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Disaster Advances

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Disaster Advances

Inferring the role of integrated geomorphology and land use / land cover on tsunami inundation through factor analysis

Selvakumar Radhakrishnan* and Ramasamy Somasundaram

The 26th December 2004 tsunami inundation had caused severe damages all along the east coast of Tamil Nadu. The features like near shore topography, geomorphology and land use dictate the extent of inundation while the post tsunami field survey shows that the extent of inundation and its resultant damage is not uniform. Further, significant variations were also noticed even within the same landform feature having similar topographic gradient indicating that the inundation is not solely controlled by an individual factor. To unveil the interrelationship between the above features and inundation, the 140-km coastal stretch of Tamil Nadu from Porto Nova in the north to Kodiyakkarai in the south was studied. The post tsunami ENVISAT satellite image was used for mapping the inundation while the controlling parameters namely the geomorphology and the land use / land cover were mapped using IRSP6 satellite images and subsequently integrated using ArcGIS 9.3 software.

To precisely deduce the causative factor, a piecewise correlation was done by laterally dividing the study area into 14 segments of 10 km each. Consequently, by integrating it with the above layers, the aerial extent of inundation and the integrated geomorphology and land use / land cover features in each segment was calculated. Then using the terrastat statistical software, factor varimax analysis was carried out between them and based on the derived factor scores, the role of the integrated features over the inundation was deduced. Consequently, mitigation strategies were suggested.

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Landslide Hazard Zonation Mapping and its Validation using Geospatial Technology and Image Processing Techniques

Anitha K.* and Vaideeswaran

Landslides can cause many problems such as human and livestock fatalities and damage to property and vital communication infrastructure. Landslide Hazard Zonation map is very useful to understand the severity level of landslide. This study presents a LHZ map for the Nilgiri District of India based on a weighted linear combination (WLC) model, geospatial technology and satellite image processing. Eight landslide occurrence factors were selected as land cover (derived from 15-m-resolution satellite images, distance from roads, railways, streams, slope gradient, slope aspect, soil type, and rainfall). These factors were analyzed using a WLC model in the adaptive open-source QGIS geospatial system software to produce the LHZ map.

Actual Landslide locations of year 2009 in the study area were identified by interpretation of satellite imagery and using global positioning system surveys. Initially, a spatial database was constructed using the GIS, following which processing of the satellite imagery was performed using a digital elevation model, soil map and rainfall map. Finally, the locations of actual landslides were used to validate the LHZ map which revealed agreement between the computed susceptibility map and actual landslide areas to 70% accuracy.

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Comparative Study on going to Evacuation Shelters in School Districts and the Nearest Shelter in the City - A Case Study of Kanazawa City, Japan

Nguyen Dinh Thanh, Shen Zhenjiang* and Sugihara Kenichi

In many countries, residents are required to go to nearest shelters for evacuation when an earthquake occurs. Moreover, in many literatures, nearest evacuation is also considered as one of principles of evacuation shelter planning. However, in Kanazawa city, residents are required to evacuate at main accommodation shelters (hereafter main shelter) in their primary school districts (hereafter school district) which are not nearest shelters from their houses in many cases. It seems there is a conflict between evacuation shelter planning and the current evacuation method in Kanazawa city.

This research, therefore, contributed a method for comparing two evacuation scenarios that include going to main shelters in school districts (hereafter scenario 1) and going to nearest main shelters in the city (hereafter scenario 2) based on total evacuation distances from evacuees’ houses to main shelters; four distance categories of 2km service areas: 0-500m, 500-1000m, 1000-2000m and over 2000m and a supply-to-demand ratio of each main shelter. Results showed that scenario 2 was better and more convenient to evacuees than scenario 1. The results may also provide a useful reference to disaster managers for reviewing current evacuation method as well as supporting them to rethink a plan for improving current evacuation method.

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Morphometric Investigation of Morna River Basin, Maharashtra, India using Geospatial Techniques

Chougale Sujit S. and Sapkale Jagdish B.*

Nowadays river systems consisting with uneven number of natural resources face different problems with a large population pressure and climate change. To overcome such problems, the river basins must monitor properly using advanced technologies. In the present research work, an effort verifying the detailed morphometric characteristics of Morna river is undertaken which itself is a part of Warna basin of Maharashtra. A morphometric analysis of Morna river proceeds using geospatial techniques. The purpose of assimilation of morphological features and analyzing properties of basins can be done by using GIS and image processing techniques. Linear and areal aspects of morphometric parameters can be evaluated using GIS. The present task copes mainly with morphometric parameters such as stream order, stream length, bifurcation ratio, drainage density, stream frequency, texture ratio, elongation ratio, circularity ratio and form factor ratio etc. For the preparation of DEM, Cartosat data can be used; whereas for the evaluation of linear, areal and relief aspects of morphometric parameters GIS technique can be taken into consideration.

The Morna river basin is estimated to have an area of 172.2 km2. The study area was concerned with 1st to 6th stream orders. There are altogether 449 streams with a total stream length of 395.25km. Present research work is useful to understand the topography, erosional status and drainage pattern of the area and also for constructing a comprehensive watershed development plan. This study plays an important role in planning rainwater harvesting and watershed management also.

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Climate Change perception and adaptation strategies among various stakeholders in Nalanda District of Bihar (India)

Kundan Sagar

The aim of the research was to assess climate change issues of relevance to traditional peoples’ views and knowledge about climate change, its impacts and activities, adaptation strategies together with any perceive hindrance to its adaptation. These people are vulnerable to the effects of climate change due to their marginal location, low levels of technology, and lack of other essential farming resources. The research study was carried out in Nalanda district of Bihar (India), commonly known for its rich culture inherited from various dynasty and birthplace of and great personalities and several religions along with rich wildlife, birds and sanctuaries and immense agricultural activity.

This research also aims to identify indigenous practices that jeopardize the sustainable development module among predominantly smallholder farmers by their knowledge of climate change impacts and adaptation strategies. This study utilizes information from questionnaire surveys administered to bureaucrats. Adaptation occurs through public policy making and decisions made by these stakeholders. The questions covered in the survey included a focus on possible holistic stakeholder perceptions in understanding the climate change effects on the environment, socio-economic status, current preparedness, coverage of climate change issues in current plans, the need to respond and the measures required. Climate change is potential threat to corrode the many development gains made by Bihar and it is believed that frequency and intensity of extreme weather events are likely to exacerbate in future.

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