A statistical analysis of watershed spatial characteristics that affect stream responses to urbanization in Maine, USA
2019
Weil, Kristen K. | Cronan, Christopher S. | Lilieholm, R. J. | Danielson, Thomas J. | Tsomides, Leonidas
Increasing numbers of streams are threatened with impairment from disturbance and stresses associated with land use changes and urbanization. Efforts to protect and to sustain the integrity of threatened streams require a means of identifying at-risk watersheds, coupled with appropriate smart growth strategies or watershed conservation actions. In this investigation, two statistical approaches were applied to identify spatially-explicit biophysical and watershed land cover factors that influence stream vulnerability to urbanization. Results indicated that Class A streams with ≥3% catchment impervious cover (IC) and Class B streams with ≥6% catchment IC have a higher risk of degradation from urbanization stress when their watersheds exhibit the following biophysical characteristics: ≥ 5% agricultural land cover, ≥ 14% wetland cover, ≥ 67% class D soils, and a soil erosion K factor > 0.08. Evidence also indicated that streams are less likely to suffer impairment from urbanization stress when their resistant or resilient watersheds are associated with the following biophysical characteristics: > 30% Class A and B soils, a depth-to-water table >167 cm, and >80% natural area or forest cover in a 60 m riparian buffer zone, coupled with <3% IC for Class A streams and <6% IC for Class B streams. Study results provide a basis for achieving two important land use planning objectives: (a) identification of vulnerable streams and watersheds that may require proactive management and conservation efforts in order to avoid future stream degradation; and (b) development of decision support tools or metrics that encourage smart growth by directing human development toward resilient, rather than vulnerable watersheds.
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