As you might have read in the previous post, water can be transported by various means. The least efficient is by hand. In the developing world, many people still transport water from rivers, creeks lakes or wells by hand. They fill up their buckets with water and then carry the bucket to the location where they will use the water. This is slow and time consuming because you are limited to what you can carry.
A step up from this is carrying water in tanks on vehicles. Many businesses make money by carting water around in trucks and delivering it to where it is needed. In some towns, water is transported into town by rail. Large trains with tanker cars fill up with water where it is available and drive to the town where they unload.
All of these methods are relatively inefficient because they involve moving much more than just the water. In the case of the person with the bucket, they are moving themselves and the buck as well as the water. Even though a motorised vehicle can carry a larger amount of water, they still have to move the vehicle. A better way is to just move the water itself by pumping it or relying on gravity.
The two main ways you can do this are by pipes and channels. The previous post covered pipes, so this post will go into channels.
Why Channels Over Pipes
The big benefit of channels over pipes is ease of construction. You just need to dig a trench, line it so that it is impervious to water and that’s it. This is much cheaper than the cost of manufacturing a pipe and then you still have to do a lot of moving dirt like a channel.
When you need to move really large amounts of water, such as transporting water to a town or irrigation district, channels are preferred over pipelines because they are so much cheaper on the large scale. To build a huge channel isn’t as difficult as a huge pipe.
Another benefit is that channels can be used for boating. Here is a photo of boats on an irrigation channel.
You can not do this with a pipeline because there is a roof over the pipe that would block the boats from passing through.
Disadvantages of Channels
One of the big benefits of pipelines is that they have lower evaporation losses. Water can evaporate from the top of a channel and it’s lost. So pipes are more water efficient.
Another problem with channels is that they always flow downhill. You can put in locks and dams to move boats and sometimes water upstream, but between the locks it has to be downhill. With a pipe you can put a pump on it and run the pipe gradually uphill. This is because with a channel if you pressurise it, it just floods the countryside where as with a pipe, because it’s enclosed, the pressure just builds up and there are no problems with laying it uphill.
There are pros and cons to using channels and the decision to use channels should be made on a case by case basis.