Modeling Sediment Trapping in a Vegetative Filter Accounting for Converging Overland Flow

Helmers, Matthew J.; Eisenhauer, Dean E.; Franti, Thomas G.; Dosskey, Michael G.

doi:10.13031/2013.18328

Cited by 25 publications

(18 citation statements)

References 15 publications

(13 reference statements)

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“…This approach to modeling converging flow using the VFSMOD has been successfully used by others (Helmers et al 2005). Values for additional soil variables that are required to run the VFSMOD simulations and are keyed to the surface soil texture class were assigned according to table 2.…”

Section: Methodsmentioning

confidence: 99%

Improved indexes for targeting placement of buffers of Hortonian runoff

Dosskey¹,

Qiu²,

Helmers³

et al. 2011

Journal of Soil and Water Conservation

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Targeting specific locations within agricultural watersheds for installing vegetative buffers has been advocated as a way to enhance the impact of buffers and buffer programs on stream water quality. Existing models for targeting buffers of Hortonian, or infiltration-excess, runoff are not well developed. The objective was to improve on an existing soil survey-based approach that would provide finer scale resolution, account for variable size of runoff source area to different locations, and compare locations directly on the basis of pollutant load that could be retained by a buffer. The method couples the Soil Survey Geographic database with topographic information provided by a grid digital elevation model in a geographic information system. Simple empirical equations were developed from soil and topographic variables to generate two indexes, one for deposition of sediment and one for infiltration of dissolved pollutants, and the equations were calibrated to the load of sediment and water, respectively, retained by a buffer under reference conditions using the processbased Vegetative Filter Strip Model. The resulting index equations and analytical procedures were demonstrated on a 67 km 2 (25.9 mi 2 ) agricultural watershed in northwestern Missouri, where overland runoff contributes to degraded stream water quality. For both indexes, mapped results clearly mimic spatial patterns of water flow convergence into subdrainages, substantiating the importance of size of source area to a given location on capability to intercept pollutants from surface runoff. A method is described for estimating a range of index values that is appropriate for targeting vegetative buffers. The index for sediment retention is robust. However, the index for water (and dissolved pollutant) retention is much less robust because infiltration is very small, compared to inflow volumes, and is relatively insensitive to the magnitude of inflow from source areas. Consequently, an index of inflow volume may be more useful for planning alternative practices for reducing dissolved pollutant loads to streams. The improved indexes provide a better method than previous indexes for targeting vegetative buffers in watersheds where Hortonian runoff causes significant nonpoint pollution. Abstract: Targeting specific locations within agricultural watersheds for installing vegetative buffers has been advocated as a way to enhance the impact of buffers and buffer programs on stream water quality. Existing models for targeting buffers of Hortonian, or infiltration-excess, runoff are not well developed. The objective was to improve on an existing soil survey-based approach that would provide finer scale resolution, account for variable size of runoff source area to different locations, and compare locations directly on the basis of pollutant load that could be retained by a buffer. The method couples the Soil Survey Geographic database with topographic information provided by a grid digital elevation model in a geographic information system. Simple em...

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Section: Methodsmentioning

confidence: 99%

Improved indexes for targeting placement of buffers of Hortonian runoff

Dosskey¹,

Qiu²,

Helmers³

et al. 2011

Journal of Soil and Water Conservation

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“…For example, both perennial fi lter strips (PFS) and riparian buff ers were shown to reduce erosion and loss of nutrients and sediment from agricultural lands into streams by acting as a physical barrier (Barling and Moore, 1994;Helmers et al, 2005). Research has also documented the ability of PFS to reduce NO 3 -N concentrations in surface runoff and/or groundwater (Lin et al, 2007;Yamada et al, 2007;Ryder and Fares, 2008).…”

mentioning

confidence: 99%

Perennial Filter Strips Reduce Nitrate Levels in Soil and Shallow Groundwater after Grassland‐to‐Cropland Conversion

et al. 2010

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Many croplands planted to perennial grasses under the Conservation Reserve Program are being returned to crop production, and with potential consequences for water quality. The objective of this study was to quantify the impact of grassland‐to‐cropland conversion on nitrate‐nitrogen (NO3–N) concentrations in soil and shallow groundwater and to assess the potential for perennial filter strips (PFS) to mitigate increases in NO3–N levels. The study, conducted at the Neal Smith National Wildlife Refuge (NSNWR) in central Iowa, consisted of a balanced incomplete block design with 12 watersheds and four watershed‐scale treatments having different proportions and topographic positions of PFS planted in native prairie grasses: 100% rowcrop, 10% PFS (toeslope position), 10% PFS (distributed on toe and as contour strips), and 20% PFS (distributed on toe and as contour strips). All treatments were established in fall 2006 on watersheds that were under bromegrass (Bromus L.) cover for at least 10 yr. Nonperennial areas were maintained under a no‐till 2‐yr corn (Zea mays L.)–soybean [Glycine max (L.) Merr.] rotation since spring 2007. Suction lysimeter and shallow groundwater wells located at upslope and toeslope positions were sampled monthly during the growing season to determine NO3–N concentration from 2005 to 2008. The results indicated significant increases in NO3–N concentration in soil and groundwater following grassland‐to‐cropland conversion. Nitrate‐nitrogen levels in the vadose zone and groundwater under PFS were lower compared with 100% cropland, with the most significant differences occurring at the toeslope position. During the years following conversion, PFS mitigated increases in subsurface nitrate, but long‐term monitoring is needed to observe and understand the full response to land‐use conversion.

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“…Differences if any were determined by the least squares means test (Kirk 1982;Snedecor and Cochran 1980;Zar 1996) for both independent and dependent variables. Statistical analyses of data were performed by PAST (Hammer et al 2001;Helmers et al 2005) and Systat (SYSTAT Institute Inc. 2007).…”

Section: Discussionmentioning

confidence: 99%

“…Some evidence indicate that limited VFS removal of fecal coliforms occurs on soils that exhibit larger overland flow volumes and low infiltration including those of contaminants like pesticides and nutrients in soil (Sullivan et al 2007;Fox et al 2010). A wide range of contradicting opinions exists on the VFS efficiency and function with respect to pathogens and/or indicator organisms' removal (Munoz-Carpena and Parsons 1999; Collins and Rutherford 2004;Helmers et al 2005;Pachepsky et al 2006;Guber et al 2007;Soupir et al 2010). These pathogens also infiltrate into soil matrix through overland flows.…”

Section: Introductionmentioning

confidence: 99%

Effect of vegetated filter strips on infiltration and survival rates of Escherichia coli in soil matrix at Mau, Njoro River Watershed, Kenya

Olilo

Muia

Onyando

et al. 2016

Energ. Ecol. Environ.

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Overland flows contaminated with manure borne pathogens pose risks to public health, because fecal pathogens may infiltrate into soil matrix from overland flows and contaminate soil water aquifers. The objective of this study was to evaluate the effect of vegetative filter strip (VFS) on infiltration rates (CFU 100 ml -1 h -1 ) of Escherichia coli (E. coli) in overland flow and their survival rates in soil matrix. Thirty samples of the specimen were collected from VFSs each sampling time. The samples were each filtered, followed by a series of ten dilutions; then analyses for E. coli using membrane filtration technique. Wet oxidation method and potassium persulfate technique were used to analyze particulate organic carbon (POC) and dissolved organic carbon (DOC) at (p \ 0.05) level of significance, respectively. A strong relationship was obtained between E. coli, POC and DOC in the overland flows (R 2 = 0.89, p B 0.05; df = 29). This study confirms the hypothesis that DOC released from Napier grass and Kikuyu grass exudates supported the initial survival, subsequent growth and adaptation of E. coli in its new secondary habitat outside its primary host. Thus, in the soil habitat, DOC and POC provided the initial energy for microbial cell multiplication from the VFS grasses. VFS influenced partitioning, infiltration and survival of E. coli in the overland flow into soil matrix. Thus, root zone retention data and information on E. coli in VFS systems are significant and could be used for scientific and management of soil erosion and the control of fecal pathogens entering surface water ecosystems both locally in Mau Ranges, Njoro River Watershed and internationally in other areas with similar environmental problems. VFS could be utilized under various designs of VFSs with different plants that have different setup of plants' root zone cover and penetrations systems that could help in infiltrating overland flow manure borne pathogens, a process that could be useful in the management of these pathogens in agro-pastoral systems locally and internationally.

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Modeling Sediment Trapping in a Vegetative Filter Accounting for Converging Overland Flow

Cited by 25 publications

References 15 publications

Improved indexes for targeting placement of buffers of Hortonian runoff

Improved indexes for targeting placement of buffers of Hortonian runoff

Perennial Filter Strips Reduce Nitrate Levels in Soil and Shallow Groundwater after Grassland‐to‐Cropland Conversion

Effect of vegetated filter strips on infiltration and survival rates of Escherichia coli in soil matrix at Mau, Njoro River Watershed, Kenya

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