November 28, 2007

Questions in Worked Example 2.7

Questions in Worked Example 2.7:

1. Question 1: Why are the cells in yellow blank?

Answer:

2. Question 2: Why are the cells in the lower diagonal all zeros?

Answer:

Congratulation to Group E for the best correct answer.

Results for this worked example:
No. 1 is Group E
No. 2 is Group B
No. 3 is Group C
No. 4 is Group A
No. 5 is Group D

Total Score so far:
Group A= 2+5+1+1+4
Group B=4+2+2+2+2
Group C=5+1+5+3+3
Group D=3+4+3+4+5
Group E=1+3+4+5+1

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Comments on Questions in Worked Example 2.7 »

November 28, 2007

LIEW TIAM MING @ 12:11 pm

Q1: It based on the formula 2.11(pg59)which have to be in staggered form to get each of sub catchment discharge.

Q2 : no sub-catchment to multiply to. It is end of the catchment.

suhayati Abd Rahman @ 12:14 pm

Group E
Q1: It based on the formula 2.11(pg59)which have to be in staggered form to get each of sub catchment discharge.

Q2 : no sub-catchment to multiply to. It is end of the catchment.

izezaidi @ 12:22 pm

Group A

Answer 1 of Question 2.7

In terms of formula, these cells in yellow are blank due to the convolution formula in page 59. If you look at the formula, q1 = I1 * A1, q2 = I2 * A1 + I1*A2, etc. For q1 there is only one term i.e. I1.

In terms of theory, it means that the cells in yellow blank is the areas where the runoff from the respective isochrones have not reached the final discharged point.

alexyap @ 12:25 pm

Group B
Q1 ans: The cell is blank because at the particular duration, this part of discharge q=I.A is not contributing to the outlet.

Q2 ans: The cells are zero because all discharge at these cells had already contributed to the outlet during the earlier time spans.

sean.leemw @ 12:31 pm

answer 1: Rainfall at A(i+1) do not contribute to Q (outlet) at time T(i), ie the contributing Q is travelling in "drain" [ie. T(d)]towards the outlet.

answer 2: when T goes beyond the rainfall duration (rain stop), the contributing runoff will only left behind the volulmn travel in the "drain", from the most remote point to the outlet, and the Q reducing (to "0") after time.

izezaidi @ 1:10 pm

The first isochrone nearest to the final discharge point (outlet) shows that the runoff of zero starting from minute of 35. This means that all the runoff from the first isochrone has been completely discharged to the final discharge point at the first 30 minutes. Similarly, for the rest of the isochrones, the longer overland flow, the longer would be for it to discharge to the final discharge point.

Therefore, the zero value of last isochrone is at 60 minute, mean that it take the longest time to discharge all the runoff to the final discharge point.

From group A!

teehornghean @ 1:13 pm

post number #6 is the answer for the seconsd part of example 2.7

sean.leemw @ 1:18 pm

Q1: Not rain yet, at the time
Q2: Rain Stop, at the time

Group C

ipshl @ 1:23 pm

Group D:

Answer 1: The yellow cells are at sub-catchment where rainfall Tc > time, T. THe flow not yet reach the outlet, hence not contributing to the discharge.

Answer 2: Time T goes beyond rainfall duration + Tc. No more flow into the outlet.

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