Soil Layer Depth Range (cm) Hydrologic, Sediment, andPhosphorus Processes
    Surface runoff, soil erosion,
Surface Layer 0-0.76 fertilization, and nutrient
    transport    
Upper Layer 0.76-15.24 Infiltration,   fertilization,
and nutrient transport
   
Lower Layer 15.24-101.6 Percolation and nutrient
transport    
   
Groundwater Layer 101.6-203.2 Base flow    
Table 22: HSPF soil layer division and major processes.