Correct Answer - Option 2 : capacity/inflow ratio
Explanation:
(i) Trap efficiency of a reservoir is the ratio of total sediments retained by reservoir to the total sediments entering into reservoir (inflow sediments).
(ii) Trap efficiency of reservoir is the function of ratio of reservoir capacity and total inflow.
(iii) The reservoir capacity is inversely related to the amount of sediments deposited. As the time passes, rate of silting or rate of deposition of sediments reduces but amount of sediments deposited will be increased which in turn reduces the capacity of reservoir. Hence, trap efficiency also gets reduced.
Other factors affecting trap efficiency:
1. Size of reservoir and stream: A larger reservoir on small stream has less capacity inflow ratio and hence having higher trap efficiency.
2.
Velocity of flow of stream: Higher velocity less deposition of sediments, lower is the trap efficiency.
