Fresh Christchurch waterways
A waterway is something that directs water around. For example, manmade waterways are water races, artificial drains and stormwater systems. Natural waterways are tributaries, estuaries and aquifers. A tributary is a small river that runs into a bigger river, then runs to an estuary and runs into the sea.
When it rains the water can land on the grass or the concrete. If it lands on the grass it soaks through the dirt using it as a sieve until the water gets to the aquifers. If it lands on the concrete it will go down a nearby drain and into the rivers.
A habitat is a home for animals. An ideal habitat for fish is the sea or a river. An ideal habitat for invertebrates is a river bed. These are all natural homes for animals. The mudfish and bully are connected because they are both fish. The pukeko and the bully connect because they both live beside or in streams. It is also very important we protect our wildlife habitats because if we don't the wildlife could die and end the food chain. So you don't throw your rubbish on the ground because it will blow into rivers and suffocate the fish or pollute the water that fish live in and affect the habitats and the waterways health.
The health of a habitat determines the health of the waterways. In an unhealthy waterway you will only find snails and worms or nothing. In a healthy waterway you will find caddisflies, water boatman, backswimmers and more. Another sign that the waterway is healthy is the water temperature. For example, a healthy waterway will be cold and have lots of oxygen which is good for fish but if it is warm it means it has no oxygen and is bad because the fish and macroinvertebrates can't breath. Macroinvertebrates also help keep water clean because they eat algae but if it is unhealthy it will have lots of algae.
Testing our waterways
Our class visited waterways all around Christchurch to test the health of the waterway ecosystems. I visited Styx river, the lake at Styx reserve and the Waimairi stream. We used the “In-stream and Riparian Habitat Survey” to visually assess the rivers. We also caught invertebrates using the technical retrieval device (TRD) or a sieve on a stick, and used the invertebrate study to see what invertebrates we found. At one place we used a turbidity tube to test the water clarity.
The Waimairi stream isn't as healthy as it can be.
The following graph shows the results for the Waimairi stream.
- There is not much variety in stream flow. It's like this because there's not much variety in depth and width.
There is a 3-9m buffer of vegetation. This keeps the banks of the waterway/riverbank up and cools the river.
Less than 25% of the river has sediment on the bottom, which is not as good as it could be as the sediment provides a hiding space for invertebrates.
Only about half the stream is shaded. It's must have shade to keep the water cool and keep invertebrates alive.
On the positive side we also tested the turbidity at the Waimairi stream and the water was clear (although no invertebrates were found)
Changes we can make
Although there are parts of the ecosystem that are unhealthy, there are many changes we can make to improve its health:
- Pick up rubbish that may pollute the water
- Plant more native trees to provide more shade over the water
- Remove the silt and replace it with stones
It is important to protect our waterways because human plants and animals need to live together within the ecosystem. We rely on each other to survive and want to be able to enjoy our waterways for many years to come.