Search Results (12)

The Hindu Kush–Himalaya (HKH) region is an essential component of the global ecosystem, playing a crucial role in global climate regulation and ecological balance. This study employed a remote sensing ecological index (RSEI) with Geodetector to evaluate the eco-environmental quality and its driving factors within the HKH region. Results revealed a statistically significant upward trend (p < 0.05) in eco-environmental quality across the HKH region during 2001–2023, with the average RSEI value increasing by 23.9%. Areas classified as the Good/Excellent grades (RSEI > 0.6) expanded by ~12%, while areas at the Very Poor grade (RSEI ≤ 0.2) shrunk by ~20%. However, areas classified as the Poor (0.2 < RSEI ≤ 0.4) and Moderate (0.4 < RSEI ≤ 0.6) grades increased by ~11% and ~5%, respectively. This resulted in ~11% of the total area degraded across the HKH. Spatially, the highest ecological quality occurred in the southern Himalayan countries (sub-region R2), followed by China’s Tibetan Plateau (sub-region R3), while the northwestern HKH region (sub-region R3) exhibited the lowest ecological quality. Notably, the sub-region R3 and eastern sub-region R1 had the most pronounced improvement. Precipitation and land cover type were the dominant driving factors, exhibiting nonlinear enhancement effects in their interactions, whereas topographic factors (e.g., elevation) had limited but stable influences. These findings elucidate the spatiotemporal dynamics of HKH’s eco-environmental quality and underscore the combined effects of climatic and geomorphic factors, offering a scientific basis for targeted conservation and sustainable development strategies. Full article

While Uncrewed Aerial Vehicle (UAV) systems and camera sensors are routinely deployed in conjunction with Structure from Motion (SfM) techniques to derive 3D models of fluvial systems, in the presence of vegetation these techniques are subject to large errors. This is because of the high structural complexity of vegetation and inability of processing techniques to identify bare earth points in vegetated areas. Furthermore, for eco-geomorphic applications where characterization of the vegetation is an important aim when collecting fluvial survey data, the issues are compounded, and an alternative survey method is required. Laser Scanning techniques have been shown to be a suitable technique for discretizing both bare earth and vegetation, owing to the high spatial density of collected data and the ability of some systems to deliver dual (e.g., first and last) returns. Herein we detail the development and testing of a UAV mounted LiDAR and Multispectral camera system and processing workflow, with application to a specific river field location and reference to eco-hydraulic research generally. We show that the system and data processing workflow has the ability to detect bare earth, vegetation structure and NDVI type outputs which are superior to SfM outputs alone, and which are shown to be more accurate and repeatable, with a level of detection of under 0.1 m. These characteristics of the developed sensor package and workflows offer great potential for future eco-geomorphic research. Full article

The microbial community composition of coastal dunes can vary across environmental gradients, with the potential to impact erosion and deposition processes. In coastal foredunes, invasive plant species establishment can create and alter environmental gradients, thereby altering microbial communities and other ecogeomorphic processes with implications for storm response and management and conservation efforts. However, the mechanisms of these processes are poorly understood. To understand how changing microbial communities can alter these ecogeomorphic dynamics, one must first understand how soil microbial communities vary as a result of invasion. Towards this goal, bacterial communities were assessed spatially along foredune microhabitats, specifically in barren foredune toe and blowout microhabitats and in surrounding vegetated monocultures of native Ammophila breviligulata and invasive Carex kobomugi. Across dune microhabitats, microbial composition was more dissimilar in barren dune toe and blowout microhabitats than among the two plant species, but it did not appear that it would favor the establishment of one plant species over the other. However, the subtle differences between the microbial community composition of two species could ultimately aid in the success of the invasive species by reducing the proportions of bacterial genera associated exclusively with A. breviligulata. These results suggest that arrival time may be crucial in fostering microbiomes that would further the continued establishment and spread of either plant species. Full article

Extensive geographic areas of the world show a long-term atmospheric moisture deficit. Desertification of Rajasthan is concurrent with the strengthened weather extremality and mean annual air temperature (MAAT) rise over the western part of the Indian subcontinent. The present landscape aridification due to the precipitation decrease and reinforced windiness generates surface-cover dryness, aeolian erosion with a mass sediment transfer, salinity of excessively irrigated lands and groundwater depletion; altogether these pose major geo-environmental threats and settlement risks of the expanding Thar Desert. Livestock-overgrazing of sparse-vegetation contributes to ecological pressure to the fragile wasteland ecosystems with approximately three-quarters of the countryside affected to a certain extent by degradation and >50% exposed to wind erosion. Sand dune stabilisation by the drought-adapted tree plantation, the regional hydrology network regulation and the arid-land farming based on new xerophytic cultigens are the key land-use and mitigation strategies. Specific geomorphic palaeosettings predetermined patterned adaptive forms of the ancient desert inhabitation. Geo- and eco-tourism contributes to the arid-zone socioeconomic sustainability with regard to the rich natural and cultural heritage of the area. This study outlines the main effects of the current climate variations on the pristine and occupied lands of western Rajasthan, and the past and present relief transformations, and reviews the modern anthropogenic responses to desertification. Full article

Salt marshes are important coastal environments and provide multiple benefits to society. They are considered to be declining in extent globally, including on the UK east coast. The dynamics and characteristics of interior parts of salt marsh systems are spatially variable and can fundamentally affect biotic distributions and the way in which the landscape delivers ecosystem services. It is therefore important to understand, and be able to predict, how these landscape configurations may evolve over time and where the greatest dynamism will occur. This study estimates morphodynamic changes in salt marsh areas for a regional domain over a multi-decadal timescale. We demonstrate at a landscape scale that relationships exist between the topology and morphology of a salt marsh and changes in its condition over time. We present an inherently scalable satellite-derived measure of change in marsh platform integrity that allows the monitoring of changes in marsh condition. We then demonstrate that easily derived geospatial and morphometric parameters can be used to determine the probability of marsh degradation. We draw comparisons with previous work conducted on the east coast of the USA, finding differences in marsh responses according to their position within the wider coastal system between the two regions, but relatively consistent in relation to the within-marsh situation. We describe the sub-pixel-scale marsh morphometry using a morphological segmentation algorithm applied to 25 cm-resolution maps of vegetated marsh surface. We also find strong relationships between morphometric indices and change in marsh platform integrity which allow for the inference of past dynamism but also suggest that current morphology may be predictive of future change. We thus provide insight into the factors governing marsh degradation that will assist the anticipation of adverse changes to the attributes and functions of these critical coastal environments and inform ongoing ecogeomorphic modelling developments. Full article

Understanding how delta islands grow and change at contemporary, interannual timescales remains a key scientific goal and societal need, but the high-resolution, high frequency morphodynamic data that would be most useful for this are as yet logistically prohibitive. The recorded water levels needed for relative elevation analysis are also often lacking. This paper presents a new approach for hindcasting intertidal marsh-top elevations (HIME) to resolve ecogeomorphic change, even in a young, rapidly changing fluvial delta setting, at sub-decadal temporal resolution and at the spatial resolution of widely available optical remote sensing imagery (e.g., 30 m Landsat). The HIME method first calculates: (i) the probability of land exposure in a set of historical imagery from a user-defined discrete timespan (e.g., months or years); (ii) the probability of water level non-exceedance from water level records, which need not be complete nor coincident with the imagery; and (iii) the systematic variation in local mean water level with distance along the primary hydraulic gradient. The HIME method then combines these inputs to estimate a marsh-top elevation map for each historical timespan of interest. The method was developed, validated, applied, and results analyzed to investigate time-lapse evolution of the Wax Lake Delta in Louisiana, USA, every three years, over two decades (1993–2013). The hindcast maps of delta island extents and elevations evidenced ecogeomorphic system self-organization around four stable attractors, or elevation platforms, at about −0.3 m (subtidal), 0.2 m, 0.4 m, and 0.9 m (supratidal) NAVD88. The HIME results also yielded a time series of net subaerial sediment accumulation, and specific locations and magnitudes of gains and losses, at scales from 30 m to delta-wide (~100 km³) and 6 to 21 years. Average subaerial net sediment accumulation at the Wax Lake Delta (WLD) was estimated as 0.6 cm/yr during the study period. Finally, multiple linear regression models were successfully trained on the HIME elevation maps to model evolving delta island morphologies based on simple geometric factors, such as distance down-delta and position on a delta island; the models also successfully reproduced an average delta topset slope of 1.4 cm. Overall, this study’s development and application of the HIME method added detailed insights to recent, transient ecogeomorphological change at the WLD, and demonstrated the potential of the new approach for accurately reconstructing past intertidal topographies and dynamic change. Full article

Soil moisture, as a crucial factor in the eco-hydrological process, is of great importance for food production, land management in response to water and soil loss, geomorphic processes, and environmental protection. Understanding the spatial variability of soil moisture induced by different land use types and topographic features is conducive to advancing the adjustment of the land use structure and preventing soil erosion on the hillslopes in the black soil (Mollisols) area of Northeast China. Classical statistical methods and Canonical Correspondence Analysis were used to analyze the spatial heterogeneity of soil moisture at 0–20, 20–40, and 40–60 cm on slopes, to identify the main controlling factors and their relative contributions. The results suggested that: the average soil moisture content followed a decreasing order of grassland > shrubland > soybean land > maize land > adzuki bean (Vigna angularis) land > forestland; the profile soil moisture content (SMC) patterns could be divided into four types, related to the comprehensive influence of vegetation types, root system characteristics, and topographic attributes; the spatial variability of soil moisture was strongly influenced by slope gradient, followed by land use types and elevation and slope position, while slope aspect had the least impact; and finally, land use type had a greater impact on the deep layer than the surface layer, while on the contrary, the influence of the topographic attributes on the deep layer was smaller than on the surface layer. Land use types and topographical elements work together on the soil moisture variability and vertical patterns at differing depths. This study provides an insight into policy making of land resource management and can be used in the modeling of hydrological processes. Full article

Farmland abandonment is considered as an important phenomenon for changing eco-environmental and sociocultural landscapes of mountainous rural landscape. Many studies have analyzed farmland abandonment, its driving factors, geophysical processes and consequences at landscape: however, very few have focused on mountainous developing countries such as in Nepal, which is a rapidly urbanizing country suffering from serious farmland abandonment. Therefore, our study was an attempt to (i) assess the spatiotemporal extent of farmland abandonment in Nepal, (ii) explore driving factors of farmland abandonment, and (iii) discuss on the eco-environmental and sociocultural consequences in Nepal. We reviewed various literature, documents, and national reports to obtain a dataset pertaining to the overall status of farmland use and changes along with political and socioeconomic changes, economic development processes, and policy and governance in Nepal. Our results showed that farmland abandonment is widespread; however, it is more prevalent in the hilly and mountainous regions of Nepal. A total of 9,706,000 ha, accounting for 23.9% of the total cultivated farmland in Nepal, was abandoned during the period of 2001 to 2010. The driving factors included population growth, scattered distribution of settlements, urbanization, socio-economic development, poor access to physical services, and poor implementation of agriculture development policies. Furthermore, the increasing extent of natural disasters, malaria eradication, land reform and resettlement programs, the complex system of land ownership, land fragmentation, political instabilities, and the intensification of trading in agricultural products also acted as drivers of farmland abandonment in Nepal. Farmland abandonment generates negative effects on rural societies eco-environmentally and sociologically. Abandoned plots were subjected to different forms of geomorphic damage (e.g. landslide, debris flows, gully formation, sinkhole development etc.). Farmland landscape fragmented into a group of smaller interspersed patches. Such patches were opened for grassland. Furthermore, farmland abandonment also has effects on the local population and the whole society in terms of the production of goods (e.g., foods, feed, fiber), as well as services provided by the multi-functionality (e.g. sociocultural practices, values and norms) of the agricultural landscape. Therefore, this study plays an important role in planning and implementing eco-environmental management and social development processes in Nepal. Full article

Globally, farmland abandonment has been a major phenomenon for eco-environmental and social landscape changes in the mountain regions. Farmland abandonment led to endangering the capacity of mountain ecosystems as well as variety of eco-environmental processes that play a pivotal role in regional as well local level eco-environment security. This research aims to (i) assess the spatiotemporal degradation of abandoned farmlands, (ii) identify the major causes of farmland degradation, and (iii) analyze the eco-environmental risks triggered or exacerbated by the degradation of abandoned farmlands. We conducted an inventory of the spatiotemporal distribution of abandoned farmlands and their degradation status with Google earth images and by modeling and interpreting low-height remote sensing images taken by an unmanned aerial vehicle (UAV). Geomorphic damages were mapped at the scale of individual abandoned farms. A multivariate regression statistical (MRS) model was used to identify the major causes of degradation. This research revealed that out of the total surveyed farmlands, 92% were already completely irreversibly damaged. The damages started with the disruption of terraces and bulging processes that occurred within the year after abandonment. This degradation induced diverse hazardous processes, such as landslides, debris flows, rock falls, the formation of gullies, soil erosion, and the development of sinkholes, which increase the negative effects of on both land resources and plant succession. Farmland abandonment does not automatically lead to plant colonization because geomorphic damage is intensified prior to colonization. Therefore, land management is required for plant colonization as well as other efforts to reduce degradation induced eco-environmental risk. This study thus could help land planners and environmentalists in the development of suitable guidelines (pre- or post-abandonment) plans, programmes, and legislation to effectively address the problem of abandoned farmland. Full article

Coastal foredunes are topographically high features that can reduce vulnerability to storm-related flooding hazards. While the dominant aeolian, hydrodynamic, and ecological processes leading to dune growth and erosion are fairly well-understood, predictive capabilities of spatial variations in dune evolution on management and engineering timescales (days to years) remain relatively poor. In this work, monthly high-resolution terrestrial lidar scans were used to quantify topographic and vegetation changes over a 2.5 year period along a micro-tidal intermediate beach and dune. Three-dimensional topographic changes to the coastal landscape were used to investigate the relative importance of environmental, ecological, and morphological factors in controlling spatial and temporal variability in foredune growth patterns at two 50 m alongshore stretches of coast. Despite being separated by only 700 m in the alongshore, the two sites evolved differently over the study period. The northern dune retreated landward and lost volume, whereas the southern dune prograded and vertically accreted. At the start of and throughout the study, the erosive site had steeper foredune faces with less overall vegetation coverage, and dune growth varied spatially and temporally within the site. Deposition occurred mainly at or behind the vegetated dune crest and primarily during periods with strong, oblique winds (>∼45 ${}^{\circ }$ from shore normal). Minimal deposition was observed on the mostly bare-sand dune face, except where patchy vegetation was present. In contrast, the response of the accretive site was more spatially uniform, with growth focused on the heavily vegetated foredune face. The largest differences in dune response between the two sections of dunes occurred during the fall storm season, when each of the systems’ geomorphic and ecological properties modulated dune growth patterns. These findings highlight the complex eco-morphodynamic feedback controlling dune dynamics across a range of spatial scales. Full article

The abandonment of farmland is a phenomenon that shows the deterioration of the physical and social landscape. It is widespread across the mountainous region of Nepal and is expected to further increase in the future. The aim of this study is to: (i) determine the driving factors of farmland abandonment; (ii) discuss its impact on social systems in terms of social networks, relations, practices; and (iii) assess the eco-environmental vulnerability of abandoned farmlands in the high mountain region of Nepal. The authors apply household surveys, focus group discussions and in-depth key informant interviews to visualize the social landscape and changes therein, thus establishing an existing history of mountain societies, social systems and management practices. Moreover, Google Earth Images and Low Height Remote Sensing Survey (UAV) are also used to observe geomorphic processes and the modification of the abandoned farmland and its characteristics. The Multivariate Linear Regression (MLR) model is run using SPSS revealing eight variables; mountain road accessibility, farm distance from residence, household size, household head age, landowner’s living place, ownership of farmland, salary and business and remittances are major factors determining the process of farmland abandonment in the region. Farmers’ social practices such as (i) an indigenous labor exchange system “Parma,” (ii) a traditionally managed irrigation system, (iii) a drinking water supply system, (iv) social practices, rituals, festive events, (v) an indigenous governance system, practices and some existing infrastructures (schools, banks, health, post, temples and more) are going to disappear as a process of abandonment. The decline in individual as well as social participation in land management practices have increased exotic vegetation and soil loss processes, modifying the physical characteristics of abandoned farmlands. Thus, this knowledge is vital for understanding appropriate social processes, natural resources and environmental management. Full article

Large numbers of people live along and depend upon the world’s coastal resources. Human modifications of the coastal zone, in combination with climate induced environmental changes, have had a major effect on the natural ecological systems. GIS analysis of remote sensed data, combined with fieldwork and laboratory tests, can be used to determine the resultant eco-geomorphic changes that need to be managed sustainably on a worldwide scale. Modelling the eco-geomorphic dynamics between 1949 and 2016 on the Wandandian Creek delta (southeastern NSW, Australia) provides a case study of management options for such coastal resources. Results from the Wandandian Creek delta show that sand/silt sediment derived from the partially (22%) modified terrestrial catchment has prograded into the wave-dominated St. Georges Basin where it is impacted by nearshore processes. Clear spatio-temporal growth of the areal extent and elevation of the deltaic levees and sandspits, with their associated mangroves and saltmarshes, has occurred over the past 65 years. Although the growth rate has fluctuated during the study period, due to flood events in 1974, 1990s and 2010, the overall subaerial and subaqueous delta area has had an average growth of 4168 m² annually with the shoreline extending 1.451 m/year on average. This geomorphic growth has stabilised the estuarine deltaic habitats with high proportions of nutrients and organic matter, particularly within saltmarsh, mangrove, Casuarina/Juncus and other mixed native plant areas. This research shows the importance of analysing morphological changes observed on the delta that can be related to both anthropogenic modifications and natural processes to the catchment and thus should be used in the development of catchment and coastal management plans. Full article