subject: Factors That Create Rapids [print this page] White water rafting is an exciting sport which anybody can have a go at. Whether it is in a designated centre or you are testing it out on a real river, there are some terminology and techniques to be aware of. Instructors will make sure that you are safe and know what you are doing but if you want to take up this as a proper hobby there will not always be an instructor around so being more aware of what you are doing will really help.
Rapids are created when a combination of a few of these four factors comes together; gradient, construction, obstruction and flow rate. Of course gradient is the elevation of the river, if there is a sudden drop the river flow will increase into this pocket and will cause a rapid. A really steep gradient is associated with torrents.
The construction of the river also contributes to rapids, if the river narrows suddenly then the large flow of water has only a small space to fit into which will cause it all to go into one place making the flow heavier. If there are rocks along the floor this will impact on the speed of the rapid too.
This leads onto obstruction which is where boulders and rocks are in the river. If there is a large boulder and the water pours over the top of it, it can cause a hole or "hydraulics" making the water on the top flow back upstream. If you get caught into these they can be tricky to manoeuvre and are usually found in grade 3 or 4 river areas.
If the flow of the water suddenly changes to slow or really fast then it can have effects on different parts of the river. With the river flow being forced into narrower sections as mentioned above this will increase the speed.
If you know the course of the river you will be aware of it is has any of these that will create rapids and be prepared to face them. Of course this can differ depending on the weather, if there has recently been a flood or heavy rain fall then the river flow will have changed due to the increased amount of water. More experienced paddlers will be able to take on rapids as opposed to those who are just beginning, instructors will inform you of this and if you are new have selected a grade 1 river course. You can pick different courses to go onto depending on the grade.
