EFFECT OF WATERSHED SUBDIVISION ON SIMULATION RUNOFF AND FINE SEDIMENT YIELD

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.