Question

a positive feedback loop: meanders make more meanders
the river has a meander.
over time, the force of the river erodes away the banks where it hits.
this causes the stream to have an even stronger meander.
this is a positive feedback loop because the system creates more of the same pattern. a meander causes more meandering. a negative feedback loop is when the system disrupts the pattern.
a negative feedback loop: oxbow lake stops meanders
the river has a strong meander.
over time, the force of the river erodes away the banks where it hits.
the river takes a straight course, ending the meander and forming an oxbow lake.

1. consider the model of feedback loops shown. does your model of erosion explain the feedback loops of meander and oxbow lake creation? why or why not?
2. what role do you think waters polarity plays in the formation of meanders and oxbow lakes?

Explanation:

Step1: Analyze positive - feedback loop

In the positive - feedback loop for meanders, a meander in the river causes the force of the river to erode the banks where it hits. This erosion further enhances the meander, creating more meandering. A model of erosion that includes lateral erosion (bank erosion) can explain this. As the river erodes the outer banks of the meander, the meander becomes more pronounced, which in turn increases the erosive force on the banks, continuing the cycle.

Step2: Analyze negative - feedback loop

For the negative - feedback loop of oxbow lake formation, the strong meander is eroded over time. Eventually, the river takes a straight course, forming an oxbow lake. An erosion model that accounts for the continuous erosion of the neck of the meander (the narrow part between two bends) can explain this. As the neck is eroded, the river can cut through it, taking a shorter, straight path and leaving behind the oxbow lake.

Step3: Consider water's polarity

Water's polarity gives it high surface tension and adhesive and cohesive properties. These properties affect the erosive power of water. The cohesive forces in water allow it to flow as a continuous mass, and the adhesive forces help it to stick to and erode the river - bank materials. Higher surface tension can also increase the impact force of water on the banks, enhancing erosion. This erosion is crucial for both meander development and oxbow - lake formation. For example, in meander development, the erosive power of water due to its polarity helps to widen and deepen the bends. In oxbow - lake formation, it helps to erode the meander neck until the river can cut through.

Answer:

1. Yes, a model of erosion can explain the feedback loops. For the positive - feedback loop of meanders, lateral bank erosion enhances meanders. For the negative - feedback loop of oxbow lake formation, erosion of the meander neck causes the river to take a straight course.
2. Water's polarity gives it cohesive and adhesive properties and high surface tension. These enhance its erosive power, which is crucial for the development of meanders and the formation of oxbow lakes.