A body of water is navigable when all requirements for the safe passage of watercraft are fulfilled. There are several factors that should be considered for making proper navigable waterways like – the depth of water, the width of the waterway, alignment, lock gate, etc. In this article, I have discussed all the major requirements of navigable waterways.
1. Depth of Water
Depth of water is the principal requirement for making a navigable waterway. The depth of waterways (eg – canals, rivers, creeks, etc.) should be sufficient so that any watercraft such as ships, boats, etc. can pass without obstruction.
The minimum depth of the navigable waterways should be 3 to 4 meters. In the case of perennial rivers, the depth of the water varies throughout the years according to the seasons. In rainy seasons, there is no such problem to get the minimum depth of water. But in winter and summer, the depth of water may be insufficient for passing watercraft over it. So, during these seasons minimum water depth needs to be maintained, to do so barrage may be necessary.
The minimum depth of water is also considered on some factors like the type of watercraft, weight of watercraft, size of watercraft, etc.
2. Width of the waterway
Width is another primary consideration for navigable waterways. Typically, 80 m width should be maintained for navigable waterways. The width of the waterway should be decided according to the size of the watercraft.
If there are need to pass the large sizes of watercrafts then the waterway width should be more. The width also depends on the volume of the watercraft and the wave action that is generated by the moving watercraft.
Now, you may ask why the wave action is important to consider. If the wave action is high there is a high chance of erosion of the bank of the waterway, to overcome this situation width should be more to get minimum wave action on the bank. Small width also creates difficulties in the movement of watercraft due to wave action. Read Also: Methods of River Bank Protection.
The alignment of navigable waterways should be as straight as possible. It should not consist of too many zig-zag courses, bends, etc. Otherwise, the movement of watercraft will be obstructed and will consume more fuel. On the other hand, straight alignment reduce travel time, and fuel consumption, hence, it is more economical. If they are not straight, then cut-off channels should be created to make it straight, sometimes other measurements also need to consider to overcome such situations.
4. Lock Gates
As I said before, to get the required depth of water, sometimes barrage construction may be necessary at some locations. To regulate the water level, lock gates are provided with the barrage. So, to make waterways more easily navigable, lock gates are used. In the case of a navigation canal, when the canal falls cannot be avoided, the lock gate has to be provided.
5. Over Bridge
Sometimes, bridges are constructed over the navigable waterway. It may be a road or railway bridge for traffic movement. In such cases, minimum clearance should be kept above the highest flood level so that the ships and boats can pass below the bridges safely without any interruption.
If any old bridges are found with insufficient clearance then a diversion canal should be constructed at that location. And also a new bridge should be constructed beside the old bridge by providing minimum clearance.
6. Terminal Facilities
The terminal facilities are very important for watercraft. The terminal station should be equipped with all the facilities like loading, unloading, storing, refueling, etc.