Thursday, 13 May 2021

The satisfaction of rePhotoSA

I spent a few days away with neither mobile reception, wifi nor internet access. I found the days to slow down considerably. As I'm back into repeat photography mode, I took the time to pull out some repeat photographs that I took in Parys three (what!?!) years ago.

I sat on these repeat photographs for months, waiting for the water level in the Vaal River to really drop. I was 95% certain of the photo location but needed more markers to really confirm and to be able to get my photographer position as close as possible to that of the original. 

We had a really rocky paddling season. It was hot and the river had been running low. And then it went really low. Bad news for paddling. Good news for my repeat photograph.

I went out two or three times, as I recall. It isn't only about the angle and photographer position, but also getting decent light (sun not directly ahead, for example) to capture the features.

I knew that I had the correct location but matching them up would need time that I didn't have. I think I was also hoping to get even better photographs. The water level came up a bit and never dipped as low as this in the next three years (which is a good thing for the river and everyone and everything downstream!).

And so, this past weekend, I pulled out the photographs and had a blast examining them. I found this to be incredibly satisfying. And very rewarding to add them to the repeat photography archives of the Plant Conservation Unit at UCT. They use these photographs to study changes in vegetation patterns over time.

The first is a photo by Pole-Evans, taken in late 1919 from what would have been a relatively new bridge across the Vaal River in Parys. It was built in 1915 and enabled people to more easily cross the river - between the Transvaal and Free State with horses and cars and wagons. Before then, there was a pricey ferry crossing that seems to have been limiting. The river is fairly wide here and very, very rocky - not easy or pleasant to cross even at very low level and certainly dangerous at higher levels.

Back to the bridge... The new bridge, that I stood on, is higher than the original bridge that Pole-Evans stood on. Even though I lay down on the sidewalk of the bridge, I was still higher up than Pole-Evans.

The level of the water in the Vaal River at Parys is regulated by release from the Vaal Barrage (built in 1923), which in turn gets water from the Vaal Dam (built in 1938) further upstream. In Pole-Evans' time (1919), the river flow would have been seasonal and thus much lower than what we experience now with regulated flow. In my five years of living in Parys (until end Oct 2020), the water level at which I took this photo in Jan 2018, was the lowest that I experienced (probably 10 cumec). I'd hoped to get even better repeats with lower water, but this was it during my time there.

The Vaal River has flooded heavily many times in the past 100 years, which would shift and move rocks around and weather them. Despite this, not a lot has changed in the rocks - remarkable. The biggest change is in the vegetation growth.
I'm posting here a comparison collage and a version with my markings on it. I've also included some close-ups of the then-and-now rocks

This first is taken looking upstream and to river-right. 

FYI - River-left and river-right are designated according to the water flow direction (downstream). So, if you were paddling downstream, the bank on your left is river-left and on your right is river right. If you paddle upstream, river-right would be on your left-hand-side and river-left would be on your right. The designations of river-left and river-right are fixed regardless of what you do.

Original photo by Pole-Evans, taken in 1919. My photo taken in January 2018.

Looking just at this image above, you may not be convinced immediately. Take a look at this version with same-same rocks circled - and the close-ups.

The second photo was taken from almost the same photographer position, but this time looking upstream towards river-left - where Mimosa is (the Parys parkrun runs through Mimosa along that bank).

Pole-Evans original taken in 1919. My photo taken in January 2018.
Note the low weir, which wasn't there in 1919.

While I can't comment with any authority on the vegetation types, it doesn't take a botanist to observe the dominance of alien Eucalyptus trees along the Vaal River.

I pulled out a third rePhoto that I also snapped in January 2018 from the Venterskroon road. Driving home from Venterskroon - a historic location in the Vredefort Dome about 30 minutes from Parys - I was looking out for this view. I had a gut-feel for the general location. I spotted what I was looking for in my rear-view mirror. I pulled over, snapped the photo and planned to come back to trespass on private land to really nail the photograph. I didn't get around to it. My photo is decent, but it isn't exact. I put it out there for someone to do better. The vegetation in this area has been impacted by at least 170 years of farming activities.

I still have a good four or five rePhotos for Parys where I'm fairly certain of the locations but would need to get out there to nail them. I'm tasking some Parys friends to take a look - especially now in winter when the vegetation thins. 

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