Streambank Erosion Research Articles

BASIC LAWS AND LOCAL FEATURES OF DEVELOPMENT OF SMALL AND MEDIUM-SIZED RIVERBEDS (results of monitoring observations)

The article describes the results of monitoring of stream-bank erosion on small and medium-sized rivers of Central Russia - the wide-bottomed Kerzhents and Sherna and the narrow-bottomed embedded Tarusa. It was found that horizontal channel deformations generally occur according to the expected patterns: erosion of concave banks of bends, alluvium of their convex banks, curvature and then straightening. However, both on medium and small rivers, local non-fluvial factors interfere with this process, disrupting the interaction of the flow and the valley floor, bringing elements of unpredictability to typical channel deformations. This is especially noticeable on embedded rivers that lack a wide floodplain - a natural buffer that protects the channel from the effects of slope and other processes occurring on the slopes and in the near-valley parts of the watersheds.

Watershed and streambank erosion modeling in a coldwater stream using the GWLF-E model: application and evaluation

While many watershed models estimate overland flow-related soil loss, streambank erosion is often overlooked even though it can be the dominant source of sediment in a catchment. We used the enhanced generalized watershed loading functions (GWLF-E) model to simulate the water budget, field erosion from the landscape, and streambank erosion along a gradient of agricultural to urban land cover from 1997 to 2015 in the Indian Mill Creek watershed of Michigan, USA. We evaluated discharge simulations using in-streamflow measurements and evaluated streambank erosion simulations using field-collected erosion pin measurements from a previous study. Annual water budget results suggest the creek is primarily groundwater fed, but that a per-subbasin average of 6–15% of precipitation becomes runoff. Field erosion contributed a per-subbasin average of 0.5–2.5 Mg ha−1 year−1 of sediment, while streambank erosion accounted for 0.2–50.1% of the subbasins’ total sediment yields. Average lateral erosion rate of streambanks in subbasins ranged from 0.04 to 7.37 cm year−1, with four subbasins exceeding 1.0 cm year−1. Evaluation with field-collected discharge data suggest that GWLF-E may have been overestimating discharge in the subbasins. Evaluation with streambank erosion data found that GWLF-E may have difficulty capturing the complexity of erosion rates, including instances where sediment is deposited on streambanks from upstream sources, and that it underestimates streambank erosion in headwater catchments sometimes over an order of magnitude. Our findings are important for watershed managers to evaluate modeling approaches and highlight the importance of modeling both field and streambank erosion.

Riparian erosion from cattle traffic may contribute up to 50% of the modelled streambank sediment supply in a large Great Barrier Reef river basin

Great Barrier Reef (GBR) catchment management has been constrained by knowledge gaps regarding streambank erosion processes in grazing lands. To help reduce these uncertainties a remote sensing study using high-resolution imagery estimated sediment contributions from cattle traffic on streambanks of a GBR river basin. Results suggest cattle ramps and ramp trails may contribute up to 50% of the modelled streambank sediment supply. Once a suitable delivery ratio is applied, this estimated supply may contribute up to 30% of the modelled fine sediment exported from the Fitzroy River Basin. These findings may also offer a plausible explanation for the first-flush of high sediment concentration observed early in flood hydrographs. Overall, the results could help identify what proportion of currently modelled subsoil erosion is generated by riparian cattle traffic. Future studies applying similar methods could provide useful initial estimates of streambank ramp erosion from grazing land use in other GBR river basins.

Automated measurement of eroding streambank volume from high-resolution aerial imagery and terrain analysis

Excessive sediment is an important form of surface water impairment throughout the continental United States. Numerous studies have investigated the role of upland soil erosion as a source of sediment and phosphorus, but contributions of streambank erosion are still poorly understood. Current methods such as delineation and automated channel planform morphometric models are either too time-intensive, or do not provide adequate spatial resolution to measure smaller rivers over large scales. To estimate sediment contributions from river migration on large scales, we have created the Aerial Imagery Migration Model (AIMM), a Python and ArcPy based automated channel migration model designed to estimate volumes of erosion and deposition related to channel migration. AIMM utilizes the Normalized Difference Water Index (NDWI) to derive binary representations of river channels from aerial photography. The location of the channel is then compared between two time periods to identify zones of erosion and deposition and the volume loss related to channel migration is then calculated using a LiDAR-derived DEM. When compared to three delineations and the RivMAP model in the South Fork Iowa River watershed, AIMM was found to have a 98% agreement with RivMAP, 79% agreement with delineations, and predicted net sediment flux that was within one standard deviation of the mean prediction from the delineation analysis. Where public imagery is available, AIMM can be widely applied to estimate volumes of sediment loss in a time and cost-efficient procedure. In particular, the use of AIMM within the project-planning phase of conservation efforts could help focus resources in areas where they can have the most impact.

Sediment dynamics and implications for management: State of the science from long‐term research in the Chesapeake Bay watershed, USA

AbstractThis review aims to synthesize the current knowledge of sediment dynamics using insights from long‐term research conducted in the watershed draining to the Chesapeake Bay, the largest estuary in the U.S., to inform management actions to restore the estuary and its watershed. The sediment dynamics of the Chesapeake are typical of many impaired watersheds and estuaries around the world, and this synthesis is intended to be relevant and transferable to other sediment‐impaired systems. The watershed's sediment sources, transport, delivery, and impacts are discussed with implications for effectively implementing best management practices (BMPs) to mitigate sediment issues. This synthesis revealed three key issues to consider when planning actions to reduce sediment loading: Scale, time, and land use. Geology and historical land use generated a template that current land use and climate, in addition to management, are acting upon to control sediment delivery. Important sediment sources in the Chesapeake include the Piedmont physiographic region, urban, and agricultural land use, and streambank erosion of headwater streams, whereas floodplain trapping is important along larger streams and rivers. Implementation of BMPs is widespread and is predicted to lead to decreased sediment loading; however, reworking of legacy sediment stored in stream valleys, with potentially long residence times in storage, can delay and complicate detection of the effects of BMPs on sediment loads. In conclusion, the improved understanding of sediment sources, storage areas, and transport lag times reviewed here can help target choices of BMP types and locations to better manage sediment problems—for both local streams and receiving waters.This article is categorized under: Science of Water > Water Quality Water and Life > Stresses and Pressures on Ecosystems Water and Life > Conservation, Management, and Awareness

Acceptance of BANCS model for predicting stream bank erosion potential and rate in the left bank of Ganga river of Diara region in Malda district, North East India

River bank erosion is a hazardous problem of Malda district. Different parts of Malda are mainly eroded by hydraulic action of River Ganga. Bank assessment for non-point source consequences of sediment model is a well accepted process for predicting stream bank erosion hazard potential. In the present study, river bank stability condition has been measured form field survey on 15 sample segments for 185 km stretched from Rajmahal in Sahibganj district, Jharkhand to upstream of Farakka barrage in Malda. In the present study, bank erosion hazard index (BEHI), near bank stress (NBS) and field based data have been considered for assessing stream bank erosion. The result shows that BEHI is high along the whole given left bank line extension of river Ganga, among these BEHI is very high in the upper segments of the river and adjacent river bank line extension of Farakka barrage, overall NBS conditions along left river bank line are less compare to the BEHI. Dominant NBS conditions are belong under moderate to low along the river bank line. Loosely compact alluvial soil, sparse vegetation, steep slope, unorganized agricultural activities; sinuous channel can be responsible for river bank erosion hazard potentiality. On an average 976,068.991 metric tons of sediments entrains to the river in a year. Bank has experienced variants bank erosion from same BEHI and NBS combinations. So, it can be concluded that BEHI and NBS are potentially not significant model for predicting bank erosion in present study.

Analysis of channel bank erosion rate using exposed roots of trees: a case study of lavij stream, northern Alborz Mountains, Iran

Powerful alluvial rivers in the northern Alborz mountain ranges erode river banks due to having high slopes. Most of these rivers flow in forest areas. In this research, the rate of the river bank erosion was examined using the exposed roots of the trees. For this purpose, 8 reaches of Lavij Stream were investigated. To determine the first year of root exposure, two sets of macroscopic and microscopic indicators were utilized. Accordingly, the rate of the stream bank erosion was estimated. The results were analyzed by using statistical test, which showed insignificant differences between the two groups of indicators. Due to its more abundance (frequency) on the margins and easy detection of its root through the exposure (macroscopic and microscopic) indicators, Alnus glutinosa (black alder) species could be more easily and accurately analyzed as compared with any other tree species in the region. The mean erosion rate of the riverbank using the extruded roots was estimated to be 0.08 m/yr. The hydrological analyses of flood flows showed that 95% of Lavij Stream bank erosion was caused by the river bank full discharges with a return period of 1–3 years.

Nutrients and Heavy Metals in Legacy Sediments: Concentrations, Comparisons with Upland Soils, and Implications for Water Quality

AbstractConcentrations of nutrients and heavy metals in streambank legacy sediments are needed to estimate watershed exports and to evaluate against upland inputs. Concentrations of nutrients and heavy metals were determined for legacy sediments in 15 streambanks across northeastern Maryland, southeastern Pennsylvania, and northern Delaware. Samples were collected from multiple bank depths from forested, agricultural, urban, and suburban sites. Analyses were performed for fine (<63 μm) and coarse sediment fractions. Nutrient and heavy metal concentrations were significantly higher in fine than coarse legacy sediments and water extractable nutrient concentrations were significantly greater for fine sediments. Nutrient and heavy metal concentrations were highest in streambank legacy sediments associated with urban land use, but few differences were found with bank depth. Total N (40–3,970 mg/kg) and P (25–1,293 mg/kg) and bioavailable P (0.25–48.8 mg/kg) concentrations for legacy sediments were lower than those for upland soils. This suggests that legacy sediments could serve as sink or source of N and P depending on the redox conditions and stream water nutrient concentrations. However, despite low concentrations, caution should be exercised since streambank erosion and legacy sediment mass loadings could be high, these sediments are in immediate proximity of aquatic ecosystems, and biogeochemical transformations could result in release of the nutrients.

Investigating the environmental response to water harvesting structures: a field study in Tanzania

Abstract. Sand dams, a popular water harvesting structure employed by rural communities, capture and store water for use during the dry season in arid and semi-arid regions. Most sand dam research has been performed on the “ideal” sand dam, despite approximately 50 % of sand dams not functioning as intended. This research involves a 1-year long, in-depth field study of three sand dams in Tanzania, one of which is essentially non-functioning. The study investigated a sand dam's impact on macroinvertebrate habitat, vegetation, and streambank erosion and explored a sand dam's water loss mechanisms. Surveys of macroinvertebrate assemblage were performed each season. Vegetation surveys were performed every other month, and erosion was recorded semi-monthly. Water table monitoring wells were installed at each sand dam, and measurements were taken twice a day. The study found that sand dams are too homogeneous to provide the sustenance and refugia macroinvertebrates need at different life stages. The non-functioning sand dam has a thick layer of silt preventing infiltration of rainwater. The functioning sand dams store a significant amount of water, but most is lost to evapotranspiration within a few months of the last rainfall. Unlike the non-functioning sand dam, the functioning sand dams have a positive impact on local vegetation and minimal impact on erosion. Sand dams can increase the water security of a community, but site characteristics and construction methods must be strongly considered to maximize the sand dam's positive impact.

Effect of bulk density, age, and water content on the erosional strength of streambank soils

The purpose of this study is to investigate the influence of physical properties, more specifically the bulk density and water content, to the erosional strength of streambank soils. Thirty (30) soil samples were extracted from the crest, midbank and toe of the bank at Clear Creek in Iowa City, Iowa. Out of those thirty (30) samples, six (6) samples were tested in the standard soil laboratory for obtaining their bulk density and particle size distribution, six (6) samples were tested their bulk density and heterogeneity using Gamma radiation scanning, and eighteen (18) samples were tested their erosional strengthr*f. In addition, six (6) pure Kaolinite-clay samples were constructed with various degrees of consolidation or age and water content for measuring their T>-:f using conduit flume technique. The results of the conduit flume tests revealed an increasing trend in magnitude of Hf moving from the crest to the toe of the bank. The T<--t values were 1.57, 1.53, and 1.92 Pa for the crest, midbank, and toe soils from the left bank. In similar order, the Tc.f values were 1.46, 1.47, and 1.83 Pa for the soils from the right bank. A similar trend was obtained for the bulk density based on standard laboratory test and gamma radiation scanning. According to standard laboratory test, the average bulk density values for the crest, midbank, and toe of the right bank were 1299, 1618, and 1880 kg/m3. Similarly, based on gamma radiation technique, the average bulk density values for the crest, midbank, and toe of the right bank soils were 1273 kg/m3, 1594 kg/m3 and 1863 kg/m3, respectively. This agreement in the trend of Tr-f and bulk density suggests a positive correlation between those to parameters. The results of Kaolinite-clay sample experiments demonstrated that samples with higher degree of consolidation or more age would have higher ^V. In addition, the Kaolinite-clay samples with higher water content would have lower rct. These findings suggest the presence of spatial and temporal variability in Ta of streambank soils. Therefore, incorporating this Tc,i variability in modelling streambank erosion will give more accurate results.

Low amplitude of streambank erosion: distinguishing mass and surface fluvial erosions

The purposes of this manuscript are in two folds e.g.: first, to promote two novel techniques using field-laboratory protocols, each for quantifying surface and mass fluvial erosion, second, to capture and highlight the regime change in the mode of bank erosion from surface to mass fluvial erosion based on real monitoring and measurements on a streambank face. In this study, conduit erosion flume and Photo Electronic Erosion Pin (PEEP) sensor technique were used for monitoring and measuring surface and mass fluvial erosions, respectively. Using those techniques the τ c,sf and τ c,mf , two key parameters which determine the onset of surface and mass fluvial erosion, can be determined successfully. The PEEP sensor can measure the mass fluvial erosion occurred under water, even capture the quasi-continues nature of erosion. More importantly, using these two methods, the presence of two regimes in the low amplitude of bank erosion, e.g. surface fluvial erosion and mass fluvial erosion can be captured. Starting from low to high shear stress, the onset of surface fluvial erosion as well as the transition from surface to mass fluvial erosion can be depicted.

Impact of an Extreme Flood Event on Streambank Retreat: Cedar River, Nebraska, USA

AbstractThe 2010 dam breach and consequent anomalous flood event on the Cedar River in Nebraska, USA provided an opportunity to study the following objectives: (1) evaluate the impact of an extreme flood event on streambank retreat along a 45 km stretch relative to the average annual retreat; (2) quantify the changes in streambank retreat for each km segment downstream of the breach; and (3) examine the influence of riparian vegetation and radius of curvature on meander bank erosion rate. During the hydrologic event, discharge peaked at nearly three times greater than the next highest recorded rate and equated to a return period of 2,000 years. Aerial images and ArcGIS were utilized to calculate the average annual streambank retreat for each year during the preflood (2006–2010), flood (2010), and postflood (2010–2016) periods. The 2010 flood period had a significantly higher average annual streambank retreat of 2,820 m2/km/yr than the preflood and postflood periods, which, respectively, measured 576 and 384 m2/km/yr. From 2006 to 2016, 29% of all streambank erosion was from this one extreme flood event, thus demonstrating the impact that one extreme flood event can have on streambank retreat and the geomorphology of a stream system.

Streambank Erosion Susceptibility Index and Flood-prone Area Mapping along the Karra River, Hetauda, Central Nepal Sub-Himalaya

The Karra River, one of the major tributaries of the Rapati River, is the 5th order stream that extends for about 21.91 km length in 92 sq. km. of watershed area. It is situated in the southern region of the Hetauda City, which is under the rapid development as a settlement and industrial area. The Karra River area is frequently impacted by streambank erosion and flooding during the heavy rainfall in monsoon due to loosely consolidated sedimentary terrain of the Upper Siwalik Subgroup and the unconsolidated Late Quaternary Deposits, which are vulnerable to erosion. Morpho-hydraulic parameters and stream cross-sectional characteristics and parameters of streambank erosion susceptibility index (SESI) rating system were assessed along the Karra River at 19 transects. The rating of the SESI are based on bank angle, bank height ratio, root depth ratio, root density, surface protection, bank materials and characteristics of stratification. The flood-prone area map was prepared based on the morpho-hydraulic parameters of the stream based on the maximum bankfull depth. The ER and W/D ratio were estimated to determine the affinity of flooding and lateral instability of the stream. Near Bank Stress Index and SESI dealt with streambank erosion potential were assessed to estimate the streambank erosion rate.

Streambank Stabilization Design, Research, and Monitoring: The Current State and Future Needs

HighlightsEleven general streambank stabilization (SBS) techniques have been used worldwide.Rules-of-thumb and practitioner experience are still heavily applied in SBS design.Research needs include assessing the spatiotemporal variability of SBS and improving numerical simulation.Future SBS experiments need to include design details with results that can be easily communicated to designers.Abstract. Streambank stabilization techniques, designed to maximize localized streambank shear strength and/or minimize the forces acting on a streambank, have been in existence for centuries and are still a popular river management technique used by practitioners worldwide. The purpose of this literature review is to identify common streambank stabilization techniques, compile and summarize the recent peer-reviewed journal articles on these techniques, and determine research needs. Eleven general streambank stabilization practices, consisting of both instream structures and streambank management techniques, are identified in this literature review. Over 140 peer-reviewed journal articles on these techniques have been published over the last 20 years. To improve design and implementation of streambank stabilization techniques, two major research needs were identified: (1) further assess and quantify the spatiotemporal effects that streambank stabilization practices have on bank erosion, hydraulics, sediment transport, and habitat and (2) continue to improve numerical models for streambank stabilization design in order to holistically evaluate and address these effects. In addition, a list of specific research needs for each stabilization technique is provided. To help address these research needs, it is recommended that future streambank stabilization publications should (1) use consistent technique nomenclature, (2) provide characteristic details about the techniques and channels studied, (3) justify the experimental setup, and (4) explain how the research will improve streambank stabilization design. Keywords: Bankfull bench, Barb, Bioengineering, Deflector, Dike, Dyke, Groin, Groyne, Jetty, Large woody debris, LPSTP, Retarder, Revetment, Riprap bank, River training, Shaping, Spur, Stream restoration, Streambank erosion, Streambank stabilization, Toe rock, Toe

Fertilizer, landscape features and climate regulate phosphorus retention and river export in diverse Midwestern watersheds

Non-point source pollution of phosphorus (P) is a primary cause of eutrophication of aquatic ecosystems, and poses a persistent management challenge due to the dynamic and poorly understood processes controlling the transport and transformation of P at the watershed scale. We examined phosphorus inputs, retention, and riverine losses in 62 diverse watersheds that included a wide range of land cover and use (minimally disturbed to human dominated) and human P inputs in Minnesota, USA. Fertilizer inputs from row crop cultivation were the dominant source of P to agricultural watersheds. A large majority of P inputs was retained in watershed soils or removed in agricultural products. However, fertilizer input was the most important factor associated with average annual river transport of total, dissolved, and particulate phosphorus (PP). Mean annual runoff increased total and dissolved P yields and decreased P retention. Dissolved P made up a significant portion of annual river loads at sites with high rates of P inputs and river TP export, with the ratio of dissolved to PP export increasing with crop cover and fertilizer inputs. PP export rose with larger extents of eroding bluffs near channels. Bluffs constitute only a small proportion of watershed area, but make a disproportionately high contribution to sediment loads due to their close proximity to river channels that are increasingly affected by human and climate-driven changes to river hydrology. Together, our results suggest that rising discharge and flow variability due to climate change and agricultural intensification coupled with high rates of P inputs will maintain elevated fluvial P export into the future. Without reductions in P inputs and reductions in both soluble P losses and stream bank erosion, reversal of water quality degradation will be difficult to achieve.

Fluvial Erosion Rate of Cohesive Streambanks Is Directly Related to the Difference in Soil and Water Temperatures

Despite decades of research in the field of cohesive soil scour, a major challenge in water resource engineering is an understanding of the fundamental processes governing the erosion of cohesive streambank soils. Given that cohesive soil erodibility is affected by many factors simultaneously, it is necessary to study these factors independently to obtain insights into the erosion process. Three natural soils with different mineralogies were chosen for this study: montmorillonite‐dominated fat clay, vermiculite‐dominated lean clay, and kaolinite‐ and illite‐dominated silty sand. The soils were remolded at maximum dry densities and optimum moisture contents and subjected to 15‐min erosion tests in a laboratory flume. Erosion tests were performed at water temperatures of 15 and 25°C and corresponding soil temperatures of 0, 15, and 25°C, and 15, 25, and 40°C. Test results show that, irrespective of soil type, erosion rate increased with an increase in water temperature but decreased with an increase in soil temperature. When soil and water temperatures were equal, there was no significant change in erosion rate (α = 0.05). Further analyses showed that, irrespective of soil type, erosion rate was a function of the difference in soil and water temperatures and not either temperature alone, indicating that the important thermal factor in the erosion process was the difference in soil and water temperatures. These results show the importance of accounting for soil and water temperatures in erosion studies and suggest that the use of stormwater control measures to control runoff temperatures may be necessary to combat streambank degradation resulting from urbanization.Core Ideas Fluvial erosion of cohesive streambanks is affected by soil and water temperatures. Soil and water temperatures have a coactive effect on cohesive streambank erosion. Increases in stream temperature increase fluvial erosion rates of cohesive banks. Increased streambank temperature reduces fluvial erosion rates of cohesive soils. Urban stormwater runoff temperatures should be reduced to maintain channel stability.

Predicting the annual erosion rates on a small stream by the BANCS model

The erosion of streambanks causes soil loss and degrades the stream habitat. To optimize the prevention of bank erosion, we first need to determine the most vulnerable places on banks. This can be done by the BANCS model. However, data are still missing on its accuracy in small streams. We measured the real annual erosion rates on 18 experimental sections established on the Lomnická stream. Using the Near Bank Stress (NBS) and Bank Erosion Hazard Index (BEHI) we developed the erosion prediction curves and evaluated the relationship between these two indices and the real annual erosion rates. We found a strong relationship between BEHI and real annual erosion rates, with R&lt;sup&gt;2&lt;/sup&gt; = 0.72. The relationship between the NBS index and real annual erosion rates was also strong, with R&lt;sup&gt;2&lt;/sup&gt; = 0.53. Then we constructed erosion prediction curves for very high and extreme BEHI and for moderate and high BEHI. Despite the strong correlation between BEHI and annual erosion rates, the prediction curves had no real relationship with real annual erosion rates, with R&lt;sup&gt;2&lt;/sup&gt;= 0.004 and 0.15, respectively.

Measuring Streambank Erosion: A Comparison of Erosion Pins, Total Station, and Terrestrial Laser Scanner

Streambank erosion is difficult to quantify; models and field methods are needed to assess this important sediment source to streams. Our objectives were to (1) evaluate and compare three techniques for quantifying streambank erosion: erosion pins, total station, and laser scanning, (2) spatially assess streambank erosion rates in the Indian Mill Creek watershed of Michigan, USA, and (3) relate results with modeling of nonpoint source pollution. We found large absolute and relative errors between the different measurement techniques. However, we were unable to determine any statistically significant differences between techniques and only observed a correlation between total station and laser scanner. This suggests that the three methods have limited comparability and differences between measurements were largely not systemic. Further, the application of each technique should be dependent on site conditions, project goals, desired resolution, and resources. The laser scanner collected high-resolution data on clear, barren streambanks, but the erosion pin and total station were more representative of complex vegetated banks. Streambank erosion rates varied throughout the watershed and were influenced by fluvial processes. We estimate that streambank erosion contributed 28.5% of the creek’s total sediment load. These findings are important to address sources of watershed impairments related to sedimentation, as choosing an applicable technique for individual purposes can help reduce the challenges and costs of a streambank erosion study.

Addressing Italy’s urban flooding problems through the holistic watershed approach by using blue/green infrastructure

Water resources have been neglected and stressed for many years, as anthropogenic changes in watersheds have increased runoff, decreased infiltration and aquifer recharge, caused stream incision and streambank erosion and degraded water quality and water resources. The watershed is the management unit to begin to solve stormwater problems and flooding issues. Reversing the mismanagement from the past is a complicated process and must consider a holistic approach factoring in all the processes that cause the aforementioned problems. There are many technological tools such as GIS and hydrologic, hydraulic and water quality models that help pinpoint the sources of problems in the watershed and help derive at a comprehensive solution. The objective of this paper is to provide researchers and practitioners a systematic, methodical and proven approach to documenting and solving water management issues cause by unmanaged anthropogenic changes that have occurred in rural and urban watersheds. There are many regulations and literature about flooding and watershed plans with very detailed guidelines composed by state authorities, however, there are few that completely address the comprehensive, inclusive approach to watershed management to solve a variety of problems. For example, the State of Pennsylvania, USA has separate flood plain management, stormwater management, erosion and sediment pollution control and nonpoint discharge and elimination system (NPDES), and water supply / wellhead protection programs and regulations as opposed to one single “water resources management” regulatory program. This paper defines an innovative approach to overcome some of the restrictions placed on engineers and planners by regulatory programs.

How geomorphic context governs the influence of wildfire on floodplain organic carbon in fire‐prone environments of the western United States

AbstractWe draw on published studies of floodplain organic carbon storage, wildfire‐related effects on floodplains in temperate and high latitudes, and case studies to propose a conceptual model of the effects of wildfire on floodplain organic carbon storage in relation to climate and valley geometry. Soil organic carbon typically constitutes the largest carbon stock in floodplains in fire‐prone regions, although downed wood can contain significant organic carbon. We focus on the influence of wildfire on soil organic carbon and downed wood as opposed to standing vegetation to emphasize the geomorphic influences resulting from wildfire on floodplain organic carbon stocks. The net effect of wildfire varies depending on site‐specific characteristics including climate and valley geometry. Wildfire is likely to reduce carbon stock in steep, confined valley segments because increased water and sediment yields following fire create net floodplain erosion. The net effect of fire in partly confined valleys depends on site‐specific interactions among floodplain aggradation and erosion, and, in high‐latitude regions, permafrost degradation. In unconfined valleys in temperate latitudes, wildfire is likely to slightly increase floodplain organic carbon stock as a result of floodplain aggradation and wood deposition. In unconfined valleys in high latitudes underlain by permafrost, wildfire is likely in the short‐term to significantly decrease floodplain organic carbon via permafrost degradation and reduce organic‐layer thickness. Permafrost degradation reduces floodplain erosional resistance, leading to enhanced stream bank erosion and greater carbon fluxes into channels. The implications of warming climate and increased wildfires for floodplain organic carbon stock thus vary. Increasing wildfire extent, frequency, and severity may result in significant redistribution of organic carbon from floodplains to the atmosphere via combustion in all environments examined here, as well as redistribution from upper to lower portions of watersheds in the temperate zone and from floodplains to the oceans via riverine transport in the high‐latitudes. © 2019 John Wiley &amp; Sons, Ltd.