Session 15 

Contour Map Preparation of Loktak LakeSalam Santosh
Loktak Development Authority, Manipur, India
Phone: (0385) – 410630 / 410631
E-mail: santoshsalam@rediffmail.com
 

Loktak Lake is a shallow fresh water lake situated in Manipur River Basin with an area of about 286 sq.km.  This paper describes the survey techniques and the use of GIS for the preparation of contour map of Loktak Lake. Since whole of the lake is covered by aquatic vegetation either emergent or submergent or floating, use of motorboat and echosounder was not possible. Instead, dugout boats, handheld GPS and gauging staff are used. Since, large portions of the lake are covered by thick floating vegetation (phumdi); the only alternative to access is on foot.

 A base map is prepared and rangelines established. Depths at appropriate intervals along the rangelines are measured using gauging staff and its position marked using GPS. Reduced level (RL) of the bottom at each point is calculated from the water level taken at the start of each day’s work. These RL points, SOI contour map for the periphery of the lake and base map are used for generation of Digital Elevation Model in Arcinfo GIS. It is observed that Loktak Lake is very shallow – maximum flood level is 769 m above mean sea level and the minimum contour value