Question 1 |
A flood control structure having an expected life of n years is designed by
considering a flood of return period T years. When T=n , and n\rightarrow \infty , the
structure's hydrologic risk of failure in percentage is .
(round off to one decimal place)
25.2 | |
68.4 | |
78.2 | |
63.5 |
Question 1 Explanation:
Risk of failure =1-q^n=1-(1-p)^n=1-\left ( 1-\frac{1}{T} \right )^n
For T=n\rightarrow \infty
Risk of failure =1-\frac{1}{e}=0.632
% risk of failure = 0.632 x 100=63.2%
For T=n\rightarrow \infty
Risk of failure =1-\frac{1}{e}=0.632
% risk of failure = 0.632 x 100=63.2%
Question 2 |
Superpassage is a canal cross-drainage structure in which
natural stream water flows with free surface below a canal | |
natural stream water flows under pressure below a canal | |
canal water flows with free surface below a natural stream | |
canal water flows under pressure below a natural stream |
Question 2 Explanation:
Cross-section of a super passage
Question 3 |
Muskingum method is used in
hydrologic reservoir routing | |
hydrologic channel routing | |
hydraulic channel routing | |
hydraulic reservoir routing |
Question 3 Explanation:
Muskingum method is used in hydrological channel routing
Question 4 |
In a homogeneous unconfined aquifer of area 3.00 km^2, the water table was at an elevation
of 102.00 m. After a natural recharge of volume 0.90 million cubic meter (Mm^2), the water
table rose to 103.20 m. After this recharge, ground water pumping took place and the
water table dropped down to 101.020 m. The volume of ground water pumped after the
natural recharge, expressed (in Mm^2 and round off to two decimal places), is ______.
0.5 | |
1 | |
1.5 | |
2.5 |
Question 4 Explanation:
\begin{aligned} V_R&=0.9Mm^3\\ V&=3 \times (103.2-102)\\ y_s \; \text{or}\; y_R&=\frac{VR}{V}=\frac{0.9}{3.6}\\ \text{Now,}\;\; y_s&=\frac{V_D}{V}\\ V_D&=\frac{0.9}{3.6}[3 \times (103.2-101.2)]\\ V_D&=1.5Mm^3 \end{aligned}
Question 5 |
The probability that the annual maximum flood discharge will exceed 25000 m^3/s, at least once in next 5 years is found to be 0.25. The return period of this flood event (in years, round off to 1 decimal place) is ____
12.2 | |
16.4 | |
17.9 | |
20.6 |
Question 5 Explanation:
\begin{aligned} \text{Risk} &=1-q^n \\ 0.25&=1-q^5 \\ q&=0.944087 \\ 1-p&=0.944087 \\ 1-\frac{1}{T}&=0.944087 \\ T&\simeq 17.9 \; \text{years} \end{aligned}
There are 5 questions to complete.