Using what you have learned about stream competence and capacity, use the questions below to make some predictions about what you might observe in the Water Erosion Lab.

In the Water Erosion Lab, various factors such as water volume, incline gradient, and temperature will significantly influence stream energy, erosion, and sediment transport. Here are predictions based on the questions provided:

1. How will water volume, incline gradient, and temperature affect the energy of a stream?

Water Volume:

• Higher water volume increases the stream's energy since more water can transport more sediment and exert greater pressure against stream banks, which enhances erosion.
• Conversely, lower water volume means less energy, resulting in reduced erosion and sediment transport.

Incline Gradient:

• A steeper incline gradient will lead to higher water velocity, increasing the stream's kinetic energy. This can result in more aggressive erosion of the stream bed and banks, as the fast-moving water has greater energy to dislodge sediments.
• A gentler gradient results in lower velocity and energy, which may lead to deposition of sediments, reducing erosion.

Temperature:

• While temperature does not directly change water energy, it can influence the water's viscosity and the metabolic rates of organisms, impacting sediment transport. Warmer water may lead to increased biological activity (like faster breakdown of organic matter), contributing to sediment mobilization.
• Additionally, temperature affects water density; at higher temperatures, water is less dense, which may slightly alter its ability to carry sediments but is generally less significant compared to volume and gradient.

2. Suppose a stream has a low volume but a steep gradient. How might the stream change the land? Provide your reasoning.

In this scenario, the stream is characterized by low volume and a steep gradient.

Erosion Characteristics:

• The steep gradient can lead to high velocity, enabling the stream to exert significant erosive power on what little water is available.
• The stream might create deep channels known as incised channels or gorges, as the eroding forces are concentrated in a smaller volume of water.
• It may result in downcutting into the stream bed, leading to steep, unstable banks, and potentially creating features like waterfalls or rapids.

Land Changes:

• High erosion rates may lead to the stripping of soil and vegetation from surrounding areas, resulting in exposed rock surfaces in some regions.
• Although there may not be much sediment transport due to low volume, the type of sediment that is carried could be larger particles (like gravel) that the stream can dislodge effectively, leading to localized areas of significant land alteration.

3. Now suppose a stream has a high volume but a low gradient. How might the stream change the land? Provide your reasoning.

In this scenario, the stream boasts a high volume of water but a low gradient.

Erosion and Sedimentation Characteristics:

• With a high volume of water but low energy due to the gentle slope, the stream may not flow quickly enough to cause significant erosion of the stream bank or bottom.
• Instead, this type of stream is more likely to promote sediment deposition rather than erosion because the slower-moving water cannot carry larger sediments effectively.

Land Changes:

• The stream might create a wider, meandering channel with features such as point bars and oxbow lakes as sediment accumulates along its banks.
• Over time, the gentle flow can lead to the development of wetlands or floodplains, as sediments are deposited in low-lying areas during flooding events, contributing to richer ecosystems.
• Additionally, vegetation growth along the banks may stabilize the area, preventing erosion and leading to more significant impacts on the surrounding landscape over time.

In summary, both the water volume and the gradient play critical roles in stream energy and landform changes. High-energy streams (steep gradient, low volume) favor erosion, while lower-energy streams (low gradient, high volume) tend to favor sediment deposition and the formation of distinct landforms.