Delineating wetland catchments and modeling hydrologic connectivity using lidar data and aerial imagery

Abstract

Abstract. In traditional watershed delineation and topographic modeling, surface depressions are generally treated as spurious features and simply removed from a digital elevation model (DEM) to enforce flow continuity of water across the topographic surface to the watershed outlets. In reality, however, many depressions in the DEM are actual wetland landscape features with seasonal to permanent inundation patterning characterized by nested hierarchical structures and dynamic filling-spilling-merging surface-water hydrological processes. Differentiating and appropriately processing such ecohydrologically meaningful features remains a major technical terrain-processing challenge, particularly as highresolution spatial data are increasingly used to support modeling and geographic analysis needs. The objectives of this study were to delineate hierarchical wetland catchments and model their hydrologic connectivity using high-resolution lidar data and aerial imagery. The graph-theory-based contour tree method was used to delineate the hierarchical wetland catchments and characterize their geometric and topological properties. Potential hydrologic connectivity between wetlands and streams were simulated using the least-cost-path algorithm. The resulting flow network delineated potential flow paths connecting wetland depressions to each other or to the river network on scales finer than those available through the National Hydrography Dataset. The results demonstrated that our proposed framework is promising for improving overland flow simulation and hydrologic connectivity analysis.

Hydrological, Physical, and Chemical Functions and Connectivity of Non‐Floodplain Wetlands to Downstream Waters: A Review

“…Riparian wetlands as aquatic refuges in dryland rivers (Leigh et al 2010) Temporary storage and subsequent release of materials or energy without affecting cumulative flux (exports = imports); delivery is delayed and can be prolonged Flood attenuation (Bullock and Acreman 2003) Conversion of a material or energy into a different form; the amount of the base material or energy is unchanged (base exports = base imports), but its composition (e.g., mass of the different forms) can vary Mercury methylation (Galloway and Branfireun 2004;Selvendiran et al 2008) Source: exchange materials within and among the surface water-connected wetland systems ( Figure 3; Wu and Lane 2016;Calhoun et al 2017). Like fill-and-spill wetlands, fill-and-merge wetlands are hydrologic sources when the maximum capacity of the bounding basin is exceeded and the wetland complex connects via continuous surface water to another aquatic system (Shaw et al 2012;Wu and Lane 2017). That is, fill-and-merge wetlands become filland-spill systems when the internal storage is exceeded and no additional merging can occur within a given basin (see also the discussion on NFW Hydrologic Lag Functions, below).…”

Wetlandscape hydrologic dynamics driven by shallow groundwater and landscape topography

“…Several methods have been proposed to identify wetlands using high-resolution images (Jaramillo et al, 2018;Montgomery, Hopkinson, Brisco, Patterson, & Rood, 2018;B. Zhang et al, 2009) or digital elevation models Chu, 2017;Wu & Lane, 2017). Characterization of landscape surface topography is essential for wetland identification.…”

Methodologies and Management Framework for Restoration of Wetland Hydrologic Connectivity: A Synthesis

“…The embankments built on both sides of the river will artificially block the HC between the river floodplain and thus affect the mutual flow of nutrients and energy between them (Dou and Cui 2014; Gallardo et al 2014). The diversification of habitats around the floodplain wetlands decrease, and the ecological integrity of the wetland landscape is interrupted (Wu and Lane 2017). Massive wetlands are reclaimed as farmland (Li et al 2014; Dong et al 2015), resulting in wetland shrinkage and the blocking of HC, which forms multiple geographically isolated wetlands (Marton et al 2015).…”