The objective of this study was to establish the subwatershed size dep
endency of the Soil and Water Analysis Tool (SWAT) erosion model to ad
equately simulate annual runoff and fine sediment (< 0.063 mm) from th
e 21.3 km(2) Goodwin Creek Watershed (GCW). Results of the GCW applica
tion show that runoff volume is not appreciably affected by the number
and size of subwatersheds. However an upper limit to subwatershed siz
e is required to adequately simulate fine sediment yield produced from
upland sources. Decreasing the size of subwatersheds beyond this thre
shold does not substantially affect the computed fine sediment yield.
The proper identification of this threshold size cart optimize input d
ata preparation requirements and computational resources needed for ef
fective utilization of the SWAT model, and simplify the interpretation
of results.