Drainage Basin in our Daily Life

Well drainage basins are very commonly found in our daily life. It is easier to find a drainage basin in an urban city like Singapore. Many drainage basin systems are built to prevent flooding. The one below is one I found near my house.

Contour line diagram of the drainage system (numbers are in cm)

Picture of the Drainage basin

When precipitation occurs water gets intercepted by the grass and other vegetation such as the mimosa. Some water gets infiltrated and through throughflow and baseflow water from zone of aeration and zone of saturation flows into a nearby reservoir. Some of the precipitation falls directly into channel storage (drain) and flow through channel flow into the underground water storage. Water that does not get infiltrated through surface runoff enters the channel storage and from there it flows (channel flow) into a reservoir nearby .Some of the water that are trapped in vegetation are lost through evaporation or transpiration. Some water enters the soil through stemflow .Therefore through this we can observe that by allowing nature and technology to work together flooding could be prevented.

Inputs: precipitation

Output: Reservoir, Evaporation, Transpiration

Through this the equation P=Q+E+S is balanced

Enjoy your weekend!!!

Hari Haran

Drainage basin system in our daily life(Mengshan)

Geography is closely related to our daily lives and protects us from miserable disasters, for example, as flooding, Tsunami and etc. Instead of just memorizing the stuffs we learned in class, it is rather more meaningful if we can apply the knowledge in our life and find raw examples in our daily lives. :)
Recap:
The diagram above shows the how the drainage basin system works.

Here come the pictures of drainage basin systems in the boarding school! :)

Drainage basin system is an example of an “open” system as it has inputs and outputs. This picture above is a typical example of drainage basin system. It has inputs which are the precipitation of raindrops, and outputs-------the evaporation and transpiration.
Basically, when there is a rain fall, most of the water drops will contact with the grassland, though part of it will flow in the sewer (Channel) directly. Water from the grassland experiences interception and finally enter the soil by infiltration. Beneath the ground, there will be through flow which is “water moving through soil” in the area of aeration, base flow which is “water slowly soak into the bedrock ” and enters the area of saturation.
In long-period rain season, the amount of input may surplus the field capacity of the soil and cause overland flow. In the example above, the water will flow into the sewer (Channel) and flow downwards the isohypse lines and prevents the flooding in our boarding school.:)

Have a nice weekends!:p

by Mengshan

Hi, this is carolyn. ;]
Today's lesson was about the drainage basin. Everything that was on the powerpoint slide is printed on the handout we have so I don't intend to summarize or mention any of it here as reflection. I think constrasting the concepts taught might be more thought provoking actually.

Firstly, we have the difference between infiltration and percolation. Percolation is a subset of infiltration, infiltration represents the overall flow of water into the soil while percolation is specifically, the downward movement of water under the influence of gravity through pores, joints and bedding planes of a permeable rock. Percolation is the flow of water into the zone of saturation while infiltration is the general flow of water into the ground surface layer and because this water flows through both the zone of aeration and saturation, we say that percolation is merely a branch of infiltration.

Secondly, the difference between stream flow and overland flow. Overland flow, as defined by our handout, is water moving above or over the ground. Stream flow comprises of surface and subsurface runoff (interflow and groundwater/base flow) *interflow-infiltration of water by means of gravity toward a stream channel, a long narrow sloping depression on land that is shaped by its flowing water

Lastly, I think that perhaps baseflow and groundwater flow cannot be used interchangeably. Because according to the handout, it states groundwater flow as the soaking of water into the permeable bedrock below water, hence I think it should be a downward motion. However, as we all know, baseflow is the lateral, steady flow of water feeding rivers. Hence, baseflow and groundwater flow are different in concepts. Besides, a book by the american society of civil engineers states baseflow as consisting of slow interflow and groundwater flow.