Impact of Flash Flood Events on the Coastal Waters Around Madeira Island: The “Land Mass Effect”

The Island Mass Effect has been primarily attributed to nutrient enhancement of waters surrounding oceanic islands due to physical processes, whereas the role of land runoff has seldom been considered. Land runoff can be particularly relevant in mountainous islands, highly susceptible to torrential rainfall that rapidly leads to flash floods. Madeira Island, located in the Northeast Atlantic Ocean, is historically known for its flash flood events, when steep streams transport high volumes of water and terrigenous material downstream. A 22-year analysis of satellite data revealed that a recent catastrophic flash flood (20 February 2010) was responsible for the most significant concentration of non-algal Suspended Particulate Matter (SPM) and Chlorophyll-a at the coast. In this context, our study aims to understand the impact of the February 2010 flash flood events on coastal waters, by assessing the impact of spatial and temporal variability of wind, precipitation, and river discharges. Two specific flash floods events are investigated in detail (2 and 20 February 2010), which coincided with northeasterly and southwesterly winds, respectively. Given the lack of in situ data documenting these events, a coupled air-sea-land numerical framework was used, including hydrological modeling. The dynamics of the modeled river plumes induced by flash floods were strongly influenced by the wind regimes subsequently affecting coastal circulation, which may help to explain the differences between observed SPM and Chlorophyll-a distributions. Model simulations showed that during northeasterly winds, coastal confinement of the buoyant river plume persisted on the island’s north coast, preventing offshore transport of SPM. This mechanism may have contributed to favorable conditions for phytoplankton growth, as captured by satellite-derived Chlorophyll-a in the northeastern coastal waters. On the island’s south coast, strong ocean currents generated in the eastern island flank promoted strong vertical shear, contributing to vertical mixing. During southwesterly winds, coastal confinement of the plume with strong vertical density gradient was observed on the south side. The switch to eastward winds spread the south river plume offshore, forming a filament of high Chlorophyll-a extending 70 km offshore. Our framework demonstrates a novel methodology to investigate ocean productivity around remote islands with sparse or absent field observations.

The floods in north India in 1988- Forecasting aspects

Severe floods/flash floods ravaged the States of Jammu& Kashmir, Haryana, Himachal Pradesh and Punjab during, (i) 2nd half of July and last half of August 1988. and (ii) 4th week of September 1988. They took place when heavy rains occurred in these States due to the interaction of mid-latitude westerly troughs with the monsoon pulses In the form of equatorial zones of maximum cloudiness (EZMC), located south of 20 N. Satellite pictures and synoptic charts suggest that: (a) The systems which formed in July-August 1988 were fed by moisture mainly from the Arabian Sea and had tropical characteristic, and (b) The systems which formed in SejJtember.198.8 had their moisture supply both from the Arabian Sea and the Bay of Bengal and were extra-tropical in character.. The paper describes two of these events in detail. The satellite picture3 show cloud formation resulting in heavy rains.

Study on the Uncertainty of Critical Rainfall for Flash Floods in Small Watersheds Based on the Random Rainfall Pattern

Flash floods cause great harm to people's lives and property safety. Rainfall is the key factor which induces flash floods, and critical rainfall (CR) is the most widely used indicator in flash flood early warning systems. Due to the randomness of rainfall, the CR has great uncertainty, which causes missed alarms when predicting flash floods. To improve the early warning accuracy for flash floods, a random rainfall pattern (RRP) generation method based on control parameters, including the comprehensive peak position coefficient (CPPC) and comprehensive peak ratio (CPR), is proposed and an early warning model with dynamic correction based on RRP identification is established. The rainfall-runoff process is simulated by the HEC-HMS hydrological model, and the CR threshold space corresponding to the RRP set is calculated based on the trial algorithm. Xinxian, a small watershed located in Henan Province, China, is taken as the case study. The results show that the method for generating the RRP is practical and simple, and it effectively reflects the CR uncertainty caused by the rainfall pattern uncertainty. The HEC-HMS model is proved to have good application performance in the Xinxian watershed. Through sensitivity analysis, the effect of the antecedent soil moisture condition, CPPC, and CPR are compared. The proposed early warning model is practical and effective, which increases the forecast lead time.

More frequent flash flood events and extreme precipitation favouring atmospheric conditions in temperate regions of Europe

In recent years, flash floods repeatedly occurred in temperate regions of central western Europe. Unlike in Mediterranean catchments, this flooding behaviour is unusual. In the past, and especially in the 1990s, floods were characterized by predictable, slowly rising water levels during winter and driven by westerly atmospheric fluxes (Pfister et al., 2004). The intention of this study is to link the recent occurrence of flash floods in central western Europe to extreme precipitation and specific atmospheric conditions to identify the cause for this apparent shift. Therefore, we hypothesise that an increase in extreme precipitation events has subsequently led to an increase in the occurrence of flash flood events in central western Europe and all that being caused by a change in the occurrence of flash flood favouring atmospheric conditions. To test this hypothesis, we compiled data on flash floods in central western Europe and selected precipitation events above 40 mm h−1 from radar data (RADOLAN, DWD). Moreover, we identified proxy parameters representative for flash flood favouring atmospheric conditions from the ERA5 reanalysis dataset. High specific humidity in the lower troposphere (q ≥ 0.004 kg kg−1), sufficient latent instability (CAPE ≥ 100 J kg−1) and weak deep-layer wind shear (DLS ≤ 10 m s−1) proved to be characteristic for long-lasting intense rainfall that can potentially trigger flash floods. These atmospheric parameters, as well as the flash flood and precipitation events were then analysed using linear models. Thereby we found significant increases in atmospheric moisture contents and increases in atmospheric instability. Parameters representing the motion and organisation of convective systems occurred slightly more often or remained unchanged in the time period from 1981–2020. Moreover, a trend in the occurrence of flash floods was confirmed. The number of precipitation events, their maximum 5-minute intensities as well as their hourly sums were however characterized by large inter-annual variations and no trends could be identified between 2002–2020. This study therefore shows that the link from atmospheric conditions via precipitation to flash floods cannot be traced down in an isolated way. The complexity of interactions is likely higher and future analyses should include other potentially relevant factors such as intra-annual precipitation patterns or catchment specific parameters.

Áreas de conexão verde e conexão fundo de vale: uma proposta para redução dos impactos de enchentes em Belo Horizonte, Minas Gerais

O presente artigo trata do saneamento pluvial de Belo Horizonte. Na capital de Minas Gerais as enchentes se repetem ano a ano, gerando prejuízos econômicos e perda de vidas. Considerando esse grave problema, foi realizada uma análise de geoprocessamento multicritério. O objetivo é apresentar um mapa de áreas prioritárias para implementação das áreas de Conexão Verde e da Conexão Fundo de Vale – estratégias do novo Plano Diretor da cidade para minimizar a ocorrências das flash floods e seus impactos negativos. Os resultados apontam para os locais onde há maior incidência de áreas de risco de inundações e a relação desses lugares com aspectos ambientais e de cunho social. Conclui-se, por meio do mapa elaborado, que as áreas a serem priorizadas coincidem com as regiões onde os níveis de IDH e a renda salarial estão entre os mais baixos do Município.

Spatial–temporal characteristics and driving factors of flash floods in Shaanxi Province considering regional differentiation

Flash floods show strong regional differentiation in spatial–temporal distribution and driving forces, thereby hindering their effective prevention and control. This study analyzed the spatiotemporal characteristics of flash floods in Shaanxi Province, China, differentiated among the northern Shaanxi (NS), Guanzhong (GZ), and southern Shaanxi (SS) regions based on the Mann–Kendall, Theil–Sen Median, and standard deviation ellipse methods. The main factors driving disasters and their interactions in each region were then identified within the three categories of precipitation factor (PPF), surface environment factor, and human activity factor (HAF) based on a geographical detector. Finally, the differences in flash flood characteristics among the NS, GZ, and SS regions were analyzed. The results showed that flash floods in Shaanxi Province are greatly affected by the PPF and the HAF, although the spatial–temporal characteristics and disaster-causing factors were significantly different in each region. The regions were ranked according to the number and growth trends of flash floods as follows: SS > GZ > NS. Furthermore, flash floods were affected by multiple factors, with the interaction between factors acting as a driving force of flash floods. The results of this study can provide a reference for the management of flash floods under regional differentiation.

Dampak Trauma Healing Terhadap Pertumbuhan Spiritualitas SMGT Jem. Rama Radda Pasca Bencana Banjir Bandang

The study in this journal aims to provide entertainment and support in the form of psychic so that it can reduce the traumatic feeling experienced after the banjir bandang disaster. This trauma healing activity is very much needed and has a very important meaning for the Toraja Church Sunday School (SMGT) Children in the Rama Radda Congregation. For this reason, it is necessary for the Church's efforts to provide assistance in repairing infrastructure that has been damaged by flash floods, especially in handling the trauma experienced by Sunday school children, especially in their spiritual growth, because after all Sunday school children are the next generation of the church. , these children must be able to rise again from the trauma they experienced and be able to resume their lives with faith, hope and make their loved ones proud who died as a result of the flash flood.

An Investigation into Emergency Planning Requirements and Challenges of Disaster Management in the Kingdom of Saudi Arabia

Every year, the Kingdom of Saudi Arabia (KSA) is exposed to different natural hazards. However, flash floods have been the most common hazard during the previous few decades. Between 2000 and 2020, over 1,000 people lost their lives from flash floods, resulting in an economic loss amounting to billions of US dollars. By focusing on flash floods, a systematic review of the extracted data was conducted. They were analyzed based on the suitability of their content and data for emergency planning requirements and disaster management challenges in the KSA. A total of 104 articles, papers, and plans were reviewed, of which only 18 complete papers met the inclusion criteria, including one plan and the General Directorate of Civil Defense (GDCD) website. The author has concluded that: 1) the essential requirements for emergency planning in the KSA include: conducting studies that show potential natural hazards, their locations, and their implications, and taking appropriate measures that reduce the possible causes of natural hazards; 2) The challenges facing the disaster management in the KSA are: lack of policies; the ambiguity of legislation and plans; poor coordination between stakeholders; lack of databases. This is the first investigation into emergency planning requirements and challenges of disaster management in the KSA. Furthermore, a scientific consensus predicts an increase in the frequency and magnitude of flash floods in the KSA. Therefore, the gaps need to be addressed in order to reduce the impact on inhabitants and infrastructure.