The alignment of a canal plays a crucial role in its design and construction. It involves determining the route and direction of the canal, taking into account various factors such as topography, land use, hydrology, and economy. The main objective of aligning a canal is to ensure the efficient conveyance of water from its source to the required destination.

There are several key considerations when aligning a canal, which are summarized below:

1. Minimum number of cross drainage works:
- Cross drainage works such as culverts and bridges are structures built to allow the canal to cross over natural or man-made obstacles such as rivers, roads, and railway tracks.
- Aligning the canal in a manner that minimizes the number of cross drainage works is desirable as it reduces construction costs, maintenance requirements, and potential disruptions to the flow of water.
- This can be achieved by selecting a route that avoids major obstacles or by designing the canal to run parallel to existing infrastructure whenever possible.

2. Economy:
- Aligning the canal along a watershed (the dividing line between two drainage basins) is considered economically advantageous.
- A watershed alignment ensures that the canal follows the natural flow of water, reducing the need for extensive excavation or embankments.
- It also minimizes the length of the canal, which in turn reduces construction costs, land acquisition requirements, and water losses due to seepage.

3. Avoidance of valuable properties:
- When aligning a canal, it is important to avoid passing through valuable properties such as residential areas, agricultural land, or infrastructure facilities.
- By selecting an alignment that circumvents these properties, potential conflicts and disruptions can be minimized.
- This not only protects the interests of property owners but also facilitates the smooth operation and maintenance of the canal.

In conclusion, the alignment of a canal should be such that it ensures the minimum number of cross drainage works, follows a watershed for economic benefits, and avoids valuable properties. By considering these factors, the design and construction of the canal can be optimized for efficiency, cost-effectiveness, and minimal social and environmental impacts.