http://dspace.dtu.ac.in:8080/jspui/handle/123456789/46 2026-06-11T22:41:10Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22774 Title: STUDY ON ASSESSMENT OF FLOODS & GROUNDWATER SUSCEPTIBLE ZONES IN IDUKKI DISTRICT, KERALA USING GIS BASED APPROACH Authors: KHAN, ZOHAIB AHMED; Jhamnani, Bharat (SUPERVISOR) Abstract: Floods constitute a recurrent and intensifying hydro-meteorological hazard in the Idukki district of Kerala, driven by the coupled influence of steep topography, high monsoonal rainfall variability, land use transitions, and complex catchment scale hydrological responses. This thesis undertakes a comprehensive assessment of flood susceptibility and its consequent impacts using an integrated geospatial and hydrological modelling framework, providing a scientific basis for understanding their broader environmental significance. The study begins with the development of a flood susceptibility map for the Idukki district using twelve hydrological and geomorphological parameters such as geology, distance from river, land use, Topographic Wetness Index (TWI), elevation, slope, Topographic Roughness Index (TRI), soil, aspect, rainfall, Stream Power Index (SPI), and Sediment Transport Index (STI) within a GIS-based Analytical Hierarchy Process framework. The developed flood susceptibility map was categorized into five susceptibility categories namely very low, low, moderate, high, and very high and these classes occupied the areas of 609.0417 km2, 1222.83 km2, 1180.45 km2, 950.48 km2 and 395.9487 km2 respectively. The analysis also identifies over 30% of the district as highly susceptible, with prominent hotspots in Thodupuzha and central Idukki where low terrain gradients, dense drainage networks, and proximity to major rivers enhance flood generation potential. To characterise subsurface conditions, groundwater potential zones were modelled using a GIS-enabled machine learning approach incorporating AdaBoost, Gradient Boosting, and Random Forest algorithms, capturing the influence of litho-structural features, slope, land use, and other recharge- controlling factors. These groundwater potential outputs were subsequently integrated with the flood susceptibility map to derive a groundwater susceptibility assessment, enabling evaluation of how flood affected areas respond in terms of recharge capacity. The coupled analysis reveals that regions repeatedly subjected to inundation experience elevated runoff coefficients, increased sediment detachment, and reduced infiltration, collectively constraining groundwater replenishment even in zones with otherwise favourable structural characteristics. To evaluate how successive flood events alter the district’s surface conditions, Land Use and Land Cover (LULC) changes associated with the major floods of August 2018 vi and October 2021 were analysed using multi-temporal satellite imagery classified with a Random Forest algorithm on the Google Earth Engine platform. The 2018 floods affected approximately 20.86 km², influencing built-up (0.48 km2), forest (10.60 km2), agricultural (5.11 km2), and barren (4.67 km2) areas, whereas the 2021 event impacted about 19.24 km² across built-up (0.24 km2), agricultural (6.23 km2), barren (2.82 km2), and forest (9.95 km²) classes. These spatial patterns illustrate the substantial modifications to vegetation cover, agricultural land, and terrain stability driven by repeated high-intensity rainfall and flooding in the region. The impact of flooding on surface runoff was further quantified using the Soil and Water Assessment Tool (SWAT) applied to the Periyar River Basin, the largest basin within the Idukki district. Model simulations indicate substantial amplification of runoff during extreme rainfall events, with several outlets exhibiting nearly a 128% rise and others showing increases exceeding nearly 126% compared to non flood conditions. These elevated discharge responses spatially coincide with the high and very high flood susceptibility zones, reinforcing the reliability of the susceptibility modelling and highlighting the presence of hydrologically sensitive regions within Idukki. Collectively, the findings demonstrate strong interactions between surface flooding, groundwater recharge dynamics, landscape transformations, and basin scale runoff behaviour. The integration of multi-criteria analysis, machine-learning modelling, remote sensing, and hydrological simulation provides a comprehensive framework for characterising flood impacts in a complex mountainous environment. The outcomes offer valuable insights for flood mitigation planning, groundwater management, and sustainable land use decision making, while establishing a robust methodological foundation for future hydrological assessments in similar data-scarce regions. 2026-04-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22762 Title: INTEGRATED ANALYSIS OF DISASTER MANAGEMENT IN WESTERN HIMALAYAN REGION Authors: SRIVASTAVA, ANUPAM; TIWARI, K. C. (SUPERVISOR) Abstract: The study presented herein delves into an exhaustive examination of Glacial Lake Outburst Floods (GLOFs) within the Chenab Basin, aiming to assess vulnerability, develop mitigation strategies, and enhance preparedness through the implementation of an Early Warning System (EWS). Leveraging remote sensing data and sophisticated algorithms, this research endeavors to classify glacial lakes, analyze temporal changes in glaciers and lakes over the period 1990-2018, and model potential GLOF impacts downstream. Two specific lakes, namely Lake 1 and Lake 2, have been identified as particularly vulnerable, prompting the application of hydrodynamic modeling to predict potential flood scenarios and assess their repercussions on downstream communities. The methodology employed in this study involves the utilization of remote sensing techniques coupled with a decision tree algorithm for the classification of glacial lakes based on specific parameters and spectral characteristics. By systematically analyzing temporal changes in glacier dynamics and lake expansion, researchers can effectively identify evolving patterns and assess potential risks associated with GLOFs. Through this process, Lake 1 and Lake 2 emerged as focal points for vulnerability assessment and subsequent mitigation measures. Hydrodynamic modeling constitutes a pivotal component of the research methodology, enabling the simulation of GLOF scenarios and the estimation of response times for downstream communities. The findings underscore the heightened vulnerability of villages SHANSHA and THOLONG to GLOFs originating from Lake 1 and Lake 2, respectively, with projected response times of 60 minutes and 4 hours 15 minutes. These insights provide valuable input for the development and implementation of an effective Early Warning System tailored to the specific needs and dynamics of the Chenab Basin. The study advocates for the integration of advanced geophysical monitoring systems, remote sensing technologies, and machine learning algorithms within the framework of the proposed EWS. By harnessing real-time data and predictive analytics, authorities can enhance early detection capabilities, facilitate timely communication, and mitigate the potential impact of GLOFs on vulnerable communities. Furthermore, the study emphasizes the importance of community engagement and capacity building initiatives to foster resilience and empower local stakeholders in disaster preparedness and response efforts. 2024-05-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22757 Title: DYNAMIC ANALYSIS OF PAVEMENT-SOIL SYSTEM WITH PIEZO-SENSORS Authors: KUMAR, YAKSHANSH; TRIVEDI, A. (SUPERVISOR); SHUKLA, SANJAY KUMAR (CO-SUPERVISOR) Abstract: The dynamic performance of pavement–soil systems under moving vehicular loads is a complex interaction of load-induced stresses, material damping, and subgrade behavior. Despite significant theoretical progress, practical implementations remain limited due to the lack of integrated modeling frameworks and sensing mechanisms that can capture in situ dynamic responses. This thesis presents a comprehensive investigation that combines finite element-based numerical simulation, experimental validation, and piezoelectric sensing to develop a generalised dynamic framework for pavement–soil systems. A finite element model incorporating viscoelastic pavement layers over an elastoplastic subgrade was developed using Lagrangian mechanics and multi-degree-of-freedom discretization. The model introduces a Generalised Dissipation Mechanism (GDM) defined by dissipation parameters (α, β, γ) and empirical coefficients (η, ϑ) to quantify damping and amplification characteristics under moving loads. Simulations revealed a 70% increase in load and a 46% increase in displacement compared to static conditions, establishing realistic velocity-dependent amplification zones. The Vibrational Compounded Stress Transfer Mechanism (V-CSTM) was formulated to explain the nonlinear amplification and post-elastic flow behavior of geomaterials, bridging cyclic strength and fatigue responses under high-velocity traffic loads. Experimental investigations employed flexible PVDF and PVDF–MoS2 piezoelectric films embedded within confined geomaterials to capture electromechanical responses under vibration. The inclusion of MoS2 nanoflakes enhanced the electroactive β-phase from 54% to 76%, producing a four-fold increase in voltage output (up to 16.2 V) and viii confirming superior energy-harvesting efficiency. Correlations between frequency, stress, deflection, and voltage established the films’ suitability for vibration sensing and renewable energy generation. The integrated numerical–experimental framework enables quantification of damping, stress transfer, and energy dissipation across multi-layered pavement systems. The developed piezo-sensors demonstrate strong potential for self-powered monitoring, while the coupled model offers predictive capability for deformation and damage evolution. Overall, this research advances the understanding of dynamic pavement–soil interaction and contributes to the development of smart, sustainable, and energyefficient infrastructure systems. The work supports Sustainable Development Goals 9 and 11 by promoting intelligent transport networks capable of real-time monitoring, reduced maintenance, and green energy harvesting. 2026-03-01T00:00:00Z http://dspace.dtu.ac.in:8080/jspui/handle/repository/22748 Title: STUDY ON HIGH EARLY AGE STRENGTHS OF POZZOLANIC CEMENTITIOUS COMPOSITES Authors: TIWARI, ABHAY; KUMAR, AWADESH (SUPERVISOR) Abstract: Cement is used for all types of constructions, be it a small residential building or a multistoreyed skyscraper, a dam, a highway, a bridge etc. Use of cement has been indispensable for development and its production has increased many-fold in last few decades. The total volume of global production of cement was 1.39 billion tonnes in 1995, which has registered 200% growth in less than three decades and has reached to 4.1 billion tonnes in 2022. This trend is likely to continue due to high demand of cement for infrastructural projects throughout the world. India is the second highest producer of cement in the world. Its overall cement production capacity for 2020-21 was placed at 537 million tonnes. Experts predict that cement demand in India will increase up to 800 million tonnes by 2030. It is also predicted that in case of high demand, it may reach up to 1.4 billion tonnes by 2050. Thus, it is quite evident that for infrastructural development, our dependence on cement is not going to diminish in near future. Unfortunately cement is not a green material, its manufacturing involves blending of various raw materials in required proportion and burning them at a high temperature. Limestone is used for calcium requirement, while clay, mudstone or shale as the source of silica and alumina. Starting from querying of raw materials then crushing, blending, burning, grinding of clinkers and finally packing of cement, the entire cycle of cement production is highly energy intensive and requires 2.8 GJ of energy for producing one tonne of cement. Production of one tonne cement consumes about 1.5 tonne of calcium carbonate (i.e. limestone), which is around 80-90% of total raw material, while remaining 10-15% is clayey raw material. On the other hand, cement manufacture accounts for 7% of world energy sector emissions, including process emissions. 40% of CO2 emissions from a cement plant are generated by combustion, while 60 percent emissions are due to calcification. The burning of fuels for maintaining high temperature, required for fusion is responsible for combustion-generated CO2 emissions. Decomposition of raw materials such as limestone at about 900°C liberates CO2 during their calcification. In recent decades, carbon dioxide emissions from cement manufacturing in India have seen a significant increase. In 2021, the recorded figures peaked at 149 million metric tons. It also releases huge amounts of air pollutants like PM (particulate matter), NOX, CO, SO2 and some volatile organic compounds. Another important concern of the construction industry in particular and entire globe as a whole is durability of concrete. Durability refers to the capacity to render its service over an extended period without notable deterioration. A durable material contributes to environmental conservation by preserving resources, minimizing waste and lessening the environmental consequences associated with repairs and replacements. In the context of concrete, durability is characterized by its resistance to weathering, chemical attacks and abrasion etc., all while retaining its intended engineering properties. Recognizing the significance of ensuring the durability of concrete structures, the Indian Standard (IS: 456-2000) has included a complete clause covering different aspects of durability of concrete. As we know, concrete is a composite material formed by combining fine and coarse aggregates, bonded with cement paste, which gain strength over time. It holds the distinction of being the second-most-utilized substance globally, following water and stands as the most extensively employed building material. It is so widely used because of its strength, durability, sustainability and versatility. Concrete structures have to withstand normal to the most severe exposure conditions. Sometimes they are so located that their repair is very difficult. Hence, their durability is very important. Additional concerns that have contributed to above mentioned pressures of environmental pollution and resource depletion on cement industry, are associated with rise in the occurrences of concrete structures, facing significant durability challenges. An effective solution to the above mentioned problem due to ever increasing use of Ordinary Portland Cement (OPC) lies in partial replacement of cement by pozzolans. Pozzolans encompass a broad range of siliceous and aluminous materials that may or may not have cementations properties. Yet, finely divided and in the presence of water, these materials undergo a chemical reaction with calcium hydroxide [Ca(OH)2] at ambient temperatures, yielding compounds that exhibit cementitious characteristics. Fortunately, a number of pozzolans are available in nature and also as industrial byproducts such as burnt clay, volcanic ash, fly ash, metakaolin etc. Thus, in order to reduce the harmful effects of OPC production, Portland Pozzolana Cement (PPC) may be used as an alternative. As per Indian Standard codes, the overall pozzolana content in Portland Pozzolana Cement (PPC) is carefully regulated, so that it remains between 10 percent and 35 percent by mass of the Portland Pozzolana Cement. The Indian Standard Codes [IS: 269 - 2015 and IS: 1489 (Part 1 and Part 2) 2015] have prescribed compressive strengths of PPCs that are significantly lesser than the OPC strengths. This difference in the strengths of OPC and PPC is definitely a hindrance in the use of pozzolanic cements as a replacement to OPC. During hydration of OPC, alite i.e. tricalcium silicate (C3S) and belite i.e. dicalcium silicate (C2S) are the two co mpounds, which contr ibute ma inly to the strength o f hydrated cement products. They react with water and transform into calcium silicate hydrate (C3S2H3) and hydrated lime [Ca(OH)2]. C2S hydrates slowly and influences gain in later age strength. The released lime from hydration of C3S and C2S reacts with pozzolanic material, if used, mostly of siliceous nature like fly ash, silica fume, ground granulated blast furnace slag etc., which makes additional calcium silicate hydrate at later stage and improves later age strength. But, addition of pozzolanic material having high alumina content may give advantage of increased initial strength and enhanced durability by consuming the free calcium hydroxide made available by the hydration of C3S in the beginning Incorporation of pozzolanic admixtures of siliceous nature results in slow gain of strength and supports later age strength gain of the cementitious composites whereas, aluminous pozzolan support early gain of strength. Hence, judicious blending of aluminous pozzolans and siliceous pozzolan has proved an effective solution in present study to enhance the compressive strength of PPC equivalent to OPC. The present research program involves the examination of effects of various blends of OPC and pozzolans on development of early age strengths of concrete and also study on their durability, so that suitable blend(s) of pozzolanic materials could be recommended to enhance the early age strengths of pozzolanic cementitious composites at par with OPC products of durable nature. In order to suggest various blends of different pozzolans of optimum proportions, for high early age strength development of acceptable durability, at par with OPC products, detailed experimental study has been carried out on 11 blends of OPC with different pozzolans with regard to development of 7 days and 28 days compressive strength, split tensile strength and flexural strength. Further, the durability aspect on these blended products and OPC product was also conducted under accelerated environmental effect by subjecting the specimens to alternate wetting and drying cycles in 10% solution of sodium sulphate. Residual strengths and weight loss of these products were measured after 150, 300 and 500 cycles. The study suggests that certain blends of OPC and pozzolans give comparable performance to pure OPC. This study has been attempted to provide alternatives to pure OPC composites by using blends of siliceous and aluminous pozzolans with OPC. These pozzolans are abundantly available either as industrial waste or natural materials. Use of industrial wastes reduces their negative environmental impact. The availability of these materials at low cost proved to be an economic alternative to the highly processed material like OPC. Findings of the research are a step towards solution of the problems due to ever increasing consumption of cement, which is a significant threat to environment because of high consumption of natural resources and energy along with generation of enormous amount of pollution. 2024-05-01T00:00:00Z