Development of a SWAT extension module to simulate riparian wetland hydrologic processes at a watershed scale

Abstract

Abstract:Using a mass balance algorithm, this study develops an extension module that can be embedded in the commonly used Soil and Water Assessment Tool (SWAT). This module makes it possible to assess effects of riparian wetlands on runoff and sediment yields at a watershed scale, which is very important for aquatic ecosystem management but rarely documented in the literature. In addition to delineating boundaries of a watershed and its subwatersheds, the module groups riparian wetlands within a subwatershed into an equivalent wetland for modelling purposes. Further, the module has functions to compute upland drainage area and other parameters (e.g. maximum volume) for the equivalent wetland based on digital elevation model, stream network, land use, soil and wetland distribution GIS datasets. SWAT is used to estimate and route runoff and sediment generated from upland drainage area. The lateral exchange processes between riparian wetlands and their hydraulically connected streams are simulated by the extension module. The developed module is empirically applied to the 53 km 2 Upper Canagagigue Creek watershed located in Southern Ontario of Canada. The simulation results indicate that the module can make SWAT more reasonably predict flow and sediment loads at the outlet of the watershed and better represent the hydrologic processes within it. The simulation is sensitive to errors of wetland parameters and channel geometry. The approach of embedding the module into SWAT enables simulation of hydrologic processes in riparian wetlands, evaluation of wetland effects on regulating stream flow and sediment loading and assessment of various wetland restoration scenarios.

Geographically isolated wetlands and watershed hydrology: A modified model analysis

“…We aimed to account for these systems via SWAT's representation of floodplain dynamics and by calibrating parameters governing the rate of water transport through the simulated stream network (e.g., CH-K2 and CH-N2 characterize the saturated hydraulic conductivity for the main channel alluvium and the Manning's "N" value for the main channel, respectively). Future work should consider testing approaches that explicitly represent riparian wetlands, such as the development and application of SWAT extension modules similar to Liu et al (2008).…”

Assessing the significance of wetland restoration scenarios on sediment mitigation plan

“…Wang et al (2008) developed the hydrologic equivalent wetland (HEW) method to represent wetlands in SWAT model and applied the method to successfully simulate streamflow in a watershed located in Minnesota. Liu et al (2008) developed a SWAT extension to simulate flow and sediment in a riparian wetland, but did not validate the model due to the limitation of observed data. Wu and Johnston (2008) compared SWAT performance between forested and a wetland/lake dominated watershed in Michigan, and reported satisfactory model calibration but discrepancies in summer streamflow prediction.…”

A hybrid model to simulate the annual runoff of the Kaidu River in northwest China

“…The Soil and Water Assessment Tool (SWAT) model is a continuation of almost 30 years of modeling efforts conducted by the USDA Agricultural Research Service and is widely used around the world. A number of scientists have used SWAT model for simulating streamflow and related hydrologic analyses (Gan and Luo, 2013;Levesque et al, 2008;Liu et al, 2008Liu et al, , 2014Luo et al, 2012;Shope et al, 2014;Lin et al, 2015;Yang and Musiake, 2003). According to the investigation by Gassman et al (2007), there have been hundreds of published articles including SWAT applications, reviews of SWAT components, or other studies of SWAT in the past decades.…”