Stream Gradient Research Articles

Relating environmental variables with aquatic community structure in an agricultural/urban coldwater stream

BackgroundUrban areas are often built along large rivers and surrounded by agricultural land. This may lead to small tributary streams that have agricultural headwaters and urbanized lower reaches. Our study objectives assessed are as follows: (1) landscape, geomorphic, and water quality variables that best explained variation in aquatic communities and their integrity in a stream system following this agricultural-to-urban land use gradient; (2) ways this land use gradient caused aquatic communities to differ from what would be expected for an idealized natural stream or other longitudinal gradients; and (3) whether the impacts of this land use gradient on aquatic communities would grow larger in a downstream direction through the agricultural and urban developments. Our study area was an impaired coldwater stream in Michigan, USA.ResultsMany factors structured the biological communities along the agricultural-to-urban land use gradient. Instream woody debris had the strongest relationship with EPT (Ephemeroptera, Plecoptera, and Trichoptera) abundance and richness and were most common in the lower, urbanized watershed. Fine streambed substrate had the strongest relationship with Diptera taxa and surface air breather macroinvertebrates and was dominant in agricultural headwaters. Fish community assemblage was influenced largely by stream flow and temperature regimes, while poor fish community integrity in lower urban reaches could be impacted by geomorphology and episodic urban pollution events. Scraping macroinvertebrates were most abundant in deforested, first-order agricultural headwaters, while EPT macroinvertebrate richness was the highest downstream of agricultural areas within the urban zone that had extensive forest buffers.ConclusionEnvironmental variables and aquatic communities would often not conform with what we would expect from an idealized natural stream. EPT richness improved downstream of agricultural areas. This shows promise for the recovery of aquatic systems using well-planned management in watersheds with this agricultural-to-urban land use pattern. Small patches of forest can be the key to conserving aquatic biodiversity in urbanized landscapes. These findings are valuable to an international audience of researchers and water resource managers who study stream systems following this common agricultural-to-urban land use gradient, the ecological communities of which may not conform with what is generally known about land use impacts to streams.

Addressing road–river infrastructure gaps using a model-based approach

Abstract The world’s rivers are covered over and fragmented by road infrastructure. Road–river infrastructure result in many socio-environmental questions and documenting where different types occur is challenged by their sheer numbers. Equally, the United Nations has committed the next decade to ecosystem restoration, and decision makers across government, non-government, and private sectors require information about where different types of road–river infrastructure occur to guide management decisions that promote both transport and river system resilience. Field-based efforts alone cannot address data and information needs at relevant scales, such as across river basins, nations, or regions to guide road–river infrastructure remediation. As a first step towards overcoming these data needs in Great Britain, we constructed a georeferenced database of road–river infrastructure, validated a subset of locations, and used a boosted regression tree model-based approach with environmental data to predict which infrastructure are bridges and culverts. We mapped 110 406 possible road–river infrastructure locations and were able to either validate or predict which of 110 194 locations were bridges (n = 60 385) or culverts (n = 49 809). Upstream drainage area had the greatest contribution to determining infrastructure type: when <10 km2 our model correctly predicted culverts 73% of the time but only 60% of the time for bridges. Road type and stream gradient also influenced model results. Our model-based approach is readily applied to other locations and contexts and can be used to inform decisions about management of smaller infrastructure that are frequently overlooked worldwide.

Response of transient rock uplift and base level knickpoints to erosional efficiency contrasts in bedrock streams

AbstractKnickpoints in bedrock streams are often interpreted as transient features generated by a change in boundary conditions. It is typically assumed that knickpoints propagate upstream with constant vertical velocities, though this relies on a stream being in erosional steady state (erosion rate equals rock uplift rate) prior to the knickpoint's formation. Recent modeling and field studies suggest that along‐stream contrasts in rock erodibility perturb streams from erosional steady state. To evaluate how contrasts in rock erodibility might impact knickpoint interpretations, we test parameter space (rock erodibility, rock contact dip angle, change in rock uplift rate) in a one‐dimensional (1D) bedrock stream model that has variable rock erodibility and produces a knickpoint with a sudden change in rock uplift rate. Upstream of a rock contact, the vertical velocity of a knickpoint generated by a change in rock uplift rate is strongly correlated with how the rock contact has previously perturbed erosion rates. These knickpoints increase vertical velocity upon propagating upstream of a hard over soft contact and decrease vertical velocity upon propagating upstream of a soft over hard contact. However, interactions with other transient perturbations produced by rock contacts make for nuances in knickpoint behavior. Rock contacts also influence the geometry of knickpoints, which can become particularly difficult to identify upstream of soft over hard rock contacts. Using our simulations, we demonstrate how a contact's along‐stream horizontal migration rate and cross‐contact change in rock strength control how much an upstream reach is perturbed from erosional steady state. When simulations include multiple contacts, the knickpoint is particularly prone to colliding with other transient perturbations and can even disappear altogether if rock contact dips are sufficiently shallow. Caution should be taken when analyzing stream profiles in areas with significant changes in rock strength, especially when rock contact dip angles are near the stream's slope.

An analytical solution for groundwater flow incorporating the effect of water bodies with sloping surfaces

Determination of hyporheic flow between surface water and groundwater is crucial to clarify the coupled water systems’ hydrological and ecological behaviour. Therefore, this study focuses on groundwater systems interacting with water bodies with sloping surfaces. A sloping stream is defined as an aquifer’s boundary condition. A recharge/discharge term is incorporated into the groundwater flow equation to represent the flux between groundwater and a water body with a sloping surface. An analytical solution of the groundwater flow equation is derived for a homogeneous and isotropic aquifer of a steady-state case. Additionally, a numerical algorithm is written for comparison purposes. The effect of water surface slope on the groundwater head distribution in horizontal plane and the flux between surface water and groundwater is investigated. The results show that the analytical solution represents the hydrodynamics of the stream-water body-aquifer system well, and the water surface slope is dominant on surface water-groundwater interactions.

Logjams and Channel Morphology Influence Sediment Storage, Transformation of Organic Matter, and Carbon Storage Within Mountain Stream Corridors

AbstractThe flow of organic matter (OM) along rivers and retention within floodplains contributes significantly to terrestrial carbon storage and ecosystem function. The storage and cycling of OM largely depend upon hydrogeomorphic characteristics of streams and valleys, including channel geometry and the connectivity of water across and within the floodplain. To examine the role of river morphology on carbon dynamics in mountain streams, we (a) quantify organic carbon (OC) storage in fine sediment, litter, and wood along 24 forested gravel‐bed stream reaches in the Rocky Mountains of CO, USA, (b) examine morphological factors that regulate sediment and OC storage (e.g., channel width, slope, logjams), and (c) utilize fluorescence spectroscopy to examine how the composition of fluorescent dissolved OM in surface water and floodplain fine sediment are influenced by channel morphology. Multivariate regression of the study reaches, which have varying degrees of confinement, slope, and elevation, indicates that OC storage per area is higher in less confined valleys, in lower gradient stream reaches, and at higher elevations. Within unconfined valleys, limited storage of fine sediment and greater microbial transformation of OM in multithread channel reaches decreases OC storage per area (252 ± 39 Mg C ha−1) relative to single‐thread channel reaches (346 ± 177 Mg C ha−1). Positive feedbacks between channel morphology and persistent channel‐spanning logjams that divert flow into multiple channels may limit the aggradation of floodplain fine sediment. Although multithread stream reaches are less effective OC reservoirs, they are hotspots for OM decomposition and provide critical resources to downstream food webs.

Gully controlling practices associated with soil geotechnical properties in the subhumid Ethiopian highlands

Check dams are business as usual practices used to avert gully erosion development and sedimentation in the downstream areas of the humid highlands of Ethiopia. We investigated the status of check dams and their relationship with geotechnical soil properties in the sub-humid Fogera floodplain. The density of gullies in the area was more sever having about 3.6 km km-2 which shows the severity of gully erosion. Thirty-two dams constructed and monitored over one rainy season. In the beginning of the rainy season, all the dams filled up with sediments, and at the end of the monitoring period ninety five percent of them had destroyed and the remainings had partially destroyed and had sediments accumulated on one side of the gully bank. The longitudinal gradient of streams above the dams decreased due to sedimentation. The morphological change of the gully showed an increase in width-depth ratio, gully bank erosion, and sediment aggradation in the gully bed. We found that the amount of sediments deposited behind the dams were higher than the amount of eroded material. The higher clay content and Atterberg limits increased soil erodibility once the gully channel formed. The erodibility and saturation in these soils were highly contributing to gully development and reducing the effectiveness of check dams. In conclusion, it is better to adopt an integrated novel practice to control gullying than solely using check dams.

Geomorphic Analysis, Morphometric-based Prioritization and Tectonic Implications in Chite Lui River, Northeast India

Abstract River morphometry is a useful approach in basin analysis which helps to interprets fluvially originated landforms. The aim of the present work is to evaluate the morphometric and morphotectonic parameters along with prioritization for soil erosion and water availability in Chite Lui watershed. Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) is a useful approach to find out soil erosion and ground water potential zone with an aim to achieve successful management of a watershed. It helps to examine the susceptibility zone in watershed. The present paper documents the delineation of 14 sub-watersheds in Chite Lui River at 3rd order stream. Its prioritization has been performed using several morphometric parameters namely drainage density, elongation ratio and many other parameters using Analytical Hierarchical Process (AHP). Sub-watersheds are ranked from 1-14 based on soil erosion and groundwater potential zones. The Chite Lui watershed is a fifth order drainage basin with a total area of 52.7 km2. The tectonic parameters of the watershed as the asymmetry value is 34%, indicates the structural control over the area either by uplift or tilting. The hypsometric integral value is 0.5 and the valley width height ratio is 0.05 which also suggest tectonic activity in the area. Sinuosity related many parameters along with geomorphic indices like stream power index (SPI), stream gradient index (SL) and topographic wetness index (TWI) were also calculated to suggest the watershed health. The present paper shows that the morphometric analysis is highly relevant and efficient in delineating susceptibility zones.

Fluvial response to active tectonics: analysis of DEM-derived longitudinal profiles in the Rangit River Basin, Eastern Himalayas, India

The Himalayan Mountain Range has originated from the ongoing collision of the Eurasian and the Indo-Australian plates since the Paleogene. It is widely accepted that this tectonically-driven uplift is still continuing, as reflected by a large number of earthquakes in the area. Apart from the sub-surface and geophysical signatures, the surficial geomorphic markers deserve due attention. Fluvial systems, which preserve the evidence of the past and present tectonic perturbations on the surface, have often been investigated to assess the imprints of uplift in a region. Sensitive to long-term tectonic, structural and climatic regimes, the general forms of the longitudinal profile and its derivatives have been analysed across the globe for determining the varying roles of tectonics, litho-structure and climate. This article assesses the degree of tectonic and lithological control on the drainage network of the Rangit Basin in the Eastern Himalayas. One of the important characteristics of the studied basin is that the Main Central Thrust (MCT), which is located between the Greater Himalayas and the Lesser Himalayas, divides the basin into two distinct domains. Longitudinal profiles and their derivatives of 16 major tributaries of the Rangit River were extracted from the ALOS–PALSAR DEM and analysed. The controls on this Himalayan river were evaluated based on investigations of longitudinal profile shapes, stream gradient (SL) indices, longitudinal profile concavities and steepness. Prominent drainage anomalies such as above-grade conditions, exponential and linear fitting of longitudinal profiles, elevated values of SL indices, barbed drainage, over-steepened stream segments and fluvial hanging valleys imply rapid erosion rates in the basin. This is noticeable particularly in the lower domain of the Rangit Basin, especially in the areas located downstream of the MCT. A comparison of steep segments with the geological and lineament maps reveals that many of these anomalies are lineament-controlled. Furthermore, a large number of such features do not conform to lithological intersections, suggesting a possible tectonic factor behind the occurrence of such anomalies.

Phosphorus Transport along the Cropland–Riparian–Stream Continuum in Cold Climate Agroecosystems: A Review

Phosphorus (P) loss from cropland to ground and surface waters is a global concern. In cold climates (CCs), freeze–thaw cycles, snowmelt runoff events, and seasonally wet soils increase P loss potential while limiting P removal effectiveness of riparian buffer zones (RBZs) and other practices. While RBZs can help reduce particulate P transfer to streams, attenuation of dissolved P forms is more challenging. Moreover, P transport studies often focus on either cropland or RBZs exclusively rather than spanning the natural cropland–RBZ–stream gradient, defined here as the cropland–RBZ–stream continuum. Watershed P transport models and agronomic P site indices are commonly used to identify critical source areas; however, RBZ effects on P transport are usually not included. In addition, the coarse resolution of watershed P models may not capture finer-scale soil factors affecting P mobilization. It is clear that site microtopography and hydrology are closely linked and important drivers of P release and transport in overland flow. Combining light detection and ranging (LiDAR) based digital elevation models with P site indices and process-based models show promise for mapping and modeling P transport risk in cropland-RBZ areas; however, a better mechanistic understanding of processes controlling mobile P species across regions is needed. Broader predictive approaches integrating soil hydro-biogeochemical processes with real-time hydroclimatic data and risk assessment tools also hold promise for improving P transport risk assessment in CCs.

Evaluating the performance of multisource digital elevation models using morphometric parameters and field survey data over the mountainous landscapes of northwest Himalaya, India

In this study, seven morphometric characteristics were assessed from three freely available multisource DEMs and correlated with extensive field observations to assess the best-fit DEM over the mountainous landscapes of Kashmir Valley, northwest Himalaya, India. The morphometric parameters were assessed using 30 m ASTER GDEM v2 (ASTERDEM), SRTMDEM, and CartoDEM v3 R1 (CARTODEM) in the Ferozpora watershed of the Jhelum Basin, Kashmir Himalaya. Our findings indicated the closeness of mean bifurcation ratio (Rbm) values between manual digitization (Rbm = 4.12) and CARTODEM (Rbm = 4.07). The GPS-based values of drainage basin asymmetry, stream gradient index, basin relief, and longitudinal river profile also indicated a strong resemblance with CARTODEM-derived values. It is hence concluded that CARTODEM is the best-fit DEM representing the topographic and morphometric characteristics over the Kashmir region, however, the results from this analysis need to be tested and validated over larger geographic domains with contrasting lithological and topographic characteristics.

Climate‐Driven Variability in Runoff Erosion Encoded in Stream Network Geometry

AbstractClimate signatures recorded in the geometry of branching streams provide insight into climate and landscape histories on Earth and other planetary bodies. Recent findings establish that branching angles are narrower and stream profiles are straighter in more arid climates. However, these two observations have been attributed to different mechanisms. Here we demonstrate that for US watersheds the difference in slope between confluent streams increases with humidity, and streams with a greater difference in slope tend to branch at wider angles. Our observations suggest a branching angle endmember of 90° when stream slopes are most different. Using a simple model of runoff erosion, we show how this variation in relative stream slopes can be explained by a shift in streamflow accumulation across climate regimes. These findings connect previously observed climate signatures in branching angles and stream profiles, suggesting that both record the same control of aridity on surface flow.

Machine learning algorithm for flash flood prediction mapping in Wadi El-Laqeita and surroundings, Central Eastern Desert, Egypt

In the work described here, flash flood prediction mapping for the Wadi El-Laqeita in the Central Eastern Desert of Egypt was established, using machine learning approaches involving two algorithms—extreme gradient boosting (XGBoost) and k-nearest neighbor (KNN). Flash flood driving factors, including elevation, slope, curvature, slope-aspect, lithological rock units, distance from streams, stream density, and topographic wetness index (TWI) were selected. Based on the machine learning models, the XGBoost and KNN algorithms were quite similar, in terms of variables importance, with distance from the stream network, slope angle, elevation, and stream density identified as the key driving factors, in order of importance. It is often difficult to allocate model parameter settings; therefore, hyper-parameter setting optimization was applied to improve model prediction performance. The models were trained using 70% flooding location and 70% non-flooding data, with the remaining 30% flooding and 30% non-flooding location data used for model and simulation result validation. The applied models exhibited accuracies of 90.2% and 80.7% for XGBoost and KNN, respectively, showing that the XGBoost algorithm performed better than KNN in this situation. Therefore, XGBoost was used in a powerful approach to flash flood prediction mapping, with the obtained predictions providing important guidance for decision-makers with respect to future study site development.

Hazard Assessment of Debris Flows by Statistical Analysis and GIS in Central Taiwan

This paper aims to build an analytical process of assessing debris-flow hazards using multivariate analysis and geographic information system (GIS) techniques. The watershed of the Chen-Yu-Lan River is investigated in this study. Factors that are believed to be critical in the occurrence of debris flow are identified and considered in the assessment of debris-flow hazards. These factors used for assessing the debris-flow hazard are: (1) rock formation, (2) fault length, (3) naked-land area, (4) slope angle, (5) slope aspect, (6) stream slope, (7) watershed area, (8) form factor, and (9) cover and management factor. Using the spatial analysis feature of GIS, the indexes of these factors are calculated. By using principal component analysis (PCA) and discriminant analysis (DA) of all indexes according to each factor, the discriminant function of overall debris-flow hazard at any particular creek in the Chen-Yu-Lan River may be assessed. The applicability of the proposed approach for hazard assessment of debris-flow in the watershed of the Chen-Yu-Lan River has been confirmed with other researches and field observations in recent debris-flow events.

A New Method to Predict Gully Head Erosion in the Loess Plateau of China Based on SBAS-InSAR

Gully head erosion causes serious land degradation in semiarid regions. The existing studies on gully head erosion are mainly based on measuring the gully volume in small-scale catchments, which is a labor-intensive and time-consuming approach. Therefore, it is necessary to explore an accurate method quantitatively over large areas and long periods. The objective of this study was to develop a model to assess gully head erosion in the Loess Plateau of China using a method based on the SBAS-InSAR technique. The gully heads were extracted from the digital elevation model and validated by field investigation and aerial images. The surface deformation was estimated with SBAS-InSAR and 22 descending ALOS PALSAR datasets from 2007 to 2011. A gully head erosion model was developed; this model can incorporate terrain factors and soil types, as well as provides erosion rate predictions consistent with the SBAS-InSAR measurements (R2 = 0.889). The results show that gully head erosion significantly depends on the slope angle above the gully head, slope length, topographic wetness index, and catchment area. The relationship between these factors and the gully head erosion rate is a power function, and the average rate of gully head erosion is 7.5 m3/m2/year, indicating the high erosional vulnerability of the area. The accuracy of the model can be further improved by considering other factors, such as the stream power factor, curvature, and slope aspect. This study indicates that the erosion rate of gully heads is almost unaffected by soil type in the research area. An advantage of this model is that the gully head area and surface deformation can be easily extracted and measured from satellite images, which is effective for assessing gully head erosion at a large scale in combination with SBAS-InSAR results and terrain attributes.

A multiple regression model to estimate the suspended sediment yield in Italian Apennine rivers by means of geomorphometric parameters

A new statistical prediction model, aimed to assess the mean annual suspended sediment yield (SY) in ungauged rivers of Italian Apennines, is here presented. A multiple linear regression equation was obtained by the stepwise technique investigating the relationships between a series of hydro-geomorphometric variables and sediment yield data from 41 river basins located along peninsular Italy and Sicily. The model variables were computed from hydrological data records and from vector river network lines and drainage divides derived from official maps and DEM. The analysis revealed a large variance in the observed sediment yield data. Nonetheless, an optimal result in terms of model significance and efficiency (r2adj = 0.91 at p < 0.05 significance level; Nash–Sutcliffe model efficiency NSE = 0.855; Willmott’s indexes of performance: d = 0.965; d1 = 0.862; dr = 0.862) was finally achieved. According to stepwise regression, the catchment relief and perimeter, together with the topological organization of stream network, the bedrock erodibility and the stream gradient, expressed by specific parameters, appeared as determinant features for SY prediction in the catchments here investigated. The developed model could be helpful to practitioners and scholars for rapid assessments of SY at any point of the river network in the geographic area here concerned. However, the same technique can be utilized wherever in the world since the statistical method itself allows to recognize the number and type of parameters to be used in a given geographic area, on the basis of their local significance.

Susceptibility to Gully Erosion: Applying Random Forest (RF) and Frequency Ratio (FR) Approaches to a Small Catchment in Ethiopia

Soil erosion by gullies in Ethiopia is causing environmental and socioeconomic problems. A sound soil and water management plan requires accurately predicted gully erosion hotspot areas. Hence, this study develops a gully erosion susceptibility map (GESM) using frequency ratio (FR) and random forest (RF) algorithms. A total of 56 gullies were surveyed, and their extents were derived by digitizing Google Earth imagery. Literature review and a multicollinearity test resulted in 14 environmental variables for the final analysis. Model prediction potential was evaluated using the area under the curve (AUC) method. Results showed that the best prediction accuracy using the FR and RF models was obtained by using the top four most important gully predictor factors: drainage density, elevation, land use, and groundwater table. The notion that the groundwater table is one of the most important gully predictor factors in Ethiopia is a novel and significant quantifiable finding and is critical to the design of effective watershed management plans. Results from separate variable importance analyses showed land cover for Nitisols and drainage density for Vertisols as leading factors determining gully locations. Factors such as texture, stream power index, convergence index, slope length, and plan and profile curvatures were found to have little significance for gully formation in the studied catchment.

Influence of different relief information sources on the geomorphological characterization of small watersheds.

Mathematical models have been widely used to quantify hydrological processes for various practical purposes. These models depend on geomorphological attributes which are derived from relief information represented by Digital Elevation Models (DEM). The objective of this study was to evaluate the influence of relief information sources (ASTER, SRTM-30, SRTM-90, and TOPO) over geomorphological characterization of five Brazilian watersheds. Geoprocessing tools were applied for extraction of the following geomorphological attributes for each DEM: drainage area, perimeter, and watershed slope; length and slope of the main stream; total length of streams; bifurcation, stream length and stream area ratios; and length of the highest order stream. The differences in the values of attributes were calculated in relation to the reference DEM (TOPO). It was found that: i) slope of main stream and bifurcation ratio were the most sensitive parameters regarding the relief information source; ii) flat watersheds were more susceptible to altimetric errors; iii) ASTER did not adequately represent drainage networks for flat watersheds; and iv) the differences in the geomorphological attributes increased as drainage area decreased. The results indicate that DEM may exert influence on the use of hydrological models that depend on geomorphological attributes.

Stream Amphibian Detectability and Habitat Associations in a Reduced Impact Logging Concession in Malaysian Borneo

Borneo's amphibians face an uncertain future due to high levels of forest degradation and a paucity of data for effective conservation management. Several studies identified strong species–habitat relationships in pristine and conventionally logged forests. However, these studies did not account for detectability or habitat associations in sustainably managed forest reserves. Here, we determined detectability and species habitat relationships in stream amphibians within the Deramakot forest reserve, a reduced impact logging concession in the Malaysian state of Sabah, northern Borneo. We analyzed data for 10 stream species collected along 32 stream transects. An occupancy modeling framework was used to determine the climatological, temporal, and environmental covariates associated with detection and occupancy probabilities. We identified high variability in detection probability between species, including significant associations with moon phase (six species), time since sunset (five species), humidity (five species), rainfall (four species), and temperature (three species). Stream slope and volume provided by far the best predictors of occurrence, with significant positive or negative associations with the occupancy of six species each. These associations were more similar to those found in pristine compared with conventionally logged habitats. The highly variable detectability associations within our amphibian community suggest a level of temporal separation in regard to activity and breeding phenology in these species. This stresses the importance of accounting for detection probability via surveying sites across varying climatic/temporal conditions to obtain a representative sample of amphibian communities in pristine and disturbed tropical forests.

Block ramps for stream power attenuation in gravel-bed streams: a review

Abstract Application of the block ramp technique in steep gradient streams for energy dissipation as well as to maintain river stability finds increasing favor amongst researchers and practitioners in river engineering. This paper dwells on a comprehensive state-of-the-art review of flow resistance, energy dissipation, flow characteristics, stability, and drag force on block ramps by various investigators in the past. The forms and equations for each type are thoroughly discussed with the objective of finding the grey areas and gaps. More research is warranted further to improve the equations, which are essential for design analysis. Block ramps can be a promising simple technique to achieve reasonable attenuation of devastating fluvial forces unleashed in gravel-bed streams during cloud bursts.

Why Do Beavers Leave Home? Lodge Abandonment in an Invasive Population in Patagonia

Research Highlights: Lodge abandonment by beavers is apparently a common phenomenon in Patagonia, but it is still poorly understood and we ignore what drives it. In relatively slow growth Nothofagus forests, resource depletion can impact abandonment while water availability may be a major driver in the semiarid steppe. Background and Objectives: North American beaver (Castor canadensis) was introduced in 1946 on the island of Tierra del Fuego (TDF) in southern Argentina. Since then, beavers have become a major disturbance affecting not only forest but also treeless steppe landscapes. Our goal was to determine the factors affecting lodge abandonment by beavers in two habitats of TDF: forest and steppe. Materials and Methods: A total of 47 lodges were surveyed between February and March from 2012 to 2014 in both habitat types, 22 in the forest and 25 in the steppe. To explain factors involved in lodge abandonment by beavers, we measured the following variables: water level variation, stream gradient, vegetation cover adjacent to shore and forest structure. Results: We recorded 24 abandonments events, with a similar proportion of lodges abandoned in both habitats. Our results revealed that lodge abandonment was mostly linked to water level fluctuations irrespective of habitat type. The water level at the entrances of the lodge generally decreased in abandoned lodges. Variables that characterize understory cover had some influence on lodge abandonment in the forest, and no effect in the steppe. Conclusions: Water level variation was associated with lodge abandonment in both habitats, and we found some evidence of resource depletion in the forest. However, we caution that changes in water level may be not only due to extrinsic factors but rather to beaver’s own activities or to a decay in pond maintenance following abandonment.