Identification of critical source areas for erosion and phosphorus losses in small agricultural catchment in central Sweden

Abstract

Identification of main contributing sources and critical source areas is a precondition for a cost-effective abatement strategy. This task is even more complicated in small ungauged catchments where inadequate amount of input, calibration, and validation data exists and thereby limit the application of process-based, parameter-heavy models. In this study, we present methodology to assess spatial variations in erosion and P losses, and based on source-apportionment and erosion modeling, to develop a base for source-and site-specific abatement countermeasures. Water quality monitoring program was developed to cover spatial variability in erosion and phosphorus (P) losses. Conducted soil survey detected high variations in soil P content within the catchment and strong correlation between soil P test and easily soluble P. A simple water balance model, calibrated for the comparable catchment with existing water flow measurements, was applied to determine water discharge, providing necessary input data for calculations of loads and source-apportionment. Source-apportionment modeling based on results from water discharge modeling, water quality monitoring program and soil survey identified P losses from arable fields as main source of P to two small lakes situated in the catchment, contributing roughly a half of total P load to the lakes. Inclusion of an assumed but previously undocumented point source considerably improved the performance of source-apportionment model. Existence of such a point-source was afterwards confirmed by results from detailed water quality monitoring program. Erosion modeling based on high-resolution digital elevation data identified areas most prone to erosion, and model results were compared to farmers' observations and analyses of Cs-137. Use of a spectrum of models and assessment tools formed a broad support for further steps in abatement efforts, and created concrete discussion base for implementation of detailed site-specific countermeasures.

Keywords

Erosion; eutrophication; modeling; monitoring; phosphorus; risk assessment

Published in

Acta Agriculturae Scandinavica, Section B - Soil and Plant Science
2012, volume: 62, pages: 229-240
Publisher: TAYLOR & FRANCIS AS

SLU Authors

• Djodjic, Faruk

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Environmental Sciences
Oceanography, Hydrology, Water Resources

Publication identifier

• DOI: https://doi.org/10.1080/09064710.2012.704389

Permanent link to this page (URI)

https://res.slu.se/id/publ/40312