Scoring guide for water erosion, rivers, and streams
Low level: Describes rain as related to streams and rivers and streams and rivers as concluding where seas and oceans begin.
Middle level: Describes rain and run-off as causing erosion and water from it as collecting in streams and rivers and emptying into seas and oceans.
Upper level: Describes rain and run-off as a powerful force proportional to the slope or volume of the flow. That water flow erodes the Earth in specific ways to create channels. And even thought large volumes of water or steep slopes can increase erosion long periods of time can erode the most erosion tolerant earth materials.
Top level: Describes rain and run-off is a powerful force that erodes the Earth and how different flows of water interact with the Earth to create stream beds. How different interactions depending on flow volume (related to precipitation and run-off), speed of the flow (related to the slope, run-off and shape of the channel), and earth materials (related to the flow of the water, mass, hardness, shape, and location of materials) create different channels and deposits.