Geoscience Reference
In-Depth Information
Chapter 6
Modeling Distribution of Point and Nonpoint
Sources Pollution Loadings in the Saginaw Bay
Watersheds, Michigan
Chansheng He, Carlo DeMarchi, Weichun Tao, and Thomas H. Johengen
Abstract This study involves developing a physically based, spatially-distributed
water quality model to simulate spatial and temporal distributions of point and
nonpoint sources in the Saginaw Bay Basin, Michigan. Databases of point sources
including combined sewer overflows (CSOs) were acquired from the governmental
agencies to map the occurrences and magnitude of the CSOs. Multiple databases of
meteorology, land use, topography, hydrography, soils, and agricultural statistics
were used to estimate nonpoint source loading potential in the study watersheds.
Results indicate that point sources from municipalities, industrial sectors and
business entities contribute approximately 25 % of the total phosphorous load to
Saginaw Bay. While total amount of nutrients (N and P) from animal manure and
fertilizer applications and atmospheric deposition declined in the Saginaw Bay
Basin, fertilizer applications in non-farmland increased significantly.
Keywords Point and nonpoint source pollution • Distributed large basin runoff
model • Saginaw Bay Watersheds
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