Search Results (100)

The complex geological environment in western Sichuan, China, leads to frequent debris flow disasters, posing significant threats to the lives and property of local residents. In this study, debris flow susceptibility models were developed using three machine learning algorithms: Support Vector Machine (SVM), Random Forest (RF), and Extreme Gradient Boosting (XGBoost). The models were trained with data in Songpan County and used for debris flow susceptibility prediction in Mao County, using small watersheds as assessment units. Seventeen key feature factors based on multi-source remote sensing data encompassing topography and geomorphology, geological structures, environmental elements, and human activities were selected as input parameters after assessment with Pearson correlation analysis. Model performance was rigorously evaluated through ten-fold cross-validation, and hyperparameter optimization was employed to enhance predictive accuracy. To assess the models’ robustness, the trained models were applied to the neighboring Mao County for cross-regional validation. The results consistently indicate that elevation, seismic nucleation density, population density, and distance to roads are the primary controlling factors influencing susceptibility. Comparative analysis between the Songpan and Mao County reveals that the RF model significantly outperforms SVM and XGBoost in accuracy and robustness. Therefore, the RF model is better suited for debris flow susceptibility assessment in western Sichuan. Although the effectiveness of this model may be limited by the relatively small sample size of debris flow events in the dataset and potential variations in environmental conditions across different regions, it still holds promise for providing a scientific basis and decision-making support for disaster mitigation in comparable areas of western Sichuan. Full article

The United Kingdom has a low percentage cover of woodland, which exists in small, highly fragmented patches. Plans to increase the cover from 14.5% to 17.5% by 2050 will require guidance to help target the planting of new forests to maximise ecological connectivity. This study develops a novel approach to landscape simulation utilising real-world spatial boundary data. The Colne Valley river watershed is chosen as a study site. Three different future woodland creation goals (+10, 30, and 50%) are tested alongside manipulations of the mean new patch size and the mode in which new woodland is created in relation to existing woodland. Scenarios which expanded existing woodland and used riparian planting created larger, more connected patches with more core area. The model outputs are used to assess the impact of the UK woodland increase plans, and past woodland creation efforts are assessed. Increasing the percentage cover generally boosted connectivity, functional connectivity (species dispersals), and increased patch size and core area index. We suggest that proximal growth offers the greatest benefits in terms of biodiversity, but in terms of habitat connectivity smaller isolated woodland patches may also be needed as stepping stones to aid dispersal. Full article

The Kundulun River Basin is the most prominent branch of the Yellow River system within the jurisdiction of Baotou City. As an important water source and ecological barrier, its ecological quality is directly related to the ecological security and sustainable development of the surrounding areas. This study selected the Kundulun River Basin in Baotou City as the research area. On the basis of collecting relevant information, a field investigation was conducted on the ecological and geological conditions of the atmospheric surface subsurface Earth system, using the watershed as the survey scope and water as the carrier for the transfer and conversion of materials and energy in the watershed. This study selected the main factors that affect the ecological geological quality of the watershed and established an evaluation model using the analytic hierarchy process, the coefficient of variation method, and the comprehensive analysis method. We have established an ecological geological quality evaluation index system for the Kundulun River Basin. We conducted quantitative evaluation and comprehensive analysis of regional ecological and geological environment quality. The results indicate that ecological environment indicators contribute the most to the ecological quality of the study area, while the impact of human activities on ecological quality is relatively small. From the perspective of evaluation indicators, grassland has the highest weight, followed by precipitation, groundwater depth, forest land, and cultivated land. Approximately 30.26% of the land in the research area is in a state of high or relatively high ecological and geological–environmental quality risk. It can be seen that the overall quality of the ecological geological environment is not optimistic and needs further protection. Full article

Nepal is known for its complex terrain, climate, and vegetation dynamics, resulting in tremendous hydrologic variability and complexity. Accurately quantifying the water balances at the national level in Nepal is extremely challenging and is currently not available. This study constructed long-term (2000–2022) water balances for 358 watersheds across Nepal by integrating watershed hydrometeorological monitoring data, remote sensing products including Leaf Area Index and land use and land cover data, with an existing ecohydrological model, Water Supply Stress Index (WaSSI). The WaSSI model’s performance is assessed at both watershed and national levels using observed water yield (Q) and evapotranspiration (ET) products derived from remote sensing (ETMonitor, PEW, SSEBop) and eddy flux network (i.e., FLUXCOM). We show that the WaSSI model captured the seasonal dynamics of ET and Q, providing new insights about climatic controls on ET and Q across Nepal. At the national scale, the simulated long-term (2000–2020) mean annual Q and ET was about half of the precipitation (1567 mm), but both Q and ET varied tremendously in space and time as influenced by a monsoon climate and mountainous terrain. We found that watersheds in the central Gandaki River basin had the highest Q (up to 1600 mm yr⁻¹) and ET (up to 1000 mm yr⁻¹). This study offers a validated ecohydrological modeling tool for the Himalaya region and a national benchmark dataset of the water balances for Nepal. These products are useful for quantitative assessment of ecosystem services and science-based watershed management at the national scale. Future studies are needed to improve the WaSSI model and remote sensing ET products by conducting ecohydrological research on key hydrologic processes (i.e., forest ET, streamflow generations of small watersheds) across physiographic gradients to better answer emerging questions about the impacts of environmental change in Nepal. Full article

Understanding the impact of vegetation on organic matter content in sediments is essential for sustainable reservoir management and water quality protection. This study examined the relationship between land cover, erosion processes, and organic matter accumulation in the sediments of four small water reservoirs in the Republic of Serbia. Organic matter content was quantified and analyzed in relation to basin characteristics, including land-use composition, absolute and mean flow gradients, and sediment grain size distribution. Field sampling was conducted across the catchments of four small water reservoirs—Duboki potok, Resnik, Ljukovo, and Sot—with sediment samples collected from main tributaries and accumulation basins. A multi-method approach was employed, combining remote sensing for vegetation-cover assessment, granulometric analysis, organic matter evaluation via loss-on-ignition at 350 °C, and statistical correlation analysis to assess the influence of land use and hydrological gradients on sediment composition. The results revealed a strong correlation (R = 0.892) between forest cover and sedimentary organic matter content, confirming the significant role of vegetation in stabilizing sediments and promoting organic matter deposition. Reservoirs with higher forest and shrub cover (e.g., Sot and Duboki potok) exhibited greater organic matter accumulation (5.79–5.98%), while the agriculture-dominated Ljukovo catchment (76.85% agricultural land) recorded the lowest organic matter content (3.89%) due to increased sediment displacement and reduced erosion resistance. These findings underscore the critical role of vegetation in regulating sediment dynamics and enhancing organic matter retention in small water reservoirs. To mitigate excessive organic matter deposition and improve water quality, sustainable watershed management strategies—such as vegetation buffer strips, afforestation, and erosion control measures—are recommended. Full article

Epiphytic organisms are characteristic elements of the Andean dry forest, playing a crucial role in ecosystem diversity and functionality, but they are threatened by deforestation-related factors. The diversity of epiphytic lichens and bryophytes was recorded in the Pisaca Reserve, which has an artificial pond locally known as “Laguna Pisaca”, serving as a critical micro-watershed. This pond provides water services to the city of Catacocha, motivating local communities to protect its biodiversity. In each zone (low, middle and high), 10 plots of 5 × 5 m were established, where the presence and coverage of lichens and bryophytes were sampled in 4 trees per plot (120 trees). Richness and diversity (Shannon–Weaver and Simpson indices) were calculated. Generalized linear models (GLM) were used to analyze the effect of the zone on richness and diversity, and multivariate analysis was used to analyze species composition. A total of 90 species were recorded (65 lichens and 25 bryophytes), distributed in three zones: 74 in the high, 67 in the low and 41 in the middle zone. Species richness and composition showed significant variations in relation to the three zones, influenced by forest structure, small altitudinal changes and forests disturbance. The forests of the Pisaca Reserve harbor a great diversity of lichens and epiphytic bryophytes, which serve as refuges for biodiversity in the Andean dry montane forest of South Ecuador. Full article

The rapid and accurate acquisition of soil moisture (SM) information is essential. Although Unmanned Aerial Vehicle (UAV) remote sensing technology has made significant advancements in SM monitoring, existing studies predominantly focus on developing models tailored to specific regions. The transferability of these models across different regions remains a considerable challenge. Therefore, this study proposes a transfer learning-based framework, using two representative small agricultural watersheds (Hongxing region and Woniutu region) in Northeast China as case studies. This framework involves pre-training a model on a source domain and fine-tuning it with a limited set of target domain samples to achieve high-precision SM inversion. This study evaluates the performance of three algorithms: Random Forest (RF), Convolutional Neural Network (CNN), and Long Short-Term Memory (LSTM) network. Results show that the fine-tuned model significantly mitigates the decline in prediction accuracy caused by regional differences. The fine-tuned LSTM model achieved the highest retrieval accuracy, with the following results: 10% samples (R = 0.615, RRMSE = 15.583%), 30% samples (R = 0.682, RRMSE = 13.97%), and 50% samples (R = 0.767, RRMSE = 16.321%). Among these models, the LSTM model exhibited the most significant performance improvement and the best transferability. This study underscores the potential of transfer learning for enhancing cross-regional SM monitoring and providing valuable insights for future UAV-based SM monitoring. Full article

This study utilizes historical monitoring data from the Xu Fan small watershed spanning 1962 to 2021 and employs the K-means clustering algorithm to classify extreme rainfall events into three distinct categories: short-duration high-intensity rainfall, sustained moderate-intensity rainfall, and long-duration heavy rainfall. Through the application of the Random Forest model, key factors influencing flood characteristics are identified, including total rainfall, maximum rainfall intensity, the timing of maximum intensity, and rainfall duration. The comparative analysis of data before and after 1990 highlights that climate change has led to increased maximum rainfall intensity, reduced rainfall duration, and shifts in the temporal distribution of rainfall, thereby exerting a significant influence on the flood generation process. Full article

Soil erosion has become an increasingly serious issue, drawing global attention. As one of the countries facing severe soil erosion in the world, China confronts significant ecological challenges. Against this backdrop, the country places great emphasis on soil conservation efforts, considering them a crucial component of ecological civilization construction. This study focuses on the carbon sink benefits of comprehensive soil conservation management in the loess hilly region and sandy slopes, using the Xiaonanshan Mountain small watershed in Youyu County, Shanxi Province, as a typical case for in-depth analysis. In terms of research methodology, an integrated monitoring approach combining fundamental data, measured data, and remote sensing data was developed. A comprehensive survey of the Xiaonanshan Mountain small watershed was conducted to categorize plant carbon pools and soil carbon pools, establish baseline scenarios, and utilize methods such as inverse distance spatial interpolation, sample calculation, and feature extraction to estimate forest carbon storage across different years and determine changes in soil and vegetation carbon storage. Simultaneously, data collection and preprocessing were carried out, including the gathering of fundamental data, field data collection, and internal data preprocessing. On this basis, a vegetation carbon storage model was constructed, and an assessment of soil carbon pool storage was conducted. The research results indicate that from 2002 to 2024, the continuous implementation of various soil conservation measures over 22 years has led to a significant increase in carbon storage within the Xiaonanshan Mountain small watershed. The vegetation carbon density of the entire small watershed increased from 14.66 t C/ha to 27.02 t C/ha, and the soil carbon density rose from 28.92 t C/ha to 32.48 t C/ha. The net carbon sink amount was 18,422.20 t C (corresponding to 67,548.08 t CO₂e in terms of carbon dioxide equivalent). Populus simonii and Pinus sylvestris var. mongholica significantly contribute to the carbon sink; however, due to partial degradation of Populus simonii, its net carbon sink amount is less than that of Pinus sylvestris var. mongholica. Additionally, the carbon sink capacity of the small watershed exhibits spatial differences influenced by conservation measures, with high carbon density areas primarily concentrated within the range of Populus simonii, while low carbon density areas are mainly found in shrub zones. The increase in carbon storage within the small watershed is primarily attributed to the contributions of vegetation and soil carbon storage, indicating that comprehensive soil erosion management has a significant carbon accumulation effect; moreover, the annual growth rate of vegetation carbon storage exceeds that of soil carbon storage, with the proportion of soil carbon storage increasing year by year. Furthermore, the vegetation carbon sink, soil carbon sink, and total carbon sink of the small watershed were separately calculated. In terms of benefit analysis, the Xiaonanshan Mountain small watershed offers ecological benefits such as increased forest coverage, carbon fixation and oxygen release, and biodiversity conservation; from an economic perspective, the value of carbon trading is substantial, promoting soil conservation and rural revitalization, with the total value of timber reaching 7.6 million yuan, of which the value of standing timber constitutes the largest proportion; social benefits include the improvement of environmental landscapes, stimulation of ecological tourism, and attraction of investment, with the Xiaonanshan Mountain Ecological Park receiving numerous visitors and generating significant tourism revenue. This research provides a theoretical basis and data foundation for comprehensive soil conservation management in project areas or small watersheds within the loess hilly and sandy slope regions, offering technical and methodological support for other soil conservation carbon sink projects in the area. Full article

Abstract: In the context of the large-scale management of the Loess Plateau and efforts to reduce water and sediment in the Yellow River, this study focuses on a typical watershed within the Loess Plateau. The potential for vegetation restoration in the Kuye River Basin is estimated based on the assumption that vegetation cover should be relatively uniform under similar habitat conditions. The potential for terrace restoration is assessed through an analysis of topographic features and soil layer thickness, while the potential for silt dam construction is evaluated by considering various hydrological and geomorphological factors. Based on these assessments, the overall potential for soil erosion control in the watershed is synthesized, providing a comprehensive understanding of target areas for ecological restoration within the Kuye River Basin. The study demonstrates that the areas with the greatest potential for vegetation restoration in the Kuye River Basin are concentrated in the upper and middle reaches of the basin, which are in closer proximity to the river. The total potential for terracing is 1013.85 km², which is primarily distributed across the river terraces, farmlands, and gentle slopes on both sides of the riverbanks. Additionally, the potential for the construction of check dams is 14,390 units. The target areas for terracing measures in the Kuye River Basin are primarily situated in the middle and lower reaches of the basin, which are in closer proximity to the river. Conversely, the target areas for forest, grass, and check dams, as well as other small watershed integrated management measures, are predominantly located in the hill and gully areas on the eastern and southern sides of the basin. The implementation of the gradual ecological construction of the watershed, based on the aforementioned objectives, will facilitate the protection, improvement, and rational utilization of soil, water, and other natural resources within the watershed. Full article

In recent years, due to the shortage of water resources and the fragile ecological environment in arid areas, the relationship between vegetation and water resources has been relatively close. The unreasonable allocation of water resources and the excessive demand for ecological water use have led to ecological and environmental problems such as river interruption, land desertification, and the extensive withering of vegetation in arid areas; therefore, rapid, accurate estimation of the vegetation ecological water demand has become a hot research topic in related fields. In this study, we classified the land use types in the lower reaches of the Kokyar River Basin based on Sentinel-2A data and calculated the water requirements of each type of vegetation using a combination of the area quota method and improved Penman–Monteith (PM) based on different vegetation coverage levels. The results revealed that in 2020, the water demand of planted woodlands within 0–2 km of the watershed will be the highest, and the water demand of naturally growing arboreal woodlands will be the lowest, and the water demand of the surrounding desert riparian vegetation forests will be very small in relation to the ecological base flow and will not affect the downstream water use for agriculture, industry, and domestic use for the time being. The ecological water demand of the vegetation in the study area can be accurately estimated using Sentinel-2A data, and the research results provide technical support and a theoretical basis for rapid estimation of the ecological water demand of vegetation in typical riparian forests in arid areas and for the allocation of water resources. Full article

Plastic production on a commercial scale began in the 1950s, reaching an annual production of 460 million metric tons in 2019. The global release of 22% of produced plastics into the environment has raised concerns about their potential environmental impacts, particularly on aquatic ecosystems. Here, we quantify and categorize plastic debris found along Richland Creek, a small, heavily forested watershed in western North Carolina, USA. Plastics within the riparian zone of seven 50 m reaches of Richland Creek and its tributaries were sampled two or three times. The 1737 pieces of collected plastic debris were returned to the lab where they were measured and categorized. A small-scale laboratory study using seven of the items collected was performed to determine their ability to break down into microplastics (particles < 5 mm in size). The majority (76%) of collected items were made of either plastic film (particularly bags and food wrappers, 43%) or hard plastics (e.g., bottles, 2%). However, when viewed on a surface area basis, films and synthetic fabrics (e.g., clothing, sleeping bags) equally dominated. Roughly three-quarters of the items collected had a width less than 10 cm, due primarily to the fragmentation of the original items; over two-thirds of the collected items were fragmented. Items composed of foams and films exhibited the highest fragmentation rates, 93% and 86%, respectively. Most collected plastics were domestic in nature, and the number of items increased downstream through more developed areas. Laboratory studies showed that plastic debris has a propensity to break down into microplastics. We believe the data collected here should be replicated in other streams, as these freshwater environments are the source of plastics that eventually enter the oceans. Full article

Changes in land use and landscape patterns significantly influence watershed water quality by affecting non-point source (NPS) pollution processes. Understanding the characteristics of water quality and the relationships between landscape patterns and water quality is crucial to informing land-use planning aimed at ensuring water security. In this study, we employed landscape index methods, correlation analysis, and redundancy analysis based on monitored water quality data and land-use types relative to the Yanshan River Basin, Guilin, China. The results show the following features: (1) Water quality in the small watershed exceeded the values of class III during the study period, and total nitrogen (TN) was the main pollutant, with a pollution load ratio reaching 67.9%. (2) Water quality was significantly impacted by the landscape patterns of the small watershed river. The monitored concentrations of TN, ammonia nitrogen (NH₄⁺-N), nitrate nitrogen (NO₃⁻-N), and total phosphorus (TP) were negatively correlated with the proportion of forest area, and the concentrations of NH₄⁺-N and TP were positively correlated with the proportions of building, orchard, and cultivated land areas. Moreover, the influences of landscape patterns during the wet seasons on water quality were stronger than those during the dry seasons. (3) The total interpretation rates of the landscape indices for the water quality indices in the dry and wet seasons were 96.7% and 94.4%, respectively. Moreover, the largest patch and aggregation indices of the building area were the most effective variables in explaining the water quality indices, with contribution rates of 30.8% and 23.2% in the dry seasons and 34.3% and 23.8% in the wet seasons, respectively. By analyzing these relationships, in this study, we obtained insights into how different landscape patterns contribute to variations in water quality. The findings contribute to sustainable land-use planning strategies that aim to mitigate the impacts of land-use changes on water resources. Full article

Engineering construction disturbs the Earth’s surface and exacerbates soil erosion, resulting in sediment contributions at the watershed scale, the spatiotemporal variation of which remains to be clarified. Based on a typically disturbed catchment, soil samples were collected from sources such as forests, grasslands, spoil heaps, and exposed slopes. Sediment deposition was sampled in 2022 and 2023 along the main channel and fingerprinting technology was employed to calculate the relative contributions of different sources. The results indicated that the optimal composite fingerprints comprising Na₂O, Li, Sr, and Ce could effectively resolve the contributions of different sources. Natural sources were the main sediment contributors, but the average contribution decreased from 72.96% to 58.73% over two periods. In contrast, the contribution of spoil heaps and exposed slopes increased from 27.04% to 41.27% and the area percentage increased from 0.18% to 0.30%. The spoil heap represents the relatively large area of disturbance and its contact length with the river determines the sediment contribution rates, which varied spatially in a quadratic trend along the channel. Meanwhile, the sediment contribution of relatively small and dispersed exposed slopes could be quantified using a linear equation of the disturbance weighting indicator (DWI) composed of disturbed area and flow distance. These results would be helpful in assessing the environmental impact of engineering disturbances and optimizing mitigation measures. Full article

Global forest plantations are expanding, causing land-use changes and impacting the water cycle. This study assesses whether eucalyptus plantations reduce groundwater levels compared to grasslands in paired subtropical watersheds. The hydrological dynamics of surface and subsurface water were compared in three small watersheds in southern Brazil, mainly occupied by Eucalyptus saligna (Es-W, 79.9 ha), Eucalyptus benthamii (Eb-W, 82.1 ha), and degraded anthropized natural grassland (G-W, 109.4 ha). Rainfall, flow, and piezometric levels were monitored. Runoff, evapotranspiration, and water balance in the soil profile were estimated, and the subsurface environment was characterized using electrical resistivity tomography. During higher accumulated rainfall, water surplus increased for all watersheds. In the wet period (accumulated rainfall of 1098.0 mm), evapotranspiration was higher for eucalyptus (624.3 mm for Eb-W and 512.5 mm for Es-W) than for the grassland watershed (299.5 mm), resulting in the highest runoff in G-W (649.6 mm). During the dry period (accumulated rainfall of 478.5 mm), water deficit and withdrawal were mainly observed in forested watersheds, decreasing groundwater. Combining water balance and electrical resistivity tomography estimations results in a better understanding of the hydrological dynamics in paired watersheds with different land uses. This information is useful for developing best-practice management strategies for sustainable water resource use and forest production. Full article