Friday, April 19, 2024

Unmanned Drones On The Lake

 I'm going to have to give Lake Expo a lot of credit for making this blog a little more obsolete. They're starting to do some decent journalism and looking into things before most of us are really aware. Good work. So I hope I give all due credit for the inspiration of this post.

To that point there is the story today about Unmanned Surface Vehicles being spotted around The Lake.

USV - Lake Expo by Tegan Pasley

In short, a company named Simple Unmanned LLC is doing a bathymetric survey of The Lake using unmanned drones. Note: Sorry, Tegan, but your suggestion that drones would be a good idea for Door Dash is not really of yet. Does anyone remember Domino's pizza delivery on The Lake?

Anyway, Tegan reports that Water Patrol and Ameren are aware and "monitoring" the drone activity, but I want to talk about Ameren on this matter. They need to do more than just monitor, they need to act on the data. Somewhat for themselves, but mostly for property owners like me.

Sedimentation map of a boat ramp launch. Source Simple Unmanned LLC

The Lake is filling in. Despite the decades of development and subsequent improvements such as concrete swales and other erosion prevention measures, sedimentation of The Lake continues. I live at the back of a cove and can honestly say I've lost 2 feet of depth since the 70s. We have dredged (permitted of course, and only within the footprint of the slip!) prior to the ban on dredging in 2007, but overall it's a losing battle anyway. Eventually, my property will no longer be waterfront and there doesn't seem to be a lot I can do about it. It sucks for my property, but what does it mean for Ameren?

Does Ameren care if The Lake fills in? Of course, but not in anyone's lifetime. Sedimentation near the shoreline can go on for centuries without affecting the performance of the dam as a power generator. The turbines only care about "head height", and with over 600 billion gallons of water, volume is never really a problem. Unless.

Heavy sedimentation of The Lake means overall volume is reduced. Volume management is the basis for Ameren's tight-assed control of the shoreline. The volume of water stored behind a dam represents it's ability to maintain energy production in periods of changing conditions. While The Lake is fed by many sources, constituting nearly 10,000 cubic feet per second flow at all times, prolonged and severe drought would have an impact. Meaning in times of extended drought, the reservoir could drain faster than it is replenished. Maintaining The Lake's ability to retain as much water as possible mediates such issues. 

Think of it this way. If the contour of the Osage River valley had been deeper and steeper, before it was flooded by Bagnell, then the main channel of The Lake would be less wide than it is, and there would be far few fewer coves, but the dam itself would still be able to generate as much power. The only difference is that it would be far more susceptible to rainfall, closer to a "run of the river" style waterwheel power generation. See my lengthy article on how Bagnell Dam works. In other terms, Tam Sauk Dam, a completely different type of dam, used more as a battery than a generator, can produce more power than Bagnell using a fraction of the amount of water. It just can't do it for very long.

As a power generating system, Ameren isn't too worried about sedimentation, but somebody is or Simple Unmanned would not have been contracted to perform this very expensive work. I wanted to do something similar with side-scan sonar systems, but didn't really see the value in a full detailed bathymetric data set for The Lake. It would be fascinating though and I do hope the results of this survey, and the data will be shared with the public (or me!).