Native trees are suckers for E. Coli

Waikawa river has high levels of E. Coli, unlike the Waikawa Reserve site about 10 Km upstream. Between there and here the river flows through cow paddocks and past the shag colony. Now interesting research by Environmental Science and Research suggests that native trees could help.

Native trees could help clean up lakes and rivers and provide a solution to New Zealand’s nitrogen and effluent problem.

Previous tests have shown E coli died off much faster under mānuka than under pasture, and significantly reduced the leaching of nitrate compared with pine trees and grass. …

Science leader of the ESR’s biowaste team, Maria Gutierrez-Gines, said they did not know how it worked yet, but they thought the native root systems may release compounds that pathogens did not like, so they either died or did not grow.

Native plants put under microscope for E coli and effluent treatment | RNZ News

So there’s something to keep in mind.

Rock, tide, sand

Many a kid has taken their bucket and spade to the beach and enthusiastically built a sand castle. The next day though usually ends in disappointment as the previous day’s efforts have been washed away by the tide. Sad, but a valuable life lesson perhaps.

River cut dam breached, from north bank looking south.

River cut dam breached, from north bank looking south.

When I was a kid I also read about the 3 little pigs: a big bad wolf blows down the first two pigs’ houses, made of straw and sticks respectively, but is unable to destroy the third pig’s house, made of bricks. Seems like maybe bricks are a pretty good building material.

Rock groyne 1993. Crown Copyright photo, cropped and zoomed.

Rock groyne 1993. Crown Copyright photo, cropped and zoomed. Look how long that rock groyne was in 1993!

Continuing the life lessons, at least one Bible verse (Matthew 7:24–27) found its way into my learning. The World English Bible puts it like this:

Everyone therefore who hears these words of mine, and does them, I will liken him to a wise man, who built his house on a rock. The rain came down, the floods came, and the winds blew, and beat on that house; and it didn’t fall, for it was founded on the rock. Everyone who hears these words of mine, and doesn’t do them will be like a foolish man, who built his house on the sand. The rain came down, the floods came, and the winds blew, and beat on that house; and it fell—and great was its fall.

Of course there’s a deeper meaning, but the message about the impermanence of sand in the face of flood and wind is highly relevant.

This was the sand dam beside the rock groyne.

This was the sand dam beside the rock groyne.

On 28 June 2018 the Council did a River Cut to divert our river more directly out to sea, rather than running beside the coast eroding properties and blocking vehicle access to the beach from Manga Pirau Street.

It took them all day and they created a good-looking straight channel and sand dam. Less than 10 days later and that sand dam has breached. The river’s busy carving sand off the edges of the channel. High tide is due and I suspect that before tomorrow dawns all the human endeavour will be reverted by the known forces of nature.

Tides 20180708.

Tides 20180708.

Wind and swell 20180708.

Wind and swell 20180708.

A delightful beach interlude

Next week the Council is scheduled to do a River Cut — cutting a channel to send the river more directly out to sea. I believe they also plan to restore the vehicle access to the beach.

It’s been around 4 months now since the river shifted and blocked vehicle access. Occasionally vehicles have made it onto the beach, but by and large we’ve had a wonderful, quiet and easy time.

It’s been bliss to walk the dogs without looking over my shoulder all the time. It’s been so relaxing and, well, beach-like.

It’s my impression that the birds are more settled, and more numerous.

It’s been so good to see the driftwood stay where the sea has left it, to watch the sand building up around it.

The shellfish beds have had a chance to remain uncompressed and undisturbed too.

I love the way the river has created a large loop, providing plenty of spots for gulls to hang out. The other day a flock of maybe 30 arrived with much commotion, swooping down to the river, presumably fishing. Then they landed and sat in the shallow water. A few didn’t have solid sand underfoot and would drift sideways downstream with the current until they reached the end of the group, when they would fly back to their starting point.

It’s been a delightful interlude.

Strong wind, near high tide, wave warning.

Strong wind, near high tide, wave warning.

How will slower and wetter storms affect Waikawa Beach?

The globe’s hurricanes have seen a striking slowdown in their speed of movement across landscapes and seascapes over the past 65 years, a finding that suggests rising rainfall and storm-surge risks …

Slower-moving storms will rain more over a given area, batter that area longer with their winds and pile up more water ahead of them as they approach shorelines, said Jim Kossin, a scientist with the National Oceanic and Atmospheric Administration and the study’s author.

Hurricanes are traveling more slowly — which makes them even more dangerous – The Washington Post

Slower wetter storms.

The percentages show how much tropical cyclones have slowed in those regions in the past 70 years. Local tropical cyclone rainfall totals would be expected to increase by the same percentage because of the slowing alone. Increases in rainfall because of warming global temperatures would compound these local rainfall totals even further. (NOAA/NCEI)

In February 2018 Waikawa Beach was affected by the remains of Tropical Cyclone Gita, which eroded the coast, especially by the river mouth. Of course any storm loads up the river and adds to our high groundwater. That 15% slowdown in our region is likely to make problems with erosion, river levels and ground water worse. It could be good news for our rainwater tanks though.

The study quoted above goes on to talk about the impact of climate change on storms too:

…it is expected that hurricanes will rain about 7 to 10 percent more per degree Celsius (1.8 degrees Fahrenheit) of warming, as the atmosphere retains more water vapor, Kossin explained. …

These two trends ought to work in tandem to make today’s storms much worse rainmakers.