1 h triangular unit hydrograph of a watershed has the peak discharge of 60 m3-s at 10 h and time base of 30h- The - - index is 0-4 cm-h and base flow is 15 m3-sIf there is rainfall of 5-4 cm in 1 hour the ordinate of the flood hydrograph at 15th hour is

Rainfall in 1 h = 5.4 cm Effective rainfall in 1 h nbsp; = 5.4 ϕ = 5.4 0.4 = 5 cm Ordinate of flood hydrograph = 5 [ordinate of UH at 15th hour] + base ...

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Hydrology & Irrigation

Introduction and Basic Assumptions of Unit Hydrograph

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Question

1 h triangular unit hydrograph of a watershed has the peak discharge of $60 m^{3} / s$ at 10 h and time base of 30h. The $ϕ - i n d e x$ is 0.4 cm/h and base flow is $15 m^{3} / s$

If there is rainfall of 5.4 cm in 1 hour the ordinate of the flood hydrograph at 15th hour is

225 m^{3} / s

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240 m^{3} / s

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249 m^{3} / s

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258 m^{3} / s

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Solution

The correct option is B $240 m^{3} / s$

Rainfall in 1 h = 5.4 cm
Effective rainfall in 1 h
$= 5.4 - ϕ = 5.4 - 0.4 = 5 c m$

Ordinate of flood hydrograph = 5 [ordinate of UH at 15th hour] + base flow
$= 5 \times 45 + 15 = 240 m^{3} / s$

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1 h triangular unit hydrograph of a watershed has the peak discharge of 60 m3/s at 10 h and time base of 30h. The ϕ−index is 0.4 cm/h and base flow is 15 m3/s If there is rainfall of 5.4 cm in 1 hour the ordinate of the flood hydrograph at 15th hour is

The correct option is B 240 m3/s Rainfall in 1 h = 5.4 cm Effective rainfall in 1 h =5.4−ϕ=5.4−0.4=5 cm Ordinate of flood hydrograph = 5 [ordinate of UH at 15th hour] + base flow =5×45+15=240 m3/s

1 h triangular unit hydrograph of a watershed has the peak discharge of $60 m^{3} / s$ at 10 h and time base of 30h. The $ϕ - i n d e x$ is 0.4 cm/h and base flow is $15 m^{3} / s$

If there is rainfall of 5.4 cm in 1 hour the ordinate of the flood hydrograph at 15th hour is

The correct option is B $240 m^{3} / s$

Rainfall in 1 h = 5.4 cm
Effective rainfall in 1 h
$= 5.4 - ϕ = 5.4 - 0.4 = 5 c m$

Ordinate of flood hydrograph = 5 [ordinate of UH at 15th hour] + base flow
$= 5 \times 45 + 15 = 240 m^{3} / s$