Channel precipitation dynamics in a forested Pennsylvania headwater catchment (USA)

✍ Scribed by Travis W. Crayosky; David R. Dewalle; Thomas A. Seybert; Thomas E. Johnson

• Publisher: John Wiley and Sons
• Year: 1999
• Tongue: English
• Weight: 268 KB
• Volume: 13
• Category: Article
• ISSN: 0885-6087
• DOI: 10.1002/(sici)1099-1085(19990630)13:9<1303::aid-hyp815>3.0.co;2-p

✦ Synopsis

Seasonal and event variations in stream channel area and the contributions of channel precipitation to stream ¯ow were studied on a 106-ha forested headwater catchment in central Pennsylvania. Variations in stream velocity, ¯owing stream surface width and widths of near-stream saturated areas were periodically monitored at 61 channel transects over a two-year period. The area of ¯owing stream surface and near-stream saturated zones combined, ranged from 0 . 07% of basin area during summer low ¯ows to 0 . 60% of total basin area during peak storm ¯ows. Near-stream saturated zones generally represented about half of the total channel area available to intercept throughfall and generate channel precipitation. Contributions of routed channel precipitation from the ¯owing stream surface and near-stream zones, calculated using the Penn State Runo Model (PSRM, v. 95), represented from 1 . 1 to 6 . 4% of total stream ¯ow and 2 . 5±29% of total storm ¯ow (stream ¯ow± antecedent base¯ow) during the six events. Areas of near-stream saturated zones contributed 35±52% of the computed channel precipitation during the six events. Channel precipitation contributed a higher percentage of stream ¯ow for events with low antecedent base¯ow when storm ¯ow generated by subsurface sources was relatively low. Expansion of channel area and consequent increases in volumes of channel precipitation with ¯ow increases during events was non-linear, with greater rates of change occurring at lower than at higher discharge rates.