Floodplain complexity and surface metrics: Influences of scale and geomorphology

Scown, Murray W.; Thoms, Martín; Jager, Nathan R. De

doi:10.1016/j.geomorph.2015.05.024

Cited by 62 publications

(40 citation statements)

References 54 publications

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“…In summary, the surface metrics are used to indicate increasing surface variability, while the spatial correlogram model parameters (range and nugget) are used to indicate increasing "patchiness" or organisation in the surface (Table 2). It is argued here, and elsewhere (Scown et al, 2015a), that increasing variability and spatial organisation results in increasing spatial complexity. All surface metrics were measured within sampling windows of 50, 200, and 1000 m radius.…”

Section: Methodssupporting

confidence: 52%

“…VSG is a composite of four surface metrics (Table 2), measured at 50 random sample locations throughout each of the floodplains, while SPO is calculated from spatial correlogram models of Moran's I over increasing lag distances for each of the four surface metrics from 1000 random sample locations ( Table 2). Details of the procedures for calculating each indicator are provided in Scown et al (2015a). In summary, the surface metrics are used to indicate increasing surface variability, while the spatial correlogram model parameters (range and nugget) are used to indicate increasing "patchiness" or organisation in the surface (Table 2).…”

Section: Methodsmentioning

confidence: 99%

“…The eight floodplains also differ in their hydrology and geomorphology, exhibiting a variety of morphological features such as flood channels, oxbows, natural levees, crevasse splays, and back swamps. Detailed descriptions of each of the eight floodplains are provided by Scown et al (2015a).…”

Section: Study Areamentioning

confidence: 99%

“…There are two main components to the spatial complexity of floodplain surfaces (Scown et al, 2015a). The first component relates to the presence/absence, abundance, and diversity of geomorphic features present.…”

Section: Introductionmentioning

confidence: 99%

“…Each level of organisation, or holon, has a spatial and temporal scale over which processes occur and patterns emerge (Holling, 1992). Thus, any measurement of spatial complexity must also acknowledge the effects of measurement scale (Scown et al, 2015a).…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

An index of floodplain surface complexity

Scown

Thoms

Jager

2016

Hydrol. Earth Syst. Sci.

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Abstract. Floodplain surface topography is an important component of floodplain ecosystems. It is the primary physical template upon which ecosystem processes are acted out, and complexity in this template can contribute to the high biodiversity and productivity of floodplain ecosystems. There has been a limited appreciation of floodplain surface complexity because of the traditional focus on temporal variability in floodplains as well as limitations to quantifying spatial complexity. An index of floodplain surface complexity (FSC) is developed in this paper and applied to eight floodplains from different geographic settings. The index is based on two key indicators of complexity, variability in surface geometry (VSG) and the spatial organisation of surface conditions (SPO), and was determined at three sampling scales. FSC, VSG, and SPO varied between the eight floodplains and these differences depended upon sampling scale. Relationships between these measures of spatial complexity and seven geomorphological and hydrological drivers were investigated. There was a significant decline in all complexity measures with increasing floodplain width, which was explained by either a power, logarithmic, or exponential function. There was an initial rapid decline in surface complexity as floodplain width increased from 1.5 to 5 km, followed by little change in floodplains wider than 10 km. VSG also increased significantly with increasing sediment yield. No significant relationships were determined between any of the four hydrological variables and floodplain surface complexity.

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Section: Methodssupporting

confidence: 52%

Section: Methodsmentioning

confidence: 99%

Section: Study Areamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An index of floodplain surface complexity

Scown

Thoms

Jager

2016

Hydrol. Earth Syst. Sci.

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Critical linkages among floodplain hydrology, geomorphology and ecology along a lowland meandering river, Illinois, USA

Shukla,

Salas,

Pankau

et al. 2024

Ecohydrology

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The ecology of forested floodplains is intricately linked to river hydrology through the frequency, magnitude, timing and duration of floodplain inundation. Spatial variability in inundation characteristics is influenced by the geomorphic template of a floodplain, both in terms of the topography of floodplain features and connectivity of these features to the main river channel. Spatial variability in inundation, in turn, has the potential to produce spatial variability in forest ecological characteristics. This study examines the influence of floodplain geomorphic features on spatial variability in inundation frequency as well as the relationship between these geomorphic features and the ecological characteristics of a floodplain forest. The frequencies of floods of different magnitudes are determined from flow‐duration analysis of over 100 years of discharge data for a lowland meandering river in Illinois, USA. Data on discharge, stage, and topography are then used to calibrate a two‐dimensional hydraulic model of flow across the floodplain at different levels of inundation. Integrating the frequency and inundation data yields mapping of average annual inundation frequency for different parts of the floodplain. Significant differences in inundation frequency correspond to three distinct floodplain geomorphic features: secondary channels (frequency = 12%), closed depressions (frequency = 4%) and the floodplain surface (frequency = %). Tree density is similar among the three types of geomorphic features, but tree species composition and canopy density differ significantly between secondary channels and the floodplain surface. The results provide insight into linkages among hydrology, geomorphology and tree characteristics of forested floodplains of lowland meandering rivers.

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River‐valley morphology, basin size, and flow‐event magnitude interact to produce wide variation in flooding dynamics

2019

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Inundation dynamics are a key driver of ecosystem form and function in river-valley bottoms.Inundation itself is an outcome of multi-scalar interactions and can vary strongly within and among river reaches. As a result, establishing to what degree and how inundation dynamics vary spatially both within and among river reaches can be challenging. The objective of this study was to understand how river-valley morphology, basin size, and flow-event magnitude interact to affect inundation dynamics in river-valley bottoms. We used 2D hydraulic models to simulate inundation in four river reaches from Maryland's Piedmont physiographic province, and qualitatively and quantitatively summarized within-and amongreach patterns of inundation extent, duration, depth, shear stress, and wetting frequencies. On average, reaches from confined valley settings experienced less extensive flooding, shorter durations and shallower depths, stronger gradients of maximum shear stress, and relatively infrequent wetting compared to reaches from unconfined settings. These patterns were generally consistent across flow-event magnitudes. Patterns of within-reach flooding across event magnitudes revealed complex interactions between hydrology and surface topography. We concluded that valley morphology had a greater impact on flooding patterns than basin size: Inundation patterns were more consistent across reaches of similar morphology than similar basin size, but absolute values of inundation characteristics varied between large and small basins. Our results showed that the manifestation of out-of-bank flows in valley floors can vary widely depending on geomorphic context, even within a single physiographic province, which suggests that hydrologic and hydraulic conditions experienced on the valley floor may not be well represented by existing hydrologic metrics derived from discharge data alone. We thus support the notion that 2D hydraulic models can be useful hydrometric tools for cross-scale investigations of floodplain ecosystems.

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Floodplain complexity and surface metrics: Influences of scale and geomorphology

Cited by 62 publications

References 54 publications

An index of floodplain surface complexity

An index of floodplain surface complexity

Critical linkages among floodplain hydrology, geomorphology and ecology along a lowland meandering river, Illinois, USA

River‐valley morphology, basin size, and flow‐event magnitude interact to produce wide variation in flooding dynamics

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