Complex sentence: Floods occur when ponds, lakes, riverbeds, soil, and vegetation cannotf the land in quantities that cannot be carried within stream channels or retained in natural ponds, lakes, and man-made reservoirs.
Split into simpler sentences: Floods occur when ponds, lakes, riverbeds, soil, and vegetation cannot absorb all the water. Water then runs off the land in quantities that cannot be carried within stream channels or retained in natural ponds, lakes, and man-made reservoirs.