Identification of Artificial Levees in the Contiguous United States

Knox, Richard L.; Morrison, Ryan R.; Wohl, Ellen

doi:10.1029/2021wr031308

Cited by 27 publications

(20 citation statements)

References 83 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…1B). These basins have the greatest (46,569 km), fourth greatest (23,222 km), and second greatest (43,659 km) lengths, respectively, of known and potential artificial levees ( 35 ).…”

Section: Resultsmentioning

confidence: 99%

“…Calibration of the floodplain model at the two-digit HUC basin level provides some mitigation. Other limitations include the current inability to ground-truth potential levees from the study by Knox et al ( 35 ) and the absence of a stream order–dependent buffer size for topography modification.…”

Section: Discussionmentioning

confidence: 99%

“…With the exception of one other study ( 18 ), this effect of artificial levees on floodplain extent has gone unreported until now, despite the well-known ability of levees to increase stage height ( 39 ). This type of alteration is a result of the massive degree of topographic adjustment represented by the construction of enough artificial levees to wrap around Earth six times ( 35 ). The concentration of artificial levees along smaller streams (73% of artificial levees are along streams of orders 2 to 6) ( 35 ) indicates the ability of this process to affect floodplain connectivity in ways that do not fit the normal conceptual model of artificial levees, which is based on larger stream systems [e.g., ( 39 )].…”

Section: Discussionmentioning

confidence: 99%

“…This type of alteration is a result of the massive degree of topographic adjustment represented by the construction of enough artificial levees to wrap around Earth six times ( 35 ). The concentration of artificial levees along smaller streams (73% of artificial levees are along streams of orders 2 to 6) ( 35 ) indicates the ability of this process to affect floodplain connectivity in ways that do not fit the normal conceptual model of artificial levees, which is based on larger stream systems [e.g., ( 39 )]. The discovery of lateral flowline alteration in addition to the traditional understanding of simple floodplain disconnection is the latest facet of our understanding of the Anthropocene.…”

Section: Discussionmentioning

confidence: 99%

“…The U.S. Army Corps of Engineers and the Federal Emergency Management Agency (FEMA) maintain a national levee database (NLD) for the United States, but it has not been evaluated for completeness until recently. In an earlier paper, we estimated the completeness of the NLD to be 20.4%, with more than 182,000 km of undocumented potential levees identified in the contiguous United States (CONUS) ( 35 ).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

A river ran through it: Floodplains as America’s newest relict landform

2022

Self Cite

View full text Add to dashboard Cite

Artificial levees are a major human modification of river corridors, but we still do not have a clear understanding of how artificial levees affect floodplain extent at regional and larger scales. We estimated changes in river-floodplain connectivity due to artificial levees in the contiguous United States (CONUS) using a combination of artificial levee databases, delineations of floodplain areas, and deletion of artificial levees from topography. Our results indicate that artificial levees do not only decrease floodplain extent but also alter locations of floodplain connectivity. Anthropogenically connected and disconnected locations are similar in land cover and are predominantly, in decreasing order of extent, cultivated, wetland, forested, and developed land cover types, with more than 30% of the entire floodplain area in the CONUS cultivated or developed. This study indicates that artificial levees cause complex changes in river-floodplain connectivity and can increase flooded areas in some rivers.

show abstract

“…1B). These basins have the greatest (46,569 km), fourth greatest (23,222 km), and second greatest (43,659 km) lengths, respectively, of known and potential artificial levees ( 35 ).…”

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

A river ran through it: Floodplains as America’s newest relict landform

2022

Self Cite

View full text Add to dashboard Cite

show abstract

River corridor beads are important areas of floodplain‐groundwater exchange within the Colorado River headwaters watershed

Schulz,

Morrison,

Bailey

et al. 2024

Hydrological Processes

View full text Add to dashboard Cite

Floodplains are essential ecosystems that provide a variety of economic, hydrologic, and ecologic services. Within floodplains, surface water‐groundwater exchange plays an important role in facilitating biogeochemical processes and can have a strong influence on stream hydrology through infiltration or discharge of water. These functions can be difficult to assess due to the heterogeneity of floodplains and monitoring constraints, so numerical models are useful tools to estimate fluxes, especially at large spatial extents. In this study, we use the SWAT+ (Soil and Water Assessment Tool) ecohydrological model to quantify magnitudes and spatiotemporal patterns of floodplain surface water‐groundwater exchange in a mountainous watershed using an updated version of the gwflow module that directly calculates floodplain‐aquifer exchange rates during periods of floodplain inundation. The gwflow module is a spatially distributed groundwater modelling subroutine within the SWAT+ code that uses a gridded network and physically based equations to predict groundwater storage, groundwater head, and groundwater fluxes. We used SWAT+ to model the 7516 km2 Colorado River headwaters watershed and streamflow data from USGS gages for calibration and testing. Models that included floodplain‐groundwater interactions outperformed those without such interactions and provided valuable information about floodplain exchange rates and volumes. Our analyses on the location of floodplain fluxes in the watershed also show that wider areas of floodplains, “beads” (e.g., like beads on a necklace), exchanged a higher net and per area volume of water, as well as higher rates of exchange, compared to narrower areas, “strings.” Study results show that floodplain channel‐groundwater exchange is a valuable process to include in hydrologic models, and model outputs could inform land conservation practises by indicating priority locations, such as beads, where substantial hydrologic exchange occurs.

show abstract

Estimating catchment‐scale sediment storage in a large River Basin, Colorado River, USA

Kemper,

Knox,

Raffae

et al. 2024

River Research & Apps

View full text Add to dashboard Cite

Catchment‐scale sediment storage is conceptualized as increasing in magnitude downstream, although reach‐scale controls may override this trend. We use empirical data from a literature review and two numerical models to quantitatively estimate sediment storage across the Colorado River Basin, USA. We use assumed alluvial thickness with floodplains delineated in the GFPLAIN model from 30 m digital elevation models. We use the SWAT+ model based on model‐estimated (i) groundwater storage and (ii) sediment storage. Existing studies indicate that sediment stored in floodplains and on low terraces is ~0.3–6 m thick. A first‐order approximation of volumetric storage capacity for natural floodplains is ~105 m3 per km. Sediment storage volumes of floodplains are ~108–1011 m3 over river lengths of 101–103 m. For the modeling estimates, we evaluated sediment storage by stream order and by elevation band within the Upper and Lower Colorado River Basins. Comparisons among the outputs cause us to place more confidence in the GFPLAIN and SWAT+ aquifer volume estimates. Each method includes substantial uncertainty and constitutes a first‐order approximation. Results suggest using 21 and 130 billion cubic meters as approximate lower and upper bounds for total sediment storage in the Upper Basin and 314 and 482 billion cubic meters as approximate lower and upper bounds for the Lower Basin. The largest proportion of sediment is stored in the montane and steppe zones in the Upper Basin and in the Sonoran zone in the Lower Basin.

show abstract

Identification of Artificial Levees in the Contiguous United States

Cited by 27 publications

References 83 publications

A river ran through it: Floodplains as America’s newest relict landform

A river ran through it: Floodplains as America’s newest relict landform

River corridor beads are important areas of floodplain‐groundwater exchange within the Colorado River headwaters watershed

Estimating catchment‐scale sediment storage in a large River Basin, Colorado River, USA

Contact Info

Product

Resources

About