Understanding Instantaneous Unit Hydrograph Rainfall Duration
The question asks about the assumed duration of rainfall for an instantaneous unit hydrograph. Let's break down what this means in hydrology.
What is a Unit Hydrograph?
- A unit hydrograph is a hydrograph (a graph showing flow rate or discharge over time) produced by a unit depth (typically 1 cm or 1 inch) of excess rainfall occurring uniformly in space and time over a drainage basin.
- It represents the direct runoff response of a catchment to a standard rainfall event.
- Unit hydrographs are fundamental tools in hydrology for predicting streamflow resulting from rainfall.
The Concept of an Instantaneous Unit Hydrograph (IUH)
An instantaneous unit hydrograph (IUH) is a theoretical concept derived from the standard unit hydrograph. It represents the response of a catchment to a rainfall input that is infinitesimally short, essentially a single vertical impulse of rainfall.
Think of it like this: instead of a rainfall event lasting for a specific duration (like 1 hour or 3 hours), the IUH considers a rainfall event that happens almost instantly.
Why Zero Hour Rainfall Duration?
The defining characteristic of an instantaneous unit hydrograph is that the rainfall event is assumed to have a duration approaching zero. This is a theoretical idealization used to simplify analysis and develop more flexible hydrological models.
- Theoretical Basis: In hydrograph separation and analysis, modeling the response to a pulse input simplifies the mathematical treatment.
- Mathematical Representation: The IUH can be seen as the result of applying a Dirac delta function (representing an instantaneous input) to the catchment's impulse response system. The duration of this input function is effectively zero.
- Practical Application: While real rainfall events always have a duration, the IUH allows hydrologists to construct hydrographs for rainfall events of any duration by treating them as a series of instantaneous bursts or using convolution integrals.
Therefore, the assumed duration of rainfall occurrence for an instantaneous unit hydrograph is Zero hour.
Important Questions from Miscellaneous
- Which of the following relationships is/are not true?
(A). Most probable velocity = $\sqrt{\frac{2RT}{M}}$
(B). PV = $\frac{3}{2}kT$
(C). Compressibility factor Z = $\frac{pV}{nRT}$
(D). Average kinetic energy of gas = $\frac{1}{2}kT$
Choose the correct answer from the options given below - Match List-I with List-II
List-I List-II Electronic Configuration First Ionisation energy (kJ mol$^{-1}$) (A). ns$^2$ (I). 2100 (B). ns$^2$np$^1$ (II). 1400 (C). ns$^2$np$^3$ (III). 800 (D). ns$^2$np$^6$ (IV). 900
Choose the correct answer from the options given below: - The shielding constant of a 2p electron (calculated using Slater's rules) is
- Match List-I with List-II
List-I List-II Spectroscopy Property (A). Raman (I). Polarizability (B). FTIR (II). Dipole Moment (C). UV-Visible (III). Absorbance (D). NMR (IV). Spin
Choose the correct answer from the options given below: - The structure of protein comprises of:
(A). Primary structure of protein is associated with amino acids
(B). Secondary structure of protein is associated to peptides
(C). Tertiary structure of protein is associated with polypeptide chains
(D). Quaternary structure of protein is associated with polypeptide chains
Choose the correct answer from the options given below:
