Just a corny title to seduce all you avid readers to a very fascinating science concept. Flight dynamics and ship motion control work on the principle of pitch ,yaw and roll. Part of writing this blog is also to refresh my own memory about these three movements.
When ever man finds a solution to one problem he inadvertently creates another problem. Automotives increased efficiency of human life ,sped up daily life but all at the cost of our environment.The demand for space and new townships is turning the earth into a concrete jungle. No doubt humans have taken nature for granted and if this continues we might have to hunt for a 'Pandora'.
The first thing to be affected by a dam is the flow of sediment, which is usually picked up along banks and stream beds, and carried downstream. Sediment collects behind dams, rather than continuing to flow out with the river, and as a result, the bed below the dam eventually becomes rocky and gnarled clean of sediment. Aquatic plants are unable to thrive. The nutrients in the sediment that nourish the fish and other aquatic life are no longer available, sometimes causing extinction in large numbers.
The most obvious impact that a dam has on fish is that it obstructs migration. For some fish species, such as salmon, which spawn in rivers and then swim out to sea, this can be devastating. For others, being unable to pass the dams means that there is not as much species diversity. Many dams in the latter part of the 20th century were built with fish ladders and other modifications that were designed to allow the passage of fish. But many fish are unable to use the ladders, or they die in the machinery of the dam. This has a profound impact on fish populations.
This decrease in the rate of migration also exposes sensitive fish species to predators that may lurk in slower flowing water. In the case of salmon, navigating multiple dams and contending with predators also affects the internal biological changes that allow them to switch from being freshwater fish to saltwater fish.
Water quality directly behind dams is also affected because dams tend to collect pollutants along with sediment, which must be released and controlled in some way. Especially in the case of deep dams, thermal stratification or a stagnant heat state develops because there is no current to mix the water. As a result, the deeper water is very cold and has poor oxygen circulation, while the surface water is warmer than usual. When colder deep water is released from dams, it can cause serious problems downstream for fish and other aquatic life due to its poor oxygenation and due to the toxins it may carry.
Legislators in California and Portland face a unique conundrum of their own. Since fishing industry is very much a part of their community's needs in addition to the moral responsibility of protecting marine life, one does not want to be on the wrong side of environmentalists among others and support construction of dams. On the other hand though, the states need to meet up the increasing demand of power, and dams are its biggest source.
California is blessed with miles and miles of rivers and most of them are harnessed by dams impacting the substantial population of wild trout and steelhead population. Many of the licenses come up for renewal and the environmentalists are faced with a golden opportunity to press upon this problem engaging the latest technologies to improve the fish's "house".
In Portland, Obama has tried to pursue a middle path envisaging the construction of new dams as well as adopting an "adaptive management implementation plan" which comes up with a series of contingency plans to protect the ecosystem should anything go wrong. Critics have panned this "insurance plan for the fish" as an eyewash as it advocates removal of dams as a last resort. Politics aside, both parties agree on the immediate need to resolve this issue as not only the fish population hangs in the balance but also the human population depends on the fish for a living.
Creating a dynamic flow within the river may be the only way to prevent stratification. Better technologies and innovative ways to maintain the nature and human balance would certainly be appreciated. The administration has to again pursue alternate means of developing power so that demand for more dams is nullified. It is a commonly known fact that it is impossible to keep everyone happy, but the challenge is to find a mutually beneficial solution so that the interdependency of nature and the human race is not at stake.
