Spatial Distribution of Glacial Depth and Volume
The spatial distribution of glacier depth and assessment of glacial-stored water is essential information for managing water resources of the Himalayas. Conventionally, several statistical techniques have been used to determine the volume or mean depth of glaciers using surface area. However, volume-area scaling technique introduces large errors in depth estimates due to the lack of field data on depth, and also small errors in delineating a glacier boundary can introduce large errors in depth estimate. Therefore, estimate of glacier-stored water in the Himalayas varies from 4000 to 12,000 Gt, depending upon the scale of glacier inventory and scaling technique. Therefore, further improvement in this assessment is necessary for better management of the Himalayan water resources.
Recent developments in the field of glaciology make it possible to improve volume estimates. The technique based on velocity, slope and flow law of ice can provide ice-thickness distribution. The technique has been successfully used in the Gangotri Glacier. Velocity and slope can be obtained using remote sensing techniques, and depth estimates can be validated using field GPR measurements. If a systematic programme is launched, the technique can be used to estimate the distribution of ice thickness of thousands of glaciers in the Himalaya. The information on spatial distribution of ice thickness can be further used to map bottom topography and assess future formation of moraine dammed lakes.