Environmental Engineering Reference
In-Depth Information
However, the resilience of the system can be disrupted by widespread effects such as acid rain and
indiscriminate logging and associated road building. Soil moisture, soil nutrients, and soil temperature
can be critically changed by these and other disturbances, as well as other factors. Several tens of years
are needed for the recovery of a system affected by widespread disturbance.
(a)
(b)
Fig. 10.21 (a) A couple of beavers began to construct a dam with tree branches on the Spring Pond in Pennsylvania,
U.S.; (b) The 3 m high beaver dam forms a pond, which provides a good habitat for fish and birds
10.2.2 Human-Induced Stresses
Human-induced stresses undoubtedly have the greatest potential for introducing enduring changes to the
ecological structure and functions of stream corridors. Physical disturbance effects occur at any scale
from landscape and stream corridor to stream and reach, where they can cause impacts locally or at
locations far removed from the site of origin. Activities such as flood control, road building and maintenance,
agricultural tillage, and irrigation, as well as urban encroachment, can have dramatic effects on the
geomorphology and hydrology of a watershed and the stream corridor morphology within it. The
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