Managing variable source pollution in agricultural watersheds

Zeyuan Qiu, M. Todd Walter, Christine Hall

Research output: Contribution to journalReview articlepeer-review

33 Scopus citations


Agricultural runoff is a major contaminant source threatening water quality in streams, lakes, and public drinking water reservoirs. Agricultural pollution control practices and programs are traditionally based on the assumption that overland flow is only generated when rainfall intensities exceed soil infiltration capacity. This paper challenges this assumption, noting that overland flow associated with agricultural pollutant transport is often physically consistent with the variable source area hydrology concept, for which overland flow is generated in parts of the landscape where the soil saturates to the surface. Incorporation of variable source area hydrology into watershed management practices reconceptualizes nonpoint source pollution as "variable source pollution," in which pollution control efforts can be focused on relatively small hydrologically sensitive areas recognizing that the extent of these areas will vary throughout the year. There are substantial technical, economic, social, and institutional barriers to implementing strategies for managing variable source pollution partially because of massive institutional inertia of existing agroenvironmental policies and programs and best management practices. Substantial research is needed to quantify the water quality risks associated with variable source pollution, expand the capacity to identify the critical management areas, and eliminate the institutional barriers for managing variable source pollution in agricultural watersheds.

Original languageEnglish (US)
Pages (from-to)115-122
Number of pages8
JournalJournal of Soil and Water Conservation
Issue number3
StatePublished - May 2007

All Science Journal Classification (ASJC) codes

  • Agronomy and Crop Science
  • Water Science and Technology
  • Soil Science
  • Nature and Landscape Conservation


  • Nonpoint source pollution
  • Precision conservation
  • Targeting
  • Variable source area hydrology
  • Variable source pollution


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