scholarly journals Hydro-meteorological preconditions and geomorphological consequences of extreme flood in the small river basin in the wet subtropical zone (the Tsanyk River case study, Sochi region)

Author(s):  
Anatoly S. Tsyplenkov ◽  
◽  
Nadezhda N. Ivanova ◽  
Dmitry V. Botavin ◽  
Yulia S. Kuznetsova ◽  
...  

The overall increase in precipitation and the frequency of extreme rainfall is confirmed by several meteorological observations both on the Black Sea coast of the Caucasus. In this context, research on the drivers of an extreme meteorological event becoming a severe flood and an extreme geomorphological (erosion) event becomes especially important. The article analyses the factors contributing to the development of a flash flood on the watershed of the river Tsanyk (Great Sochi area) and estimates its geomorphological impact. Analysis of hydrologic-meteorological situation during the Tsanyk flood on 7-9 September 2018 and in the previous period showed that the event is unique for the investigated watershed from the hydrologic perspective. After a prolonged period without precipitation, the rainfall on 7-8 September resulted in a flash flood with a rapid water level rise (117 cm in 40 min). We determined the rates and volumes of channel erosion based on a repeated survey of the channel section, estimation of the speed and length of the banks being flushed out, composed of loose sediments and bedrock using the pin method. The amount of erosion on the banks composed of loosened sediments is on average 2-3 times higher than on the flysch banks. At the same time, the material export for one erosion event in September 2018 is comparable (or even exceeds) the total amount of bank erosion for the year, previously identified based on stationary observations.

Author(s):  
L. S. Lebedeva ◽  
O. M. Semenova ◽  
T. A. Vinogradova ◽  
M. N. Kruchin ◽  
N. V. Volkova

Abstract. The probability of heavy rains and river floods is expected to increase with time in the Northern Caucasus region. Densely populated areas in the valleys of small mountainous watersheds already frequently suffer from catastrophic peak floods caused by intense rains at higher elevations. This study aimed at assessing the flood characteristics of several small basins in the piedmont area of the Caucasus Mountains adjacent to the Black Sea coast including ungauged Cemes River in the Novorossiysk city. The Deterministic-Stochastic Modelling System which consists of hydrological model Hydrograph and stochastic weather generator was applied to evaluate extreme rainfall and runoff characteristics of 1% exceedance probability. Rainfall intensity is shown to play more significant role than its depth in formation of extreme flows within the studied region.


2020 ◽  
Author(s):  
Anatolii Anisimov ◽  
Vladimir Efimov ◽  
Margarita Lvova ◽  
Viktor Popov ◽  
Suleiman Mostamandi

<p>We present a case study on extreme rainfall event in Crimea in September 2018. The event was caused by extratropical cyclone forming above the Black Sea. The cyclone approached the Crimean Mountains from the south, producing over 100 mm of rainfall in Yalta on September 6 and causing a flash flood. In the mountains, about 140 mm of rainfall was reported. </p><p>To study this extreme event, we use the WRF model v.4.0.1 forced by the boundary conditions from ECMWF operational analysis with the spatial resolution of approximately 10 × 10 km. The model was run for 8 days of September 1 – 8, and 5 microphysical schemes were tested (WDM6, Morrison, Milbrandt, NSSL, and Thompson). Other model parameters were set identical to CONUS configuration suite. The simulations were done for two one-way nested convective-resolving domains with spatial resolution of 2.7× 2.7 km and 0.9 × 0.9 km. The simulations were verified using the meteorological radar observations in Simferopol airport and GPM measurements.</p><p>All of the microphysical schemes substantially underestimate the amount of rainfall reaching the ground compared to observations. However, several schemes (Milbrandt, Morrison, and WDM6) do add value to the forecasts, producing significantly larger amount of rainfall compared to the driving model that almost completely missed it on the local scale. WDM6 performs best to capture the proper location of the squall line and to reproduce the rainfall orographic enhancement in the mountains. The amount of rainfall in the child domain was also slightly larger compared to the parent one. Despite the rainfall underestimation, we also show that the simulated reflectivity patterns are in good agreement with observations, although the convective cores are wider and less intense compared to the observed by the radar.</p>


1970 ◽  
Vol 6 (1) ◽  
pp. 44-48 ◽  
Author(s):  
Suresh Marahatta ◽  
Jagat Kumar Bhusal

Flash floods, debris flows and landslide disaster on the steep sloping terraces of hilly region are so challenging that even a real time hydro-meteorological forecasting system would not be applicable for all cases in Nepal. Flash floods are localized in short ranges with respect to time and distance; and it is very difficult to measure these flash floods in time. On the other hand, such phenomena need to be assessed for sustainable design of hydro- structures and for relocating the settlements from risk areas. A study was carried out to find the suitable relationship between area and extreme flood as well as area and extreme rainfall depth. Analysis is mainly based on the case of torrential rains in July 1993 over south central Nepal, which caused floods and debris torrents those were probably the worst in the disaster history of Nepal damaging lives and properties in Nepal during the 20th century. A relation for rainfall depth and other relation for specific flood are presented in this paper.Keywords: South-central Nepal; specific discharge; rainfall intensity; depth area duration.DOI: http://dx.doi.org/10.3126/jhm.v6i1.5487Journal of Hydrology and Meteorology, Vol. 6, No. 1 44-48


2014 ◽  
Vol 142 (1) ◽  
pp. 222-239 ◽  
Author(s):  
Samantha L. Lynch ◽  
Russ S. Schumacher

Abstract From 1 to 3 May 2010, persistent heavy rainfall occurred in the Ohio and Mississippi River valleys due to two successive quasi-stationary mesoscale convective systems (MCSs), with locations in central Tennessee accumulating more than 483 mm of rain, and the city of Nashville experiencing a historic flash flood. This study uses operational global ensemble forecasts from the European Centre for Medium-Range Weather Forecasts (ECMWF) to diagnose atmospheric processes and assess forecast uncertainty in this event. Several ensemble analysis methods are used to examine the processes that led to the development and maintenance of this precipitation system. Differences between ensemble members that correctly predicted heavy precipitation and those that did not were determined, in order to pinpoint the processes that were favorable or detrimental to the system's development. Statistical analysis was used to determine how synoptic-scale flows were correlated to 5-day area-averaged precipitation. The precipitation throughout Nashville and the surrounding areas occurred ahead of an upper-level trough located over the central United States. The distribution of precipitation was found to be closely related to the strength of this trough and an associated surface cyclone. In particular, when the upper-level trough was elongated, the surface cyclone remained weaker with a narrower low-level jet from the south. This caused the plume of moisture from the Caribbean Sea to be concentrated over Tennessee and Kentucky, where, in conjunction with focused ascent, heavy rain fell. Relatively small differences in the wind and pressure fields led to important differences in the precipitation forecasts and highlighted some of the uncertainties associated with predicting this extreme rainfall event.


2020 ◽  
Author(s):  
Libor Elleder ◽  
Ladislav Kašpárek ◽  
Jakub Krejčí ◽  
Jolana Šírová ◽  
Stanislav Racko

<p>According to the present knowledge, the second half of the 19<sup>th</sup> century meant the end of the Little Ice Age and gradual warming.  This is, however, undoubtedly a fairly simplified statement.  Our contribution presents the period of 1858–1878: (1) from the point of view of drought but also (2) regarding frequency of floods. The aggregation for this period of weather-driven risks such as droughts, floods, strong winds and high tides, is worth attention.  The length of the drought period of 1858–1878, the absolute value of rainfall deficits and the length of seasonal droughts, as well as their impacts, are a certain warning in terms of our present.</p><p>Surprisingly, in such a dry period we witness an accumulation of important and extreme flood episodes as well. The regional catastrophic floods of 1858, and winter extensive floods of 1862 and 1876, may serve as excellent examples.  Furthermore, the Elbe catchment recorded floods with return periods of 10–20 years in 1860, 1865 and 1872. For this period, an occurrence of intensive mesoscale flash flood events with extreme hydrological parameters, high number of fatalities and large damages are of the utmost importance (e.g. 1868-Switzerland, 1872-Czechlands, 1874- Catalonia, 1875-South France). Our contribution builds on earlier analysed flood events of 1872, 1875 and drought period presented at EGU earlier. The contribution stresses the analogies and differences with present situation in 2014–2019.  We mainly address the situation in Czech lands, Central Europe interpreted in wider European context.</p>


Author(s):  
N. A. Konnov ◽  
N. N. Karpun ◽  
A. V. Kelina

The lawn coverings creation in the humid subtropics zone of Russia is one of the topical areas of ornamental horticulture. This is due to the high requirements for year-round decorative plantings, the peculiarities of natural and climatic conditions and the general lack of issue knowledge. This direction is of particular importance in plantations located in shaded areas under the canopy of tree crowns, where, in addition to common for the region unfavourable factors of the hydrothermal regime, insufficient illumination is added, which together limits the possibility of traditional cereal grasses cultivating. Evergreen grass-like ground cover plants can be a complete substitute for lawn grasses in shaded areas. The aim of the research was to determine the degree of drought resistance of Liriope graminifolia (L.) Baker and Ophiopogon japonicus (Thunb.) Ker Gawl. and the ability to maintain decorativeness during the period of unfavourable hydrothermal conditions in the summer in the humid subtropics of Russia. The studies were carried out in 2013-2018 on the Black Sea coast of the Caucasus in the Sochi region, in plantations (on test plots with an area of 5-10 m2) and in conditions of vegetation experiments (in containers with a volume of 2 liters) on the territory of the Kuban Subtropical Botanical Garden (settlement Uch-Dere), according to generally accepted methods adapted to the studied taxa. It was found that an important mechanism of adaptation of the studied plants to drought is the ability to accumulate and redistribute moisture between vegetative organs, providing a high water content in the leaves. The decorativeness of O. japonicus and L. graminifolia in open ground in the atmospheric moisture absence lasts up to 12-14 days, in a vegetation experiment (container culture) – up to 14-16 days. O. japonicus and L. graminifolia retained the ability to self-regenerate up to 35-37 days of the experiment, and then the plants died. The consequences of summer drought in the studied plants were compensated by active autumn growth. Unlike classic lawns, which require daily watering, lawns from O. japonicus and L. graminifolia should be irrigated with a long (more than 12-14 days) absence of precipitation in the summer months.


Author(s):  
Н.Н. Карпун

Влажные субтропики Черноморского побережья России являются региономреципиентом для большого количества инвазионных видов вредных организмов. В начале XXI в. в зоне влажных субтропиков России выявлены 35 новых видов дендрофильных насекомых, из которых 26 можно отнести к инвазионным: из них 17 видов новые для территории России, а 9 новые для субтропической зоны Черноморского побережья Кавказа. Особенности инвазионного процесса у фитофагов изучались на основе анализа таксономического состава, регионовдоноров, векторов и путей инвазии, биотопического распределения видов и динамики инвазий. За период 2000 2017 гг. в общем количестве появившихся инвазионных видов отмечено снижение доли представителей отряда Hemiptera и увеличение доли представителей отряда Lepidoptera. В последние годы наибольшее количество инвазионных видов вредителей имеет североамериканское, а не восточноазиатское происхождение, что было характерно для региона на протяжении предыдущих полутора столетий. Установлены векторы инвазии для новых видов: непреднамеренный завоз с посадочным материалом, проникновение с транспортными потоками, непреднамеренный завоз с грузами нерастительного происхождения, самостоятельные перелеты. Все инвазионные виды восточноазиатского, американского и австралийского происхождения характеризуются двухступенчатой инвазией, т. е. они проникали в Россию из вторичного ареала в Европе. Максимальное количество чужеродных видов обосновалось в насаждениях декоративных пород (садовопарковые экосистемы), причем эта тенденция традиционна для региона. Частота появления инвазионных видов на Черноморском побережье Кавказа в начале XXI в. 1 вид в 9 месяцев, что в 7,4 раза чаще, чем в начале XX в. Humid subtropics of the Russian Black Sea coast are the recipient region for many invasive species of harmful organisms. At the beginning of the XXI century, 35 new species of dendrophilous insects were identified in the humid subtropical zone of Russia, 26 of which can be considered invasive: 17 species are new for Russia and 9 are new for the subtropical zone of the Black Sea coast of the Caucasus. Special features of the invasive process among phytophages were studied using following parameters: taxonomic composition, donor regions, vectors and pathways of invasion, biotopic distribution of the species and invasion dynamics. During the period of 2000 2017, a decrease in the representatives of order Hemiptera and an increase in the representatives of order Lepidoptera has been recorded. In recent years, the largest number of invasive species has North American origin rather than East Asian, which was typical for the region over the previous one and a half centuries. The following invasion vectors were specified for the newly recorded species: unintentional importation with planting material, invasion with traffic flow, unintentional importation with goods of nonplant origin, independent migration. All invasive species of East Asian, American, and Australian origin are characterized by twostage invasion, namely arriving to Russia from the secondary invasive range in Europe. The maximum number of alien species has settled in the plantations of ornamental species (landscape ecosystems), and this trend is traditional for the region. The rate of invasive species on the Black Sea coast of the Caucasus in the early XXI century was once in nine months, which is 7,4 times higher than in the early XX century.


2020 ◽  
Vol 21 (3) ◽  
pp. 475-499 ◽  
Author(s):  
Francesca Viterbo ◽  
Kelly Mahoney ◽  
Laura Read ◽  
Fernando Salas ◽  
Bradford Bates ◽  
...  

AbstractThe NOAA National Water Model (NWM) became operational in August 2016, producing the first ever real-time, distributed, continuous set of hydrologic forecasts over the continental United States (CONUS). This project uses integrated hydrometeorological assessment methods to investigate the utility of the NWM to predict catastrophic flooding associated with an extreme rainfall event that occurred in Ellicott City, Maryland, on 27–28 May 2018. Short-range forecasts (0–18-h lead time) from the NWM version 1.2 are explored, focusing on the quantitative precipitation forecast (QPF) forcing from the High-Resolution Rapid Refresh (HRRR) model and the corresponding NWM streamflow forecast. A comprehensive assessment of multiscale hydrometeorological processes are considered using a combination of object-based, grid-based, and hydrologic point-based verification. Results highlight the benefits and risks of using a distributed hydrologic modeling tool such as the NWM to connect operational CONUS-scale atmospheric forcings to local impact predictions. For the Ellicott City event, reasonably skillful QPF in several HRRR model forecast cycles produced NWM streamflow forecasts in the small Ellicott City basin that were suggestive of flash flood potential. In larger surrounding basins, the NWM streamflow response was more complex, and errors were found to be governed by both hydrologic process representation, as well as forcing errors. The integrated, hydrometeorological multiscale analysis method demonstrated here guides both research and ongoing model development efforts, along with providing user education and engagement to ultimately engender improved flash flood prediction.


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