Explanation:
A hydrograph is a graph showing the rate of flow versus time past a specific point in a river. It is a useful tool for studying the impact of rainfall on a watershed. The recession limb of a hydrograph is the part of the graph that shows how the river flow decreases after a rain event.

The point of inflection on the recession limb of a hydrograph represents the condition of maximum storage in the catchment. This means that the point on the graph where the curve changes from being concave upwards to concave downwards represents the point where the maximum amount of water has been stored in the catchment.

To understand why this is the case, consider the following:

- When it starts to rain, the water that falls on the catchment is either absorbed into the soil or runs off into the river. This is called the initial abstraction.
- As the rain continues, the soil becomes saturated and the runoff increases. This is called the rising limb of the hydrograph.
- Eventually, the runoff reaches a peak and starts to decrease. This is the point of inflection on the rising limb.
- As the rain stops, the amount of water in the catchment starts to decrease. This is called the recession limb of the hydrograph.
- At some point, all the water that can be stored in the catchment has been stored, and the amount of water in the catchment starts to decrease rapidly. This is called the point of inflection on the recession limb.

Therefore, the point of inflection on the recession limb of a hydrograph represents the point where the maximum amount of water has been stored in the catchment. Once this point has been reached, the amount of water in the catchment starts to decrease rapidly, and the river flow decreases accordingly.

Conclusion:
The point of inflection on the recession limb of a hydrograph represents the condition of maximum storage in the catchment. It marks the point where the maximum amount of water has been stored in the catchment, and once this point has been reached, the amount of water in the catchment starts to decrease rapidly, and the river flow decreases accordingly.