Modeling Miscanthus in the Soil and Water Assessment Tool (SWAT) to Simulate Its Water Quality Effects As a Bioenergy Crop

HighlightsSWAT used to address watershed scale nitrate-N abatement of instream wetlands (ISWs).Experimental ISW results were incorporated into the watershed modeling framework.SWAT successfully captured and reproduced ISW impact on nitrate-N at sub-basin level.Scenarios of ISWs implementation were simulated, effects on nitrate-N export were evaluated.Results show ISWs can be used as conservation structures aimed at enhancing water quality.Abstract. In watersheds under high agricultural production, nitrate nitrogen (nitrate-N) pollution often originates from intensive application of fertilizers and animal manure to croplands. Surface runoff and nitrate-N export from farmlands contributes to the pollution of nearby reaches which flow into the watershed stream network. Experimental studies reported significant nitrate removal capacities of constructed instream wetlands (ISWs). However, cases of large-scale implementations of ISWs are uncommon, probably due to a paucity of watershed-scale studies which highlight the influence of ISWs on riverine water quality. To elucidate the ISWs nitrate-N abatement potential at the watershed scale, the Soil and Water Assessment Tool (SWAT) was used to model nitrate-N export in a highly agricultural watershed located in the Coastal Plain of North Carolina. SWAT was first calibrated and validated for streamflow and for nitrate-N export using data collected from the inlet and outlet of an experimental instream wetland. The validated SWAT model was used to simulate a decade of nitrate-N export under two scenarios: 1) watershed with ISWs implemented; and 2) watershed without ISWs. The results of the case study indicated that a watershed-wide implementation of ISWs is likely to curtail annual nitrate-N export by 49%. The study also evaluated cases where ISWs are implemented in selected percentage of sub-basins across the watershed. The outcomes show higher increments of nitrate-N curtailment when ISWs are implemented in the first top agricultural sub-basins. Hence, implementation of ISWs on selected sub-basins can mitigate nitrate-N from non-point sources and enhance water quality in the watershed’s stream network. Keywords: Runoff, Croplands, Instream wetland, Nitrate-N export, Denitrification, SWAT model, Watershed.

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Deriving a country-wide soils dataset from the Soil Landscapes of Canada (SLC) database for use in Soil and Water Assessment Tool (SWAT) Simulations

10.5194/essd-2017-66 ◽

2017 ◽

Author(s):

Marcos R. C. Cordeiro ◽

Glenn Lelyk ◽

Roland Kröbel ◽

Getahun Legesse ◽

Monireh Faramarzi ◽

...

Keyword(s):

Water Quality ◽

Assessment Tool ◽

Swat Model ◽

Complete Information ◽

Runoff Generation ◽

Screening Process ◽

Country Level ◽

Runoff Potential ◽

Water Assessment ◽

Soil And Water

Abstract. The Soil and Water Assessment Tool (SWAT) model has been commonly used in Canada for hydrological and water quality simulations. However, pre-processing of critical data such as soils information can be laborious and time-consuming. The objective of this work was to pre-process the Soil Landscapes of Canada (SLC) database to offer a country-level soils dataset in a format ready to be used in SWAT simulations. A two-level screening process was used to identify critical information required by SWAT and to remove records with information that could not be calculated or estimated. Out of the 14,063 unique soils in the SLC, 11,838 soils with complete information were included in the dataset presented here. Important variables for SWAT simulations that are not reported in the SLC database [e.g. hydrologic soils groups (HSGs) and erodibility factor (K)] were calculated from information contained within the SLC database. These calculations, in fact, represent a major contribution to enabling the present dataset to be used for hydrological simulations in Canada using SWAT and other comparable models. Analysis of those variables indicated that 21.3 %, 24.6 %, 39.0 %, and 15.1 % of the soils in Canada belong to HSGs 1, 2, 3, and 4, respectively. This suggests that almost two-thirds of the soils have a high (i.e., HSG 4) or relatively high (i.e., HSG 3) runoff generation potential. A spatial analysis indicated that 20.0, 26.8, 36.7 and 16.5 % of soil belonged to HSG 1, HSG 2, HSG 3, and HSG 4, respectively. Erosion potential, which is inherently linked to the erodibility factor (K), was associated with runoff potential in important agricultural areas such as southern Ontario and Nova Scotia. However, contrary to initial expectations, low or moderate erosion potential was found in areas with high runoff potential, such as regions in southern Manitoba (e.g. Red River Valley) and British Columbia (e.g. Peace River watershed). This dataset will be a unique resource to a variety of research communities including hydrological, agricultural and water quality modellers and are publicly available at https://doi.org/10.1594/PANGAEA.877298a.

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