Aug 2026· Progress in Physical Geography: Earth and Environment· 0 citations· 20 references
Abstract
This study delves into the previously uncharted territory of dayas, ephemeral wetlands dotting the arid limestone plateau of Northwest Egypt. As the first comprehensive investigation of these ecologically and geologically vital features, it addresses the critical lack of research on their origins, evolution, and spatiotemporal dynamics. Employing a multi-method approach that integrates high-resolution Sentinel-2 satellite imagery, multi-decadal Landsat time-series analysis, ALOS PALSAR digital elevation model (DEM) processing, and systematic field validation, we identify and delineate 5430 dayas encompassing 258.1 km
2
within a study area of 11,254 km
2
. The supervised maximum-likelihood image classification, validated against 346 stratified field control points, achieved an overall accuracy of 91% (kappa = 0.88). Morphometric analysis characterizes dayas as shallow saucer-shaped depressions with diameters ranging from a few meters to several hundred meters and depths of 0.75 to 5.5 m, etched into the limestone surface filled with loose sediments. 0.75 m is the minimum depth recorded among field-confirmed dayas during the March 2025 survey; the DEM-based automated detection employed a minimum sink-depth threshold of 0.5 m, which represents the lowest depth reliably resolvable at 12.5 m DEM resolution without incurring unacceptable false-positive rates from surface noise. A daya typology comprising bowl-shaped, small flat-bottom, and large flat-bottom classes is established, each reflecting distinct stages within a continuum from active to relict karst. Spatiotemporal analysis of Landsat imagery from 1984 to 2025 documents a 32.63% net increase in daya surface area, corresponding to a mean annual expansion rate of ∼0.8%. Their evolution appears to be a complex interplay of karstic processes, surface-water runoff, hydro-geomorphological interactions, and erosional forces, all influenced by the interplay of structural and climatic factors. This underscores the critical need for sustainable land management practices that acknowledge the dayas’ significance for environmental stability and potential aquifer recharge. In conclusion, this study not only sheds light on the origins and hydrological dynamics of these enigmatic wetlands but also emphasizes their crucial role in the Northwest Egyptian landscape. By advocating for sustainable land-use practices and conservation efforts, we can ensure the continued presence and beneficial influence of these unique dayas for generations to come.
Understanding the hydrologic response of a river basin is essential for evaluating water resource potential and environmental sustainability, especially in fragile mountain ecosystems. The present study investigates the hydrologic behavior of the Beas river basin, situated in the northwestern Himalayan region of India, through morphometric analysis using high resolution Advanced Land Observing Satellite Phased Array type L-band Synthetic Aperture Radar (ALOS PALSAR) DEM at 12.5 m within Google Earth Engine (GEE) environment. The basin covers an area of approximately 19338 km2, exhibiting a wide elevation range from about 159 m in the foothills to over 6,570 m in the upper Himalayas. Land use analysis revealed that 45.12% of the area is occupied by forest cover, while 29.95% is under agricultural land. The drainage network is of seventh order, comprising 4126 identified streams, of which 3120 are first-order streams, with a total stream length of 12287.50 km. The basin displays a dendritic drainage pattern, characterized by a stream frequency of 0.21 and a mean bifurcation ratio is 3.98. The drainage density (0.64) signifies moderate vegetation and semi-permeable rocks, while the very coarse drainage texture (3.21) suggest the occurrence of sharp storm hydrographs with short duration peaks, leading to intense soil erosion within the river basin. Furthermore, morphometric indices such as the form factor (0.23), circularity ratio (0.15), and elongation ratio (0.27) indicate that the basin exhibits a moderately elongated shape with medium to high relief and moderately permeable sub-soil conditions. These characteristics collectively imply moderate runoff and peak discharge, which contribute to significant soil erosion and siltation issues in existing water harvesting structures. The present study provides valuable baseline information for watershed prioritization, soil and water conservation planning, flood risk mitigation and sustainable water resource management in Himalayan region.
N. L. Kushwaha, Nilesh Biwalkar, K. Sur· Journal of Soil and Water Co...· 0 citations
Abstract. This study examines the landscape dynamics in the region surrounding Comandante Ferraz Antarctic Station, Keller Peninsula, King George Island, focusing on the quantification of land cover changes over 23 years. Emphasis is placed on the integration of a multitemporal Landsat time series (2001–2024) within a standardized spatio-temporal data cube framework, coupled with a Random Forest (RF) classification approach. This methodology enables consistent pixel-wise trajectory analysis across seven distinct epochs. The RF models achieved robust performance, with F1-scores for dominant classes like water and soil typically exceeding 0.90, although seasonal snow and ice showed greater spectral ambiguity in transitional months. Quantitative results from the transition matrices reveal a significant landscape reconfiguration: while ice (85.3%) and soil (81.2%) showed high persistence, a prominent trend of deglaciation was identified, characterized by the transition of ice and snow into exposed soil and the emergence of pioneer vegetation communities detected from 2014 onwards. The study demonstrates that the integration of machine learning and data cubes provides a powerful tool for monitoring environmental shifts in high-latitude maritime Antarctica, supporting long-term ecological assessments and climate impact modeling.
E. S. Nascimento, R. C. dos Santos, G. Cardim et al.· ISPRS Annals of the Photogra...· 0 citations
Understanding the influence of topography on vegetation distribution and land use/land cover (LULC) is essential for the sustainable management of fragile Himalayan landscapes, where difficult terrain often limits detailed field investigations. This study was conducted in Ganderbal district, central Jammu and Kashmir, India, during 2020–2023 to characterise the topography, assess vegetation distribution, and map LULC using Sentinel-2A imagery, SRTM DEM data, and GIS techniques. Sentinel-2A imagery from 2020 was used to derive the Normalised Difference Vegetation Index (NDVI) and prepare the LULC map, while SRTM-derived digital elevation data were used to generate topographic layers. The LULC classification comprised six categories: tree-based vegetation, open lands, settlements, water bodies, snow, and rocky wasteland. The study revealed a highly diverse mountainous landscape, with slopes ranging from nearly level to very steep and considerable variation in aspect. NDVI values ranged from −1 to +0.83, indicating marked spatial differences in vegetation density across the district. Tree-based vegetation was the dominant land-cover class, occupying 49.60% of the total area, followed by open lands (26.59%). The LULC classification achieved an overall accuracy of 88.18%, with a Kappa coefficient of 0.845. Vegetation patterns closely reflected the topographic setting, with lower elevations largely occupied by agriculture, horticulture, and settlements, while higher elevations were characterised by temperate forests, alpine meadows, rocky terrain, and seasonal snow. Variations in slope and aspect further influenced vegetation distribution by modifying solar radiation, soil moisture, and local microclimatic conditions. The findings provide useful spatial information for land-use planning, forest and watershed management, biodiversity conservation, and sustainable natural resource management in the Kashmir Himalayas.
Basira Mehraj, A. Wani, M. A. Islam et al.· International Journal of Env...· 0 citations
The Western Ghats of India are highly susceptible to rainfall-induced landslides owing to steep topography, deeply weathered basaltic terrain, and increasing anthropogenic disturbances. This study investigates landslide morphology and post-failure slope instability in Miraswadi habitation, Satara district, Western Ghats, India using Unmanned Aerial Vehicle (UAV) based remote sensing integrated with field observations and multi-temporal satellite analysis. A UAV survey acquired 283 georeferenced high-resolution images which were processed to generate an ortho mosaic, digital elevation model (DEM), contour dataset, and a dense point cloud of ~ 31 million points with mean ground sampling distance of 5.52 cm. Morphometric analysis revealed that the July 2021 landslide affected ~ 1.34 ha, while the associated debris spread extended over ~ 2.95 ha area. The landslide extended approximately 255 m from crown to toe, with widths ranging between 112 and 162 m and an estimated displaced volume between 42,050 and 46,076 m. Geomorphological evidence indicates that the event initiated as a debris slide and subsequently evolved into a channelized debris-flow along a pre-existing second-order drainage course. UAV imagery and field investigations identified several post-failure instability indicators, including tension cracks (up to 70–90 m long and 0.5 m wide), active slumping, ground settlement, and vegetation tilting, indicating ongoing slope deformation adjacent to the habitation. Multi-temporal land-use analysis (2011–2022) revealed expansion of settlement areas and modification of vegetation and agricultural land. The study highlights the utility of UAV-based surveys for rapid, high-resolution characterization of landslide morphology and ongoing instability, providing valuable information for local hazard mitigation and slope management.
A. Shirke, Abhijit Khandge, B. Umrikar et al.· Discover Geoscience· 0 citations
Across the mountainous regions of the East African Rift, interactions between human activities and extreme rainfall events can intensify urban hydro-geomorphological hazards. Yet, observation remains challenging, as remote sensing in humid tropical terrains can be constrained by e.g., persistent cloud cover and dense canopy. This study focused on Uvira (Democratic Republic of the Congo), a city built on narrow alluvial fans along Lake Tanganyika’s northwestern shores, where recent rainfall events (2020-2021) culminated in severe floods. We examined the upstream-downstream sediment cascade to clarify the processes driving flood genesis. We applied an integrated approach combining extensive field observation campaigns, morpho-dimensional classification of 225 erosive events, Sentinel-2 imagery processed via Google Earth Engine, and statistical workflow. Results revealed a predominance of landslides (44.40%) and sheet erosion (38.20%), largely influenced by steep gradients between 900 and 1700 m. Statistical analysis (χ2 = 35.42; p > 0.05) showed no significant link between land-cover class and slope failures, suggesting that fragmented vegetation cover, likely linked to unplanned urbanization, may drive localized infiltration and slope instability. Hazards appeared controlled by dual rainfall regimes: seasonal accumulation (800-1000 mm) followed by short, intense pulses (e.g., 114 mm in 6 h). These conditions generated rapid hydro-sedimentary responses, with 3-4 m riverbed aggradation at the Kavimvira and Mulongwe River’s outlets, severely affecting downstream residential areas. Conversely, the Kalimabenge River carried a smaller sediment load, likely reflecting upstream reforestation. This work advances understanding of sediment connectivity and vegetation fragmentation in tropical rift environments. It highlights the need to move beyond curative dredging toward integrated watershed management, eco-protective measures, and participatory monitoring. Given the scarcity of hydrometeorological data in Uvira, these findings provide a baseline for land-use planning and risk reduction.
Patient Tomombwa Kumbusa, P. Masilya Mulungula, Silvanos Fiama Bondo et al.· Discover Environment· 0 citations
Karst features are widespread, yet many remain insufficiently documented despite their scientific and environmental importance. The present study focuses on the area between Al-Abyar and Benina villages in Cyrenaica, where large-scale dolines have developed within the Upper Miocene Wadi Al Qattarah Formation. Field surveys and morphometric analyses revealed sixteen representative dolines distributed across two geomorphic levels: the coastal fluvial plain and the first plateau of Al Jabal al Akhdar. These dolines vary in size, morphology, and genesis, ranging from solutional depressions to collapse and alluvial dolines. Their formation is interpreted in relation to tectonic evolution, groundwater circulation, surface runoff dynamics, and lithological variability. The study highlights how structural discontinuities and lithological heterogeneity have controlled doline development, while human activities such as agriculture, groundwater extraction, and infrastructure expansion have contributed to their enlargement and reactivation. This anthropogenic influence increases the hazard potential of dolines, posing risks to land use and settlement stability. By integrating petrographic analysis, GIS mapping, and morphometric characterization, the research provides new insights into karst evolution in Cyrenaica and establishes a baseline for future comparative studies with other doline fields in Al Jabal al Akhdar. Ultimately, the findings emphasize the need for conservation strategies to protect these natural karst systems, not only for their geomorphological and hydrogeological significance but also for their potential value in geotourism and sustainable regional development.
Mohamed S. Al Faitouri, Ahmed M. Muftah, Kalifah A. Ashahomi et al.· Libyan Journal of Science &...· 0 citations