Geomorphic Variables Research Articles

Reconstructing the late Pleistocene glacial history of the Cairngorm Mountains, Scotland, using paired cosmogenic 10Be and 14C

ABSTRACTChronologic and geomorphic evidence of past glaciations is largely recorded in areas at relatively low elevation and/or landscapes defined by high glacial erosion. As a result, data from areas that did not experience significant glacial erosion and the highest elevation locations are lacking from reconstructions of past ice masses. Here, we use paired 10Be and 14C exposure dating on quartz derived from glacial erratics and bedrock to resolve past ice mass fluctuations across an elevation and geomorphic gradient in the Cairngorm Mountains of Scotland. We find that the highest elevation samples in our dataset, at 1140 m above sea level, yield 10Be ages indicating 23 000 years of exposure and are at secular equilibrium for 14C, indicative of a single period of exposure starting as a nunatak during the Last Glacial Maximum. Other samples from above 1000 m elevation produce 14C exposure ages indicating deglaciation during the Bølling–Allerød Interstadial, while 10Be concentrations display varying levels of inheritance due to local variations in glacial and non‐glacial erosion. Samples from lower elevations indicate a Lateglacial moraine building event 15 000 years ago, coincident with the Wester Ross readvance, followed by a period of glacier retreat interrupted by moraine deposition at ~14 000 and ~11 000 years ago. This dataset reconstructs both thinning and marginal recession of paleo‐ice masses within the Cairngorm Mountains across a >600 m vertical gradient during the most recent glacial–interglacial transition, demonstrating the utility of paired 10Be/14C exposure dating in ice mass reconstructions in areas of low glacial erosion, increasing the geomorphic diversity of chronologic data available for glacial reconstructions.

Spatiotemporal Changes and the Drivers of Ecological Environmental Quality Based on the Remote Sensing Ecological Index: A Case Study of Shanxi Province, China

Ecological transition zones spanning semi-humid to semi-arid regions pose distinctive monitoring challenges owing to their climatic vulnerability and geomorphic diversity. This study focuses on Shanxi Province, a typical ecologically fragile area in the Loess Plateau of China. Based on the Google Earth Engine (GEE) platform and Moderate Resolution Imaging Spectroradiometer (MODIS) datasets, we established the Remote Sensing Ecological Index (RSEI) series from 2000 to 2024 for Shanxi Province. The Theil–Sen Median, Mann–Kendall, and Hurst indices were comprehensively applied to systematically analyze the spatiotemporal differentiation patterns of ecological environmental quality. Furthermore, geodetector-based quantification elucidated the synergistic interactions among topographic, climatic, and anthropogenic drivers. The results indicate the following: (1) From 2000 to 2024, ecological restoration initiatives have shaped an “aggregate improvement-localized degradation” paradigm, with medium-quality territories persistently accounting for 30–40% of the total land area. (2) Significant spatial heterogeneity exists, with the Lüliang Mountain area in the west and the Datong Basin in the north being core degradation zones, while the Taihang Mountain area in the east shows remarkable improvement. However, Theil–Sen Median–Hurst index predictions reveal that 60.07% of the improved areas face potential trend reversal risks. (3) The driving mechanisms exhibit spatial heterogeneity, where land use type, temperature, precipitation, elevation, and slope serve as global dominant factors. This research provides scientific support for formulating differentiated ecological restoration strategies, establishing ecological compensation mechanisms, and optimizing territorial spatial planning in Shanxi Province, contributing to the achievement of sustainable development goals.

Spatiotemporal morphodynamics of an ephemeral Himalayan River impacted by sand mining: A process-response framework.

Spatiotemporal morphodynamics of an ephemeral Himalayan River impacted by sand mining: A process-response framework.

Geomorphic river classifications based on different methods coincide in predicting fish assemblage structure

AbstractRiver classification is a necessary starting point for understanding river ecosystems and developing management guidelines. Using GIS to analyse an Andean river basin, we compare the application of two geomorphic classification methods at the segment scale: The Geomorphic Units Survey Classification System (GUS) and the Functional Process Zones (FPZ). Segment definition follows a manual procedure in GUS and a semi‐automated procedure in FPZ. Our objective was to assess the relationship between geomorphology and fish assemblages' structure. Fish sampling was carried out in collaboration with participants from local indigenous Mapuche‐Pewenche communities. Non‐parametric multivariate statistical analyses were conducted in order to quantify and describe geomorphic patterns and whether fish assemblages responded consistently with river classifications. Both classifications give insight into the physical characteristics of rivers, such as slope and floodplain width, that make habitat available for different fish assemblages. The two methods provide results that consistently coincide in their identification of geographic distribution and main geomorphic variables of different river types (geomorphic types) throughout the river network. The variation of different river geomorphologies was associated with variation in fish assemblage structure. Geomorphic variables that best characterize the distribution pattern of fish assemblages were elevation, confinement and valley floor width. Confined rivers accommodated highly similar fish assemblages dominated by invasive trout (Salmo trutta and Oncorhynchus mykiss). Unconfined rivers located at higher elevations had greater temporal variability and were mainly composed of trout and native catfish Trichomycterus areolatus. Semiconfined rivers presented the highest geomorphic variability and were associated with high spatial and temporal variability of fish assemblages characterized by both native and non‐native species. The association between fish assemblages and fluvial geomorphology could help in prioritizing rivers for exotic fish species control. These findings should aid in restoring highly intervened Andean rivers and improving management techniques in basins with a variety of human activities.

Inferring on fluvial resilience from multi-temporal high-resolution topography and geomorphic unit diversity

Inferring on fluvial resilience from multi-temporal high-resolution topography and geomorphic unit diversity

Declining geomorphic diversity and potential adaptive management opportunities on a highly regulated reach of the Bighorn River, Montana

ABSTRACT Rivers downstream from dams often experience decreased flow variability and disrupted sediment transport. We investigated a highly regulated 35.5-kilometre reach of the Bighorn River, downstream from Yellowtail Dam, emplaced in 1965. This dam created a thriving trout fishery, but more recently, side channel networks and habitat diminished. We document how the Bighorn River's anabranching morphology responded to flow regulation and a near cessation of sediment supply. Geomorphic diversity drastically decreased since 1939 and the Bighorn River abandoned numerous side channels. By 1980, geomorphic loss slowed, and the river became laterally static. The 1980 river and side channel network could represent the maximum areal extent of a downscaled morphology, maintained through restoration and adaptive management. However, side channel restoration alone will not return natural alluvial processes to this river reach. The Bighorn River needs sediment to reinstate dynamic lateral movement, even within a downscaled morphology. Sediment augmentation is an option, but more complex to implement on rivers where potential downstream impacts and landowners must be considered. The decline of geomorphic diversity and potential adaptive management solutions on the Bighorn River has wide applicability to numerous dammed rivers, where similar changes to the flow and sediment transport regime are common.

Multiscaling behavior of braided channel networks: An alternative formulation of Taylor's law variate transformations.

Braided channel networks exhibit a complex interplay between spatial and temporal dynamics. Their behavior is characterized by both simple and multiscaling patterns, and the mechanisms underlying the stochastic processes associated with this dynamics remain incompletely understood. Leveraging Taylor's pioneering work [Nature (London) 189, 732 (1961)NATUAS0028-083610.1038/189732a0], which unveiled scaling relations in a plethora of natural phenomena through what is now known as the Taylor power law (TPL), we propose a physical interpretation of braided channel systems. This interpretation utilizes a specific class of transformation functions applied to the mean of fluvial geomorphic variables measured along cross sections, namely, the number of wet channels, the average width of wet channels, and the entropic braiding index. By analyzing remotely sensed data of the Brahmaputra-Jamuna River in Bangladesh we obtain valuable insight into the spatiotemporal scaling of these geomorphological variables and gather a deeper understanding of the complexity of braided channel systems. Finally, through a direct analysis employing the TPL in conjunction with a fixed-mass multifractal algorithm, we prove that braided channel networks exhibit a multiscaling behavior.

Impact of Geomorphic Variables on Dissection Index in Western Doon of Dehra, Uttarakhand, India

Dissection Index is a scale of measure of degree of roughness of the earth surface. The degree of roughness of earth surface is consolidated outcome of morphometric elements like – average slope, relative relief, absolute relief, drainage density and lithology. The dissection index is very useful variable in the study of the terrain. The purpose of researcher is to explore the effect of morphometric elements on the dissection index. The formula put forth by Dove Nir (1957) has been adopted to find out the dissection Index. The Wentworth Method has been adopted to calculate the average slope. Study reveals that the coefficient of correlation between relative relief and dissection index is 0.882. It is 0.627, in case of average slope and dissection index. The coefficient of correlations is 0.527 in respect of absolute relief and dissection index. Investigation reveals that relative relief has highly impacted the dissection index in the area. Average slope has moderately influenced the dissection index. The value of coefficient of correlation between drainage density and dissection index, suggests the less impact of drainage density on dissection index.

Interrelation between factors controlling sediment yield in the largest catchment of Peninsular India

Interrelation between factors controlling sediment yield in the largest catchment of Peninsular India

Changing Seasonality of Annual Maximum Floods over the Conterminous US: Potential Drivers and Regional Synthesis

Understanding the flood-generating mechanisms that influence flood seasonality in a region provides information on setting up relevant contingency measures. Although former studies estimated flood seasonality at regional/continental scale, limited/no studies have investigated the climate/basin drivers that influence the changes in flood seasonality. Considering this, the current study performed two analyses: (1) estimated the changes in the seasonality of annual maximum floods (AMF) between pre- and post-1970 across Hydroclimate Data Network basins over the conterminous US, and (2) identified the predictors that influence the change in the seasonality from a set of climate and geomorphic variables. Significant changes in the AMF seasonality were noted for approximately half of the basins in the eastern US, but low to no change was found in most basins in the central/western US. We found, except in the Northeast and mid-Atlantic basins, a decrease in the seasonality index, indicating floods arriving more uniformly is typically associated with an increase in the precipitation days in basins. On the other hand, increase in the seasonality index, indicating floods occurring more concentrated in time, is typically associated with an increase in the extreme precipitation in basins. Among the basin characteristics, elevation has a more dominant role than the drainage area in changing the flood seasonality. Elevation affects the form of precipitation, particularly in the western US, because floods arrive more distributed over the year (i.e., decrease in flood seasonality index), which potentially indicates increased warming resulting in early snowmelt.

Geomorphic diversity of the Newfoundland and Labrador Shelves Bioregion

The Newfoundland and Labrador Shelves Bioregion, located on the glaciated continental shelf and adjacent continental slope of eastern Canada, is classified into units that reflect its great physiographic diversity. There are ten shelf units: bedrock zone, fjord systems, major inlet, shelf-crossing troughs, four types of offshore banks, basin, and disturbed (glaciotectonic) terrain. There are three units on the continental slope: channelized areas, trough-mouth areas, and large sedimentary drifts. A series of vignettes illustrates both the distinguishing characteristics of the principal geomorphic units and the morphologic diversity within them. A sediment mobility analysis reveals that wave- and current-generated disturbances are dominant and largely depth-controlled within the shelf units, while the south-flowing Labrador Current impacts sediment transport and mobility along the continental slope.

Numerical modelling of soil–landscape relationships using diversity indices and conditional probability: a case study from an Iranian arid region

Context Quantitative and numerical modelling of conceptual and qualitative concepts in the soil–landscape relationship is of great interest for soil mapping. Aims We quantified some conceptual and qualitative concepts concerning soil–landscape relationships by numerical analysis of landforms in soil identification using diversity indices (DIs) and conditional probability (CP). Method The geomorphology map was prepared based on the method of Zinck (1989) and used as a basic design for soil sampling. Finally, 200 soil profiles were excavated and described. The DIs and CP were calculated based on soil taxonomic and geomorphological hierarchies. Key results The DIs increased from landscape to landform level. The lowest and highest DIs were obtained for the soil order and soil family at each geomorphic level. The geomorphic diversity based on the soil taxonomy hierarchy showed that soil orders, including Entisols and Inceptisols, were observed in various landscapes and landforms. In contrast, some soil classes, such as Mollisols and its lower levels, did not have geomorphic diversity. The CP based on the geomorphological hierarchy indicated that the present possibility of a specific soil at the higher level (landscape) was less than at the lower level (landform), indicating more soil homogeneity at lower geomorphic levels. However, the probability of observing a certain geoform increased according to the soil classification hierarchy, consistent with the DI results. Conclusions The efficiency of DIs and CP in showing the distribution and possibility of soil separation depends on the alignment of soil and geomorphological processes and the diagnosis of these processes.

Geomorphic diversity of the middle Araguaia River, Brazil: A segment-scale classification to support river management

Geomorphic diversity of the middle Araguaia River, Brazil: A segment-scale classification to support river management

Landslide Risk Assessment in Eastern Kentucky, USA: Developing a Regional Scale, Limited Resource Approach

Rapidly changing remote sensing technologies (lidar, aerial photography, satellites) provide opportunities to improve regional-scale landslide risk mapping. However, data limitations regarding landslide hazard and exposure data influence how landslide risk is calculated. To develop risk assessments for a landslide-prone region of eastern Kentucky, USA, we assessed risk modeling and applicability using variable quality data. First, we used a risk equation that incorporated the hazard as a logistic regression landslide susceptibility model using geomorphic variables derived from lidar data. Susceptibility is calculated as a probability of occurrence. The exposure data included population, roads, railroads, and land class. Our vulnerability value was assumed to equal one (worst-case scenario for a degree of loss) and consequence data was economic cost. Results indicate 64.1 percent of the study area is classified as moderate to high socioeconomic risk. To develop a more data-limited approach, we used a 30 m slope-angle map as the hazard input and simplified exposure data. Results for the slope-based approach show the distribution of risk that is less uniform, with large areas of over-and under-prediction. Changes in the hazard and exposure inputs result in significant changes in the quality and applicability of the maps and demonstrate the broad range of risk modelling approaches.

The role of subway network in urban spatial structure optimization – Wuhan city as an example

The role of subway network in urban spatial structure optimization – Wuhan city as an example

Latitudinal and Altitudinal Gradients of Riverine Landscapes in Andean Rivers

Exact knowledge of the physical structures of different river sections that govern their ecological structure and function is essential for the efficient conservation and management of riverine ecosystems. Eleven Andean river basins (Maipo, Rapel, Mataquito, Maule, Itata, Biobío, Toltén, Valdivia, Bueno and Puelo) comprise large scale latitudinal and altitudinal gradients and accommodate 71% of the Chilean population that strongly depend on their ecosystem services. Here, based on 16 hydrogeomorphic variables (on basin, valley and channel scales), we assessed the riverine landscapes (Functional Process Zones; FPZs) of these river basins using a top-down multivariate statistical approach. Two steep valley and downstream slope FPZs, three sinuous FPZs and two braided FPZs emerged in 8906 river sections. The proportion of the occurrence of FPZs was characterised by a clear latitudinal pattern which is strongly related to the proportions of each river basin within the large morphostructural units of Chile. As such, the proportion of each river basin within the Andes Cordillera, Central Valley and Coastal Cordillera is a strong driver of the fluvial geomorphology and, thus, of the FPZs’ arrangement in each river network. FPZ classification captured geomorphic diversity that coincided with the latitudinal and altitudinal gradients of Chilean Andean river basins strongly related to the hydrological characteristics of the assessed river basins and large scale spatial distribution of fish fauna endemism. As such, the identified large geomorphic units (FPZs) that are strongly tied up with hydrology and ecology hierarchies of riverine landscape provide robust operational tools that can be instrumental for river ecosystem monitoring and management at a basin scale.

Predicting the potential distribution of Dactylorhiza hatagirea (D. Don) Soo-an important medicinal orchid in the West Himalaya, under multiple climate change scenarios.

Climate variability coupled with anthropogenic pressures is the most critical driver in the Himalayan region for forest ecosystem vulnerability. Dactylorhiza hatagirea (D.Don) Soo is an important yet highly threatened medicinal orchid from the Himalayan region. Poor regenerative power and growing demand have resulted in the steep decline of its natural habitats populations. The present study aims to identify the habitat suitability of D. hatagirea in the Western Himalaya using the maximum entropy model (MaxEnt). The community climate system model (CCSM ver. 4) based on representative concentration pathways (RCPs) was used to determine suitable future areas. Sixteen least correlated (< 0.8) bioclimatic, topographical and geomorphic variables were used to construct the species climatic niche. The dominant contributing variables were elevation (34.85%) followed by precipitation of the coldest quarter (23.04%), soil type (8.77%), land use land cover (8.26%), mean annual temperature (5.51%), and temperature seasonality (5.11%). Compared to the present distribution, habitat suitability under future projection, i.e., RCP 4.5 and RCP 8.5 (2050 and 2070), was found to shift to higher elevation towards the northwest direction, while lower altitudes will invariably be less suitable. Further, as compared to the current distribution, the climatic niche space of the species is expected to expand in between11.41-22.13% in the near future. High habitats suitability areas are mainly concentrated in the forest range like Dharchula and Munsyari range, Pindar valley, Kedarnath Wildlife Sanctuary, West of Nanda Devi Biosphere Reserve, and Uttarkashi forest division. The present study delineated the fundamental niche baseline map of D. hatagirea in the Western Himalayas and highlighted regions/areas where conservation and management strategies should be intensified in the next 50 years. In addition, as the species is commercially exploited illegally, the information gathered is essential for conservationists and planners who protect the species at the regional levels.

Loss of geomorphic diversity in shallow tidal embayments promoted by storm-surge barriers.

Coastal flooding prevention measures, such as storm-surge barriers, are being widely adopted globally because of the accelerating rise in sea levels. However, their impacts on the morphodynamics of shallow tidal embayments remain poorly understood. Here, we combine field data and modeling results from the microtidal Venice Lagoon (Italy) to identify short- and long-term consequences of flood regulation on lagoonal landforms. Artificial reduction of water levels enhances wave-induced sediment resuspension from tidal flats, promoting in-channel deposition, at the expense of salt marsh vertical accretion. In Venice, we estimate that the first 15 closures of the recently installed mobile floodgates operated between October 2020 and January 2021 contributed to a 12% reduction in marsh deposition, simultaneously promoting a generalized channel infilling. Therefore, suitable countermeasures need to be taken to offset these processes and prevent significant losses of geomorphic diversity due to repeated floodgate closures, whose frequency will increase as sea levels rise further.

Development of a geomorphic monitoring strategy for stage 0 restoration in the South Fork McKenzie River, Oregon, USA

AbstractThe South Fork McKenzie River (SFMR) in western Oregon, USA hosts one of the largest Stage 0 stream restoration projects implemented to date. Stage 0 refers to a multichannel planform with strong hydrologic connectivity to the adjacent floodplain and surface–subsurface connectivity. Stage 0 restoration was implemented on a 900‐m‐long reach of the SFMR by re‐grading the channel and floodplain using 65,000 m3 of sediment to raise the channel bed. Thousands of large logs were added and the ends of some logs were buried in the sediment to provide foundations for future log jams. Our primary objective is to present a monitoring protocol based on randomly located sampling plots. We also analyze results from 2 years of data collection since project implementation. Within each plot, we measured canopy cover, wood volume, flow depth and velocity, organic cover (area covered by coarse and fine organic material), and substrate grain size. We used intracluster correlation coefficients and variance of measured variables to assess heterogeneity at three spatial scales: within plots, between adjacent plots, and across the entire site. Here, we evaluate changes in the first 2 years after restoration (i.e., not pre‐ vs. post‐restoration). We hypothesized that heterogeneity within a plot would decrease as the plot adjusted to local‐scale hydraulics and sediment and particulate material transport. We hypothesized that heterogeneity would increase between adjacent plots and across the entire site. We found that spatial heterogeneity of geomorphic variables decreased within plots. Heterogeneity of organic cover, sediment size, and flow depth increased between adjacent plots, although other variables did not change. Site‐scale heterogeneity decreased for all variables except organic cover and substrate. We interpret the observed geomorphic responses to reflect decreased longitudinal connectivity and increased lateral and vertical connectivity at the restoration site.

Geomorphological diversity of rivers in the Amazon Basin

Geomorphological diversity of rivers in the Amazon Basin