Hydrological parameters affecting overland flow in an agricultural watershed Public Deposited

http://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/mg74qp44p

Descriptions

Attribute NameValues
Creator
Abstract or Summary
  • Surface and subsurface hydrological parameters affecting overland flow from cultivated land were studied in three small sub-watersheds located in the western foothills of the Willamette Valley. The sub-watersheds, which ranged in size from 0.46 to 6.0-ha, were fall-planted to grass or small grain. The parameters studied were infiltration, rainfall, runoff and subsurface water measurements. Infiltration measurements were obtained monthly using a portable infiltrometer. Rainfall was measured with recording and non-recording rain gages. Runoff was monitored from the sub-watershed outlets and within the watersheds using H-flumes and erosion plots, respectively. Subsurface moisture conditions were monitored with wells, piezometers and tensiometers. Seasonal changes in soil surface and moisture conditions caused seasonal variations in steady state infiltration rates. Low antecedent moisture and fail cropping practices produced rough, highly permeable surfaces which resulted in a high steady state infiltration rate (6.8 cm/hr). Winter rains caused increased antecedent moisture and surface sealing, and the final infiltration rate was found to decreased to a low of 4.0 cm/hr. Decreased storm events in the spring caused cracks to develop in the crust producing infiltration rates similar to those of the fall. Saturated hydraulic conductivities, measured with core samples from different horizons indicated decreased hydraulic conductivities in lower horizons. In some cases the hydraulic conductivities were virtually zero in the Cr horizon. Bimodal pore desaturations were noted in unsaturated hydraulic conductivities measured by a continuous drainage method. Piezometers and tensiometers indicated positive pore water pressures above moisture flow impeding layers. Hydrostatic pressures developed after rainy seasons started, producing ephemeral perched water tables. Ephemeral perched water tables were at or near ground surfaces during storm periods, causing saturated surface conditions. In lower landscape positions the ephemeral water table intersected the soil surface producing seepage zones. Seepage areas produced runoff between and during storm periods from plots located in the lower landscape position. Runoff from plots in the lower landscape position occasionally exceeded that of plots in upper landscape position by more than 50%. Overland flow occurred in sub-watersheds when the ephemeral perched water table approached the soil surface. In some cases during large storm events, the water table surfaced in both the lower and upper landscape position. Usually the water table was close enough to the surface to cause saturated or near saturated surface conditions via capillary rise.
Resource Type
Date Available
Date Copyright
Date Issued
Degree Level
Degree Name
Degree Field
Degree Grantor
Commencement Year
Advisor
Committee Member
Academic Affiliation
Non-Academic Affiliation
Subject
Rights Statement
Peer Reviewed
Language
Digitization Specifications
  • File scanned at 300 ppi (Monochrome) using ScandAll PRO 1.8.1 on a Fi-6770A in PDF format. CVista PdfCompressor 5.0 was used for pdf compression and textual OCR.
Replaces
Additional Information
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-08-22T21:09:43Z (GMT) No. of bitstreams: 1 LoweryBirl1981.pdf: 1695262 bytes, checksum: 17035f5ab80091bbbf7b77d5893ebecc (MD5)
  • description.provenance : Submitted by Kirsten Clark (kcscannerosu@gmail.com) on 2013-08-22T19:03:48Z No. of bitstreams: 1 LoweryBirl1981.pdf: 1695262 bytes, checksum: 17035f5ab80091bbbf7b77d5893ebecc (MD5)
  • description.provenance : Made available in DSpace on 2013-08-27T17:20:39Z (GMT). No. of bitstreams: 1 LoweryBirl1981.pdf: 1695262 bytes, checksum: 17035f5ab80091bbbf7b77d5893ebecc (MD5) Previous issue date: 1980-08-29
  • description.provenance : Approved for entry into archive by Patricia Black(patricia.black@oregonstate.edu) on 2013-08-27T17:20:39Z (GMT) No. of bitstreams: 1 LoweryBirl1981.pdf: 1695262 bytes, checksum: 17035f5ab80091bbbf7b77d5893ebecc (MD5)

Relationships

In Administrative Set:
Last modified: 08/07/2017

Downloadable Content

Download PDF
Citations:

EndNote | Zotero | Mendeley

Items