The base of the non-recording type rainfall is permanently fixed in the concrete block.

Question

Examoogle · Accepted Answer

The correct answer is Option A: TRUE. A non-recording rain gauge, such as the Symons' gauge, requires a stable and level platform to ensure accurate measurement. It is standard engineering practice to fix the base of the gauge to a masonry or concrete foundation to prevent tilting or displacement due to wind, soil moisture, or animal activity.

Step-by-Step Solution & Concepts:
A non-recording rain gauge, such as the Symons' gauge, requires a stable and level platform to ensure accurate measurement. It is standard engineering practice to fix the base of the gauge to a masonry or concrete foundation to prevent tilting or displacement due to wind, soil moisture, or animal activity.

Working Principle: The gauge is anchored to a concrete block that is typically flush with the ground level. The foundation ensures the rim remains strictly horizontal, which is critical because any tilt in the rim would result in an incorrect catchment area for the rainfall, leading to systematic errors in the volume measurement.

Key Formulas: $A_{catchment} = \pi r^2$ — area of the collector rim used for rainfall depth calculation; $h = \frac{V}{A}$ — depth of rainfall calculated by dividing volume ($V$) by area ($A$)

Key Points: Non-recording gauges rely on the manual measurement of water collected in a graduate cylinder.; The standard height of the gauge rim above ground level is typically 30 cm to minimize splash errors.; A level, horizontal rim is mandatory for uniform precipitation capture.; Concrete foundations prevent the gauge from being affected by differential settlement of the ground.

Advantages: Simplicity in design and maintenance.; Cost-effective installation for widespread monitoring networks.

Disadvantages: Does not provide a record of rainfall intensity over time.; Requires daily human intervention for measurements.

Applications: Meteorological observation stations.; Hydrological networks in remote areas where power is unavailable.

Additional Info: The concrete block serves as a dead weight to maintain the gauge's vertical alignment.. Option B (FALSE) is incorrect because an unfixed gauge is prone to tilting, which creates significant errors in catch efficiency.

Answer: A is correct — The non-recording rain gauge must be permanently fixed to a level concrete block to maintain its geometric alignment and accuracy of the catchment rim.

Exam Tip: Always ensure the rim of any precipitation gauge is strictly horizontal; even a small deviation can cause an 'overshadowing' or 'undershadowing' effect depending on the wind direction.

Examoogle · Answer

Option B: FALSE

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