Mapping landscape-level hydrological connectivity of headwater wetlands to downstream waters: A catchment modeling approach - Part 2

In Part 1 of this two-part manuscript series, we presented an effective assessment method for mapping inundation of geographically isolated wetlands (GIWs) and quantifying their cumulative landscape-scale hydrological connectivity with downstream waters using time series remotely sensed data (Yeo et al., 2018). This study suggested strong hydrological coupling between GIWs and downstream waters at the seasonal timescale via groundwater. This follow-on paper investigates the hydrological connectivity of GIWs with downstreamwaters and cumulativewatershed-scale hydrological impacts overmultiple time scales. Modificationsweremade to the representation ofwetland processes within the Soil andWater Assessment Tool (SWAT). A version ofSWATwith improved wetland function, SWAT-WET, was applied to Greensboro Watershed, which is located in the MidAtlantic Region of USA, to simulate hydrological processes over 1985-2015 under two contrasting land use scenarios (i. e., presence and absence of GIWs). Comparative analysis of simulation outputs elucidated how GIWs could influence partitioning of precipitation between evapotranspiration (ET) and terrestrial water storage, and affect water transport mechanisms and routing processes that generate streamflow. Model results showed that GIWs influenced the watershed water budget and stream flow generation processes over the long-term (30 year), inter-annual, andmonthly time scales. GIWs in the studywatershed increased terrestrialwater storage during the wet season, and buffered the dynamics of shallow groundwater during the dry season. The interannual modeling analysis illustrated that densely distributed GIWs can exert strong hydrological influence on downstream waters by regulating surface water runoff, while maintaining groundwater recharge and ET under changing (wetter) climate conditions. The study findings highlight the hydrological connectivity of GIWs with downstream waters and the cumulative hydrological influence of GIWs as hydrologic sources to downstream ecosystems through different runoff processes over multiple time scales. (c) 2018 Elsevier B. V. All rights reserved.