Aditya
Hi all,
On Tuesday we had our lesson near the fish pond where Mr. Heah taught us about the drainage basin. In the previous lessons we had about learnt the basic water cycle. Water evaporates from the water bodies, rises, expands and cools. Then the clouds get heavy and water droplets fall from sky as raindrops.
So, when a water droplet falls what can happen to it?--
1. So when the water droplet falls it reaches the ground surface and is soaked by the soil (Infiltration). The Infiltration capacity is the rate at which water soaks into the soil. If the amount of water received by the ground exceeds the capacity of the soil, this leads to collection of water on the surface. This is what we saw on the backside of staff room.
2. The water droplet can flow down the slope laterally. (throughflow)
3. The water droplets may flow laterally horizontally (baseflow)
4. It may fall on the trees and leaves (interception). Tree by itself acts like an inverted drainage system.
5. The water droplets that fall on the leaf may be evaporated or it may drop down from leaf (Through fall)
6. The water droplets may flow down the stem of the tree.(stemflow)
If we change the ground from soil to concrete then it can affects the drainage system and the water reaching the ground will decrease. This will severely affects the amount of groundwater and the water available to the plants.
Thank You.
posted by 08ip01 at
5:21 PM
8 Comments:
Yeah, when the area is urbanised, there will be more overland flow. Concrete is not really permeable, thus less water gets into the soil. The plants won't be able to survive.
Thats why urbanisation comes at a price-the vegetation.And with that gone, pretty much everything else will be gone too. Plants are the food producers. The entire ecosystem, not to mention the food chain, begins with them. That sort of illustrates how the term "concrete jungle" came about. In many cities today, all you see are rows of skyscrapers and not a single leaf in sight.
It's a kinda sad what mankind has done to Mother Earth, after she did(and still does) so much for us.
The fifth point, the water droplet fall on the leaf and drop down from the leaf-Isn't it considered as overland flow?
-Zhao Pei
Regarding what Zhao Pei said, its not considered as overland flow sometimes because the water may fall back to the soil, where it will intercept the soil and flow through it, no water is flown (flow?) overland here. And when it said that water drop down from leaf is called through fall, I think its mean water drop from leaf to leaf, that process is throughfall, not water falling from leaf to ground. But yes, if water falls from leaf to ground, and doesn't infiltrate the soil, we have overland flow:) Sometimes plants are intercept much water, it can be the great difference to an area, like whether there is a flood or not, for if the vegetation is thick, interception is high, and the time taken for the water to reach the ground is increased. In such a way, there is a staggering of time of water reaching the ground, giving the soil sufficient time to let water infiltrate through, minimizing overland flow, and reducing floods. Plants, the work of mother nature, is such useful diverse creatures, and yet sometimes we overlook them for our own greed for wealth, cutting down acres of trees and forests. All these actions have now resulted in great devastating consequences- there are landslides and floods and global warming. Why is it that humans cannot see the long term effects of our actions on the environment, if we can see long term economic effects and such? Why are we blind to the needs of our world, when we yet rely on it so much? Just because the earth cannot speak up does not mean its any less important, and in fact, now we face the repurcusions of our actions, which it seems we cannot atone for despite technological advancements and such. Perhaps it is simply the way of humans, our limitations. We were not made perfect, and this is perhaps one of our flaws. But a great flaw with heavy consequences indeed.
Although concrete used in urbanization reduces the amount of water reaching the ground, but doesn't drainage pipes lead to water going back to the ground again?
Also, mankind seems to be slowly realizing the damage we caused to mother nature and are trying to atone for the mistakes, hence, maybe in the near future, concrete jungles would be replaced by cities where nature can coexist togetehr with rows of skyscrapers.
For further information, natural plants and soil also play an important role in purification of water. Plants take in ions and various soluble compounds in water while the spongy soil layer serves as a natural filter paper to trap all the particles such as dust in rain water.
To add on, I think it is also important to note that in countries like Singapore, our drainage basin and the system in general is heavily dependent on overland flow which does not necessarily mean flooding, but also the proper drainage we have. Example of this would be the little longkangs we see at the sidewalks which help to reduce the flooding.
We do also have many objects which obstruct percipitation in the country, seeing that most of Singapore is filled with high rise buildings which is to make up for what little land we have.
Seeing that we may not have much land which is able to allow water to infiltrate easily, infiltration and baseflow and throughflow are mode of transport of water which isnt commonly occuring in this country. and that is why we have such a complicated yet awesome and efficient drainage system :D
While I do agree with Nurul that even with urbanization, it does not necessarily mean flooding, but I still do believe that what Mother nature has initially provided us with is still better than the world's best drainage system. While drains can be large and deep, we still can't deny that all the water is passed off as overland flow unlike in forests. In fact, the drains might not be able to withstand a torrential rain and sometimes there can be flaws in man-made structures such as leaks.
i think when discussing drainage systems, we should consider what our purposes are, for instance, farmers would want to redirect the flow of water so that crops get sufficient amounts of it, whereas cities generally want their cars to be able to move around without obstruction, hence the sophisticated drainage systems.
However, with nature, is there a purpose? Arent all these things just occuring due to random chance?
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