Question

Which of the following is not a bed load sampler?

• A. Pressure difference
• B. Integrating
• C. Pan
• D. Basket

Hint:

Remember:
Bed load samplers are placed directly on the river bed (Basket, Pan, Pressure-difference).
Suspended load samplers are suspended in the water column (Integrating, Bottle type).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Sediment transport in rivers occurs as suspended load (particles moving in water column) or bed load (coarser particles rolling or sliding along the river bed).
Different instruments are used to sample these two sediment types.
Detailed Explanation:
Let us analyze the samplers in the options:
- Pressure difference samplers (A): These samplers (such as the Helley-Smith sampler) utilize a expanding nozzle structure to create a pressure drop.
This ensures that the water entrance velocity is equal to the stream velocity, allowing accurate sampling of coarser bed load. This is a bed load sampler.
- Pan samplers (C): These feature a pan-like structure that is lowered onto the stream bed to catch sediment rolling along the bottom. This is a bed load sampler.
- Basket samplers (D): These are heavy wire-mesh baskets lowered to the river bed to collect gravel and coarse sand. This is a bed load sampler.
- Integrating samplers (B): These include depth-integrating and point-integrating samplers (such as the US DH-48).
They collect a continuous water-sediment mixture from the water column at a rate proportional to the local stream velocity to measure the suspended load.
They do not sample bed load.

Step 2: Final Answer:
Integrating samplers are suspended sediment samplers, not bed load samplers, making option (B) the correct answer.