scholarly journals Lake Nyos, a Multirisk and Vulnerability Appraisal

Geosciences ◽  
2018 ◽  
Vol 8 (9) ◽  
pp. 312
Author(s):  
Mesmin Tchindjang

Situated at the northern flank of the Oku Massif, Lake Nyos crater epitomizes landscape features originating from volcanic explosions during the Quaternary. The Cameroon Volcanic Line (CVL), to which it belongs, constitutes the most active volcanic region in Cameroon. In 1986, an outgas explosion occurred from beneath the lake and killed 1746 people in several neighbouring villages. The event influenced a radial area of 25 to 40 km wide, particularly in eastern and western direction. This was mainly due to: (1) the rugged nature of the landscape (fault fields), which enabled the heavier gas to follow valleys framed by faults corridors without affecting elevated areas; and (2) the seasonal dominating western wind direction, which channeled the gas along tectonic corridors and valleys. This paper assesses the geological risk and vulnerability in the Lake Nyos before and after several proposal to mitigate future outgas events. Remotely sensed data, together with GIS tools (topographic maps, aerial photographs), helped to determine and assess lineaments and associated risks. A critical grid combining severity and frequency analysis was used to assess the vulnerability of the local population. There is evidence that along the main fault directions (SW–NE), anthropogenic activities are most intensive and they may play an aggravating role for disasters. This requires the local population’s consciousness-raising. The results also show that population around Lake Nyos still remains vulnerable to volcanic hazards and floods. However, the area has been safe since the last degassing and jet grouting through multiple procedures and actions proposed in the National Contingency Plan, and equally by the relief organization plan (DROP or ORSEC plan) for the Menchum Division. Another issue is that the local population is concerned with the idea of returning to the affected areas in order to stay close to their ancestors or the deceased. Therefore, even after jet grouting and degassing, the problem of risk minimization for local residents remains.

2018 ◽  
Vol 12 (7-8) ◽  
pp. 38-45
Author(s):  
A. N. EFREMOV ◽  
N. V. PLIKINA ◽  
T. ABELI

Rare species are most vulnerable to man-made impacts, due to their biological characteristics or natural resource management. As a rule, the economic impact is associated with the destruction and damage of individual organisms, the destruction or alienation of habitats. Unfortunately, the conservation of habitat integrity is an important protection strategy, which is not always achievable in the implementation of industrial and infrastructural projects. The aim of the publication is to summarize the experience in the field of protection of rare species in the natural habitat (in situ), to evaluate and analyze the possibility of using existing methods in design and survey activities. In this regard, the main methodological approaches to the protection of rare species in the natural habitat (in situ) during the proposed economic activity were reflected. The algorithm suggested by the authors for implementing the in situ project should include a preparatory stage (initial data collection, preliminary risk assessments, technology development, obtaining permitting documentation), the main stage, the content of which is determined by the selected technology and a long monitoring stage, which makes it possible to assess the effectiveness of the taken measures. Among the main risks of in situ technology implementation, the following can be noted: the limited resources of the population that do not allow for the implementation of the procedure without prior reproduction of individuals in situ (in vitro); limited knowledge of the biology of the species; the possibility of invasion; the possibility of crossing for closely related species that сo-exist in the same habitat; social risks and consequences, target species or population may be important for the local population; financial risks during the recovery of the population. The available experience makes it possible to consider the approach to the conservation of rare species in situ as the best available technology that contributes to reducing negative environmental risks.


Author(s):  
Begüm Hergüvenç ◽  
Mehmet Hacısalihoğlu

This paper deals with the image and perceptions that Turkish migrants from Bulgaria had about the Turks in Turkey, the Turkish state, Bulgarians, and the Bulgarian state both before and after 1989. Perceptions of the Turkish minority among the Bulgarian communist elite are analysed according to published reports and statements made by Bulgarian Communist Party members. The perceptions that Turkish migrants had about Bulgaria and Turkey are the main focus of this study which is based on field research and interviews conducted with Turkish migrants from Bulgaria now living in Turkey. This article shows that these migrants held both positive and negative perceptions of Bulgaria and Turkey, largely depending on the context. The Turkish minority in Bulgaria was regarded as a problem for the Communist government and as an in-ternal enemy to the Bulgarian state. Moreover, the locals in Turkey regarded the Turkish migrants from Bulgaria as “Bulgarian migrants” who possessed a non-Muslim or “liberal” culture. In this way, they experienced exclusionary attitudes from their neighbours both in Bulgaria and in Turkey. The Turks of Bulgaria perceived the Communist regime as oppressive and as a threat to their Turkish identity. Despite their dislike of the regime, prior to the period of forced assimilation that began in 1984, they still possessed a relatively positive perception about the Bulgarian people. Interestingly, while they perceive Turkey as their homeland, they nonetheless held certain prejudices against the local population in Turkey. All of these various interaction helped to strengthen their group identity as migrants from Bulgaria.This paper deals with the image and perceptions that Turkish migrants from Bulgaria had about the Turks in Turkey, the Turkish state, Bulgarians, and the Bulgarian state both before and after 1989. Perceptions of the Turkish minority among the Bulgarian communist elite are analysed according to published reports and statements made by Bulgarian Communist Party members. The perceptions that Turkish migrants had about Bulgaria and Turkey are the main focus of this study which is based on field research and interviews conducted with Turkish migrants from Bulgaria now living in Turkey. This article shows that these migrants held both positive and negative perceptions of Bulgaria and Turkey, largely depending on the context. The Turkish minority in Bulgaria was regarded as a problem for the Communist government and as an internal enemy to the Bulgarian state. Moreover, the locals in Turkey regarded the Turkish migrants from Bulgaria as “Bulgarian migrants” who possessed a non-Muslim or “liberal” culture. In this way, they experienced exclusionary attitudes from their neighbours both in Bulgaria and in Turkey. The Turks of Bulgaria perceived the Communist regime as oppressive and as a threat to their Turkish identity. Despite their dislike of the regime, prior to the period of forced assimilation that began in 1984, they still possessed a relatively positive perception about the Bulgarian people. Interestingly, while they perceive Turkey as their homeland, they nonetheless held certain prejudices against the local population in Turkey. All of these various interaction helped to strengthen their group identity as migrants from Bulgaria.


Author(s):  
Pertiwi Jaya Ni Made ◽  
Fusanori Miura ◽  
A. Besse Rimba

A large-scale earthquake and tsunami affect thousands of people and cause serious damages worldwide every year. Quick observation of the disaster damage is extremely important for planning effective rescue operations. In the past, acquiring damage information was limited to only field surveys or using aerial photographs. In the last decade, space-borne images were used in many disaster researches, such as tsunami damage detection. In this study, SAR data of ALOS/PALSAR satellite images were used to estimate tsunami damage in the form of inundation areas in Talcahuano, the area near the epicentre of the 2010 Chile earthquake. The image processing consisted of three stages, i.e. pre-processing, analysis processing, and post-processing. It was conducted using multi-temporal images before and after the disaster. In the analysis processing, inundation areas were extracted through the masking processing. It consisted of water masking using a high-resolution optical image of ALOS/AVNIR-2 and elevation masking which built upon the inundation height using DEM image of ASTER-GDEM. The area result was 8.77 Km<sup>2</sup>. It showed a good result and corresponded to the inundation map of Talcahuano. Future study in another area is needed in order to strengthen the estimation processing method.


2021 ◽  
Vol 30 (3) ◽  
pp. 539-545
Author(s):  
Theophilus N. Mukete-Moto

The study analyses anthropogenic influence on the mangrove forests of the Cameroon coast and focuses on the development and improvement of the constructive- geographical foundations of rational nature management for the conservation and possible renewal of its natural resources base. The exploitation of mangrove forest landscapes has yielded significant benefits to the local population living within the mangrove forest limits, but the beneficiaries have not made commensurate investments in their sustainability and rational use. Therefore, this habitat must be carefully conserved or protected from wanton anthropogenic activities for the development purpose. The study made use primary and secondary data in establishing the facts analysed in this work. The secondary data comprised of materials of prominent authors who have contributed much to the findings related to coastal mangroves. Primary data collection was field visits carried out by the author in 2016. Questionnaires and semi- structural questions were used to collect information from mangrove exploiters. The findings confirm that the coastal mangrove forests in Cameroon have multiple functions beneficial to the communities adjacent to the coast, but, unfortunately, the beneficiaries have not made commensurate efforts to their sustainability and rationale. The Mangrove forests covered a surface area of 200 000 km2, but Cameroon lost 30 % of its mangrove forest cover in 1980–2006. If projected under ceteris paribus, Cameroon lost approximately 45 % of its mangrove forest cover in1980–2020. Haven understood that man has raped huge surfaces of mangrove forest for his selfish economic gains, the study proposed an urgent need for environmentally sustainable adaptive strategies like those earmarked in the Ramsay agreement and the ICZM (Integrated Coastal Zone Management) for the rational management of coastal mangroves in Cameroon.


Author(s):  
R. Kaczynski ◽  
A. Rylko

Old topographic map published in 1975 elaborated from aerial photographs taken in 1972, Landsat TM data acquired in May 1986 and Landsat ETM+ from June 2002 have been used to assess the changes of the lake Aba Samuel in Ethiopia. First map of the lake has been done in the framework of UNDP project running in 1988-90 in the Ethiopian Mapping Authority. The second classification map has been done as M.Sc. thesis in the MUT in 2015. Supervised classification methods with the use of ground truth data have been used for elaboration of the Landsat TM data. From the year 1972 up to 1986 the area of the lake has decreased by 23%. From 1986 up to 2002 the area of the lake has decreased by 20%. Therefore, after 30 years the lake was smaller by 43%. This have had very bad influence on the lives of the local population. From other recent data in the period from 2002-2015 the lake has practically disappeared and now it is only a small part of the river Akaki. ENVI 5.2 and ERDAS IMAGINE 9.2 have been used for Radiometric Calibration, Quick Atmospheric Correction (QUAC) and supervised classification of Landsat ETM+ data. The Optimum Index Factor shows the best combination of Landsat TM and ETM+ bands for color composite as 1,4,5 in the color filters: B, G, R for the signature development. Methodology and final maps are enclosed in the paper.


Author(s):  
Pertiwi Jaya Ni Made ◽  
Fusanori Miura ◽  
A. Besse Rimba

A large-scale earthquake and tsunami affect thousands of people and cause serious damages worldwide every year. Quick observation of the disaster damage is extremely important for planning effective rescue operations. In the past, acquiring damage information was limited to only field surveys or using aerial photographs. In the last decade, space-borne images were used in many disaster researches, such as tsunami damage detection. In this study, SAR data of ALOS/PALSAR satellite images were used to estimate tsunami damage in the form of inundation areas in Talcahuano, the area near the epicentre of the 2010 Chile earthquake. The image processing consisted of three stages, i.e. pre-processing, analysis processing, and post-processing. It was conducted using multi-temporal images before and after the disaster. In the analysis processing, inundation areas were extracted through the masking processing. It consisted of water masking using a high-resolution optical image of ALOS/AVNIR-2 and elevation masking which built upon the inundation height using DEM image of ASTER-GDEM. The area result was 8.77 Km<sup>2</sup>. It showed a good result and corresponded to the inundation map of Talcahuano. Future study in another area is needed in order to strengthen the estimation processing method.


Rangifer ◽  
2007 ◽  
Vol 27 (3) ◽  
pp. 35
Author(s):  
Eigil Reimers

Wild reindeer in Norway, presently (winter 2005-06) numbering some 25 000 animals, are found in 23 more or less separated areas in the mountainous southern part of the country (see map in appendix). All herds are hunted and management is organized in close cooperation between owner organizations and state agencies. I will provide a historical review of the wild reindeer management and research in Norway and conclude with the present situation. We identify 3 types of wild reindeer on basis of their origin: (1) the original wild reindeer with minor influence from previous domestic reindeer herding activities (Snøhetta, Rondane and Sølenkletten), (2) wild reindeer with some influx of animals from past domestic reindeer herding in the area (Nordfjella, Hardangervidda, Setesdal-Ryfylke) and (3) feral reindeer with a domesticated origin (reindeer released or escaped from past reindeer husbandry units; Forolhogna, Ottadalen North and Ottadalen South, Norefjell-Reinsjøfjell and several smaller areas). In Norway, genetic origin (wild or domesticated), body size and reproductive performance of reindeer differ among areas. Feral reindeer have higher body weights and enjoy higher reproductive rates than their originally wild counterparts. These differences may partially be explained by differences in food quality and availability among the populations. However, there is a growing suspicion that other explanatory factors are also involved. Wild reindeer are more vigilant and show longer fright and flight distances than feral reindeer. Number of animals harvested was 4817, or ca. 20% of the total population in 2005, but varies between 40% in feral reindeer areas to below 20% in some of the "wild" reindeer areas. Causal factors behind this variation include differences in age at maturation, postnatal calf mortality and herd structure. The Norwegian Institute for nature research (NINA) in cooperation with the Directorate for nature management (DN) allocate considerable resources to monitoring 36 wild reindeer herds and pastures, especially winter pastures. A total of 8 wild reindeer areas are monitored annually (the monitoring program was initiated in 1991), recording calf recruitment rates in nursery bands in June/July from aerial photographs and herd composition from ground counts of rutting groups in September/October. Carcass weights and mandibles are sampled at regular intervals from harvested animals in the same areas in order to investigate reindeer body weight development. The botanical part of the monitoring program is concentrated on renewal growth of lichen in areas under variable reindeer grazing pressure, and annual measurements of radiocesium load in plants and reindeer meat from fall-out areas following the Chernobyl accident in 1986. Reindeer research relating to the wild reindeer herds in southern Norway is mainly conducted by NINA in Trondheim and the Biology Institute, University of Oslo. Most mountain ranges and wild reindeer populations in Norway are experiencing an increase and expansion of human use, including infrastructure such as road and power-lines, and private cabins, tourism/recreation, etc. Present research activities focus on wild reindeer area use, behaviour and activity budgets in selected areas on a 24 hour and a seasonal basis by use of GPS-technology. An important part of the ongoing projects emphasizes a close monitoring and investigation of reindeer behaviour and activity in relation to human activities and infrastructure. Furthermore, development and quality control of methods for measurement of response towards anthropogenic activities and population reproduction and early calf mortality are included in the research activities.Villrein i Norge; Populasjonsøkologi, forvaltning og jaktAbstract in Norwegian / Sammendrag: Villreinen i Norge utgjør i 2005-06 en vinterbestand på ca. 25 000 dyr fordelt på 23 stort sett isolerte villreinområder (kart i appendiks) som jaktelig sett forvaltes enkeltvis og i et samarbeid mellom rettighetshavere og statlige forvaltningsorganer. Presentasjonen gir en historisk fremstilling av villreinforvaltningen i Norge og den forskningsutvikling som ligger bak dagens situasjon. Vi har 3 typer villrein i Norge: (1) den opprinnelige med liten tamreininnblanding karakterisert ved områdene Snøhetta, Rondane og Sølenkletten, (2) villrein med varierende innslag av tamreinpåvirkning (Nordfjella, Hardangervidda, Setesdal-Ryfylke) og (3) villrein med tamreinopphav (dvs. forvillet tamrein; Forolhogna, Ottadalen Nord og Ottadalen Syd, Norefjell-Reinsjøfjell og en rekke mindre områder). Reinens kroppsvekter i kategori 3-områdene er vesentlig høyere enn de i kategori 1 og 2. Forskjeller i beiteforhold områdene i mellom er nok medvirkende årsak, men adferdsundersøkelser som omfatter vaktsomhetsadferd og frykt- og fluktadferd i ulike områder tyder på at vaktsomhet og aktivitetsmønster kan være andre viktige påvirkningsfaktorer. Avkastningen i form av felte dyr var i 2005 ca. 20% av samlet vinterbestand, men varierer mellom 40% i områder der kroppsvektene er store til under 20% der reinen har lavere kroppsvekter. Forklaringsfaktorer omfatter forskjeller knyttet til alder for kjønnsmodning og reproduksjon, postnatal kalvedødlighet og kjønns- og alderssammensetning i de ulike villreinområdene. Norsk villreinforvaltning i regi av Norsk institutt for naturforskning (NINA)/Direktoratet for naturforvaltning (DN) satser store ressurser på overvåkning av villrein og deres beiter, særlig vinterbeiter. Til sammen 7 spesielt utvalgte villreinområder overvåkes årlig (start 1991) med flyfotografering av fostringsflokker i juni/juli for å bestemme kalvetilvekst og bakkeregistreringer om høsten for å bestemme bestandsstruktur. Med jevne mellomrom innsamles også kjever og slaktevekter fra høstjakten for å vurdere reinens kondisjonsutvikling i overvåkningsområdene. I den botaniske del av overvåkningsaktivitetene måles gjenvekst av lav i områder utsatt for vekslende beitepress og radiocesiumbelastningen etter Tsjernobylulykken i 1986 i næringsplanter og i kjøttprøver fra felt villrein i de områdene som ble hardest rammet av nedfall. Villreinforskningen er særlig lokalisert til NINA og Universitetet i Oslo. Forskningsaktivitetene omfatter måling av reinens adferd og aktivitet gjennom døgnet og dyrenes sesongmessige områdebruk i relasjon til menneskelig infrastruktur i utvalgte områder ved hjelp av bl.a. GPS-instrumentering og utvikling og kvalitetskontroll av metodeverktøy til bestemmelse av reproduksjon og tidlig kalvedødlighet.


Author(s):  
Victorita Radulescu

Abstract In Romania, in the last decades, was not realized any complex plan of management concerning the environmental rehabilitation of the natural riverbeds, even if there are even in present many places confronted with repeated floods. After the floods from 2004, 2005 and 2014 have been recorded in some places large deposits of sediments or contrary, in other zones with erosion and uncontrolled coastal slides. As an immediate effect, zones with risk for the local population and not only, have appeared. The present paper estimates the capacity of transport for a riverbed in natural conditions, based on the local measurements registered before and after a flood. The model is tested for a tributary of the Bistrita River, the Cracau River, near the Siret basin, an area well-known for such repeated floods sometimes even two or three recorded in the same year, as it was in 2005 and 2008. Three of these floods were confronted with human losses, many dead animals, and agricultural flooded areas. Near the analyzed watercourse there are many localities, with a high density of population. The realized numerical model for the flow with free surface was taking into account the possibility of the permanent changing of the lateral surfaces (riverbeds) during the floods. A continuous balance of the entered and transported sediments is realized, due to the erosion and sediment transportation. The time variation of the discharged liquid and the solid phases are directly connected with the sediment transport. In these conditions, the fine fractions of sediments from the bed’s structure are removed from its surface. In some places, the sediments become “armored” with the coarser part of the bed sediment. It is proposed a mathematical model to simulate the effect of both types of deposits into a fluid flow in open channels, with a movable bed. The entire alluvial stream, until the base rock, is considered with a small thickness so the non-uniformity of the grain size in the vertical distribution in riverbed could be neglected. The boundary conditions in the flood analysis consist of the upstream hydrograph and the stationary level of the downstream watercourse. Knowing the flow rate and the water levels by direct measurements, there is possible to establish the risk zones, far away from the river borders. The primary purpose of this study is to minimize the effects of such uncontrolled floods by determining the risk zones and to present a solution for increasing population safety which lives near the riverbed. Finally, some conclusions and references are mentioned.


2019 ◽  
Vol 100 (1) ◽  
pp. 71-92 ◽  
Author(s):  
Sarah A. Tessendorf ◽  
Jeffrey R. French ◽  
Katja Friedrich ◽  
Bart Geerts ◽  
Robert M. Rauber ◽  
...  

AbstractThe Seeded and Natural Orographic Wintertime Clouds: The Idaho Experiment (SNOWIE) project aims to study the impacts of cloud seeding on winter orographic clouds. The field campaign took place in Idaho between 7 January and 17 March 2017 and employed a comprehensive suite of instrumentation, including ground-based radars and airborne sensors, to collect in situ and remotely sensed data in and around clouds containing supercooled liquid water before and after seeding with silver iodide aerosol particles. The seeding material was released primarily by an aircraft. It was hypothesized that the dispersal of the seeding material from aircraft would produce zigzag lines of silver iodide as it dispersed downwind. In several cases, unambiguous zigzag lines of reflectivity were detected by radar, and in situ measurements within these lines have been examined to determine the microphysical response of the cloud to seeding. The measurements from SNOWIE aim to address long-standing questions about the efficacy of cloud seeding, starting with documenting the physical chain of events following seeding. The data will also be used to evaluate and improve computer modeling parameterizations, including a new cloud-seeding parameterization designed to further evaluate and quantify the impacts of cloud seeding.


Author(s):  
Ned Horning ◽  
Julie A. Robinson ◽  
Eleanor J. Sterling ◽  
Woody Turner ◽  
Sacha Spector

New remote sensing challenges arise from the addition of the water column to the remote sensing signal. At the same time, new opportunities for use of remotely sensed data are possible in the marine environment. Marine environments can have organisms in such great abundance that they are readily monitored using remote sensing. From measuring ocean productivity, to harmful algal blooms (HABs), to fisheries management, remote sensing is a key component of many efforts to manage and conserve marine ecosystems. For example, the small giant clam, Tridacna maxima, is endangered in some areas of the Pacific, and because of commercial harvest pressure is listed in Appendix II of the Convention on the International Trade of Endangered Species (CITES, meaning they are not yet threatened by extinction but could become so if their trade is not tightly regulated). Andréfouët et al. (2005a) used field observations and remotely sensed data to study the productivity of the clam fishery in tiny (22.2 km2, including a 9.9 km2 lagoon) Fangatau Atoll (Eastern Tuamotu, French Polynesia). The fishery was under pressure due to the large (4 ton per year) export of clams to Tahiti. Remotely sensed data included a mosaic of aerial photographs (1.5 m resolution), a digital photograph taken from the International Space Station (red, green, blue, 5.6 m resolution), and Landsat TM imagery (30 m resolution). The authors classified each image of key lagoon habitats, using maximum likelihood supervised classification, with each image classified independently. They estimated the population size for the entire lagoon by multiplying the mean clam density in each habitat (from field data) by the total area of each habitat (in the maps made from the remotely sensed data). Amazingly, an estimated 23.65 ± 5.33 million clams (mean ± 95 percent confidence interval) inhabited the 4.05 km2 area of suitable habitat in the lagoon. The high spatial resolution data (1.5 m aerial and 5.6 m astronaut photography data) both gave equivalent estimates of the biomass with good estimates of accuracy, but the Landsat 30 m data overestimated the population.


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