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Title: Effects of scale on phosphorus transfer in small agricultural catchments
Author: Deasy, Clare
Awarding Body: University of Sheffield
Current Institution: University of Sheffield
Date of Award: 2007
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Our understanding of phosphorus (P) transfer is limited by a lack of available data with which to investigate the effects of scale. To rectify this, an extensive programme of field monitoring was undertaken at ADAS Rosemaund, Herefordshire. Monitoring was carried out at the hillslope patch (37 m to 111 m), the hillslope/field (1.9 to 3.7 ha) and the catchment (30.6 ha) scales, which were nested where possible and designed to ensure connectivity between scales. Twenty-eight hydrological events were monitored within the 2004-2005 and 2005-2006 hydrological years for discharge and suspended sediment, of which six events were monitored for P. The results showed that surface runoff was relatively unimportant in P transfer within the catchment, accounting for 1% of the catchment P loads from 6% of the area, as surface runoff generation and stream connectivity were spatially limited. Drainflow was the main process of P transfer from the hillslopes, which is likely to relate to the linkage of macropores to the field drains. The influence of land management practices, particularly artificial drainage and tractor wheelings, on P transfer processes and connectivity was evident throughout the analysis. The dominant P transfer processes varied between scales; P transfer was dominated by rainfall intensity and surface runoff at the hillslope patch scale, by rainfall volume and drainflow at the hillslope/field scale, and by rainfall volume, drainflow and instream processes at the catchment scale. Despite the differences in process operation observed, the data showed strong linkages between scales, allowing empirical relationships to be developed between concentration data for the hillslope patch and hillslope/field scales, and between event characteristics for the hillslope/field and catchment scales. A conceptual model of P transfer was revised to include modifications to the processes and to show the effects of scale on P transfer in small agricultural catchments.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: GE Environmental Sciences