Submitted to: Transactions of the ASAE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: June 30, 2005
Publication Date: September 30, 2005
Citation: Graff, C.D., Sadeghi, A.M., Lowrance, R.R., Williams, R.G. 2005. Quantifying the sensitivity of the riparian ecosystem management model (REMM) to changes in climate and buffer characteristics common to conservation practices.Transactions of the ASAE. 48(4):1377-1387. Interpretive Summary: Conservation practices, such as buffers, are often installed to mitigate the effects of nutrients and sediment runoff from agricultural practices. The Riparian Ecosystem Management Model (REMM) has been developed as a process based model to evaluate the fate of nutrients and sediment through a riparian buffer up to the edge of a stream. Buffer characteristics such as vegetation, soil, slope and climate conditions can be changed in REMM in order to evaluate the effect different buffer scenarios will have on water quality parameters. Key to understanding model output is knowledge on how changes in the parameter input affects model outcomes. A sensitivity analysis was performed on REMM to quantify these effects. Input parameters were varied within the ranges typically found in riparian systems. It was found that few of the vegetation parameters greatly affected nutrient and sediment outputs. However, slope, surface soil conditions, and overland flow parameters greatly influenced the pollutant loads to surface waters. This work will be used to assist in evaluating how specific buffers changes will affect nutrient and sediment load reductions giving rise to the most effective buffer systems.
Technical Abstract: Conservation practices, such as buffers, are often installed to mitigate the effects of nutrients and sediment runoff from agricultural practices. The Riparian Ecosystem Management Model (REMM) was developed as process based model to evaluate the fate of nutrients and sediment through a riparian buffer up to the edge of a stream. A single- variable sensitivity analysis was performed on REMM to evaluate the effects changing buffer characteristics have on N, P and sediment in surface and ground water. Vegetation characteristics such as rooting depth, LAI, and plant height, along with some physical buffer characteristics were varied within their 'typical' range and compared to a 'base case' scenario. Model outputs were not sensitive to plant height, LAI, or SLA, and only sensitive to rooting depth when roots became shallower in the soil profile. Sediment yield and dissolved nitrate in surface water were the most sensitive to changes in Manning's N, while other soil physical characteristics such as surface roughness surface condition, and % bare soil had no effect on model outcomes. Dissolved surface nitrate, organic P out, and subsurface nitrate were all moderately sensitive to changes in permeability rate and the slope of the buffer. Results indicate that vegetation characteristics do not directly play a role in the physical transport of nutrients and sediment, therefore utilizing REMM to evaluate effects of specific plant types may be ineffective. However, it may possible to achieve specific load reductions by modifying slope and other physical characteristics.