Canal

Canals are “artificial waterways” that are “constructed to allow the passage of boats or ships inland or to convey water for irrigation, human-made strip of water used for irrigation or boat access to a more significant body of water” [1]. They “modify existing rivers or streams; or are dug into wetlands or uplands” [2]. Canals are distinguished based on usage, discharge, providers, or alignment, with usages as “aqueducts which are used for the conveyance and delivery of water for consumption, and agricultural irrigation,” and waterways, which “carry ships and boats and convey people” with features that include “weirs, locks, and rapids” [1]. Aqueducts also transport water for “hydroelectric power” (NOAA, n.d.). In other words, they are “human-made waterways that allow boats and ships to pass from one body of water to another,” and “transport water for irrigation and other human uses” [3].

By discharge, “main canals, branch canals, major distributaries, minor distributaries, watercourses or field channels,” with main canals “carrying discharge directly from the river,” and branch canals “offtake from the main canal” and “play the role of feeder channel for major and minor distributaries” [1]. Major and minor distributaries “supply water to the field directed through outlets” and getting water from the “branch canals,” and watercourses or field channels are even smaller than distributaries, “carrying water from the outlet of a major or minor distributary” [1].

Classifying based on the provider, there are “unlined canals” and “lined canals,” where “unlined canals consist of beds and banks made of natural soil” and are “not provided with a lining of impervious materials,” which may lead to “growth of aquatic weeds” to “retard flow” [1]. Visible in “lined canals” is a “lining of impervious materials on its bed and banks,” and the most “commonly used types of padding are concrete, shotcrete, boulder, stone masonry, and sand-cement” [1].

Furthermore, canals set themselves apart with differing alignment, and these include “contour canals, watershed canals, and side slope canals,” with “contour canals distinguished by the meandering course,” watershed canals being recognizable as being “aligned on a ridge to ensure gravity irrigation on both sides of a canal” (Bhuiyan, n.d.). Side slope canals are aligned with “the right gradient to the contours” [1]. Finally, “canals are now considered to be a source of pleasure to many people,” with rented “residential boats” being seen on canals along with “wildlife and interesting plant life” [4].

References

[1] Civil Today. What is a Canal? 12 Types of Canals. Retrieved (2021, August 3), from https://civiltoday.com/water-resource-engineering/open-channel/265-what-is-a-canal-types-of-canals

[2] University of Florida IFAS Center for Aquatic and Invasive Plants. (2020, October 27). Canals. Retrieved (2021, August 3), from https://plants.ifas.ufl.edu/manage/overview-of-florida-waters/waterbody-types/canals/

[3] National Oceanic and Atmospheric Administration (NOAA). (2021, May 25). What is a Canal? Retrieved (2021, August 3), from https://oceanservice.noaa.gov/facts/canal.html

[4] The Waterways Trust. (2017). What are Canals? Retrieved (2021, August 3), from http://www.thewaterwaystrust.org.uk/what-are-canals/