WATERSHED-SCALE TERRAIN ANALYSIS FOR DETERMINING NUTRIENT LOSS POTENTIAL

Authors: Bryant, Ray; GIASSON, ELVIO - CORNELL UNIVERSITY; DEGLORIA, STEPHEN - CORNELL UNIVESITY

Submitted to: International Soil Science Society Conference Proceedings
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/15/2002
Publication Date: 8/1/2002
Citation: Bryant, R.B., Giasson, E., DeGloria, S.D. 2002. Watershed-scale terrain analysis for determining nutrient loss potential. International Soil Science Society Conference Proceedings. 38(608):1-10.

Interpretive Summary: For agricultural lands in areas with water quality problems, sources of nutrients and the processes responsible for transporting excess nutrients to water bodies need to be characterized to improve management plans. An important part of these management plans is the identification of land areas, or regions, where practices for reducing nutrient source transport will be more effective and result in a greater reduction of surface and groundwater contamination. This study combines geographical information, nutrient indices and nutrient application data in an index approach for identifying and ranking watersheds and larger geographical areas in the Northeast Region of the USA with respect to potential for nutrient export to streams. Detailed landscape analyses may be extrapolated across physiographic regions, thus facilitating characterization of large watersheds where detailed soil and landscape information is not uniformly available. In the intensely studied Cannonsville Reservoir Basin, in Delaware County, NY, this index approach to terrain analysis is used to rank sub-watersheds with respect to relative risks of nutrient loss that may have negative environmental impacts on water quality. Sub-watersheds that rank relatively high are priority areas for implementing best management practices or enrollment in programs like the Conservation Reserve Program. Comparisons across different physiographic regions illustrate where livestock production operations are well suited or poorly suited to the physical environment in which they are located.

Technical Abstract: As in other regions, individual states in the Northeast Region of the USA have developed indices to assess the risk of diffuse loss of phosphorus (P) and nitrogen (N) to surface waters at the field scale. Many of these indices have identified the soil and management conditions that are of state-specific importance for characterizing the potential for nutrient movement in landscapes. Some indices distinguish between the various modes of transport (erosion, runoff and leachate), assigning risk values for the various transport pathways. This study combines geographical information, nutrient indices and nutrient application data for identifying and ranking watersheds and larger geographical areas in the Northeast Region of the USA with respect to potential for nutrient export to streams. Concepts, such as the delivery ratio (DR) and the availability factor, are used in combination with soil drainage class and other soil parameters that influence risk of nutrient loss. This index approach to terrain analysis for assessing the environmental status of watersheds is a much simpler alternative to complex hydrologic modeling. Where water-monitoring data and modeling results are available, such as in the intensely studied Cannonsville Reservoir Basin, in Delaware County, NY, this index approach to terrain analysis may be calibrated and tested. Terrain analysis results show the potential for application of the index approach for selecting priority areas for implementing best management practices or enrollment in programs like the Conservation Reserve Program. Comparisons across different physiographic regions illustrate where livestock production operations are well suited or poorly suited to the physical environment in which they are located.