Following are some of the situations where necessity of cross drainage works occurs: (i) In the head reaches where a main canal is led to the water shed, it must cross several natural streams. (ii) When canal is aligned (based on alignment criteria) as contour canal it requires the number of cross drainage works is maximum. So, contour canals below the ridge will have to cross a very large number of drainages. (iii)If, due to certain reason, the canal alignment leaves the watershed and catches it again after some distance, the area enclosed by the watershed and the alignment of canal, must be drained. (iv)When various canal systems must be linked with one another, necessity of cross drainage work may arise.