Thursday, April 2, 2009

More about Hydrographs!!!!=P

Today's lesson is just have an hour, so we don't have so many content compare with yesterday's lesson. Yeah!!=P
During today's lesson, we have discussed more about Hydrographs.
Firstly, we need to clarify some terms.
Stormflow:
stormflow contains overland flow, throughflow and direct channel precipitation.
Bankfull discharge:
Bankfull discharge is over flow the actual bank, which means flood will start to occur.
Secondly, we have discussed the factors that may change the shape of Hydrographs.
  • Amount of rain fall If there is a period of torrential rainfall, over land flow will become very significant. Thus, the gradient of the Hydrographs will become steeper, which means the graph will have steeper limbs and higher peaks.

  • Relief The steeper the long profile, the faster the stormflow. Thus, the time of rise will become shorter if the profile is steeper. The gradient of the graph will also become steeper, it may go very high, which means the graph can have very high peak flow rate.

  • Drainage density More drainage density, which means the drainage basin has more tributaries, the amount of water will also be greater. So there will be more water flow during the same time interval. Compare with the drainage basin with fewer tributaries,the graph of the drainage basin with more tributaries is higher. The graph will have steeper limbs and higher peak flow rate as well.

That's all for today's lesson.
Thanksssssss
Nianchen :)