Validation of a vegetated filter strip model (VFSMOD)

Abu‐Zreig, Majed; Rudra, R. P.; Whiteley, H. R.

doi:10.1002/hyp.101

Cited by 56 publications

(38 citation statements)

References 20 publications

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“…All these variables are in imperial units as given by Renard et al (1997). The value for D 50 is assigned based on texture of the surface soil according to Table 1; R is obtained from the map in Figure 2-1 of Renard et al (1997); K (without rock fragments) is obtained from tables in a USDA soil survey; L and S are computed according to Renard et al (1997) Abu-Zreig et al 2001). Values of SF and STE were calculated for 24 combinations of soil texture, slopes, rainfall amounts representing a wide range of cultivated lands in the eastern US (Fig.…”

Section: Methodsmentioning

confidence: 99%

Methods to prioritize placement of riparian buffers for improved water quality

Tomer¹,

Dosskey²,

Burkart³

et al. 2008

Agroforest Syst

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Agroforestry buffers in riparian zones can improve stream water quality, provided they intercept and remove contaminants from surface runoff and/or shallow groundwater. Soils, topography, surficial geology, and hydrology determine the capability of forest buffers to intercept and treat these flows. This paper describes two landscape analysis techniques for identifying and mapping locations where agroforestry buffers can effectively improve water quality. One technique employs soil survey information to rank soil map units for how effectively a buffer, when sited on them, would trap sediment from adjacent cropped fields. Results allow soil map units to be compared for relative effectiveness of buffers for improving water quality and, thereby, to prioritize locations for buffer establishment. A second technique uses topographic and streamflow information to help identify locations where buffers are most likely to intercept water moving towards streams. For example, the topographic wetness index, an indicator of potential soil saturation on given terrain, identifies where buffers can readily intercept surface runoff and/or shallow groundwater flows. Maps based on this index can be useful for site-specific buffer placement at farm and small-watershed scales. A case study utilizing this technique shows that riparian forests likely have the greatest potential to improve water quality along first-order streams, rather than larger streams. The two methods are complementary and could be combined, pending the outcome of future research. Both approaches also use data that are publicly available in the US. The information can guide projects and programs at scales ranging from farm-scale planning to regional policy implementation. RightsWorks produced by employees of the U.S. Government as part of their official duties are not copyrighted within the U.S. The content of this document is not copyrighted. Abstract Agroforestry buffers in riparian zones can improve stream water quality, provided they intercept and remove contaminants from surface runoff and/or shallow groundwater. Soils, topography, surficial geology, and hydrology determine the capability of forest buffers to intercept and treat these flows. This paper describes two landscape analysis techniques for identifying and mapping locations where agroforestry buffers can effectively improve water quality. One technique employs soil survey information to rank soil map units for how effectively a buffer, when sited on them, would trap sediment from adjacent cropped fields. Results allow soil map units to be compared for relative effectiveness of buffers for improving water quality and, thereby, to prioritize locations for buffer establishment. A second technique uses topographic and streamflow information to help identify locations where buffers are most likely to intercept water moving towards streams. For example, the topographic wetness index, an indicator of potential soil saturation on given terrain, identifies where buffers can readily intercept surface ru...

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Section: Methodsmentioning

confidence: 99%

Methods to prioritize placement of riparian buffers for improved water quality

Tomer¹,

Dosskey²,

Burkart³

et al. 2008

Agroforest Syst

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“…This variation is believed to be due to the different soils, slopes, and flow rates used across experiments (1) and to differences in the degrees of bacterial attachment to particles (31). To develop effective strategies for controlling runoff and to monitor the performance of such systems, an improved understanding of how bacteria enter overland flow and are transported within it is required (15,35).…”

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Erosion and Subsequent Transport State of Escherichia coli from Cowpats

Muirhead

Collins

Bremer

2005

Appl Environ Microbiol

105

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Processes by which fecal bacteria enter overland flow and their transportation state to surface waters are poorly understood, making the effectiveness of measures designed to intercept this pathway, such as vegetated buffer strips, difficult to predict. Freshly made and aged (up to 30 days) cowpats were exposed to simulated rainfall, and samples of the cowpat material and runoff were collected. Escherichia coli in the runoff samples were separated into attached (to particles) and unattached fractions, and the unattached fraction was analyzed to determine if the cells were clumped. Within cowpats, E. coli grew for 6 to 14 days, rather than following a typical logarithmic die-off curve. E. coli numbers in the runoff correlated with numbers inside the cowpat. Most of the E. coli organisms eroded from the cowpats were transported as single cells, and only a small percentage (about 8%) attached to particles. The erosion of E. coli from cowpats and the state in which the cells were transported did not vary with time within a single rainfall event or over time as the cowpats aged and dried out. These findings indicate that cowpats can remain a significant source of E. coli in overland flow for more than 30 days. As well, most of the E. coli organisms eroded from cowpats will occur as readily transportable single cells.

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“…Retention of sediments and water by the filter strip is simulated by the process-based VFSMOD submodel (Muñoz-Carpena and Parsons 2004). Good agreement between VFSMOD-modeled and observed trapping efficiencies has been determined for conditions in North Carolina , Mississippi (Hayes and Hairston 1983), and Ontario, Canada (Abu-Zreig et al 2001). The combined model, hereafter referred to as VFSMOD, has undergone testing (Sadeghi et al 2004) and extensive sensitivity and uncertainty analysis (Muñoz-Carpena et al 2007).…”

Section: Methodsmentioning

confidence: 90%

A design aid for sizing filter strips using buffer area ratio

Dosskey¹,

Helmers²,

Eisenhauer³

2010

Journal of Soil and Water Conservation

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Nonuniform field runoff can reduce the effectiveness of filter strips that are a uniform size along a field margin. Effectiveness can be improved by placing more filter strip where the runoff load is greater and less where the load is smaller. A modeling analysis was conducted of the relationship between pollutant trapping efficiency and the ratio of filter strip area to upslope contributing area, i.e., buffer area ratio. The results were used to produce an aid for designing filter strips having consistent effectiveness along field margins where runoff load is nonuniform. Simulations using the process-based Vegetative Filter Strip Model show that sediment and water trapping efficiencies of a filter strip increase nonlinearly as the buffer area ratio gets larger. Site characteristics, including slope, soil texture, and upslope soil cover management practices, help to define this relationship more accurately. Using the Vegetative Filter Strip Model simulation results, a graphical design aid was developed for estimating the buffer area ratio required to achieve specific trapping efficiencies for different pollutants under a broad range of agricultural site conditions. A single graph was produced showing simulation results for seven scenarios as a family of lines that divide the full range of possible relationships between trapping efficiency and buffer area ratio and into fairly even increments. Simple rules guide the selection of one line that best describes a given field situation by considering slope, soil texture, and field cover management practices. Relationships for sediment-bound and dissolved pollutants are interpreted from the Vegetative Filter Strip Model results for sediment and water. The design aid is easy to use, accounts for several major variables that determine filter strip performance, and is based on a validated, process-based, mathematical model. The use of this design aid will enable a more precise fit between filter size and runoff load where runoff from agricultural fields is nonuniform.Key words: models-nonpoint source pollution-precision conservation-surface runoffvariable-width buffers-vegetative buffers-water quality-watershed planning Filter strips are commonly installed for improving and protecting water quality in agricultural watersheds. Filter strips (Code 393) reduce the load of sediment, nutrients, and other pollutants in overland runoff from fields by promoting infiltration and sediment deposition (Haan et al. 1994;USDA 1997). Typically, they are designed to have a constant width (parallel to flow) along a field margin, and maximum pollutant trapping efficiency is achieved when field runoff is uniformly dispersed across the entire filter strip (USDA 1997). Several design methods have been developed for determining the appropriate width for a filter strip treating spatially uniform runoff (see review in Dosskey et al. 2008). However, researchers have observed that surface runoff commonly concentrates in fields and flows mainly through only small portions of filter strips...

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Validation of a vegetated filter strip model (VFSMOD)

Cited by 56 publications

References 20 publications

Methods to prioritize placement of riparian buffers for improved water quality

Methods to prioritize placement of riparian buffers for improved water quality

Erosion and Subsequent Transport State of Escherichia coli from Cowpats

A design aid for sizing filter strips using buffer area ratio

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