Chapter 2 River Savvy (River Reading and Tactics)

Enabling Learning Objectives 1. Given a diagram of the cross section of a low head dam, the student will match the corresponding parts according to the class materials. 2. Given river hazards and characteristics, the student will match them with the corresponding description. 3. Given a diagram of a river section, the student will match the current differentials according to the class materials. Given a diagram of a hypothetical creek and a multiple choice question, the student will identify the velocity of the hypothetical creek according to the class materials. Given diagrams of a river, the student will draw boat movement of river tactics for each situation according to the class materials.

Cubic Feet per Second CFS 200 feet Hypothetical Creek 4 feet Velocity of river is 2 feet per second CFS is equal to 1600 feet per second

Cubic Feet per Second formula Velocity = CFS Width x Depth Or Depth x Width x Velocity = CFS

Current Speed Timing Measure 100 feet of river Time how long it takes a floating object to travel the 100 feet. TIME FOR FLOAT TO TRAVEL 100 FT. CURRENT SPEED Seconds Ft. per Second MPH 5 20.0 13.60 10 10.0 6.80 12 8.3 5.64 15 6.7 4.56 16 6.3 4.28 17 5.9 4.00 18 5.6 3.81 20 5.0 3.40 21 4.8 3.26 23 4.4 2.99 25 4.0 2.72 29 3.5 2.43 37 2.7 1.84 50 2.0 1.36 80 1.3 .884 140 0.7 .676

Forces of Water Explain speed vs. force on body in moving water. If a current of three feet per second exerts a force of 17 pounds on your legs, then you might expect that a current speed of six feet per second would exert a force of 34 pounds. SUCH IS NOT THE CASE because actually the force of water obeys a square law and this means that if the water speed doubles, the force goes up by four times. CURRENT VELOCITY AVERAGE TOTAL FORCE OF THE WATER Miles per hour on legs body swamped boat 3 16.8 lbs. 33.6 168 6 67.2 134.0 672 9 151.0 302x0 1512 12 269.0 538.0 2688

Current Differentials Current differentials result when there are currents of different speeds and /or direction existing side by side in a river. Many things cause these differentials including boulders, two rivers coming together, and river-bends. These differentials can be seen on the surface by a experienced water enthusiasts. Velocity differences in straight, bent channels, and laminar flow, helical flow.

River Scale International river scale system Class 1- Moving water, few riffles, and small waves Class 2-Rapids with waves up to 3 ft. wide, clear channels, and easy maneuvering. Class 3-Rapids with high, irregular waves, narrow passages, complex maneuvering, may require scouting from shore before navigating Class 4-Long, difficult rapids, precise maneuvering, scouting required, rescue conditions difficult. Class 5-Extremely difficult. Violent rapids, scouting required to navigate congested routes. Contains significant hazards to life if problems occur. Class 6-Nearly impossible to navigate, life hazards are more numerous, scouting is required.

Pillow Pillow—created when the river or water hits an object just below the water’s surface and creates a lifting effect on the water above the object. The closer the object to the surface the bigger the pillow.

Hole Hole-created when water drops vertically over an object that is in the water. Usually creates downstream wave.

Hydraulic A hydraulic is a hole that backfills and creates a hydraulic that recirculates the water back upstream and continues to refill the hole. Mostly seen as part of a low head dam

Eddy’s River flows downstream around rock Eddy Line River flows downstream except when an object sticking out of the water creates an area for water to flow and fill in behind object, then current moves upstream toward object. Water differential back toward object Eddy Line

Examples of Eddy’s List of possible objects that create an eddy Trees Rocks Bridge pier Debris in the river Islands Cars

Upstream and Downstream V’s River Flow Downstream

Standing Waves Standing Wave– caused by water increasing in speed as it drops over or through gentle sloping area and then piles into slower water below. Usually found in chutes and after downstream V’s Named because, the waves ‘stand’ in one place (the water moves through the wave; not the wave moving through the water) as in an ocean wave

Types of Boats Jon Boat Inflatable

Boats and Swift Water Current- most overlooked hazard on any river. River Right—the right bank when looking downriver River Left– the left bank when looking downriver Up current/Down current- the direction of current flow in relation to the hull of the boat

Rotational Turning Force Force experienced when boat is midway across a current differential. Ex: Eddy line (two different current differentials) Very helpful in river reading and river running if the force is anticipated and used correctly. Rotational capsizing force– hull is perpendicular to the current.

River Running Tactics Ferrying– a way to cross a river without moving upstream of downstream. Dynamic ferrying using a static line- used during time of horse and buggy.

Forward Ferry The current pushes the boat across. The motor simply neutralizes the current from pushing the boat downstream. Set angle across the river up to 45° The Greater the angle to 45°, the faster the crossing, the more power needed to maintain position. The smaller the angle, the slower the crossing, less power needed to hold the position.

Going Upstream from an Eddy While underway leave eddy with power crossing current differential heading upstream with power. Power forward toward and across river using ferrying style crossing. Slow power as the other eddy current pulls you in across it’s differential line.

Peel Out Peel out– getting out of an eddy into a current and going downstream. Start with the boat facing upstream in the eddy Power forward and cross the “eddy line” at approximately a 45° angle Lean down-current while turning (taking advantage of the rotational turning force).

Additional River Running Tactics Crossing standing waves Crossing from eddy to eddy Entering an eddy from up-stream Ascending a current Descending a current Review international scale of river difficulty.

River Hazards: Current Velocity and the effect on your body in river current handout. Current on top of the surface is much stronger the current on bottom of river. Review-bends in river, helical, laminar flow of current in river.

River Savvy (River Hazards) A little lesson in river current----The most overlooked hazard on the river. Pictures taken on the Tombigee River in 1979 Notice what effect the current has on the vessel once the captain realizes that he is in trouble

Getting a little to close to the bridge

Notice the current forcing rotational capsizing forces on the up-stream side of the boat

Capsized and underneath the bridge she goes

Pops up on the other side

Emptying a little water

She still works!!!

Dams High Dams Built for flood control, water supplies. Lakes created by the dams used for recreational purposes. Usually do not present a threat to the boater.

Low-head Dams Perfectly engineered– “Drowning Machine” Usually less than ten feet in height Uniform flow of water over the top creates a keeper hydraulic, thus allowing no breaks to form where objects can get flushed out and there-fore recirculating everything within the hydraulic.

Low-head dam Terminology Hydraulic—formed when water flowing over the top hits the water below and creates a depression which is filled in by the downstream water. Boil---aerated water boils up downstream of the drop creating a hill. Water on the upstream side of the hill rushes back toward face of dam to fill in the depression and water downstream continues downstream. Escape route---below the aerated boil line, the escape route is from the base of the dam along the river bottom, and downstream.

Types of Hydraulics Downstream curved Straight across Convex Concave

Solid Obstructions Bridge piers Rocks Homes Undercut rocks These all can cause accidents by a. Catching boater off guard b. Boat strikes object , becomes swamped or capsizes c. Unmovable object can cause people, objects to become pinned against from rushing water current.

Strainers An obstruction that allows water to pass through but which strains out boats, boaters, debris, and other objects Examples: Trees, fences,cars,dams.

Undercuts Rocks can also form strainers from being undermined. The picture to the right shows an undercut rock during low flow, be aware that this could potentially trap someone and keep them underwater during a flooding or high water event. Remember to check these locations carefully and with training to determine location of missing persons. Avoid these undercuts as they can trap your boat and create problems with rotational capsizing force.

ICE Ice can be a layer on top of moving water Boaters colliding with ice may capsize, current then pushes boater under ice surface.

Floods River can take on a whole new characteristic and hazards at flood stage. These men here give us job security! Are they going to get all the cars???

Dangers of Floods Dams, other features, can be washed out so only standing waves are present. Water rising to bridge levels can cause strainers or hydraulics downstream. Water flowing over island and trees creates strainers. Water being forced through a small opening creates a vortex and sucks debris into the opening.