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Question about current

For my trip on the Ohio river am I more interested in flow rate as stated in cubic feet per minute(or is it per second) or do I look at current velocity stated in miles per hour?

My sister who is into the play baoting and whitewater basis things on flow rate (cubic feet thing) but I think the velocity(MPH) would be more pertinent to the Ohio river.

Also noted that the current is pretty irregular at various locations along the river and are mostly measured at the locks and dams. How does one include current in planning a target number of miles per day?

Comments

  • Velocity
    Velocity is more important for planning speed & distance as long as there are no significant features that are affected by depth.

    Volume flow matters to whitewater folks because river features in rapids -- holes, waves, etc. -- can change dramatically with changes in water level.
  • Speed
    In the whitewater world flow in cubic feet per minute or second, or height on some arbitrary gauge are correlated by experience to acceptable conditions to go paddle and play in a particular river.

    Not enough flow = rocks. Too much flow = wash out, or danger.

    On a "flat water" river with current you are interested in the speed of the current.

    Current is not uniform, and as you note, is only reported at some locations.

    Since the flow is constant (unless other rivers are entering) the current is proportional to the product of width x depth.

    As for factoring current into planing. If your average not-moving water speed is 4 mph, and you are going with a current of 1 mph, then you are effectively covering distance at 5 mph.
  • Options
    Thanks
    for the quick reply. One more question if you don't mind. When the velocity is only 0.3 mph is it worth including in planning a target distance for each day or should I just use the general 3 mph paddling rate that I have seen referred to frequently?
  • Depends
    How long a time do you plan to paddle?

    0.3 mph x 10 hours is 3 miles.

    0.3 x 5 hours is 1.5 miles.

    How accurate to you need to be?
  • Factor in the wind
    That may be just as important as the current. Rivers tend to funnel wind and you can be going several directions as the river curves and the wind may always be in your face.

    Wind velocity changes day to day. I would take 2.5 mph as more realistic. Plan on some days being shorter in distance than others. When you get bound to a schedule, that's often where trouble starts.
  • Options
    Paddling
    time I haven't nailed down yet but will be roughly 8 to 10 hours on good weather days. I need to check the sunrise sunset charts for the time of year I plan to go. From what I have read in journals of others trips storms can cut that down quite abit as can the process of locking through.
  • Ohio River Trip?
    What is this Ohio River trip?
  • An Illustration
    All that's been said is correct. I will add one other thing. Not only is flow rate meaningless UNLESS you are familiar with the river and have seen what various flow rates look like, determining what changes in flow rate will mean to your trip is practically impossible. For example, in the last month, flow rate on the part of the Wisconsin River that I usually paddle has varied from approximately 4,200 to 21,000 cubic feet per second. That sounds like a huge change, but it represents a change in gauge readings (water elevation) of about four feet, and a change in current speed that is surprisingly small, especially within the upper three feet of that four-foot span in gauge readings. If it weren't for the fact that at normal summer levels one needs to zig-zag all over the channel to follow the deeper water, and occasionally become slowed down in extreme shallows, there'd be very little difference in travel speed no matter what the flow rate is. On a bigger river where there's plenty of depth most places, I'd expect a similar trend so I really wouldn't care much about flow rate in cubic feet per second.
  • Don't forget about the wind!
    Big open water like the Ohio can be tough wind-wise. And you'll be paddling into the prevailing westerlies.

    Unless you have a reason to be precise or aggressive, I'd just figure around 3 to 3.5 mph overall. That also gives you time for breaks.
  • Options
    Experience
    A paddler with experience on that river will likely be a better predictor than a simple equation. Having said that, my experience is 2 mph for a leisurely trip of short boats and fairly new paddlers up to about 4 mph for a focused group of long-boaters. A fairly strong flow will add up to 3 or 4 mph if they stay in the channel.

    On many big rivers, you can't really stay in the shipping channels, so you will be relegated to slower and often shallower water.

    Jim
  • speed is, probably, more relevant
    Here is one site that gives forecasts
    http://www.erh.noaa.gov/ohrfc/flows.shtml

    This one gives current ( as now ) conditions
    http://www.erh.noaa.gov/ohrfc/OHRFCrg.shtml

    You might notice that both volume and speed are given, since they are related. Another useful measure is the water gauge height - everything else is calculated based on that.
  • Options
    gauges
    It may be different on "big" rivers like the Ohio, but around here all of the USGS gauges are simply a level gauge. Flow and any current speed reporting is simply an extrapilation based on water depth and river width at the gauge site. Do they actually have a gauge to measure water velocity (water wheel or similar) on these other rivers?
  • The gauge information site will say.
    On a very slow river in my town there's a gauge located about a mile upstream of a very large lake, so water level is meaningless without also knowing current velocity. Information about the gauge on the USGS site says current velocity is measured by a "side looking velocity meter system", whatever that is. I've been there, and whatever the device is, it's completely under water.
  • Options
    This trip
    is starting in Maysville Ky and I am following the Ohio river to Paducah Ky where I will turn onto the Tennessee River and proceed through the locks or portage around them and end up at KenLake Resort State Park. This will be in late October or early November.

    Kayak is a 17' Prijon Kodiak.
  • Options
    Thanks
    I have bookmarked the forecast page as it gives me the ability to start watching the river flow up to 90 ahead of time.

    I went up to Maysville yesterday and found that the site where I planned to launch from has been gated off. While looking for another place to launch I found the office for the riverboat company that I know of and stopped in to ask some questions. To my good fortune the riverboat captain that I know is now working in the office and he had another guy look up some info for me.

    We talked about current on the river and a bit about the stage of the river which is currently at pool stage. Regarding current, he has seen it in the 9 to 10 mph range. Not sure I would want to be on the river in that kind of flow.

    The guys I talked to also gave me signs to watch for in the water that may be an indication to get off the river for a little while. Also they talked about some of the hazards regarding the barges bot on the move and tied up along the shore which they call fleets.

    Overall lots of good info from them.

    They did recommend protaging around the locks as being safer and quicker. At least to of the locks I will encounter are using only the small 600 ft chamber instead of teh larger 1200 ft chamber. This is causing the barges to slit and lock through twice to get the entire tow through. This really racks up the wait time for recreational craft. Read another journal last night and the guy in a pontoon boat had to wait 10 hours for his turn to lock through.
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