Looking to build a large pondless waterfall?
This article is written to help homeowners and clients in Grants Pass, Medford, Ashland, Roseburg, and Eugene to avoid the pitfalls when designing a large pondless waterfall project. What is a pondless waterfall? Check out this article for the basics. There are so many poorly built features in the rogue valley and southern oregon. One of my goals is to raise the standard of construction and aesthetic so that people will finally appreciate the beauty of constructed water features.
When building a large scale feature, lets say anything larger than 16′ long, you need to understand scale, viewing angles, rock calculation and sizing, as well as dynamic head and pumping needs.
Check out this youtube video of a pondless waterfall build done in Grants Pass, Oregon.
Pondless Waterfall Location
First and foremost you need to assign a proper location for the feature. Most people have a great idea for a large scale feature. Hillsides are great starts, but if there is not a good viewing area the build will not be enjoyed. Even if you have a hill running away from a main viewing area such as a deck, patio, or back of a house, it might be beneficial to build up and create retaining walls to force the falls towards that area.
The most important factor in choosing where the waterfall will be placed is its ability to be viewed and observed. With the hillside running away example, you can create destination seating areas, but generally you want to work with what is already native and natural.
Waterfall Design
Generally most aquatic artists can not tell you what a feature will look like exactly due to the random choice in boulders and their unique inspiration during construction. This is why it is imperative to research local contractors, look at their previous work, and find an aesthetic that you find appealing.
As told in this article about building natural waterfalls, choosing appropriate sized boulders to scale the feature is imperative. With larger pondless waterfalls you need larger boulders. Building streams and waterfalls with all small rock gives a contrived and unnatural appearance. The goal should be to mimic the natural bedrock and mountainous appearance we have locally in the pacific northwest.
The rule of thumb for waterfall width to pump ratio is 1500gph per foot of weir. The weir is the opening where the water goes over the rocks. With larger features, especially when the viewing area is farther away, you need to at least double the gph to 3000gph per foot of weir. A wider weir means even larger boulders.
But just using large boulders will not suffice. You need to mix in varying sized boulders to break up the build. Smaller rock gives contrast to the larger boulders and brings the aesthetic together.
Water in Motion
When building pondless waterfalls, there is no pond to feed the waterfall. Instead, we build reservoirs which hold a minimum of twice the capacity of the stream. This is done in case power is cut to the pump. If the pump turns off then the basin will not overfill with the water in motion, and you will not need to continuously feed the basin to get the system going again.
This happens with novice builders all the time. They do not size their basins correctly and the systems are then what we call ‘top heavy.’
To properly size a basin, you need to figure out the water in motion. Water in motion is the water that is in the waterfall and the plumbing. When using larger pumps for increased head pressure and water flow, you need to be using 3″ flex line. This is because the maximum capacity of 2″ flex line is around 5000gph.
Each foot of 3″ line holds around one gallon. To figure out your waterfall reservoir needs multiply the distance of the stream by its average width, then by its average depth, and then by gallons per cubic foot which is 7.48.
For example, lets say we have a 24′ long pondless waterfall, which is average 2′ wide, with an average water depth of 3″, calculated as .25, then multiply that by 7.48. You will get about 90 gallons of water in motion. But you also need to calculate possible pooling areas as well as the flex line needed.
So with 30′ of 3″ flex (overestimate for curves) you get 30 gallons of water, add in some small pooling areas (3′ x 3′ x .5 (6″ depth) x 7.48) will get around 35 gallons per pool. Pooling areas will be determined by the slope as well as the individual contractors style. I would guess off the top of my head you will have minimum of three pooling areas for the example above. So that will be an extra 100 gallons, plus the 90 for the stream, plus the 30 for the plumbing. So 220 gallons of water in motion. This means you need a minimum 440 gallon reservoir. Depending on the sun exposure, pump needs, and slope you might need more.
These are just a few calculations and examples of potential pitfalls for large scale pondless waterfalls that your builder needs to have a firm grasp on before attempting a project of this scale.
You should also have an understanding of how to strap and move boulders effectively while protecting the liner. Many times novice builders puncture the liner and without the skills necessary to locate it, you will need to rebuild the entire feature.
If you are interested in having a large pondless waterfall built in southern oregon check out my waterfall packages.
Or fill out the contact form, include a couple photos of your space, and we will get started.