Flood characterisation of the Haor region of Bangladesh using flood index

The paper presents the flood characterisation of the Haor region in the north-east of Bangladesh. The region consists of a system of Haors, each of which is a saucer-shaped depression and interconnected by a river system. A portion of the Haor area, known as the deeply flooded area, consisting of about 15 Haors, was chosen as the study area. A 1D2D model, with one-dimensional model for the rivers and a two-dimensional model for the Haors, was developed. Flood hydrograph characteristics such as the rising curve gradient, flood magnitude ratio (with respect to the average discharge) and time to peak were assessed for different river floods. Using these characteristics an integrated flood index (FI) was developed. The FI is an aggregated indicator based on the flood hydrograph characteristics and indicates the relative overall severity of a flood. The spatial and temporal variations of the index were investigated as well. The computed FI at different locations of the region and for different flood hazard frequencies provide a broad understanding of the flooding characteristics of the region. The developed methodology can also be applied to other river basins to analyse flooding risk provided some historical flood data are available.

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Temporal Variations in Chemical Composition of Snow Cover in Moscow

GEOGRAPHY ENVIRONMENT SUSTAINABILITY ◽

10.24057/2071-9388-2019-79 ◽

2019 ◽

Vol 12 (4) ◽

pp. 148-158 ◽

Cited By ~ 2

Author(s):

Irina D. Eremina ◽

Jessica Yu. Vasil’chuk

Keyword(s):

Chemical Composition ◽

Major Ions ◽

Temporal Variations ◽

Snow Melting ◽

The Road ◽

Seasonal Snow ◽

North East ◽

The North ◽

Snow Precipitation ◽

Different Parts

This article summarizes the data of the chemical composition and the acidity of the seasonal snow precipitation for the cold periods 1999-2006 (n=180), 2010-2013 (n=82) and 2018-2019 (n=18) in different parts of Moscow. Major ions content was measured, such as SO42-, НСO3-, Cl-, NO3-, Са2+, Mg2+, Na+, K+ and NH4+, also pH and sum of ions (mg/L) were measured. During the 2018-2019 season, snowpack samples were taken twice at 4 sites in Moscow: two in the North-East Administrative Okrug (NEAO) near the road and in the park at the distance of 3 km from each other, and two in the South- Western Administrative Okrug (SWAO) and in the Western Administrative Okrug (WAO) near the road and in the park at the distance of 6 km from each other. Samples were taken with a break of 5 days to determine the dynamics of the chemical composition within the beginning of the snow-melting. In each pair of sampling sites there was one that is located in the park and one located near the road. This experiment showed a slight variability of the chemical composition of snow during 5 days under the influence of the new snowfall. In general, there is a trend of changing the composition of snow from calcium carbonate to calcium chloride, which is mainly connected to the use of anti-icing reagents; for the same reason, the areas that are closer to the roads are the most polluted.

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Spatial-temporal variations of surface diffuse CO2 degassing at El Hierro volcano, Canary Islands

10.5194/egusphere-egu2020-11805 ◽

2020 ◽

Author(s):

Pedro A. Hernández ◽

Christopher A. Skeldon ◽

Jingwei Zhang ◽

Fátima Rodríguez ◽

Cecilia Amonte ◽

...

Keyword(s):

Canary Islands ◽

Temporal Variations ◽

Graphical Analysis ◽

Homogeneous Distribution ◽

Submarine Eruption ◽

El Hierro ◽

North East ◽

The North ◽

Total Data ◽

Destructive Processes

El Hierro (278 km2), the youngest, smallest and westernmost island of the Canarian archipelago, is a 5-km-high edifice constructed by rapid constructive and destructive processes in ~1.12 Ma, with a truncated trihedral shape and three convergent ridges of volcanic cones. It experienced a submarine eruption from 12 October, 2011 to 5 March 2012, off its southern coast that was the first one to be monitored from the beginning in the Canary Islands. As no visible emanations occur at the surface environment of El Hierro, diffuse degassing studies are a useful geochemical tool to monitor the volcanic activity in this volcanic island. Diffuse CO2 emission surveys have been performed at El Hierro Island since 1998 in a yearly basis, with much higher frequency during the period 2011-2012. At each survey, about 600 sampling sites are selected to obtain a homogeneous distribution. Measurements of soil CO2 efflux are performed in situ following the accumulation chamber method. During pre-eruptive and eruptive periods, the diffuse CO2 emission released by the whole island experienced significant increases before the onset of the submarine eruption and the most energetic seismic events of the volcanic-seismic unrest (Meli&#225;n et al., 2014. J. Geophys. Res. Solid Earth, 119, 6976&#8211;6991). The most recent diffuse CO2 efflux survey was carried out in July 2019. Values ranged from non-detectable to 28.9 g m&#8722;2 d&#8722;1. Statistical-graphical analysis of the data shows two different geochemical populations; Background (B) and Peak (P) represented by 97.5% and 0.5% of the total data, respectively, with geometric means of 1.2 and 23.6 g m&#8722;2 d&#8722;1, respectively. Most of the area showed B values while the P values were mainly observed at the interception center of the three convergent ridges and the north-east of the island. To estimate the diffuse CO2 emission for the 2019 survey, we ran about 100 sGs simulations. The estimated 2019 diffuse CO2 output released to atmosphere by El Hierro was 214 &#177; 10 t d-1, value lower than the background average of CO2 emission estimated on 412 t d-1 and slightly higher than the background range of 181 t d-1 (&#8722;1&#963;) and 930 t d-1 (+1&#963;) estimated at El Hierro volcano during the quiescence period 1998-2010 (Meli&#225;n et al., 2014, JGR). Monitoring the diffuse CO2 emission has proven to be a very effective tool to detect early warning signals of volcanic unrest at El Hierro.

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A Quantitative Framework for Analyzing Spatial Dynamics of Flood Events: A Case Study of Super Cyclone Amphan

Remote Sensing ◽

10.3390/rs12203454 ◽

2020 ◽

Vol 12 (20) ◽

pp. 3454

Author(s):

Mohammad Mehedy Hassan ◽

Kevin Ash ◽

Joynal Abedin ◽

Bimal Kanti Paul ◽

Jane Southworth

Keyword(s):

Spatial Association ◽

Spatial Dynamics ◽

Cost Effective ◽

Support Vector ◽

Water Index ◽

North East ◽

The North ◽

Super Cyclone ◽

Flooding Risk ◽

Flood Maps

Identifying the flooding risk hotspot is crucial for aiding a rapid response and prioritizes mitigation efforts over large disaster impacted regions. While climate change is increasing the risk of floods in many vulnerable regions of the world, the commonly used crisis map is inefficient and cannot rapidly determine the spatial variation and intensity of flooding extension across the affected areas. In such cases, the Local Indicators of Spatial Association (LISA) statistic can detect heterogeneity or the flooding hotspot at a local spatial scale beyond routine mapping. This area, however, has not yet been studied in the context of the magnitude of the floods. The present study incorporates the LISA methodology including Moran’s I and Getis–Ord Gi* to identify the spatial and temporal heterogeneity of the occurrence of flooding from super cyclone Amphan across 16 coastal districts of Bangladesh. Using the Synthetic Aperture Radar (SAR) data from Sentinel-1 and a Support Vector Machine (SVM) classification, “water” and “land” were classified for the pre-event (16 May 2020) and post-events (22 May, 28 May, and 7 June 2020) of the area under study. A Modified Normalized Difference Water Index (MNDWI), and visual comparison were used to evaluate the flood maps. A compelling agreement was accomplished between the observed and predicted flood maps, with an overall precision of above 95% for all SAR classified images. As per this study, 2233 km2 (8%) of the region is estimated to have been inundated on 22 May. After this point, the intensity and aerial expansion of flood decreased to 1490 km2 by 28 May before it increased slightly to 1520 km2 (2.1% of the study area) on 7 June. The results from LISA indicated that the main flooding hotspots were located in the central part, particularly in the region off the north-east of the mangrove forest. A total of 238 Unions (smallest administrative units) were identified as high flooding hotspots (p < 0.05) on 22 May, but the number of flooding hotspots dropped to 166 in the second week (28 May) after Amphan subsided before it increased to a further 208 hotspots (p < 0.05) on 7 June due to incessant rainfall and riverbank failure in the south-west part of the study area. As such, an appropriate, timely, and cost-effective strategy would be to assess existing flooding management policies through the identified flooding hotspot regions. This identification would then allow for the creation of an improved policy to help curtail the destructive effects of flooding in the future.

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A GIS based approach for the prediction of the dam break flood hazard – A case study of Zardezas reservoir “Skikda, Algeria”

Journal of Water and Land Development ◽

10.1515/jwld-2015-0020 ◽

2015 ◽

Vol 27 (1) ◽

pp. 15-20 ◽

Cited By ~ 3

Author(s):

Oussama Derdous ◽

Lakhdar Djemili ◽

Hamza Bouchehed ◽

Salah Eddine Tachi

Keyword(s):

Land Use Planning ◽

Flood Hazard ◽

Flow Simulation ◽

Dam Break ◽

Geographical Information ◽

Hydraulic Modelling ◽

North East ◽

The North ◽

Potential Failure ◽

Gis Environment

Abstract The construction of dams in rivers can offer many advantages, however the consequences resulting from their failure could result in major damage, including loss of life and property destruction. To mitigate the threats of dam break it is essential to appreciate the characteristics of the potential flood in realistic manner. In this study an approach based on the integration of hydraulic modelling and GIS has been used to assess the risks resulting from a potential failure of Zardezas dam, a concrete dam located in Skikda, in the North East of Algeria. HEC-GeoRAS within GIS was used to extract geometric information from a digital elevation model and then imported into HEC-RAS. Flow simulation of the dam break was performed using HEC-RAS and results were mapped using the GIS. Finally, a flood hazard map based on water depth and flow velocity maps was created in GIS environment. According to this map the potential failure of Zardezas dam will place a large number in people in danger. The present study has shown that Application of Geographical Information System (GIS) techniques in integration with hydraulic modelling can significantly reduce the time and the resources required to forecast potential dam break flood hazard which can play a crucial role in improving both flood disaster management and land use planning downstream of dams.

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Temporal and Territorial Analysis of Multiple Deliveries in Spain (1900–2006)

Twin Research and Human Genetics ◽

10.1375/twin.13.2.207 ◽

2010 ◽

Vol 13 (2) ◽

pp. 207-216 ◽

Cited By ~ 3

Author(s):

Vicente Fuster ◽

Pilar Zuluaga ◽

Jorge Román-Busto ◽

Sonia E. Colantonio

Keyword(s):

Maternal Age ◽

Birth Rate ◽

Crude Birth Rate ◽

Extended Period ◽

Temporal Variations ◽

North East ◽

The North ◽

Using Data ◽

Agricultural Areas

AbstractTemporal variations in the frequency of multiple maternities in many Western European countries have been described. However, within a single country, regional differences are observed. Urban industrialized regions and rural agricultural areas have experienced in recent decades a distinct decline in multiple deliveries, which in cases have been related to maternal age and parity changes. Research on multiple deliveries in Spain is scarce and none of the studies go back to the beginning of the 20th century or consider regional variation over an extended period of time. The present paper is a yearly study on multiple deliveries in Spain since 1900 including a geographical analysis. Rather than dealing with recent changes in multi-parity, this paper is concerned with Spain's long-term national variation (between 1900 and 2006). The changing pattern of double and triple deliveries was analyzed using data from the Spanish National Statistics Institute (INE). Twinning rates in Spain are low in comparison to those of equivalent periods in other countries, and the minimum rates correspond to the 1980s decade. Results were interpreted by taking into account the influence of age at maternity and reproductive variation up to 1990. A good fit between observed and predicted rates was obtained after the application of models, which besides maternal age and parity, include their interaction. Regarding territorial variability, the values corresponding to southern, northern and insular Spanish provinces are consistent with an earlier reduction of the crude birth rate in the north-east regions and latter in the southern regions and the Canary Islands.

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Inventories of point and diffuse sources and estimated nutrient loads - a comparison for different river basins in Central Europe

Water Science & Technology ◽

10.2166/wst.1996.0493 ◽

1996 ◽

Vol 33 (4-5) ◽

pp. 99-107 ◽

Cited By ~ 19

Author(s):

Horst Behrendt

Keyword(s):

River System ◽

Strong Relationship ◽

River Basins ◽

Nutrient Load ◽

Nutrient Loads ◽

Diffuse Sources ◽

North East ◽

The North ◽

Point And Diffuse Sources ◽

Diffuse Emissions

A comparison of the estimated emissions (input) with the measured loads at monitoring stations (output) is presented for the large Rivers Rhine, Elbe and its main tributaries and for the River Warnow, a smaller river in the north-east part of Germany. The comparison shows that the discrepancies between the estimated emissions and the measured load is small for the Rhine and its main tributaries, Mosel, Neckar and Main. Large discrepancies were found for the Elbe and its main tributaries. For all investigated river systems a strong relationship exists between the quotient of measured nutrient load versus the estimated sum of point and diffuse emissions of nutrients and the areal specific runoff. A function is derived for the dependency of the sum of retention and/or losses in a river system on the specific runoff and the nutrient concentration in the river. The high accuracy of the estimated retention and/or losses within the different river basins offer the possibility to use these equations for a prediction of the emitted nutrients from measured nutrient load in similar rivers.

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Multi-proxy evidence for the impact of the Storegga Slide Tsunami on the early Holocene landscapes of the southern North Sea

10.1101/2020.02.24.962605 ◽

2020 ◽

Cited By ~ 2

Author(s):

Vincent Gaffney ◽

Simon Fitch ◽

Martin Bates ◽

Roselyn L. Ware ◽

Tim Kinnaird ◽

...

Keyword(s):

North Sea ◽

River System ◽

Seismic Survey ◽

Southern North Sea ◽

North East ◽

The North ◽

Sediment Deposits ◽

Land Mass ◽

Storegga Slide ◽

The Impact

AbstractDoggerland was a land mass occupying an area currently covered by the North Sea until marine inundation took place during the mid-Holocene, ultimately separating the British land mass from the rest of Europe. The Storegga Slide, which triggered a tsunami reflected in sediment deposits in the Northern North Sea, North East coastlines of the British Isles and across the North Atlantic, was a major event during this transgressive phase. The spatial extent of the Storegga tsunami however remains unconfirmed because to date no direct evidence for the event has been recovered from the southern North Sea. We present evidence that Storegga associated deposits occur in the southern North Sea. Palaeo-river systems have been identified using seismic survey in the southwestern North Sea and sedimentary cores extracted to track the Mid Holocene inundation. At the head of one palaeo-river system near the Outer Dowsing Deep, the Southern River, we observed an abrupt and catastrophic inundation stratum. Based on lithostratigraphic, macro and microfossils and sedimentary ancient DNA (sedaDNA) evidence, supported by optical stimulation luminescence (OSL) and radiocarbon dating, we conclude these deposits were a result of the Storegga event. Seismic identification of this stratum to adjacent cores indicated diminished traces of the tsunami, largely removed by subsequent erosional processes. Our results demonstrate the catastrophic impact of Storegga within this area of the Southern North Sea, but indicate that these effects were temporary and likely localized and mitigated by the dense woodland and topography of the area. We conclude clear physical remnants of the wave are likely to be restricted to inland basins and incised river valley systems.

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Ras al Khaimah: further archaeological discoveries

Antiquity ◽

10.1017/s0003598x00150070 ◽

1976 ◽

Vol 50 (200) ◽

pp. 216-222

Author(s):

Beatrice De Cardi

Keyword(s):

United Arab Emirates ◽

The State ◽

Focused Attention ◽

North East ◽

The North ◽

History Of ◽

The City

Ras a1 Khaimah is the most northerly of the seven states comprising the United Arab Emirates and its Ruler, H. H. Sheikh Saqr bin Mohammad al-Qasimi, is keenly interested in the history of the state and its people. Survey carried out there jointly with Dr D. B. Doe in 1968 had focused attention on the site of JuIfar which lies just north of the present town of Ras a1 Khaimah (de Cardi, 1971, 230-2). Julfar was in existence in Abbasid times and its importance as an entrep6t during the sixteenth and seventeenth centuries-the Portuguese Period-is reflected by the quantity and variety of imported wares to be found among the ruins of the city. Most of the sites discovered during the survey dated from that period but a group of cairns near Ghalilah and some long gabled graves in the Shimal area to the north-east of the date-groves behind Ras a1 Khaimah (map, FIG. I) clearly represented a more distant past.

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