Intense Rainstorms Research Articles

Global assessment of production benefits and risk reduction in agroforestry during extreme weather events under climate change scenarios

Climate change and extreme weather events are threatening agricultural production worldwide. The anticipated increase in atmospheric temperature may reduce the potential yield of cultivated crops. Agroforestry is regarded as a climate-resilient system that is profitable, sustainable, and adaptable, and has strong potential to sequester atmospheric carbon. Agroforestry practices enhance agroecosystems’ resilience against adverse weather conditions via moderating extreme temperature fluctuations, provisioning buffers during heavy rainfall events, mitigating drought periods, and safeguarding land resources from cyclones and tsunamis-type events. Therefore, it was essential to comprehensively analyze and discuss the role of agroforestry in providing resilience during extreme weather situations. We hypothesized that integrating trees in to the agro-ecosystems could increase the resilience of crops against extreme weather events. The available literature showed that the over-story tree shade moderates the severe temperature (2–4°C) effects on understory crops, particularly in the wheat and coffee-based agroforestry as well as in the forage and livestock-based silvipasture systems. Studies have shown that intense rainstorms can harm agricultural production (40–70%) and cause waterlogging. The farmlands with agroforestry have been reported to be more resilient to heavy rainfall because of the decrease in runoff (20–50%) and increase in soil water infiltration. Studies have also suggested that drought-induced low rainfall damages many crops, but integrating trees can improve microclimate and maintain crop yield by providing shade, windshield, and prolonged soil moisture retention. The meta-analysis revealed that tree shelterbelts could mitigate the effects of high water and wind speeds associated with cyclones and tsunamis by creating a vegetation bio-shield along the coastlines. In general, existing literature indicates that implementing and designing agroforestry practices increases resilience of agronomic crops to extreme weather conditions increasing crop yield by 5–15%. Moreover, despite its widely recognized advantages in terms of resilience to extreme weather, the systematic documentation of agroforestry advantages is currently insufficient on a global scale. Consequently, we provide a synthesis of the existing data and its analysis to draw reasonable conclusions that can aid in the development of suitable strategies to achieve the worldwide goal of adapting to and mitigating the adverse impacts of climate change.

Evolution of regional rainstorm events in China's South-to-North Water Diversion Area, 1960–2022

The objective of this paper is to elucidate the patterns of evolution of regional rainstorm events (RREs) in a large-scale water resources allocation area. This is crucial for the safe operation of water transfer projects and water resources management. The Objective Identification Technique for Regional Extreme Events (OITREE) method is employed to identify all RREs in the South-to-North Water Diversion Area (SNWDA) between the years 1960 and 2022. The results indicate that among the 1397 RREs identified, the extreme RREs are significantly more severe than other classes of rainstorm events. While the extreme intensity (Im) of RREs exhibits a decreasing trend, their frequency, comprehensive index (Z), maximum area (Am), summed area (As), and summed intensity (Is) all demonstrate increasing trends. Some of these indices (Z, Am, As, and Is) exhibit a strong periodicity of approximately 20 years, while the shortening of the decline period will result in more frequent rising periods of RREs. In the second year following the water transfer operation (2015), all RRE indices exhibit abrupt changes. Furthermore, the rainy season lengthens, with more frequent and extreme RREs occurring in July, which may have implications for the Middle Route of year-round water transfers. Spatially, the occurrence frequency of regional rainstorm days (RRDs) increases by 35.9% since the 21st century, while regional rainstorm intensity (RRI) increases by 11.8%. The high-frequency zones (HFZs) of RRDs are primarily located in the southeast, with intensity increases of at least 30%. While their location remains stable, there is a clear trend of northward spread. Following the water transfer, the frequency of RREs is higher in the Eastern Route, and the high-intensity zones (HIZs) appear for the first time in the Beijing area of the Middle Route. These findings provide a scientific understanding of regional rainstorms and serve as a reference for rainstorm disaster response and optimal allocation of water resources in water transfer projects.

Statistical Analysis of Moisture Sources and Quantitative Contribution of Cold Vortex Rainstorms in Northeast China during the Warm Season

Abstract The northeast cold vortex (NECV) is an essential system in the northeast region (NER) of China. Understanding the moisture source and associated transport characteristics of NECV rainstorms is the key to the knowledge of its mechanisms. In this study, we focus on two NECV rainstorm centers during the warm season (May–September) from 2008 to 2013. The Flexible Particle (FLEXPART) model and quantitative contribution analysis method are applied to reveal the moisture sources and their quantitative contribution. The results demonstrate that for the northern NECV rainstorm center (R1), Northeast Asia (35.66%) and east-central China and its coastal regions (29.14%) make prominent moisture contributions, followed by R1 (11.37%), whereas east-central China and its coastal regions (45.16%), the southern NECV rainstorm center itself (R2, 17.90%), and the northwest Pacific (10.24%) principally contribute to R2. Moisture uptake in Northeast Asia differs between R1 and R2, which could serve as one of the vital indicators to judge where the NECV rainstorm falls in NER. Moisture from the Arabian Sea, the Bay of Bengal, and the South China Sea suffers massive en route loss, although these sources’ contribution and uptake are positively correlated with the intensity and scale of NECV rainstorms in the two centers. There exists intermonth and geographical variability in NECV rainstorms when the main moisture source region contributes the most. Regulated by the atmospheric circulation and the East Asian summer monsoon, the particle trajectories and source contributions of NECV rainstorms vary from month to month. Sources’ contribution also turns out to be diverse in the overall warm season.

Numerical simulation study on the effect of underground drainage pipe network in typical urban flood

Rapid urbanization and climate change have heightened urban flood risks. An in-depth examination of the underground drainage pipe network’s effect on urban flood inundation can enhance urban stormwater management and mitigate disaster risks. This study presents a full hydrodynamic urban flood model (FHUM) coupling the pipe transport module of the Storm Water Management Model (SWMM) with a shallow water model. Based on unstructured grid cells, runoff yield and confluence calculations are carried out to effectively separate the underground drainage pipe network from other factors. The model is applied to Minzhi Area and Haidian Island to quantitatively assess the influence of the underground drainage system on urban flooding. Results indicate that FHUM performs well, accurately reflecting the process from rainfall to inundation. The underground drainage pipe network reduces surface inundation in the study area and improves the city’s stormwater drainage capacity. With increasing rainstorm intensity, the impact of the pipe network does not exhibit a consistent trend. During heavy rainstorms, the pipe network consistently plays a significant and stable role, particularly in reducing high inundation depths. However, attention should be paid to the potential flood risk transfer associated with using pipe networks in urban flood management. This work provides a scientific basis for urban stormwater management, holding significant importance in improving flood control and disaster reduction capabilities.

Assessment of urban waterlogging-induced road traffic safety risk and identification of its driving factors: A case study of Beijing

Due to the increasing number of urban waterlogging events, systematic risk assessment and cause exploration are needed to ensure the safety of people's lives and property on roads. In this paper, the urban waterlogging-induced road traffic safety risk (UWRTSR) in the central part of Beijing was assessed and its driving factors were investigated. We obtained the simulation data of road inundation for five rainstorm return periods (5-year, 10-year, 20-year, 50-year and 100-year) through the InfoWorks ICM hydrodynamic model. Then, the safety risk levels of pedestrians and vehicles are evaluated with safety criteria formulas and standards, and the driving factors are identified by the Geodetector model. The results show that the proportion of the total length of road sections at different risk levels for pedestrians, stationary vehicles and moving vehicles increased with increasing rainstorm return period, while for the same road section, the risk level for pedestrians or vehicles may increase due to a higher intensity rainstorm event. The results of subsequent driving factor analysis show that slope, terrain ruggedness index (TRI) and LS factor were the top three single-factor explanatory powers, with the joint effect of slope and rain pipe capacity (RPC) possessing the largest explanatory power. It is found that a high level UWRTSR is to be generated in road sections with low drain network specifications and high slope gradients. Our research may help smooth emergency resource management, road network construction and reconstruction to mitigate the waterlogging risk.

Impacts of Rainstorm Intensity and Temporal Pattern on Caprock Cliff Persistence and Hillslope Morphology in Drylands

AbstractHillslope topographic change in response to climate and climate change is a key aspect of landscape evolution. The impact of short‐duration rainstorms on hillslope evolution in arid regions is persistently questioned but often not directly examined in landscape evolution studies, which are commonly based on mean climate proxies. This study focuses on hillslope surface processes responding to rainstorms in the driest regions of Earth. We present a numerical model for arid, rocky hillslopes with lithology of a softer rock layer capped by a cliff‐forming resistant layer. By representing the combined action of bedrock and clast weathering, cliff‐debris ravel, and runoff‐driven erosion, the model can reproduce commonly observed cliff‐profile morphology. Numerical experiments with a fixed base level were used to test hillslope response to cliff‐debris grain size, rainstorm intensities, and alternation between rainstorm patterns. The persistence of vertical cliffs and the pattern of sediment sorting depend on rainstorm intensities and the size of cliff debris. Numerical experiments confirm that these two variables could have driven the landscape in the Negev Desert (Israel) toward an observed spatial contrast in topographic form over the past 105–106 years. For a given total storm rain depth, short‐duration higher‐intensity rainstorms are more erosive, resulting in greater cliff retreat distances relative to longer, low‐intensity storms. Temporal alternation between rainstorm regimes produces hillslope profiles similar to those previously attributed to Quaternary oscillations in the mean climate. We suggest that arid hillslopes may undergo considerable geomorphic transitions solely by alternating intra‐storm patterns regardless of rainfall amounts.

Flood Protection of the Non-Urban Area

Due to global warming, the risk of floods is constantly increasing due to the drying up of the soil, followed by more intense rain showers and storms. Therefore, it is essential to pay more attention to this topic now. The article deals with the design of flood protection in the municipality. A flood control measure is proposed for each type of slope of the soil relief in which the municipality is located. Based on the proposed measures, the article aims to minimize the level of flood risk to the lowest possible level with the use of flood protection aimed at the non-urban area of the municipality. The proposed measures are intended not only for smaller municipalities but also for cities.

An Integrated Geophysical and Unmanned Aerial Systems Surveys for Multi-Sensory, Multi-Scale and Multi-Resolution Cave Detection: The Gravaglione Site (Canale di Pirro Polje, Apulia)

Gravaglione represents one of the main swallow holes of the Canale di Pirro, low Murge, Apulia region, Italy. Here, after an intense rainstorm, a huge volume of rainwater accumulates at the surface. The drainage dynamics suggest that the Gravaglione could be part of a large, and potentially unknown, karst system. To verify this hypothesis and to acquire useful information on the possible karst environment features, an integrated aerial and geophysical multiscale and multimethod approach was applied. In particular, aerial photogrammetry, ground penetrating radar measurements and electrical resistivity tomography surveys were hence conducted and integrated to potentially detect the caves, define the subsurface volume possibly affected by karst systems and to verify the existence of links between the surficial morphology and the subsoil structure. The results provided interesting insights regarding the presence of a complex karst system extending up to 200 m b.g.l. and with a marked 3D nature. Overall, the Gravaglione case study demonstrates the geophysical approach validity and poses the basis for the development of an expeditive and low-cost high-resolution strategy for detecting and characterizing karst caves.

Assessments of Use of Blended Radar–Numerical Weather Prediction Product in Short-Range Warning of Intense Rainstorms in Localized Systems (SWIRLS) for Quantitative Precipitation Forecast of Tropical Cyclone Landfall on Vietnam’s Coast

This research presents a blended system implemented by the Vietnam National Center for Hydro-Meteorological Forecasting to enhance the nowcasting and forecasting services of quantitative precipitation forecasts (QPFs) of tropical cyclone (TC) landfalls on Vietnam’s coast. Firstly, the extrapolations of rain/convective systems from multiple radars in Vietnam in ranges up to 6 h were carried out using Short-Range Warning of Intense Rainstorms in Localized Systems (SWIRLS) developed by the Hong Kong Observatory. Secondly, the forecast from the numerical weather prediction (NWP) system, based on the WRF-ARW model running at 3 km horizontal resolution, was blended with radar-based quantitative precipitation estimates and nowcasts of SWIRLS. The analysis showed that the application of the nowcast system to TC-related cloud forms is complicated, which is related to the TC’s evolution and the different types and multiple layers of storm clouds that can affect the accuracy of the derived motion fields in nowcast systems. With hourly accumulated rainfall observation, skill score validation conducted for several TCs that landed in the center of Vietnam demonstrated that the blending of nowcasting and NWP improve the quality of the QPFs of TCs in forecast ranges up to 3 h compared to the pure NWP forecasts.

Climate-smart forestry in the world’s drylands: A review of challenges and opportunities

Land degradation and desertification are widespread across the world’s drylands. These processes are substantially affected by climatic change, with long-term and severe droughts on the one hand, and high intensity rainstorms and devastating floods on the other hand. Simultaneously, land-use change and mismanagement practices have led to processes of accelerated soil erosion, depletion of soil organic carbon pools, and the degradation of extensive drylands. Forestry has been accepted as an effective means for restoring degraded drylands, and for attaining a range of regulating, provisioning, supporting, and cultural ecosystem services. Specifically, forestry is widely perceived as an effective means for soil erosion control, organic carbon sequestration, microclimate improvement, and climate change mitigation. However, forestry in drylands often proves to generate substantial environmental challenges, resulting in deterioration of ecosystem functions and health. The objective of this essay is to review the challenges and opportunities induced by dryland afforestation and reforestation, and highlight the need to attain climate-smart strategies for establishing and managing these land-uses. Particularly, tree species invasion and allelopathy, which are common in dryland forestry projects, jeopardize species richness and diversity of native vegetation communities. Further, the challenges linked with tree invasiveness necessitate predicting the distribution of potentially invasive species and foreseeing their impacts on the recipient ecosystems under projected climate change scenarios. The effect of allelopathy is significant under limited water availability conditions and is expected to be determined by the expanding drylands and intensifying aridity worldwide. Therefore, judicious selection of tree species should not only focus on ones with high water-use efficiency, low flammability, high pest resistance, and fast growth, but also on low invasiveness and allelopathic capacities. Insights of this essay may be used by land managers, stakeholders, and policy makers involved in environmental development of drylands.

Assessing the controlling factors on watershed soil erosion during intense rainstorm events using radar rainfall and process-based modeling

The evaluation of erosion risk in dry areas is challenging because erosion is often an outcome of individual rainstorms and is highly dependent on rainfall spatiotemporal patterns and on local land-use and topography. This study integrates a hybrid erosion model with rainfall data from high-resolution weather radar to simulate soil erosion during 22 high-intensity flash-flood generating rainstorms in a Mediterranean watershed (69 km2). We examine erosion over individual hillslopes and their spatial average over the watershed, representing intra-watershed and watershed-scale erosion, respectively. Our objectives are to: (a) determine how intra-watershed erosion corresponds to various physiographic factors (rainfall, land-use, topography); (b) determine which of these factors contributes to intra-watershed erosion the most; (c) quantify the effect of temporal variations in rainfall intensities on storm-scale erosion in relation to land-use type. We use for the first time a hybrid erosion model (K2-RHEM-DWEPP) based on the watershed-scale KINEROS2 model, that integrates the hillslope-scale Dynamic WEPP (DWEPP) and RHEM models, which were individually developed to represent erosion processes in croplands and rangelands, respectively. Watershed-scale storm erosion is best correlated with spatially-averaged 10-minutes maximum intensities (R2 = 0.58), and the correlation decreases for longer durations (R2 ≤ 0.54). When the spatially-averaged 10-minutes maximum intensity is multiplied by the area that contributes sediment, a better correlation with watershed-scale erosion is observed (R2 = 0.75). Hillslope erosion rates are higher when both rainfall intensities and topographic slopes are high, while land-use has a second-order effect. Higher storms maximal intensities result in higher hillslope erosion rates, especially over croplands.Our conclusions are useful to target locations for conservation practices and to better understand the effects of climate change on soil erosion.

Synergistic Effect of the Planetary-scale Disturbance, Typhoon and Meso-β-scale Convective Vortex on the Extremely Intense Rainstorm on 20 July 2021 in Zhengzhou

Synergistic Effect of the Planetary-scale Disturbance, Typhoon and Meso-β-scale Convective Vortex on the Extremely Intense Rainstorm on 20 July 2021 in Zhengzhou

Increasing areas of aquaculture ponds and reservoirs reshape runoff coefficients: evidence from a subtropical catchment, China.

Detention pond is a key storm water management measure employed both to attenuate surface runoff and to regulate depression storage, yet the effects of aquaculture ponds and reservoirs on runoff coefficient are not well quantified in a subtropical humid monsoon climate zone, China. Here, a set of six subcatchments ranging in size from 0.7 hm2 to 10,000 hm2 were evaluated over the 2011-2015 period. (i) The annual average runoff coefficient differed with different subcatchments due to the spatial heterogeneity of landscape patterns, while the event-based runoff coefficient under the same catchment showed a decreasing trend with increasing rainfall intensity. (ii) The annual average and event-based runoff coefficients initially increased and then decreased with an increase in the area ratio of aquaculture ponds and reservoirs. The critical area ratio of aquaculture ponds and reservoirs for the maximum runoff coefficient in annual, light, and moderate rainfall intensity was about 4%; but this value would be transferred forward to the position of < 4% under the intensity of heavy rain, rainstorms, and heavy rainstorms. (iii) All runoff coefficients decreased with increasing forestland but increased with increasing paddy fields, and the decreasing rate was greater than the increasing rate. The trends of runoff coefficient for the annual and event-based rainfall are opposite between river development coefficient and watershed shape coefficient. The results provide underlying insights for decision-makers in aquaculture land-use planning and the sustainable utilization of water resources in the upstream and downstream systems of a catchment.

Objective definition of discharge thresholds for post-fire debris flows

Runoff-generated debris flows are a common post-fire hazard in the western United States and a growing number of regions around the world. As wildfire continues to emerge across a broader range of geographic regions and plant communities, there is an increasing need for generalizable methods to predict post-fire debris-flow initiation. The prediction of post-fire debris flow during intense rainstorms has traditionally relied upon empirical rainfall thresholds. Rainfall intensity-duration thresholds are often developed based on rainfall data and the hydrologic response to those rainstorms. They are most applicable to the specific regions where data are collected. Here, we present a new predictive approach that utilises processes-based models with fundamental physics and machine learning methods to estimate discharge thresholds for runoff-generated debris-flow initiation in four recently burned areas in the western United States. We assess the performance of the objectively defined discharge threshold-based predictions for post-fire debris-flow initiation from our hybrid framework, which utilises debris-flow timing within rainstorms, physically based numerical simulations of runoff, and the support vector machines method. The proposed thresholds have a good balance between true and false predictions for debris flow and floods. Importantly, our method permits the direct estimation of rainfall intensity-duration thresholds for areas where post-fire debris flow observations are limited.

Characteristics of Rainstorm Intensity and Its Future Risk Estimation in the Upstream of Yellow River Basin

Under the background of climate warming, the occurrence of extreme events upstream of the Yellow River Basin has increased significantly. Extreme precipitation tends to be even more intense, and occurs more frequently. The impacts of various extreme weather and climate events in the basin have become increasingly complex, which is increasingly difficult to cope with and affects the basin’s long-term stability and ecological security. Based on the daily precipitation data of 33 meteorological stations in the upper reaches of the Yellow River Basin from 1961 to 2021, this paper analyzes the characteristics of rainstorm intensity. Moreover, combined with the simulation results of 10 global climate models of the Coupled Model Intercomparison Project (CMIP6) and the social and economic prediction data from SSPs, it analyzes the possible changes of rainstorm disaster risk in the upper reaches of the Yellow River Basin in the 21st century, under the three emission scenarios of SSP126, SSP245, and SSP370. The results show that the precipitation in the upstream area of the Yellow River Basin is increasing at a rate of 8.1 mm per 10 years, and the number of rainstorm processes and their indicators is increasing, which indicates an increase in the extremeness of precipitation; the rainstorm process intensity index shows an increasing trend, especially in the northeast region with a concentrated population and economy, where the rainstorm process intensity index is high; it is estimated that the number of rainstorm days in low-, medium-, and high-risk scenarios will increase, which leads to an increase in the social risk by at least 60% by around 2050 (2036–2065); with the increasing disaster risk, the population exposure to rainstorm disasters is also on the rise. If no measures are taken, the population exposure will increase to 7.316 million people per day by around 2050, increasing by more than double, especially in the northeast. This study shows that, with the increasing rainstorm disaster risk and population exposure in the upper reaches of the Yellow River Basin, relevant measures need to be taken to ensure the safety of people’s lives and property.

Assessment of shelter location-allocation for multi-hazard emergency evacuation

Intense rainstorms often trigger multiple disasters in mountain regions, such as floods and landslides. In disaster planning, the local administration allocates nearby schools or open fields as emergency evacuation shelters. However, access to these shelters is often cut off for certain population clusters during disaster impact on routes. We develop a framework for selecting emergency evacuation shelter locations for multi-disaster impact planning (floods and landslides). The framework consists of two parts. Firstly, we develop susceptibility maps of individual hazards using Random Forest algorithm and Google earth engine. Secondly, we assess the shelter's location-allocation by implementing two models in GIS: P-median and maximal covering location problem. Our framework treats existing schools as evacuation shelters and individual households as demand points in an emergency. The P-median method finds the shelter locations by minimizing maximum distances between the households. The maximal covering location problem method evaluates the coverage of households by the facilities of the evacuation shelters within an impedance cutoff. We tested our work in a mountainous village in the Western Ghat region, India, by recreating the 2005 rainstorm disaster that caused more than 190 fatalities and damaged 400 households. The result shows that existing shelters are insufficient to provide services to all households within 30 min and 60 min. This methodology helps develop simultaneous-hazard impact plans by local administration units in mountain regions to ensure emergency facilities' safe operation.

Study on preparation and characterization of a functional porous ultra-thin friction course (PUFC) with recycled steel slag as aggregate

The research aims at the preparation and characterization of a functional porous ultra-thin friction course (PUFC) with recycled steel slag as aggregate. At first, the PUFC was designed by modified Bailey method and Particle interference theory, and selected through the Technique for Order Preference by Similarity to an Ideal Solution (TOPSIS) method with index of weight. Then the resistance to dynamic water damage of PUFC was characterized byMoisture Induced Sensitivity Tester (MIST). Meanwhile, the SWMM software was used to simulate drainage performance of PUFC under different rainstorm intensities in Wuhan. Finally, the induction heating efficiency, self-healing property and snow and ice melting property of PUFC with steel wool fibers were investigated. The results demonstrate the PUFC gradation with pores ratio of 21.2% presents the best durability performance. The factors of cycles, temperature, and pressure during the dynamic water damage processing will conduct the weaken impact on the mechanics of PUFC, particularly the temperature. It is also found that the PUFC has the capacity to reduce the runoff, but there is a limitation to this reduction which is 10a of the return period. Furthermore, PUFC with steel wool fibers can be inductively heated, which helps to heal the cracks inside PUFC meanwhile also melt the ice and snow on the surface. Thus, the PUFC can be effectively prepared and its performance of self-healing, drainage, and snow and ice melting contribute its applicability in sponge city engineering.

Water-Vapour Monitoring from Ground-Based GNSS Observations in Northwestern Argentina

The Central Andes in northwestern Argentina are characterized by steep topographic and climatic gradients. The humid foreland areas at 1 km asl elevation rapidly rise to over 5 km in the eastern Cordillera, and they form an orographic rainfall barrier on the eastern windward side. This topographic setting combined with seasonal moisture transport through the South American monsoon system leads to intense rainstorms with cascading effects such as landsliding and flooding. In order to better quantify the dynamics of water vapour transport, we use high-temporal-resolution global navigation satellite system (GNSS) remote sensing techniques. We are particularly interested in better understanding the dynamics of high-magnitude storms with high water vapour amounts that have destructive effects on human infrastructure. We used an existing GNSS station network with 12 years of time series data, and we installed two new ground stations along the climatic gradient and collected GNSS time series data for three years. For several stations we calculated the GNSS signal delay gradient to determine water vapour transport direction. Our statistical analysis combines in situ rainfall measurements and ERA5 reanalysis data to reveal the water vapour transport mechanism for the study area. The results show a strong relationship between altitude and the water vapour content, as well as between the transportation pathways and the topography.

Monitoring of Post-Fire Bedload Transport Using Hydrophone in a Small Burnt Catchment, South Korea

Understanding the properties of wildfire-disrupted catchments is crucial for managing river floods and landslide risks. Using a hydrophone, we investigated the changes in sediment supply conditions in small mountainous catchments (30.8 ha) in southern Korea for 6 years (March 2014–December 2019). Bedload transport rates mostly increased in burned catchments 1–2 years post-wildfire (early post-fire sediment regime) but decreased 3 years post-wildfire owing to the coverage of burned slopes (late post-fire sediment regime). Landslides triggered 5 years post-wildfire increased the bedload transport rates by approximately one order of magnitude (post-landslide sediment regime). Although sediment activity decreased in wildfire-disturbed catchments after recovery of the ground-cover layer 1–3 years post-fire, thy increased during events such as landslides. Furthermore, even in undisturbed mountainous catchments (139.7 ha), bedload transport rates increased after intense rainstorm events (≥100.0 mm), with this change lasting for approximately 2 years. Our observations showed that the forest restoration after a wildfire should be planned and implemented from a min- to long-term perspective. In addition, during rainstorms, the relationship between flow and bedload transport showed large variability even in undisturbed catchments. Furthermore, surrogate monitoring using a hydrophone was useful in understanding the changes in bedload transport characteristics according to various supply conditions of the catchment.

Real-time urban rainstorm and waterlogging disaster detection by Weibo users

Abstract. With the process of urbanization in China, the urban waterlogging caused by rainstorms occurs frequently and often leads to serious damage to the natural environment, human life, and the city economy. Rapid detection of rainstorm and urban waterlogging disasters is an essential step to minimize these losses. Weibo, a popular microblog service in China, can provide many real-time Weibo posts for rapid detection. In this paper, we propose a method to identify microblogs with rainstorm and waterlogging information and apply them to waterlogging risk assessment. After pre-processing the microblog texts, we evaluate the performance of clustering (k-means) and classification (support vector machine, SVM) algorithms in the classification task. Apart from word vector features, we also introduce sentiment and publisher features for more real-time and accurate results. Furthermore, we build a waterlogging intensity dictionary to assess the waterlogging risk from the Weibo texts and produce a risk map with ArcGIS. To examine the efficacy of this approach, we collect Weibo data from two rainstorms and waterlogging disasters in Beijing city as examples. The results indicate that the SVM algorithm can be applied for a real-time rainstorm and waterlogging information detection. Compared to official-authentication and personal-certification users, the microblogs posted by general users can better indicate the intensity and timing of rainstorms. The location of waterlogging points is consistent with the risk assessment results, which proves our proposed risk assessment method can be used as a reference for timely emergency response.