Question

Given below are two statements: Statement (I): The rising limb of hydrograph, also known as concentration curve represents the increase in discharge due to the gradual building up of storage in channels and over the catchment surface. Statement (II): The basin and storm characteristics control the shape of the rising limb of a hydrograph. In light of the above statements, choose the most appropriate answer from the options given below:

• A. Both Statement (I) and Statement (II) are correct.
• B. Both Statement (I) and Statement (II) are incorrect.
• C. Statement (I) is correct but Statement (II) is incorrect.
• D. Statement (I) is incorrect but Statement (II) is correct.

Hint:

The rising limb is controlled by both basin and storm characteristics, whereas the falling limb (recession curve) is governed primarily by basin storage characteristics and is largely independent of storm properties.

Answer 1

The Correct Option is A

Step 1: Understanding the Concept:
A storm hydrograph is a graph showing the rate of flow (discharge) over time at a specific point in a river or channel.
It represents how a catchment basin responds to a rainfall event.
A typical hydrograph consists of a rising limb, a peak segment, and a falling limb (or recession curve).

Step 2: Detailed Explanation:
Let us evaluate both statements:
Statement (I): The rising limb (concentration curve) is the ascending portion of the hydrograph leading up to the peak.
As rainfall continues, water flows over the ground surface and through small channels, gradually filling up storage spaces and reaching the main stream.
This concentration of runoff causes a steady increase in stream discharge, making Statement (I) correct.
Statement (II): The shape of the rising limb is influenced by both the physical properties of the drainage basin and the characteristics of the storm.
Basin characteristics include basin shape, size, slope, drainage density, and soil infiltration capacity.
Storm characteristics include rainfall intensity, duration, and the direction of storm movement.
For example, a circular basin with a steep slope will produce a steep rising limb, while a long, narrow basin will produce a gentler slope.
Thus, both basin and storm characteristics control the shape of the rising limb, making Statement (II) correct.
Consequently, both statements are correct.

Step 3: Final Answer:
Both Statement (I) and Statement (II) are correct.