1. A surge of depth H moves into a stagnant tidal pool of depth 1 m at a speed of 6 m/s relative to a stationary observer on the bank of the pool. Find H, and then find the drift velocity behind the surge, relative to the stationary observer.
2. A surge is observed to enter a tidal channel that is moving at 1 m/s against the surge. If the depths of the water upstream and downstream of the surge are 1 m and 2 m, respectively, what is the speed of the surge relative to a stationary observer on the bank of the channel?