Importance of Trees In Flood Control

As the rain begins to fall from the sky, some particles are caught by the leaves for a time until the rain drops accumulate and trickles to the twigs, then branches, and further to the ground. The water enters the spaces of the soil and infiltrates beneath until it reaches the root system of the tree, where the root takes the necessary amount of water and hold the moist and wet soil.

Trees are canopies which delay the raindrops to reach the ground, and the roots and the soil they hold are small natural reservoirs for a definite time. Under normal condition,  trees can help delay fast runoff or prevent flash floods.

However, during  extreme and prolonged rainfall there are times when  the ground is saturated while the  roots could not hold the stability of  steep slopes leading to inevitable collapse. Land slides, debris flow, or mud flow  occurs carrying uprooted trees, boulders and sediments.

On the other hand, rain drops that accumulate on the leaves and  falls at bigger volume and energy may  dislodged bare soil particles on the ground. Hence, trees cannot prevent but induce soil erosion under bare ground condition.  However, leaves that fall on the ground and the undergrowth vegetation, -such as grass, herbs, bushes, etc. - could armor the ground from bigger drops from the trees.