How to merge ‘Winter Pool’ sonar data with ‘Summer Pool’ data — C-MAP Genesis Water Level Offsets Primer

This merged map, comprising 45 sonar-log files recorded at various times during a year of wildly varying water levels, is emerging as the most accurate and precise map of Lake St. Croix, because careful attention was paid to offsetting every sonar-log file to a standard water-level benchmark.

One of the best features of C-MAP Genesis is the ability to aggregate sonar data recorded in numerous trips over time in a complete, merged map. However, fluctuating water levels over time can impact the accuracy of aggregated maps if recorded water depths are not offset against a standard benchmark water level.

Naturally flowing rivers, dam-regulated river pools and vast reservoirs can all fluctuate greatly in water level from season to season, due to both natural and man-made forces. Natural forces include snowfall, rainfall and droughts. Man-made forces include flood-prevention measures and power-generation practices. Water levels are measured in feet above sea level.