Answer:
Soil erosion causes siltation in rivers, dams, etc. In some areas, huge river deltas are formed (such as River Nile delta) because of soil erosion. Such places are good for agriculture but not good for urbanization. However, some people do not care about it, they just want to construct buildings on alluvium type soils.
a windmill collects energy from the wind
The sun's energy drives various processes on earth. One of these processes is photosynthesis in plants whereby light energy is converted into chemical energy by forming carbohydrates from carbon dioxide plus water, which is a process which usually gives off oxygen which animals need to breathe. Another process driven by the sun's energy could be evaporation of water into the air to form water vapour and clouds which then precipitate when cooled off over mountains so is involved in the water cycle.
