Wetlands coming back to Christchurch

Once upon a time, most of Christchurch and, indeed,  most of the Canterbury Plains were wetlands – areas that provide a buffer between land and water. 
European Settlers drained nearly all of our wetlands. Unfortunately, now we are finding that we need some of them back!  Wetlands hold water back in a flood, can supply water to the surrounding area in a drought, help to filter pollutants out of water before it gets into waterways. 

People living in the lower reaches of the Otakaro/Avon and Opawaho/Heathcote have noticed that flooding is becoming more of an issue as areas upstream have been hardened and no longer soak up rain when it falls. Partly this is about our climate changing so that where we used to have more regular light rain, we are not getting more irregular heavy rain which overwhelms our river systems when it falls but leave them drying out in between. 
We have lots of new wetlands being developed in and around Halswell specifically to hold water back in a big rain so that people in the lower Opawaho/ Heathcote are flooded less than they otherwise would be.


The wetlands in the picture to the left are in Shirley near Horseshoe Lake.
The man made floating wetlands that you see in this picture will support plants that will take up nitrogen, phosphates and heavy metals, through their roots.  This will improve water quality in Horseshoe Lake and the Otakaro/ Avon River.





As well as being very important in a flat city like Christchurch, these wetlands are also good at sequestering carbon and the make wonderful places for walking.   Check one out near you soon

Speed Limits and Travel Times

Speed limits around our city and our suburb are lowering in busy places or where safety is an issue (eg outside rest homes and schools).    

I have had quite a few conversations recently about how speed limits affect travel times.  Many people that I talk to think that if the speed limit drops from 60km/hr to 30 km per hour around town that travel times will double.   I must admit that if I’m in a hurry, it sometimes  feels like that is the case, but the reality is actually quite different.  Knowing this helps me to be more patient.

 

We often don’t travel at 50km/hr round town even when that is the speed limit, particularly in busy areas.    In rush hour, for example,  the sheer number of cars mean that we are not travelling very quickly and traffic speeds into the city are seldom much more than 30km/hour and often much less than 20km/hr (and we see this as people on bicycles go sailing past us).

This NZ Transport Agency report  shows that driving at a slower speed usually results in a relatively small increase in travel time, particularly when travelling around the city.   Factors, such as lights, traffic, and intersections have a much greater effect on our travel time.  No matter what, even out here in Halswell, we have to stop at traffic lights and intersections, slow down near schools and go slow for any road works.

Some figures from the NZTA report: 

·         Reducing the maximum speed from 100km/h to 80km/h on trip from Christchurch to Kaikoura (tested 42 times by different drivers) showed an overall increase in travel time of 12 minutes.

·         For trips round Wellington reducing the maximum speed 25% from 50km/h to 40km/h showed travel time increases ranged from 1-2 minutes over a 6-10 km trip.

These extra times seem a fairly small price to pay for fewer injuries and deaths from crashes.  In Christchurch, as in other centres, where 30km per hour limits have been used in busy areas, crash rates and injury rates have dropped significantly.