Spatial Relationships of Levees and Wetland Systems within Floodplains of the Wabash Basin, USA

Abstract

Given the unique biogeochemical, physical, and hydrologic services provided by floodplain wetlands, proper management of river systems should include an understanding of how floodplain modifications influence wetland ecosystems. The construction of levees can reduce river–floodplain connectivity, yet it is unclear how levees affect wetlands within floodplains, let alone the cumulative impacts within an entire watershed. This paper explores spatial relationships between levee and floodplain wetland systems in the Wabash Basin, United States. We used a hydrogeomorphic floodplain delineation technique to map floodplain extents and identify wetlands that may be hydrologically connected to river networks. We then spatially examined the relationship between levee presence, wetland area, and other river network attributes within discrete subbasins. Our results show that cumulative wetland area is relatively constant in subbasins that contain levees, regardless of maximum stream order within the subbasin. In subbasins that do not contain levees, cumulative wetland area increases with maximum stream order. However, we found that wetland distributions around levees can be complex, and further studies on the influence of levees on wetland habitat may need to consider finer resolution spatial scales.

Integrating VGI and 2D hydraulic models into a data assimilation framework for real time flood forecasting and mapping

“…Boundary conditions were assigned considering both the flow measurements in the upstream part of the Tiber River and the flow hydrographs from 15 ungauged basins simulated by the adopted WFIUH hydrologic model. The computational domain was optimized adopting a hydrogeomorphic model (Nardi, Vivoni, and Grimaldi 2006;Nardi et al 2018b;Morrison et al 2018) according to Annis et al (2019) approach.…”

Effects of Two-Stage Ditch and Natural Floodplains on Sediment Processes Driven by Different Hydrological Conditions

“…These ditches are created by lowering the terrain immediately adjacent to the channel to facilitate flooding of parts of former riparian areas. The overall aim is to restore the connectivity of the stream with the surrounding land, mimicking processes occurring at larger scales in river-wetland corridors [28][29][30][31][32]. However, while river-wetland corridors can have a width of several kilometers and occupy lengths of up to hundreds of kilometers [28], the two-stage ditch is generally employed in already modified reaches, with lengths limited to a few hundreds or thousands of meters [33,34] and a small upstream catchment.…”

Predictive Modeling of Envelope Flood Extents Using Geomorphic and Climatic‐Hydrologic Catchment Characteristics

“…Some authors take advantage of the causality between historical floods and the floodplain hydraulic geometry (e.g., Bhowmik, 1984; Dodov & Foufoula‐Georgiou, 2006; McGlynn & Seibert, 2003) and make use of digital elevation models (DEMs) that are data sets representing the Earth's surface, distributed as gridded values of local terrain elevations (Tavares da Costa, Mazzoli, & Bagli, 2019). For example, Nardi et al (2006, 2013, 2019), Morrison et al (2018), and Annis et al (2019) employed a flat‐water approach (i.e., intersection of a water level with the surrounding DEM, or a variation of it, such as the HAND—Height Above the Nearest Drainage; Rennó et al, 2008; Nobre et al, 2016) to delineate floodplains. The authors used a variable water level at each stream pixel from a stream‐order averaged linear scaling relation (power law of upslope contributing area), obtained either from a generalization of outlet discharges and the Manning uniform flow equation (Manning, 1891) or through calibration with reference data.…”