Department of Geography & Applied Geography
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Item Open Access Causes and effects of flash flood in Alipurduar District, West Bengal(University of North Bengal, 2023) Biswas, Sanjay; Mandal, D.K.Throughout human history, hazards have been a recurring occurrence, and it is widely recognized that we cannot completely eliminate their existence. This is especially true for natural hazards, as they are beyond our control. However, while we may not be able to prevent these events from happening, we can take measures to mitigate their impact and prevent them from escalating into catastrophic disasters through efficient planning and preparedness. Among the multitude of disasters, flash floods stand out as particularly devastating on a global scale. These events have the potential to escalate rapidly and inflict widespread damage in a very short span of time. Flash floods have posed a significant threat to Alipurduar District, earning it the reputation of being a flash flood-prone area. This study provides an overview of the factors contributing to flash floods in the District, their impact on the local ecosystem and socio-economy, and potential measures to mitigate the damage caused by these natural disasters. The region's diverse topography directly influences the severity of flash floods, with the hilly areas and foothills in the north of Alipurduar District being particularly susceptible. The rivers originating from the Bhutan Himalayas play a crucial role in triggering sudden slope changes and heavy rainfall, carrying substantial amounts of water, sand, and stones through the District. When these rivers reach the foothill areas, they deposit excess materials, elevating the riverbeds and causing sporadic flash floods during the monsoon season. Human activities such as mining, quarrying, and deforestation further exacerbate the impact of flash floods, disrupting the natural balance and increasing the District's vulnerability. Over the past few decades, numerous flash flood incidents have occurred, predominantly affecting the foothill areas in the north of the District. This research aims to shed light on the causes of flash floods in Alipurduar District and explore potential mitigation methods. The study delves into the relationship between flash floods and heavy rainfall, drainage systems, topography, human influence, and the elevation of riverbeds. Additionally, the research highlights the extensive impact of flash floods on human and livestock casualties, river course alterations, water quality, ecosystems, cultivation, forests, tea gardens, and the socio-economic condition of the District. The thesis is divided into eight chapters. The introductory chapter (Chapter I) provides an overview of flash floods, the study area, research objectives, the database and methodology employed, statement of the problem, and the significance of the study. Chapter II offers a brief description of the physical and cultural characteristics of Alipurduar District, covering topography, geology, climate, natural vegetation, drainage systems, population resources, and tea gardens. Chapter III discusses the drainage system of Alipurduar District in detail. This chapter provides detailed information about several small rivers in the study area. Source, course details, total catchment area and total length of each river are determined. Basically, the detailed information about the rivers has been presented with the help of long term field observation experience and Google earth. In this chapter river bank erosion sites are identified through field observation and discussed through photographs. The morphological characteristics of the rivers in the study area are discussed in details. Morphological features like alluvial fan, braided channel, meander, ox-bow-lake, point bar, sand bar, river island etc. are identified and discussed. Finally, in this chapter, the channel transformation of various rivers is discussed in details. Chapter IV extensively explores the causes of flash floods in Alipurduar District, with a particular emphasis on rainfall data. Rainfall data for the last 30-35 years has been reviewed in detail by collecting data from CWC, Irrigation and Waterways Department, Tea Gardens and Govt. agricultural farms. Each flash flood that has occurred in the study area, is discussed with evidence by collecting newspaper cuttings. The causes and damages of flash floods of 1993, 1998, 2000, 2004, 2007, 2010, 2014 and 2017 are highlighted. A separate household survey was conducted to discuss the causes of the 1993 flash flood. Data regarding the date and years of flash flood was collected from the clock offices and the cause of flash flood was discussed. The relationship of rivers with slope is discussed to determine the extent to which topography is responsible for flash floods in Alipurduar District. Field observations and photographs were collected as evidence to determine the extent to which river projects and construction barriers were responsible for flash floods. The details of the quarrying of various rivers in the study area have been discussed. The impact of upper catchment area dolomite mining on flash floods is discussed. During the field observations various photographs were collected to know the impact of mining and quarrying activities on flash floods. Chapter V examines the nature of flash floods in Alipurduar District, including flash flood frequency, flash flood magnitude index, duration of flash floods, and a historical overview of flash flood events. The discussion of this chapter is mainly based on CWC’s discharge data, water level data and rainfall data. Recurrence Intervals of three major rivers (Torsa, Raidak-I, Raidak- II) of Alipurduar District are discussed to obtain information about the frequency of flash floods. Generally, the effect of flash flood is seen in the whole District mainly after 2-3 years. However, flash flood occurs every year in Ballalguri, Totopara, Jamtala, Bandapani, Jayanti, Mechpara, Radhrani, Chuapara, Hatipota etc. In the northern foothill areas of Alipurduar District, flash flood water mainly stays for 2-3 hours, but in the southern plains it stays for 12-36 hours. On the basis of flash flood susceptibility, Alipurduar District has been divided into four parts and discussed about them in details. Flash Flood Magnitude Index (FFMI) of Torsa, Raidak-I and Raidak-II Rivers have been determined through discharge data. From the information of the District Disaster Management Plan, it has been seen that in this District, Madarihat-Birpara, Kalchini and Kumargram block are the most flash flood prone. Data of Qmax and water level of 1993, 1998, 2000, 2007, 2010 and 2017 were reviewed to know the nature of flash flood in details. Chapter VI, considered the core of the research, focuses on the effects of flash floods in the District. In this chapter, a household survey was conducted on 860 households to know the various effects of flash flood in Alipurduar District. Based on that, it has been possible to bring out various information. Data on human life lost in 1993 was collected through CWC integrated data book, newspaper cuttings as well as household survey. The mainstay of Alipurduar District’s economy is the tea industry. Naturally, the effect of flash flood is more on the tea gardens. The effect of flash flood of last 30-35 years on tea plantations has been discussed through the data obtained from Dooars Branch Indian Tea Association (DBITA). Tea gardens affected by flash flood have been identified through field observations and maps have been made with the help of Google earth and ArcGIS software. Information about the effect of flash flood on forest has been collected and discussed through field survey. Photographs of tea gardens and forests affected by flash flood in different years were collected during direct field observation. Some secondary data regarding flash flood affected forests were collected from different secondary sources. The impact of flash floods on crop pattern change in the northern part of the study area is discussed in detail. Information on flash flood affected construction and property loss across the District has been presented. Photographs of flash flood affected constructions and properties have been collected through field observations. This chapter discussed the effect of flash floods on soil properties. The water of various rivers of Alipurduar District is being affected for dolomite mining and in-stream quarrying. Water samples have been collected and tested from different rivers to provide detailed information on this matter. The Water Quality Index (WQI) table is created based on the weighted Arithmetic Water Quality Index (WAWQI) method. To collect data on river bed rising in the study area, river bed elevation has been measured regularly in different rivers during Pre-monsoon and Post-Monsoon periods for the last 6-7 years. Data and photographs of river bank failure in different parts of the District due to the effect of flash flood have been collected and discussed. Field observation was done and photographs were collected to know about the river valley enlargement. River channel transformation due to flash floods is also discussed. Finally, this chapter briefly discusses the positive effects of flash floods. Chapter VII outlines proposed remedial measures for flash floods in the study area, identifying vulnerable zones and rivers, and suggesting strategies and measures to mitigate the effects of flash floods. In this chapter, the guidelines given by WHO regarding flash floods have been discussed in detail. During the field observation, it was observed that the presence of forest in the foothill regions of the northern part of Alipurduar District has been able to resist the intensity of flash floods to a great extent. Hence the importance of forest in flash flood prevention is discussed in detail with photographs. Uses of local available materials (Sand, boulder, bamboo, bad materials, etc.) also discussed with photographic evidences. Finally, Chapter VIII presents the major findings of the research and offers a comprehensive conclusion. Finally, this research contributes to understanding the causes and impacts of flash floods in Alipurduar District. It provides insights into the vulnerabilities of the region and proposes potential solutions to minimize the devastating effects of flash floods. By addressing the various aspects discussed in this study, stakeholders can work towards building a more resilient Alipurduar District in the face of flash flood events.Item Open Access Geographical analysis of urban growth in Siliguri planning area, West Bengal(University of North Bengal, 2023) Saha, Arjun; Roy, RanjanTitle: A Geospatial Analysis of Urban Growth in Siliguri Planning Area, West Bengal Introduction: Urban growth is a universal phenomenon. It takes place in almost all the cities in the world. In developed countries, this growth had taken place much before than the developing and underdeveloped countries respectively. In developed countries, this has been taken place in a planned and efficient way, whereas in the developing and underdeveloped countries, it does not follow any rules and regulations, though in maximum cities of developing world there has some certain rules. Due to this unplanned nature of growth of urban built-up features, several productive lands that surround the city are going to extinct which creates an adverse effect on that city. India is a country which falls still in the developing world is facing this same situation in many cities. Some megacities which lie at the top of the table are comparatively follow better regulations and extending themselves in a sustainable way, but maximum cities which have an great economic importance in the country does not follow those rules. Growths in these cities are taking place due to the excessive increase of population mainly for the migration from rural areas primarily for better economic opportunities. Siliguri is a city that lies in the northern part of West Bengal is facing this same problem after its formation. From the beginning this area had been exploited for different purposes and besides this, as this urban centre playing a role of primate city for the entire North Bengal after independence, maximum people had shifted to this place for better livelihood, which makes the growth in a faster rate comparing to other. This faster growth of population and simultaneously urban built-up often captures the productive lands, like forests and agricultural land that surround this city in all sides. So, for this reason, this city with its surrounding area, known as Siliguri Planning Area (SPA) that demarcated by Siliguri Jalpaiguri Development Authority (SJDA) has been taken to find out the land use and land cover changes from 1992 to 2021, to identify the growth of urban built-up in this region, to identify the sustainably suitable places for new development, to analyze the relation between infrastructural development and urban growth and lastly to identify and analyze the possible problems that are occurring in this area due to unplanned and limitless urban growth. Database and Methodology: For this entire work, researcher has used different secondary data that are openly available in different repositories. For the analysis of land use and land cover and to analyze the urban built-up growth from 1992 to 2021, land surface temperature, vegetation index, Landsat satellite images for the year 1992, 2001, 2011 and 2021 have been used in this work. Beside this, for the identification of suitable places for new built-up development and for the analyze of infrastructural development, Census data of 2001 and 2011, Google earth data, data from different government sources, like department of food supply and distribution, department of mass education extension and library services, govt. of West Bengal, department of posts, govt. of India, Bank master data for West Bengal, etc. have been considered. Primary data has also been collected for the analysis of water quality of major two rivers of this region, Mahananda and Balason from total 17 sites. Beside these, some ground verification data has also been collected from using handheld Global Positioning System. First objective that is land use and land cover change analysis from 1992 to 2021 has been performed by using maximum likelihood classification technique after different processing of images in the GIS platform. Urban growth pattern has been analyzed by taking Shannon’s entropy in two ways; first by direction-wise and second by distance-wise and beside this, trends of urban growth and its speed of expansion has been identified by urban density analysis and Urban Expansion Intensity Index (UEII). Multi-criteria Decision Making (MCDM) and Analytical Hierarchy Process (AHP) has been taken for the identification of new preferable built-up locations. To analyze the relation between different infrastructural facilities and urban built-up growth Borda rule has been used in this work. Unplanned urban growth has some negative impacts on the natural surroundings. For this, in this work, impacts on river water, vegetation and in local temperature have been calculated and identified. Water Quality Index (WQI) has been used to monitor the river water quality, Vegetation index, such as Normalized Difference Vegetation Index (NDVI) has been performed for the vegetation density analysis and Land Surface Temperature (LST) has been used for analysing temperature fluctuation from 1992 to 2021. Different correlations have been performed for the analysis of relation between different indices and parameters. Brief Outline of the Study: This whole work has been completed by making total seven chapters. First chapter has been divided into two sections. Section A mainly deals with the overview of the whole thesis, problem of the statement, objectives that are taken, hypotheses that has been framed, rigorous literature surveys, about the study area, chapter details, scopes and etc. and Section B describes the general characteristics of the study area, like its different socio-physical characteristics. Second chapter is about the land use and land cover (LULC) dynamics in this study area and it has been done from the year 1992 with a ten year interval and up to 2021. Third chapter is the heart of this thesis that deals with the pattern, trends and speed of urban built-up growth in this region. Urban built-up growth has been calculated by using the extracted built-up features from the satellite images from 1992 with a ten year interval and up to 2021. Like this the trend and speed also has been analyzed and calculated from 1992 to 2021. Fourth chapter has tried to identify the perfect or suitable patches of land for new urban built-up area. This has been done using the data for the year 2021. Fifth chapter is about to study the relation between different infrastructural developments that has taken place in this region with population growth. This study has been carried out for the two years due to the availability of the data and these are, 2001 and 2011. Sixth chapter has tried to identify the problems or negative impacts on different parts of the environment due to the unplanned and fast built-up development. Negative impacts on river water, local temperature and on vegetation have been analyzed by using primary and secondary sources. Lastly, seventh chapter has summarized the major findings of this work and also put some remedial suggestions with concluding remarks to overcome different problems that this area has been facing. Major Findings: This study area lies in the piedmont of Darjeeling Himalaya and that is why the overall gradient maintains from the north and north-west to the south and south-eastern portion with an average height is about more than 150 metres. Connectivity is good in this region with three major railway stations and one airport and some national and international highways are also present here. Population growth due to the natural and migration is huge in this whole region. As this area lies in the piedmont of the Darjeeling Himalaya and Terai tract, so this area from very beginning is dominated by different forest cover and as this area was facing huge population growth due to its locational importance, so drastic positive and negative changes in different categories of LULC has been seen. Vegetation cover has been lost about 56 sq. km. from 1992 to 2021. Agricultural land has been changed into built-up land in Chandmuni tea estate area. Built up land has occupied the core zone of this study area almost entirely. A significant growth of built up land has seen along the highways that radiated from the core city centre. In case of built-up pattern, the whole area from the 1992 is showing dispersed pattern of development instead of compact one. Though in the last calculated year, it is moving towards the compact pattern just because for the restrain of available lands. In first three years, Shannon’s entropy value lies close to the logn value and for that it can be said that this area has experienced an urban sprawl that destructs different productive lands. The analysis revealed that the urban growth in Siliguri Planning Area follow a regular radial pattern. Ribbon pattern of sprawl is observed along the highways and leapfrog pattern towards southern and northern direction due to working opportunities, educational facility and because of tea planted areas of the study area. This study has identified that the maximum suitable area for new built-up development has seen in between the 5 km. to 9 km. from the core of the city and after this, suitable area decreases. Very little amount of lands has been identified as highly suitable area that is 4.58 sq. km. that denotes this study area presently stays at its well condition in case of built-up categories. Further construction will harm the nature. This study area is mainly dominated by medium suitable area and mostly lies along the accessible roads. Maximum areas of highly suitable area and moderate suitable areas come from wasteland and the vegetated land has been preserved. The core area that is Siliguri city is highly dominated by different infrastructural facilities with the highest score in both two years from the beginning as this area holds more than half of the population of the total study area. Other old centres like Bagdogra, Bairatisal also shows comparatively better infrastructural condition in this region. Dabgram and Binnaguri that are very close to Siliguri city have shown a higher score of infrastructural facilities. Analysis of water quality reveals that Balason River is much better than the river Mahananda as Balason mainly flows from the outer periphery of the core area and population pressure is much lower than that of river Mahananda. Water quality is worst in the Airview sampling site of Mahananda in both seasons due to the pressure of population and their different activities. It has been seen that, a significant change of river water quality between upstream and urban and also urban and downstream. In the southern portion of the study area a fresh water canal has mixed up with river Mahananda which makes is better quality in the downstream portion. Land surface temperature has been calculated for the year 1992 and 2021 and it has been seen that about 0.5⁰C temperature has risen in the highest temperature. Maximum temperature has been recorded in the core of the study area and this is due to the highest density of population, maximum traffic movements, absence of thick vegetation cover etc. Vegetation density has also been analyzed in this region from 1992 to 2021 by using Normalized Difference Vegetation Index or NDVI. Results reveal that highest value of NDVI was 0.75 in the year 1992 which has reduced in to 0.43 in the year 2021 due to the expansion of impervious surfaces on the study area. Values of NDVI also suggest that in the year 1992, high dense vegetation was there which has come in the medium dense category in the year 2021. Conclusion: Development and destruction goes in the similar way. If any area has seen any major developmental projects then it is obvious that, same place has faced some kind of destruction in the natural environment. Urban built-up growth and successive population growth is now a natural phenomenon and this will happen and increase its magnitude in near future. Developed countries has faced this situation much before than present developing and underdeveloped countries and that is why they had faced different problems in earlier and now they are in a stable condition due to low and even zero population growth. India falls on the developing one and that is why most of the cities in this country are facing tremendous population growth, unplanned urban built-up growth, shortages of suitable lands for new built-up places, and also problems on different parts of natural environment. Siliguri Planning Area is also facing this same problem mainly after the partition at the time of independence. That is why this work has tried to identify the built-up growth, urban sprawling, and different problems of this growth on natural environment, like on water, forest, and also in the local temperature. Overall study in this region reveals that unplanned and haphazard built-up growth and urban sprawling and huge population growth has taken place and due to this local temperature has risen in this area, high dense and thick vegetation cover has almost lost in thirty years, water quality degrades when river enters in the core urban and highly populated area. Outcomes and findings of this study will help to the locals, planners, government officials, policy makers to take necessary and suitable steps for the proper planning and betterment for this areaItem Open Access Impact of hydrological changes and adaptation practices of the rural people in the lower teesta river basin of West Bengal, India(University of North Bengal, 2023) Das, Dipankar; Roy, RanjanThe Teesta River, which is regarded as a source of sustenance in the landscape, is situated in the Himalayan and Sub-Himalayan region and has hydrological characteristics that are frequently significantly altering. In this regard, morphometric analysis has been created for the Teesta River basin area, and different morphometric data have been produced utilizing topographical maps released by the Survey of India as well as Remote Sensing and GIS platforms. The examination of physical characteristics and human interference allows for the identification of numerous hydrological changes. Anthropogenic activities have created adjustments along the Teesta, which change the hydro-morphological properties across the basin area. These changes are manifested in a variety of dangerous circumstances, primarily flooding across the concerned river's flood plain, while concurrently, for most portions of the basin, agriculture denotes a leading role in this regard. Agriculture in the study area has advanced significantly in recent years. But lately, it has been struggling with issues including tiny land holdings, traditional agriculture with poor infrastructure, a lack of surface water, and rising climatic and hydrological variability. The River Teesta's flood plain is a significant source of natural resources that provide high economic and livelihood values to the locals who live along the river's banks in the study region. Local rural residents are currently dealing with a different kind of issue as a result of hydrological and hydro-morphological changes. Due to the high demand for agricultural products, smart agriculture and appropriate adaptation strategies are required to ensure agricultural output. As a result, this is a reform of the agricultural system to increase productivity and reduce its impact on the environment. An effort has been made to uncover some little-known information about the restoration, conservation, and management of the floodplain through sustainable agricultural adaptation practices that closely resemble hydrological changes, which are more beneficial to socioeconomic development as well as serve to lower the risk of human habitation and promote sustainable use of the land in the nearby riparian areas. The current research aims to conduct an in-depth analysis of the Teesta River's hydrological processes, including any changes or issues they may have, and to add value to assessments of the socioeconomic resilience of the areas around the channels by offering some suggestions for long-term adaptation and management and The supposition of this research is that the adoption of climate-smart agriculture results in increased agricultural output as well as field-level water and energy savings. Smart agriculture is one example of an adaptation practice that can lessen many of the negative effects of hydrological variability and hydrological change. These practices can also improve socioeconomic situations and many other advantages. The peasants are less vulnerable due to inadequate infrastructure, scarce economic resources, insufficient water supply, and traditional agriculture. However, adaptation techniques like mulching, zero tillage, solar-powered irrigation pumps (SPIP), etc. tend to benefit the villages on several levels, including energy and water savings, as well as production increases. Our research demonstrates that smart agriculture is a framework to integrate its use at the national, state, and local level strategies for wide-scale and long-term support of it in developing nations, such as India. Overall, adaptation practices such as smart agriculture play a key role in preserving agricultural sustainability in the face of increasing hydrological risk and variability. The methods employed in this study are to evaluate a conceptual framework of vulnerability and adaptability in agriculture using various indicators related to the study's central issue. It is based on the integration of numerous climate risks and hazards, environmental elements, and socioeconomic aspects that generate evaluations using the multi-criteria decision-making technique and the association between hydrological, socioeconomic, economic governance, biophysical, and coping mechanisms of locals in the research area was examined using the binary logistic regression model. Consequently, it suggests that policymakers incorporate smart agriculture into their development planning which is essential for lowering agricultural susceptibility to the hydrological risk and flood occurrences that have a devastating impact.Item Open Access Trends and patterns of agricultural hand use in Maldah district, West Bengal(University of North Bengal, 2022-11) Mandal, Tapash; Saha, SnehasishItem Open Access Effects of terrain characteristics on land use land cover in sanka river basin (West Bengal and Jharkhand)(University of North Bengal, 2021) Biswas, Baidurya; Saha, SnehasishItem Open Access Bank erosion and associated problems in upper mahananda basin in Darjeeling district, West Bengal(University of North Bengal, 2021) Sarkar, Pompi,; Mandal, D.K.Item Open Access Changes in agricultural land use scenario in Uttar Dinajpur District, West Bengal(University of North Bengal, 2021) Sarkar, Goutam ,; Mandal, D.K,