The Upside to Rerouting Water

The dams first constructed in the early 1830s were designed with one specific goal in mind: to ease transport along United States major rivers. Dams built in the past century fill a number of roles; the Federal Emergency Management Agency (FEMA) states they "provide a range of economic, environmental, and social benefits, including recreation, flood control, water supply, hydroelectric power, waste management, river navigation, and wildlife habitat". Let's examine some of these roles in greater detail.

This website would be negligent if it didn't cover the most commonly associated function of dams of minimizing the affect of floods on cities located on rivers and lakes. Floods represented 30% of all natural disasters Between 1975 - 2000 with 95 significant floods occurring all over the world. Flood control dams impound overflows in water and either safely release it to the river below the dam or divert the water to be used in other ways. For centuries, people have built dams to help control devastating floods.

And while dam's function usually follows it's form, there are devastating instances where missteps and lack of upkeep lead to mass destruction. Western Washington has a local instance where a state of emergency was declared in late 2009 due to a dam, Howard Hanson Dam, 30 miles southeast of Seattle warned residents of the potential for massive flooding in the Green River Valley. Due a year of heavy rainfall, the dam would not hold back the flood level waters. Luckily those in the local government were spurred by his news to take immediate action shoring up levees and making plans to protect human life and resources. When problems like this arise, it highlights the importance of dam revival and planning. They provide a vital service in maintaining many aspects of human life, and realistic solutions need to be considered before more dams face irreparable damage. It's easy to find videos posted on YouTube of the aftermath, but here's one I found particularly revealing:

 

 

The concept of watershed projects is a simple one. Upstream flood control dams are built across small tributaries to a larger steam to temporarily trap and store water runoff after heavy rainstorms. The dams slowly release the water over a period of several days through a pipe in the dam. This reduces the amount of water that reaches the main water course immediately after a rain, reducing flooding downstream. 

river navigation arguably ensures an average daily flow in our rivers

There is a critical need for integrated water management in a river basin or watershed. Dams and reservoirs strategically located in a river basin allow for the storage of water during rainfall events and then manage the releases to ensure that our rivers have a minimum daily flow at all times. Integrated water management means storing water in all of the reservoirs in the watershed during periods of rainfall and then managing the releases of a coordinated and predetermined amount of water from each dam to maintain a consistent daily flows in the rivers downstream of the dams.