing room for the river, rather than through written theory or by referencing peer-reviewed articles. I do this by presenting current and historical aerial images of rivers and their floodplains, along with aerial images of recent flooding, where it exists.
Lower Hutt and Te Awakairangi (the Hutt River) in 1939 (left) and now (right). Notice how the river channel has been narrowed and areas alongside the river, which used to be available for the river to move within, have been developed.
In this way, decision-makers can often see that a river overwhelmed it's stopbanks or avulsed simply because that's where it has been before – not within the memory of the decision-makers or community, but within our recorded history. In my experience, there’s no substitute for a photo, orthophoto, or historical map to communicate the room for the rivers concept.
If we can convey what a river used to or should look like to the public and decision-makers through pictures and maps, we can help people understand we might need to give a river more room again. We can also provide for Te Mana o te Wai and all the benefits that come with it.
Tukituki River at Waipukurau in 1943 (left) and 2020 (right). Notice how the channel has been constrained significantly and lots of habitat within and alongside the river lost.
Activate your freshwater comms!
I implore and encourage councils, geomorphologists, ecologists, river managers, and others working in the freshwater management space to be active visual communicators, and to use visual communications with decision-makers and communities to improve outcomes for river management in Aotearoa.
If you’d like help communicating or understanding the importance of room for the rivers, Te Mana o te Wai, or the implications of new freshwater laws in your region, we’d love to help.
1 “95–99% of river length in urban, pastoral, and exotic forest areas exceeds water quality guidelines (according to computer models).” https://environment.govt.nz/assets/Publications/Files/our-freshwater-2020.pdf
2 From “Summary of the Evidence of Thomas James Kay (dated 11 May 2021) on Behalf of Royal Forest and Bird, in the matter of HBRC’s Plan Change 9 / TANK (21/06/21)” https://www.hbrc.govt.nz/assets/Document-Library/TANK/TANK-evidence/Evidence-Received-Week-3/210-Forest-Bird.pdf
5 Promoting fluvial geomorphology to “live with rivers” in the Anthropocene Era https://www.sciencedirect.com/science/article/abs/pii/S0169555X2100057X
6 Making room for rivers: quantification of benefits from a flood risk perspective https://www.researchgate.net/publication/309337830_Making_room_for_rivers_quantification_of_benefits_from_a_flood_risk_perspective
7 Making room for rivers: quantification of benefits from a flood risk perspective https://www.researchgate.net/publication/309337830_Making_room_for_rivers_quantification_of_benefits_from_a_flood_risk_perspective