Contribution of Frequency Ratio model for flood susceptibility risk analysis: Case of Oued Toudgha catchment (Southern flank of central high Atlas, Tinghir - Morocco)

Elbadaoui Kamal, Algouti Ahmed, Algouti Abdelah and Ait Naceur Hassan

Page No. 1-10

Risk of flash floods is one of the most commonly occurred natural hazards in Morocco. In Tinghir district located in the southeast of High Atlas Mountains, the main river is called Oued Toudgha which is the study area and causes damage to both life and property every year. Due to the huge soil and land losses in this area due to natural disasters, development of appropriate flood modeling is required. Geographic information system techniques can support overall flood management as they can produce rapid data collection and analysis for hydrological studies. This study focuses on the analysis of flood susceptibility using frequency ratio model in Oued Toudgha catchment and to achieve the study objectives, a recognition survey was conducted and frequent flood inundated areas were identified in the study area. A total of 200 flooded locations were demarcated at different part of the catchment. As a result, an inventory of spatial database of past flood inundation was generated and role of all the influencing factors for detecting the extent of flood susceptibility. During flood susceptibility analysis, 13 conditioning parameters were considered and analyzed for the development of flash flood susceptibility maps of the basin including elevation, slope, lithology, rainfall, NDVI, aspect, curvature, plan curvature, profile curvature, distance to roads, distance to faults, distance to rivers and land use. A correlation between these conditioning factors and flood was calculated using FR model.

Consequently, the summation of frequency ratio values was taken for all the parameters for development of flood susceptibility index which was then classified into five zones of very low risk (53.5%), low (39.34%), moderately susceptible (6.02%), high susceptible (0.22%), very high (0.88%). Performance of the models was validated by area under the Receiver Operating Characteristic (AUC) curve. The area under curve acquired for the model was 84%. These flood susceptibility zones of Oued Toudgha basin could be used for flood risk management and land use planning for minimizing the potential risk in the floodplain of streams flowing through the Toudgha River.

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Evaluation and Comparison of Seismic Hazard Parameters for Amaravati Region

Madhusudhan Reddy M., Rajashekara Reddy K., Hanumantha Rao Ch. and Kalyan Kumar G.

Page No. 11-22

In the present study, an attempt was made to analyze the conflict of Seismic Hazard Parameters (SHP) like a-value, b-value, Mmax, λ, β and Mc for the Amaravati region by considering 500km circular distance from the Velgapudi (16⁰ 52' N, 80⁰ 51’E) as a center. To develop the homogeneous in size of the earthquake catalogue, we collected seismicity converted into moment magnitude (Mw) scale for the span of 219 years (1801 to 2020). The declustering process was fetched out to remove the dependent events from the main events. The catalogue completeness period was estimated using CUVI and Stepp’s method for proposed scenarios. The Mc-value was investigated using Zmap software by considered the Entire Magnitude Range (EMR) technique.

The SHP values are analyzed from the Least Square Method (LSM) and Maximum Likelihood Method (MLM) by the incremental value of 0.5 Mw to maximum observed magnitude ( M_max^obs) and Kijko-Sellevoll-Bayes (KSB) method. The results show variation in b- value from 0.35 to 0.99, whereas the Mmax varies from 5.67 ± 0.26 to 7.70 ± 1.32. The value of λ varies from 0.14 ± 0.03 to 1.66 ± 0.41. During the study, a total of 38 faults, six lineaments and three shear zones are identified within the selected study area.

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Assessing the Accuracy of Image Classification Algorithms Using During-Flood TerraSAR-X Imagery

Umar Lawal Dano, Mohammed A.M. Alhefnawi, Faez Al-Shihri, Mohamed Ahmed Said, Elhadi Eltahir Mohamed, Aymen Hashem A. Alsayed and Shoaib Arif

Page No. 23-33

Extracting and determining floods affected zones is one of the most crucial stages in floods hazard management to reduce damages caused by floods. Assessing and determining the accuracy of image classification algorithms is essential in producing accurate flood hazard maps. This study put forward the application of Remote Sensing and GIS computer programs to carry out a comparative analysis of three image classification algorithms: neural network, parallel-pipe and minimum distance to test which technique best classifies the 2010 during-flood TerraSAR-X image of Perlis, Malaysia. Confusion matrix was calculated to assess the accuracy of each algorithm.

The best result of the flood extent extraction model is from the network algorithm classification with an overall accuracy of 99.7661% and a kappa coefficient of 0.9862. These findings could be used to assist the Government to design appropriate measures to safeguard the lives and properties of the residents of Perlis.

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Benthic foraminifera as an Environmental Proxy Linked to Monsoon Changes from Beach Sediments of Kerala Coast, India

Ravichandran M. and Lakshumanan C.

Page No. 34-43

The study on 290 sediment sub samples have been analyzed for benthic foraminifera from Chellanam andhakaranazhi and Azheekal beach sediments of Kerala coast, India. A total 36 species of benthic foraminifera were recorded in the study. Benthic foraminiferal faunal study, dry samples were sieved over 125 μm-size sieve and split into suitable aliquots to obtain approximately 250 specimens of benthic foraminiferal species identified and counted. The oceanographically most dominant benthic foraminiferal species are Ammonia beccarii followed by Ammonia gaimardii, Cancris oblongus, Discopulvinulina bertheloti, Gyroidinoides nitidula and Quinqueloculina seminulum were identified from the study region. The Chellanam beach sediment of benthic foraminifera species suggests that a high productivity species like Ammonia beccarii, Ammonia gaimardii, Anomalina globulosa and Quinqueloculina seminulum from 100 to 70cm and 30 to 5cm indicates of high organic productivity during the summer winds, whereas surface productivity changes may also be driven by winter winds from 70 to30cm.

Species of Cancris oblongus from 25 to 15cm indicate by tolerance to mesotrophic-eutrophic conditions and Gyroidinoides nitidula indicates low organic carbon flux or pulsed food supply and high oxygen environment during 50 to 23cm. From Anthakaranazhi beach sediment of benthic foraminifera species are Ammonia beccarii, Ammonia gaimardii from 100 to 80cm and 20 to 5cm depth indicates of shallow-marine environment. From 70 to 40cm depth, species of Gyroidinoides nitidula indicates low organic carbon flux or pulsed food supply and high oxygen environment. From Azheekal beach sediment as an instance high productivity species of Ammonia beccarii and Ammonia gaimardii shows an abrupt increase and Cancris oblongus, Gyroidinoides nitidula, Gyroidinoides neosoldanii and Miliolinella subrotunda showing abrupt decrease at 90 to 70cm and 18 to 5cm depth,suggest that rapid response of benthic foraminifera to the organic flux to the shallow seafloor.

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Modeling of Earthquake Hazard for Three Seismogenic Areas on Sumatra Island: A Comparison of Some Discrete Counts Time-series Modelling

Rizal Jose, Gunawan Agus Yodi, Indratno Sapto Wahyu and Meilano Irwan

Page No. 44-54

Earthquake hazard prediction can be obtained by discrete time-series modelling which assumes that the counting process follows the Poisson process. One problem encountered for this approach is overdispersion due to the presence of latent heterogeneity and serial dependence in a data set. Undetected two sources of overdispersion may entail important misleading inferences; how to detect and to solve overdispersion becomes an essential issue. To do so, mixture models of the Poisson process, namely Quasi-Poisson, Negative Binomial, Zero-inflated Poisson, Poisson Hurdle, Poisson Mixture Model, and Poisson Hidden Markov Model (PHMM) are here proposed. Real data of three seismogenic areas on Sumatra Island with a period from 1971 to 2018 are used to model earthquake hazards.

Generally, for any given data set which is analyzed using the maximum likelihood, two information criteria (i.e. AIC and BIC) are often used to assess the data fitting model. However, those two criteria do not usually give the same conclusion. In this case, the likelihood ratio test and ordinary pseudo-residuals are commonly used to decide. Our results show that for all sub-areas, the PHMM provides a better fit to the data. Furthermore, using that selected model, we obtain the prediction of earthquake hazard for our data.

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Assessment of Slope Stability using General Limit Equilibrium (GLE) Method in South Sikkim Himalaya, India

Sarkar Kallol and Mandal Sujit

Page No. 55-63

The slope stability analysis is a computational extent for determining the stability of the slope and it is performed to minimize the occurrence of landslides and slope failures. The fundamental criterion for stability analysis is the factor of safety against sliding which should always be greater than or equal to one for the slope to be safe. The objective of the study is to find out the factor of safety (FS) of the given slope under static conditions using the General Limit Equilibrium method (GLE). In this study, SLOPE/W has been applied for computing FOS under different shear surfaces.

The study aims to determine geotechnical and geometrical properties, i.e. cohesion (KPa), unit weight (KN/m³) and friction angle (˚) of five landslide prone locations of Jorethang, Singtam, Melli, Mellidara-Turuk and Farashey of South Sikkim Himalaya. The estimated safety factor value of all sites ranges from 0 to 0.5. It has been found that the Daling group of lithological composition is very much prone to landslide events where the safety factor is calculated close to ‘0’. The frequent earthquake phenomena in South Sikkim Himalaya have given birth to numerous faults and lineament which introduce favourable condition of slope instability.

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Adversities of monsoon rain in Chennai (TN) and isolation of pathogenic leptospires from the Environment and Screen the effect of Sodium hypochlorite

Thiruvengadam S. and Mazher Sultana

Page No. 64-71

The present study was carried out in order to find out environmental contamination of spirochetes and accounts for leptospirosis. We attempted for isolation of leptospires from 66 soil and 80 water samples collected from different zones of Chennai. Isolated strains allowed checking the efficacy of chlorine and it was correlated with meteorological data. Leptospires was found by dark-field microscopy in the cultures of 13 (16.25%) water samples and 11(19.5%) soil samples. Serovar which are isolated, found icterohaemorrgiae, australis, hebdomodis, autumnalisand canicola. In the chlorine's efficacy test, autumnalis was completely inactivated in the study period of two hours.

The highest positive isolation frequency occurred during the months of August to December (18.7%) with maximum and the minimum temperature of 30°C and 13°C respectively. Samples with average 81 % of moisture content, 38 % organic content and pH of 7.2 had shown the highest positivity with different proportion isolation.

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Fostering Societal Resilience and Sustainability to Disasters

Kamarudin Khairul Hisyam and Chong Noraini Omar

Page No. 72-80

The term resilience is originally derived from the Latin word ‘resilio’ which means ‘to jump back’. Nowadays, the term resilience is being adopted in many fields of research and for real life applications including disaster management. For researchers as well as the decision makers, the concept of resilience is to lead to a new way of attempting disaster and provide policy options. Furthermore, phrases such as sustainable and resilient communities, resilient livelihoods as well as building community resilient have gained wider popularity. Community resilience concept can best describe the adaptation of group of communities and societies to constant changing in their environmental, social, economic and political climates.

The communities possessed unique coping mechanism to deal with internal and external stresses as well as disturbances and are able (to certain degree) to bounce back and regain control of their daily activities even after the disasters. The adoption of community resilience concept as mentioned by several authors has been widespread into disaster-related research as well as in emergency management studies. The purpose of this study is to critically review the concept of disaster resilient community which has now gained a wider recognition in disaster risk reduction (DRR) discourse particularly at international level. Local stakeholders together with local disaster managers, government agencies at federal, state and local levels and non-governmental agencies (NGOs), now enthusiastically embrace resilience concept as a desirable objective in formulating frameworks and strategies for reducing disaster risks. By drawing upon an extensive array of relevant secondary sources, this study intends to provide discussions and basic knowledge regarding the concept and application of resilient community to broader audience of DRR stakeholders and implementors.

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