These cyclic and cumulative effects mean that urban ecological relations can become particularly complex. One change leads to another and another in a complicated, spiraling series of feedback loops. Sometimes it is easy to see how urbanization shapes the environment, particularly in peripheral areas were large suburban developments may consume hundreds of acres per year. But the impacts of urbanization begin early. Sometimes, the period of initial urban settlement produces the most radical changes in watersheds as tracts of land are cleared for the first time.
Encroachment continues long beyond initial settlement as an almost continuous process.
Click here to see examples of encroachment of Austin rivers and streams.