Christchurch has many different waterways, some natural and some artificial. One example of a natural waterway is the Avon river. An artificial part is the concrete pipes giving us water from the aquifers underground. When it rains, the water sinks into the ground and eventually travels into an underground river which is called an aquifer. Then we pump it up (sometimes the water travels for 100s of years first.) and use it in our homes. This water is called groundwater. Groundwater can turn into springs because when ever there's some clay blocking the way, the groundwater will build up strength and it will make a spring. The springwater will feed into rivers, lakes, streams and creeks and into some taps.
A habitat is an animal's home. The eels eats fresh water crayfish, and the crayfish eats the mayfly larvae, and the mayfly larvae hides under rocks, so if I took all the rocks out of the river then the mayfly larvae will die because they won't be able to hide. The crayfish also won't have anything to eat so they will die and then the eels will die because they won't have to eat either. So that shows you what can happen just by taking a rock out of a river.
You can tell if a waterway is clean because there will be lots of animals living there. If there's only snails and worms, or nothing, it will be unhealthy. But if there's invertebrates and macroinvertebrates like caddis fly, stonefly and mayfly, then it could be healthy (but don't drink it) because they like clean water.
They also like the water colder than 15 degrees. If the water is over 20 degrees then it's not going to be clean.
Testing our waterways
My class have been visiting Christchurch waterways to check the health of them. We used the “In-stream and Riparian Habitat Survey” to assess how clean the water is. On it, it has questions like how much algae is in the river, or what the water flow is like, and then you add up the numbers. If you get 14-25 then it's not healthy, if you get 26-40 then it's good, and if you get 41-57 then it's excellent. We also caught invertebrates with a technical retrieval device (TRD), a stick with a sieve on the end, and counted and classified what we found. We also measured the turbidity of the water using a turbidity tube.
The stormwater drain behind Waimairi school could be healthier as it is in very poor health. There is no shade over the water so the water won't be under 15 degrees and that's bad because the invertebrates won't be cool enough. The bank was also not as stable as it could be so the water won't be fresh if it erodes.
There was lot's of sediment (mud) on the drain bed this will affect macroinvertebrates because they won't be able to breath. There wasn't any algae in the stormwater drain this is bad because the common bullies won't be able to eat it.
There also weren't any native trees and there wasn't any shade or native birds. When it rains the water is very murky this is bad for the waterway because nothing will live there. When we looked for macroinvertebrates we couldn't find any. I didn't give it a very high mark.
When we had a look at the stormwater drain, lots of people got different answers to me. This is probably because some people were only looking at the part of the drain that was right in front of them and other people might have been looking at the whole of the drain.
Although he waterway ecosystem looks unhealthy, there are many ways we can make to improve it's health. That includes:
Planting more trees on the bank to make it sturdy and shady
Take all the sediment (mud) out and put stones and rocks into it to make hiding places for the invertebrates
Don't litter otherwise the fish could swim into it and get trapped
These changes are important Because
Then everyone can go swimming in clean water.
It is also important to protect the waterways because in Maori tradition when someone dies they become part of the land and we need to respect ancestors.
Please listen to me because if we look after our waterways it will make the world a better place to live.