Stagnant water is usually more damaging than flowing water. Flowing water can carry debris that physically damage trees. Flowing water does have turbulent mixing that move oxygen more effectively to root surfaces than standing water. Middle-aged trees tolerate flooding better than young and old trees. Dormant season flooding with cold air and water temperatures are the best conditions for flooding.
Foliage covered by flood water is extremely damaging to the tree.
Drain excess water from the site as soon as possible without causing more root damage. Immediately cover exposed tree roots with a thin layer of soil, composted organic matter, and mulch. Remove deposited sediments quickly and carefully without further damaging roots. Prevent further soil erosion. Correct and modify site drainage patterns.