Trend Of Erosion Research Articles

Spatial and temporal variations of rainfall erosivity in the middle Yellow River Basin based on hourly rainfall data

Understanding spatial and temporal variations in rainfall erosivity is essential for estimating the variability in soil erosion. However, rainfall erosivity in the middle Yellow River Basin is usually calculated based on daily rainfall data, which fails to consider the impact of the changing rainfall intensity at the subdaily scale. In this study, we collected hourly rainfall data from 355 meteorological stations within and around the region to calculate rainfall erosivity during 1960–2017. We found that the rainfall erosivity calculated based on hourly data had much larger variability than that calculated based on daily data, and the calculated spatial and temporal variability were substantially different in periods when the rainfall intensity was highly variable. Based on our new estimation, we found that the spatial distribution of rainfall erosivity was highly heterogeneous, with high erosivity values in the Loess Regions and Rocky Mountain Regions with high soil erodibility and low erosivity values in the Aeolian Regions and Soft Sandstone Regions with low soil erodibility. This heterogeneity was mainly due to the distinct spatial distribution patterns of rainfall amount and rainfall intensity. Although the long-term increasing trend of rainfall erosivity was statistically insignificant from 1960 to 2017, its rate of increase was higher than that of the annual rainfall amount. Decadal changes showed a slight decrease from the 1960 s to the 1980 s and an increase since the 1990 s, which was substantially different from the decadal changes in the annual rainfall amount. These differences in temporal variability were mainly caused by the contribution of changing rainfall intensity, which was greater in the Aeolian Regions and Soft Sandstone Regions than in the other subregions. Our study highlighted the importance of considering the changing rainfall intensity at a subdaily scale in semiarid and semihumid climate zones and provided the first estimation of the long-term variability in rainfall erosivity based on hourly rainfall data in this region.

Assessment of the Role of Nearshore Marine Ecosystems to Mitigate Beach Erosion: The Case of Negril (Jamaica)

Coastal and marine ecosystems are supplying a wide range of services. With accelerated Sea Level Rise, intensification of waves and storm surge severity and increasing anthropogenic pressures, these areas are under multiple threats and society may not receive the same level of ecosystems services. This study aims at measuring the trend of beach erosion and at identifying and quantifying the role of some coastal and marine ecosystems in mitigating beach erosion in the region of Negril (Jamaica). In this location, the tourism industry provides the main source of economic revenue. Even at the national level, the two beaches are important assets linked with 5% of the national revenue as 25% of the hotel rooms are located around Negril. In Jamaica, the tourism industry is a significant component of national GDP. 25% of hotel rooms are located around the two beaches of Negril, which have lost an average of 23.4 m of width since 1968. Given the importance of Negril’s beaches to their economy, the Government of Jamaica asked UNEP to conduct a study to identify causes of beach erosion in Negril and potential solutions to address trends of beach erosion, in the context of future sea level rise scenarios induced by climate change. This paper addresses the current beach erosion status and future trends under different climate scenarios. We explain how, by using remote sensing, GIS, wave modelling and multiple regressions analysis associated with national, local and community consultations, we were able to identify and quantify the role of ecosystems for mitigating beach erosion. We show that larger widths of coral and seagrass meadows reduce beach erosion.

Coastal Vulnerability Assessment for Community Resilience on Abrasion: Case of Bugel Coast, Kulon Progo Regency, Indonesia

The coastal boundary can be optimized for settlement and agriculture site based on a spatial plan for Kulon Progo Regency 2012–2032 within a minimum distance of 100m from the coastline. The location of ring 1 local transmigration settlement on the Bugel Coast is less than 100 m. The increasing trend in coastal erosion caused by climate change is a major contributing factor to the reduction of coastal borders. Thus, rapid assessment of coastal erosion vulnerability is necessary to determine an effective coastal management response. This paper aims to analyze the coastal erosion level using vulnerability assessment, geomorphology of coastal areas, and community resilience impact. The methods used in the mapping of coastal segments are smartline and coastal vulnerability index (CVI). The Smartline method is depicted with a line that runs along the coast with information on geomorphological conditions, whereas the CVI method will give weight to each physical parameter of coastal erosion vulnerability. Results showed that the average area of Bugel Coast decreased by 4,794.94 m2 /year and retreated by 4.36 m/year until the borders become closer to one another, thereby threatening the settlement area. The coastal erosion vulnerability was dominated by a moderate level of 325.14 m (30.48%) to a high level of 322.31 m (30.22%) of the total study areas. This result indicated the huge risk of coastal erosion. Therefore, effective community adaptation and mitigation strategies should be considered to reduce the degradation of coastal border resources and ensure the sustainability of local life, such as the combination of structural and non-structural mitigations that prioritize the sustainability of coastal ecosystems.

Increasing trends in rainfall erosivity in the Yellow River basin from 1971 to 2020

Hourly precipitation data from 1971 to 2020, collected from 98 stations distributed across the Yellow River basin, were analyzed to detect changes in characteristics on rainfall and rainfall erosivity for all storms and storms with extreme erosivity (greater than 90th percentile). Results showed that over the past 50 years, rainfall erosivity at both event and seasonal scales over the whole basin increased significantly (p < 0.05) with rates of 5.46% and 6.86% decade-1, respectively, compared to the 1981–2010 average values. Approximate 80% of 98 stations showed increasing trends and 20% of stations had statistically significant trends (p < 0.1). The increase of rainfall erosivity resulted from the significant increasing trends of average storm precipitation (p < 0.1), duration (p < 0.1), rainfall energy (p < 0.05) and maximum 1-h intensity (p < 0.05). In addition, the total extreme erosivity showed significant upward trends at a relative rate of 6.05% decade-1 (p < 0.05). Extreme erosivity storms occurred more frequently and with higher rainfall energy during the study period (p < 0.05). Trends for seasonal total and extreme erosivity were also estimated based on daily rainfall data, and the changing magnitudes were similar to those based on hourly rainfall data, which suggested daily rainfall can be applied to detect interannual and long-term variations of rainfall erosivity in the absence of rainfall data with higher resolution. It was suggested that soil and water conservation strategies and vegetation projects conducted within the Yellow River basin should be continued and enhanced in the future.

Coastal erosion trend analysis using a combination of remote sensing and hydrodynamic models: Case study of Ca Mau Cape, Mekong Delta

BackgroundCoastal erosion and the loss of protective forest areas have recently become serious problems in the Ca Mau Cape (CMC) area of the Mekong Delta. Specifically, in 2016–2020, the rate of erosion in some subsections of the east coast reached 25–37 m/year and the forest area decreased significantly. ObjectivesTo analyse erosion and accretion trends in the period 2016–2020 and to determine the mechanism underlying erosion in the CMC using a hydrodynamic model focused on tides, currents, waves, and sediment transport. MethodsSatellite images (Google Earth), remote sensing images (Landsat 8 OLI/TIRS C1 Level-1), and a combination of hydrodynamic modules were used to evaluate the combined effects of tides, currents, waves, and sediment transport on erosion. ResultsRemote sensing image analyses revealed that the east coast has a very high rate of erosion, with the highest erosion rates of 35 m/year in both 2016–2018 and 2019–2020, while the west coast showed an accretion trend in 2016–2018, followed by strong erosion in 2019–2020, with a rate of 10 m/year. Hydrodynamic models showed that hydrodynamic factors, such as tides, currents, waves, and a low suspended sediment concentration (SSC), directly contribute to the erosion trend in the area. The differences in water level between the high tide and low tide on the east coast, reaching 2 m (dry season) and 0.8 m (wet season), were consistently two times higher than those on the west coast, i.e. 0.9 m (dry season) and 0.4 m (wet season). The flow rates on the east coast (i.e. 0.4–0.6 m/s, on average) were significantly higher those on the west coast (0.2 m/s, on average). Wave heights on the east coast, reaching 1.5–2 m in the dry season and 0.6–1 m in the wet season, were consistently higher than those on the west coast, reaching 1–1.2 m (dry season) and 0.4–0.6 m (wet season). In addition, the SSC was lowest under strong erosion, with average concentrations of 0.04–0.06 kg/m3 in the wet season and 0.02–0.04 kg/m3 in the dry season. The SSC was highest in the sections showing accretion trends, with concentrations of >0.3 kg/m3 in the wet season and 0.08–0.1 kg/m3 in the dry season. ConclusionEvaluating shoreline changes using remote sensing technology and validating these results using hydrodynamic models provides a better understanding of the mechanism underlying coastal erosion and its development and provides a basis for the development of a coastal protection strategy.

Influences of beach berm height on beach response to storms: A numerical study

The field observation at two neighboring beaches showed significant effects of berm height on beach profile changes during a major storm. The fully nonlinear Boussinesq wave model, FUNWAVE-TVD, with a sediment transport module was used to simulate the beach erosion processes of the two beaches. The model reproduced the beach profile changes in good agreement with the measured data. The model results revealed that, for the beach with a higher berm, the wave force, wave-induced undertow flow, along with the higher sediment concentration on the berm induce more offshore sediment transport and cause significant beach profile changes compared to the beach with a lower berm. The erosion trend with different berm heights was predicted by using a series of numerical tests with different berm heights and offshore forcing conditions. The test results suggested that beach erosion increases with the berm height until the berm height reaches a certain level.

Rates of Historical Anthropogenic Soil Erosion in the Midwestern United States

AbstractErosion degrades soils, reduces crop yields, and diminishes ecosystem services. The total amount of soil that has been eroded since the initiation of farming is unknown in most agricultural landscapes, which hinders assessment of soil erosion trends. In the Midwestern U.S., erosion has caused native prairie remnants to become perched above surrounding farmland, providing an opportunity to measure historical soil erosion rates. We use high‐resolution topographic surveys conducted across erosional escarpments at the boundary between 20 prairies and adjacent agricultural fields and show the median reduction in soil thickness ranges from 0.04 to 0.69 m, corresponding to erosion rates of 0.2–4.3 mm year−1, with a median value of 1.9 mm year−1. We used an association between the measured reduction in soil thickness and topographic curvature to predict regional soil erosion integrated since the beginning of farming to the present. We estimate a median historical erosion rate of 1.8 ± 1.2 mm year−1, which is nearly double the rate considered tolerable by the U.S. Department of Agriculture (USDA). Current soil loss predictions from the USDA National Resources Inventory (NRI) and the Daily Erosion Project (DEP) are lower than our historically averaged erosion rate by a factor of 3 and 8, respectively. We suggest that the NRI and the DEP underpredict soil loss rates because they do not include tillage erosion, a process shown to be important throughout the Midwestern U.S. Our findings indicate that further implementation of conservation practices is needed to reduce the high centennial‐averaged soil erosion rates that we measure to sustainable levels.

CliffDelineaTool v1.2.0: an algorithm for identifying coastal cliff base and top positions

Abstract. Correct quantification of coastal cliff erosion requires accurate delineation of the cliff face bounded by the cliff top and base lines. Manual mapping is time consuming and relies on the mapper's decisions and skills. Existing algorithms are generally site specific and may be less suitable for areas with diverse cross-shore cliff geometries. Here we describe CliffDelineaTool (v1.2.0), a MATLAB/Python-based algorithm that identifies cliff base and top positions on complex cliffs using cross-shore transects extracted from digital elevation models. Testing on four 750–1200 m cliffed coastlines shows that the model performance is comparable to manual mapping and provides some advantages over existing methods but provides poor results for cliff sections with ambiguous cliff top edges. The results can form the basis for a range of analyses, including coastal inventories, erosion measurements, spatiotemporal erosion trends, and coastline evolution modeling.

Morphological Development and Behaviour of a Shoreface Nourishment in the Portuguese Western Coast

Current coastal protection strategy in Portugal defines beach and shoreface nourishment as a valid measure to mitigate coastal erosion in some erosional hot-spots, being considered as an adaptation measure under the present climate change scenario, including the impacts of sea level rise. However, scant objective data on shoreface nourishments are available to evaluate performance of this type of intervention in mitigating beach erosion and managing coast risk. We present the first monitoring results of a ≈2.4 × 106 m3 shoreface nourishment on the Aveiro coast (Costa Nova—Ílhavo), the largest until now in Portugal, focusing on its morphological development, impacts on adjacent beaches due to alongshore spreading and cross-shore redistribution, and contribution to the sediment budget of the nourished sediment cell. The analyses are based on high-resolution coastal monitoring data, provided by the Portuguese COaStal MOnitoring Program (COSMO). A Multiple Monitoring Cell (MMC) approach was used to evaluate local and feeder efficiency of the nourishment, sediment budget exchanges within both the placement and wider survey domains (≈1 km2 and 12 km2, respectively). Results show rapid (ca. 6 months) morphological change over the placement area, with a decrease of about 40% of the initial volume. Fast onshore sediment redistribution explains part of this change, placed sand having merged with the pre-existing bar system increased the volume of the shallower nearshore. Longshore transport is reflected by increasing the robustness of the bar downdrift of the placement area and also explains the negative sediment budget (0.75 × 106 m3) of the survey domain, which corresponds to losses through its southern boundary. Sediment spreading also induced accretion of the subaerial section of Costa Nova beaches in front of the placement area, reversing their long-term erosive trend. In contrast, this trend persisted at downdrift beaches. This suggests that the time lag of the subaerial beach response to this intervention increases with the distance to the placement area, and reversal of the erosive trend will only be noticeable in the following years. This study provides new insights on the time scales of beach response to high-magnitude shoreface interventions in high-energy wave-dominated sandy coasts, which will support decision making regarding similar operations designed to manage erosional hot-spots elsewhere.

Recapturing creative space in architectural design unravelling the production network of a young, innovative architectural practice in Rotterdam

In this article, we unravel the production network of a large acoustic wall in a newly built theatre in Rotterdam. This project can be seen as a deviant case in the sense that it goes against the grain of the often observed long-term trend of erosion of the role of architects. This erosion signifies not just a loss for this specific group of professionals, but – given the omnipresence of the built environment in everyday life – also entails risks for society at large. We depart from the Global Network Approach, which can be considered as a heuristic tool to analyse complex production networks, spread out over several interdependent actors and locations. By focusing on the production process, we open up the black box of design in a creative industry based on in-depth interviews with the key players of the production network of the wall. We argue that the prominent role of the architectural practice involved is based on (1) their ‘digital workflow’ strategy; and (2) the specific network structure and relations which allowed them to be important in both design and realisation of the wall.

Geomorphic Evolution of Radial Sand Ridges in the South Yellow Sea Observed from Satellites

The radial sand ridges consist of more than 70 sand ridges that are spread out radially on the continental shelf of the South Yellow Sea. As a unique geomorphological feature in the world, its evolution process and characteristics are crucial to marine resource management and ecological protection. Based on the multi-source remote sensing image data from 1979 to 2019, three types of geomorphic feature lines, artificial coastlines, waterlines, and sand ridge lines were extracted. Using the GIS sequence analysis method (Digital Shoreline Analysis System (DSAS), spatial overlay analysis, standard deviational ellipse method), the evolution characteristics of the shoreline, exposed tidal flats, and underwater sand ridges from land to sea were interpreted. The results demonstrate that: (1) The coastline has been advancing towards the sea with a maximum advance rate of 348.76 m/a from Wanggang estuary to Xiaoyangkou Port. (2) The exposed tidal flats have decreased by 1484 km2 including the reclaimed area of 1414 km2 and showed a trend of erosion in the north around Xiyang channel and deposition in the southeast around the Gaoni and Jiangjiasha areas. (3) The overall sand ridge lines showed a trend of gradually moving southeast (135°), and the moving distance is nearly 4 km in the past 40 years. In particular, the sand ridge of Tiaozini has moved 11 km southward, while distances of 8 km for Liangyuesha and 5 km for Lengjiasha were also observed. For the first time, this study quantified the overall migration trend of the RSRs. The imbalance of the regional tidal wave system may be one of the main factors leading to the overall southeastward shift of the radiation sandbanks.

Simulation and Prediction of Soil Erosion in Daning River Basin

Calculating soil erosion intensity and predicting its change trend is essential for the precise implementation of control measures. We had estimated and quantitatively analyzed the current situation of soil erosion in the Daning River basin in 2008, 2013 and 2018 using the Revised Universal Soil Loss Equation (RUSLE) model. We had also analyzed the correlation between distance from the river, elevation and slope, followed by the analysis and prediction of the soil erosion in the Daning River basin in 2023 by constructing a Cellular Automaton (CA)-Artificial Neural Network (ANN)-Markov model. The results demonstrated the total soil erosion to be 798.49, 746.38 and 628.78 10⁴ t in 2008, 2013 and 2018, respectively. The overall trend of soil erosion was found to be decreasing and the spatial distribution of soil erosion was strongly correlated with the distance from the river, elevation and slope. Based on the CA-ANN-Markov model prediction, the trend of soil erosion from 2018 to 2023 is consistent with that from 2008 to 2013. Light, moderate, and intense erosion demonstrated an increasing trend, whereas slight, very intense and intense erosion demonstrated a decreasing trend. By estimating and predicting soil erosion in the Daning River basin, this paper provides a reference for ecological restoration and the control of soil erosion in small watersheds under similar environments.

Assessment of soil erosion in the Dongting Lake Basin, China: Patterns, drivers, and implications.

Soil loss caused by erosion is a global problem. Therefore, the assessment of soil erosion and the its driving mechanism are of great significance to soil conservation. However, soil erosion is affected by both climate change and human activities, which have not been quantified, and few researchers studied the differences in the driving mechanisms of soil erosion depending on the land use type. Therefore, the spatiotemporal characteristics and changing trends of soil erosion in the Dongting Lake Basin were analyzed in this study. Geographic detectors were used to identify the dominant factors affecting soil erosion in different land use types. In this study, a sensitivity experiment was conducted to clarify the relative contributions of climate change and human activities to soil erosion changes. In addition, we studied the effects of different land use types and vegetation cover restoration on soil erosion. The results show that soil erosion in the Dongting Lake Basin decreased from 2000 to 2018. Human activities represented by land use types and vegetation coverage significantly contributed to the alleviation of soil erosion in the Dongting Lake Basin, whereas climate change represented by rainfall slightly aggravated soil erosion in the study area. The restoration of grassland vegetation and transfer of cultivated land to woodlands in the study area improved the soil erosion. The slope steepness is the key factor affecting the intensity of soil erosion in dry land, paddy fields, and unused land, whereas the vegetation coverage is the key factor affecting the intensity of soil erosion in woodland, garden land, and grassland. Detailed spatiotemporally mapping of soil erosion was used to determine the connections between soil erosion and potential drivers, which have important implications for vegetation restoration and the optimization of land use planning.

Morphology impact of the dike of the autonomous port of Kribi on the Cameroonian coast

This paper presents an assessment of the impact of the Kribi autonomous port dike (Cameroon) on the morphological evolution of the coastaline. The methodological approach consisted in the diachronic analysis of shorelines positions extracted from Landsat 7/8 satellite image archives acquired between November 2003 and May 2020, i.e. a total of 8 images acquired before and after the construction of the dike. In addition, GPS surveys were conducted in the study area to recalibrate the satellite images. Atmospheric, radiometric and geometric corrections were performed on these images using ENVI 5.2 software. DSAS (digital Shoreline Analysis system) version 5.2, an extension of ESRI ArcGIS software, was used to digitize the shoreline and calculate their rate of change. The results obtained show that before the establishment of the port (2003–2012) we observe overall on 9.5 km of portion of the shorelines studied a stability on 64.39% of the coast; 24.14% is in accretion followed by some notches of erosion observed on 11.47% of the coast. The average speed of overall change of the shorelines is +0.34 ± 0.24 m/year. After the implementation of the port (2014–2020), accretion is observed on 26.42% of the shoreline located upstream of the transit and a permanent erosive trend downstream of the structure (dike) and located on 29.97% of the shoreline. The overall average speed of change of the shoreline is −1.90 ± 0.12 m/year. A prediction of the shorelines by the Kalman filter method estimates a maximum accretion of 20.4 m in upstream transit and a maximum retreat in downstream transit of 13.7 m in 2040, which could endanger the fishing camps of the village Nlende during episodes of high tides and cause the loss of habitats (residential areas and nesting beaches of marine turtles).

Soil Erosion Assessment Using the RUSLE Model and Geospatial Techniques (Remote Sensing and GIS) in South-Central Niger (Maradi Region)

A systematic method, incorporating the revised universal soil loss equation model (RUSLE), remote sensing, and the geographic information system (GIS), was used to estimate soil erosion potential and potential area in the Maradi region of south-central Niger. The spatial trend of seasonal soil erosion was obtained by integrating remote sensing environmental variables into a grid-based GIS method. RUSLE is the most commonly used method for estimating soil erosion, and its input variables, such as rainfall erosivity, soil erodibility, slope length and steepness, cover management, and conservation practices, vary greatly over space. These factors were calculated to determine their influence on average soil erosion in the region. An estimated potential mean annual soil loss of 472.4 t/ac/year, based on RUSLE, was determined for the study area. The potential erosion rates varied from 14.8 to 944.9 t/ac/year. The most eroded areas were identified in central and west-southern areas, with erosion rates ranging from 237.1 to 944.9 t/ac/year. The spatial erosion maps can serve as a useful reference for deriving land planning and management strategies and provide the opportunity to develop a decision plan for soil erosion prevention and control in south-central Niger.

Use of an accelerated testing method to characterize inner front pole cover erosion in a high power Hall thruster

Erosion characteristics on the cover of the inner front pole in a 12.5 kW Hall thruster were measured over a wide range of operating conditions in tests of 6–14 h duration using an accelerated test method and a very sensitive, radioactive tracer-based erosion diagnostic. The operating points included the nominal 300–600 V conditions on a constant 20.8 A throttle curve and conditions at other currents spanning the throttling envelope and with varying magnetic field strength, facility pressure, and discharge voltage oscillation amplitude. Surprisingly, the results show that the highest wear rates occur at the lowest voltages and currents. The wear rates were insensitive to discharge voltage ripple but increased monotonically with magnetic field strength, particularly near the inner radius of the pole cover. The inner region was also sensitive to facility pressure, showing lower rates at a higher pressure level. Separate experiments in which the energy distributions of ions generated by the hollow cathode were measured suggest that the cathode plume may be a source of energetic ions responsible for some of the erosion trends, in addition to ions originating in the thruster plume.

Seven Decades of Coastal Change at Barter Island, Alaska: Exploring the Importance of Waves and Temperature on Erosion of Coastal Permafrost Bluffs

Observational data of coastal change over much of the Arctic are limited largely due to its immensity, remoteness, harsh environment, and restricted periods of sunlight and ice-free conditions. Barter Island, Alaska, is one of the few locations where an extensive, observational dataset exists, which enables a detailed assessment of the trends and patterns of coastal change over decadal to annual time scales. Coastal bluff and shoreline positions were delineated from maps, aerial photographs, and satellite imagery acquired between 1947 and 2020, and at a nearly annual rate since 2004. Rates and patterns of shoreline and bluff change varied widely over the observational period. Shorelines showed a consistent trend of southerly erosion and westerly extension of the western termini of Barter Island and Bernard Spit, which has accelerated since at least 2000. The 3.2 km long stretch of ocean-exposed coastal permafrost bluffs retreated on average 114 m and at a maximum of 163 m at an average long-term rate (70 year) of 1.6 ± 0.1 m/yr. The long-term retreat rate was punctuated by individual years with retreat rates up to four times higher (6.6 ± 1.9 m/yr; 2012–2013) and both long-term (multidecadal) and short-term (annual to semiannual) rates showed a steady increase in retreat rates through time, with consistently high rates since 2015. A best-fit polynomial trend indicated acceleration in retreat rates that was independent of the large spatial and temporal variations observed on an annual basis. Rates and patterns of bluff retreat were correlated to incident wave energy and air and water temperatures. Wave energy was found to be the dominant driver of bluff retreat, followed by sea surface temperatures and warming air temperatures that are considered proxies for evaluating thermo-erosion and denudation. Normalized anomalies of cumulative wave energy, duration of open water, and air and sea temperature showed at least three distinct phases since 1979: a negative phase prior to 1987, a mixed phase between 1987 and the early to late 2000s, followed by a positive phase extending to 2020. The duration of the open-water season has tripled since 1979, increasing from approximately 40 to 140 days. Acceleration in retreat rates at Barter Island may be related to increases in both thermodenudation, associated with increasing air temperature, and the number of niche-forming and block-collapsing episodes associated with higher air and water temperature, more frequent storms, and longer ice-free conditions in the Beaufort Sea.

Ephemeral gully recognition and accuracy evaluation using deep learning in the hilly and gully region of the Loess Plateau in China

Ephemeral gullies are widely distributed in the hilly and gully region of the Loess Plateau and play a unique role in the slope gully erosion system. Rapid and accurate identification of ephemeral gullies impacts the distribution law and development trend of soil erosion on the Loess Plateau. Deep learning algorithms can quickly and accurately process large data samples that recognize ephemeral gullies from remote sensing images. Here, we investigated ephemeral gullies in the Zhoutungou watershed in the hilly and gully region of the Loess Plateau in China using satellite and unmanned aerial vehicle images and combined a deep learning image semantic segmentation model to realize automatic recognition and feature extraction. Using Accuracy, Precision, Recall, F1value, and AUC, we compared the ephemeral gully recognition results and accuracy evaluation of U-Net, R2U-Net, and SegNet image semantic segmentation models. The SegNet model was ranked first, followed by the R2U-Net and U-Net models, for ephemeral gully recognition in the hilly and gully region of the Loess Plateau. The ephemeral gully length and width between predicted and measured values had RMSE values of 6.78 m and 0.50 m, respectively, indicating that the model has an excellent recognition effect. This study identified a fast and accurate method for ephemeral gully recognition in the hilly and gully region of the Loess Plateau based on remote sensing images to provide an academic reference and practical guidance for soil erosion monitoring and slope and gully management in the Loess Plateau region.

Spatiotemporal Variation in Rainfall Erosivity and Correlation with the ENSO on the Tibetan Plateau since 1971.

Soil erosion is a serious ecological problem in the fragile ecological environment of the Tibetan Plateau (TP). Rainfall erosivity is one of the most important factors controlling soil erosion and is associated with the El Niño southern oscillation (ENSO). However, there is a lack of studies related to the spatial distribution and temporal trends of rainfall erosivity on the TP as a whole. Additionally, the understanding of the general influence of ENSO on rainfall erosivity across the TP remains to be developed. In this study, long-term (1971–2020) daily precipitation data from 91 meteorological stations were selected to calculate rainfall erosivity. The analysis combines co-kriging interpolation, Sen’s slope estimator, and the Mann–Kendall trend test to investigate the spatiotemporal patten of rainfall erosivity across the TP. The Oceanic Niño Index (ONI) and multivariate ENSO Index (MEI) were chosen as ENSO phenomenon characterization indices, and the relationship between ENSO and rainfall erosivity was explored by employing a continuous wavelet transform. The results showed that an increasing trend in annual rainfall erosivity was detected on the TP from 1971 to 2020. The seasonal and monthly rainfall erosivity was highly uneven, with the summer erosivity accounting for 60.36%. The heterogeneous spatial distribution of rainfall erosivity was observed with an increasing trend from southeast to northwest. At the regional level, rainfall erosivity in the southeastern TP was mainly featured by a slow increase, while in the northwest was more destabilizing and mostly showed no significant trend. The rainfall erosivity on the whole TP was relatively high during non-ENSO periods and relatively low during El Niño/La Niña periods. It is worth noting that rainfall erosivity in the northwest TP appears to be more serious during the La Niña event. Furthermore, there were obvious resonance cycles between the rainfall erosivity and ENSO in different regions of the plateau, but the cycles had pronounced discrepancies in the occurrence time, direction of action and intensity. These findings contribute to providing references for soil erosion control on the TP and the formulation of future soil conservation strategies.

MORPHODYNAMICS OF CHILIKA MOUTH- STUDY ON SHIFTING OF TIDAL INLETS AND ASSESSMENT OF SHORELINE CHANGE ALONG EASTERN COASTAL INDIA, USING GEOSPATIAL TECHNIQUES AND DSAS EXTENSION

This study is focused on the spatio-temporal change in shoreline along Chilika coast and migration of tidal inlet of Chilika lagoon using multi temporal satellite images from the year 1972-2019. This study is carried out over decadal analysis with utilization of EPR and LRR system of DSAS model. For this change analysis studies the Landsat satellite images and IRS-P6 LISS-III images has been used. From the study it reveals that there is one new mouth opening in 2019 after occurrence of cyclone Fani. Based on calculations, the mouth of Chilika mostly has shifted in northward direction. It may due to frequently occurrences of cyclonic storm surges, which usually associated with winds and tidal actions over the coast. This study shows the high erosion trend along 8.3 km in northern part of shoreline. The accretion found along 6.5km in central part of shoreline. The coastal region is now more vulnerable to natural disaster as well as manmade disaster. Most of the areas are prone to floods. This problem may become very serious due to rapid increase in population. Every year the eastern coastal region is destroyed by cyclone and floods.