Question

1. Question: What is the relationship between how far a stream meanders (the pre-cutoff length) and its gradient after cutoff happens?

2. Question: Why does the border not follow the river in these places?

Answer 1

1) There is a negative or inverse relationship between the how far a stream meanders (the pre-cutoff length) and its gradient after cutoff happens.

When they river enters to a flat or low gradient surface then its starts meandering more. The more flat the or less gradient surface the more will be the meandering.

2) River border doesn't follow the river in these places because it depends on the amount of sediment load, amount of erosion and amount of water flow.