Question

What are cartographic methods used to depict drainage on topographical sheets?

Answer 1

Drainage features are shown using blue lines and symbols on topographical sheets. Small rivers or rivulets like Mehandwari Nadi, Li Nala, Dhulaint Nala, and Badshahpur Nala are depicted using thin blue lines indicating their flow direction. Seasonal streams, which flow only for part of the year and disappear later, are usually represented by broken or dashed blue lines. The presence of a rectangular drainage pattern formed by tributaries and rivulets flowing northward is recognised through their angular junctions and straight courses. Lakes such as Damdama Lake and other inland water bodies are marked by blue shaded areas. Additionally, small seasonal tanks, locally called ‘Johars’, are shown using small blue symbols like circles or squares. These features together help represent the drainage characteristics of the region on a topographical sheet.