3.1.3 - Human-Caused Flooding
Floods from rivers can be devastating. They can destroy homes, wash away buildings, ruin land, and cause death. Often, river flooding is unavoidable and part of a natural recycling effort of the earth, and humans tend to avoid areas prone to flooding...but there are human actions that can cause an area around a river that is normally not to become prone to flooding. The main anthropogenic (human) causes of river flooding are urban development, deforestation and agriculture.
Urban Development - If a place along a river is developed, the land is cleared and buildings, roads, and other structures are constructed. When water builds in heavy rains, instead of percolating into the ground, it will run off the concrete/asphalt into the lowest elevation...the river. This, in turn, will cause the river water levels to rise and then flood the developed area from which it originally flowed. Place can combat river flooding by installing dams (floods the area behind the dam instead), installing levees (walls to protect the urbanized land), and divert the natural flow of water away. Of course, all of these disrupt some other area and ecosystem.
Deforestation - Because roots provide structure needed to hold soil, they in turn are needed to hold water,. Without a strong soil/hummus layer, there is no way a forest can have water percolation. Thus, in essence, this acts just like urban development...if an area is clear-cut or deforested, the water will run to the lowest part, the river, and can cause flooding of the area, thus destroying even more of the ecosystem. Watch this video of the devastating impacts of deforestation of flooding in Haiti.
Agriculture - In much the same way as the other two causes, changing a land from what it naturally is to farm land disrupts the natural water flow, and can again cause river flooding. The flooding can then, in turn, ruin the crops on the farm land. To combat this, farms may build water storage systems in case of flooding, build water diversions, or build their own levees around the farm to prevent flooding.
More - There is some good information and specific case studies on this site that will help you further understand the human causes of river flooding. Please read over the entire site (all 6 parts) and the case studies associated with it, as they give you a really great understanding of not only the causes, but management solutions you will need to know and recall.
Your turn to put your knowledge into action! Play the following simulation game for the flooding scenario. If you can win the game (not fail), show me a screenshot of your score for 5 bonus points on the next exam!
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