Factors affecting sediment trapping in vegetated filter strips: simulation study using VFSMOD

Abstract

Abstract:Soil and water conservation practices have been promoted for a long time, in order to sustain agricultural activities and prevent environmental pollution. Vegetated filter strips (VFS) have been used to reduce sediment pollution into water bodies at or near the pollutant source. However, factors effecting VFS performance under natural conditions have not been well understood owing to the physical, time and financial limitations of field experiments. The use of well-validated simulation models to understand the performance of VFS and factors affecting sediment deposition is highly justified. The objective of this research is to investigate sediment trapping in VFS and to study various factors affecting VFS performance using the simulation model VFSMOD, which was developed by researchers at University of North Carolina. Recently, VFSMOD has been validated successfully by using 21 filters with varying length, slope and vegetated cover. A wide range of five parameters was selected for the simulations, namely filter length, filter slope, manning roughness coefficient, soil type and characteristics of incoming sediment from adjacent fields. Computer simulations revealed that the length of filter is the most significant factor affecting sediment trapping in VFS. The relative increase in trapping efficiencies was not linearly related to an increase in filter length. Inflow sediment class also has a major influence on sediment trapping in VFS. The trapping efficiency of clay sediments in a 15 m length VFS was 47% compared with 92% for silt from incoming sediment. Manning roughness coefficient had a moderate effect on sediment trapping and was more significant in short filters. Land slope and soil type of VFS had a minor influence on the performance of VFS.

Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips – Part 2: model coupling, application, factor importance, and uncertainty

“…Input-factor distributions are assigned based either on experimental measurements on the case study plots, scientific publications, or expert knowledge (Table 2). Although the VFS dimensions FWIDTH and VL were measured in the field (Table 1), the effective dimensions are known to be different in practice as the runoff does not follow perfectly uniform sheet flow (Abu-Zreig, 2001). Thus, the measured values were chosen to vary uniformly within −10 and +10 % for FWIDTH and VL, respectively .…”

“…Pesticide degradation on the filter is included between runoff events for long-term pesticide assessments , but neglected during events due to their short duration (minutes to hours). VFSMOD has been successfully tested against measured data for predictions of flow, infiltration, and sediment trapping efficiency (Muñoz-Carpena et al, 1999;Abu-Zreig, 2001;Dosskey et al, 2002;Fox et al, 2005;Han et al, 2005;Pan et al, 2017); tracers and multireactive solutes (Perez-Ovilla, 2010); phosphorus (Kuo and Muñoz-Carpena, 2009); pesticides (Poletika et al, 2009;Sabbagh et al, 2009;Winchell et el., 2011); and colloids (Yu et al, 2013). Previous work studied the global sensitivity of simulated outflow, sediment, and pesticide trapping to VFS-MOD input factors (Muñoz-Carpena et al, 2007Fox et al, 2010).…”

Development of Web GIS-Based VFSMOD System with Three Modules for Effective Vegetative Filter Strip Design

“…The VFSMOD was successfully tested with natural events with North Carolina Piedmont data [2] and Coastal Plain [16]. Researchers at the University of Guelph, in Canada, have tested the model with field experimental data [17]. They reported good agreement between model simulations (infiltration, outflow, and sediment trapping) and measured values, moreover the results of the model has been used to improve the Soil and Water Assessment Tool (SWAT) [18,19].…”

Shallow water table effects on water, sediment, and pesticide transport in vegetative filter strips – Part 1: nonuniform infiltration and soil water redistribution

“…Mechanistic understanding of VFS behavior has advanced significantly in the last 20 years, and numerical simulation tools are available to analyze this important best management practice (BMP) under upland field conditions where runoff is governed by excess rainfall and field inflow processes (Muñoz-Carpena et al, 1993, 1999Abu-Zreig, 2001;Muñoz-Carpena and Parsons, 2004;Poletika et al, 2009;Sabbagh et al, 2009;Carluer et al, 2017). A recent linked mechanistic model has investigated multiple input factors and their relative importance and uncertainties on the predicted reduction of runoff, sediments, and pesticides Lambrechts et al, 2014;Muñoz-Carpena et al, 2010.…”