Real Causes of Flooding

For so many years, I have been watching on television floods happening practically around the world. Many of their reasons (I find them as excuses) are caused by deforestation and garbage, or trash, on drainage systems. These are actually secondary reasons of the main reasons. The people who make these statements are engineers or supposed to be specialists in those fields. I have never heard any of them release a statement like what I have to say later on this article. They lack observation and facing reality because they could lose earning income from their profession. They still teach in schools that the causes of flood and landslides were cutting down of trees, deforestation in short. It is partly correct and lacks the details, which probably they do not know or understand. Let's go back to the state of cities before they became "concrete jungles". The creeks, streams, tributaries and rivers then, were able to drain whatever kind of heavy rainfall. If you have ever been in a forest during a heavy rainfall, it will be easy to understand. The trees, its leaves, twigs, branches and trunks delay the flow of rain water. They serve as a sieve, filter and channel before flowing down. The raindrops do not hit the ground outright. In short, there is time delay in the flow of rainwater going to natural drainage. But, before rain water flows down, the initial water that hits the ground is either absorbed by the soil. If the ground is not absorbent, there are natural crevices, ducts or cracks that channel these waters underground. Also, the forest ground has smaller plants like bushes, shrubs and grass. They further delay the drainage flow of rain water. With all of that, estuaries, tributaries and rivers have enough time to normally drain rainfall. Most of them do not have deposits of whatever the rain water brings along. Why? Because the flow is right and continuous, therefore, that has a characteristic of scouring the river beds. The angle of the drainage towards its final destination is maintained. It maintains balance and equilibrium of cleaning and draining in the process.

The present time has all those concrete buildings, roads and whatever concrete constructions. Trees, bushes, shrubs and grass are minimal and negligible for proper effect. Everything constructed by human is designed to drain rain water as fast as it can to empty out to natural or man-made canals and finally onto natural drainage such as rivers, lakes or coasts. With the speed of draining rain water from roofs, downspouts, roads and other concrete passages, the natural drainage system can only take so much at a given time. It could not unload the abnormal volume it is being given. In that case, the main drainage system that carries soil, dirt and trash is deposited on its bed because of the relatively slow flow to carry them away. Dredging river beds is a short and temporary solution aside from being costly and time consuming. It needs to be done at regular intervals, or the problem of flooding will persist. To prove this effect, take a sheet of metal, set it at an inclined angle so water would flow in only one direction towards a half-pipe that serves as drainage then sprinkle-hose it for a given time, say, two minutes. Observe how quickly the water flows and fill the half-pipe. Next, put a foam mattress over the sheet of metal and hose it down for the same time you did earlier. It will take time for the water to flow down to the half-pipe at lesser volume. Also, note that some water will be retained by the foam mattress. That explains what I am trying to say above.

We are good at complaining about flooding and that nothing is being done about it. What is being done about it is partially wrong on the bigger side of it! What needs to be done could cost something now but will pay for itself in the long run. The objective is to delay or prolong the flow of rainwater before it reaches the main drainage system. Downspouts are going straight down, why not make a coil or spiral out of it with sufficient speed to wash down dirt or any foreign matter. It could even be used to cool down or heat up a building, if need be. If applicable, construct large underground water reservoirs that would collect rainwater from a building or house downspouts that would drain off only when it is full. Quite sure, if that is done, many flood prone cities will be relieved from being flooded.