2. Thesis and Dissertations
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Item Hydrological Impact of Land Use and Climate Change on The West Coast River Basins of Karnataka(National Institute Of Technology Karnataka Surathkal, 2023) T.M, Sharannya; Mahesha, AmaiThe Western Ghats of India is an environmental and climate-sensitive region of India. The Western Ghats are the mountainous forest range of a tropical region that play significant role in distributing Indian monsoon rains. Three west-flowing rivers of the Western Ghats representing different levels of anthropogenic influence were chosen for this study to understand the individual and combined effect of land use land cover (LULC) and climate change (CC) on the hydrology of river basins that spread over the northern, middle and southern portion of the west coast Karnataka. The study was carried out with five objectives which include (i) Assessment of satellite and India Meteorological Department (IMD) rainfall products for streamflow simulation in the study area, (ii) To investigate long-term changes in current LULC and model predicted future LULC scenarios on streamflow, (iii) To evaluate the impact of long-term climate change on regional hydrology using SWAT and to assess the river basin responses, (iv) To assess the combined impact of land use land cover change and climate change over the study area, (v) Scenario analysis of the combined effect of land-use change and climate change on blue water and green water availability. Evaluation of satellite precipitation data was performed using the Tropical Rainfall Measuring Mission (TRMM) and Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS), employing a semi-distributed hydrological model, i.e., Soil and Water Assessment Tool (SWAT), for simulating streamflow and validating them against the flows generated by the India Meteorological Department (IMD) rainfall dataset. The historical land use (LU) changes were studied for four decades (1988– 2016) using the maximum likelihood algorithm and the long-term LU (2016–2100) was estimated using the Dyna-CLUE prediction model. Five General Circulation Models (GCMs) were utilized to assess the effects of climate change (CC) and the SWAT model was used for hydrological modeling of the three river basins. To characterize granular effects of LU and CC on regional hydrology, a scenario approach was adopted and three scenarios depicting near-future (2006–2040), mid-future (2041–2070), and far future (2071–2100) based on climate were established. iIt was observed that the IMD rainfall-driven streamflow emerged as the best followed by the TRMM, CHIRPS-0.05, and CHIRPS-0.25. The impact of climate change was more predominant than the impact due to land use land cover. However, deforestation and the conversion of other LULC into an unorganized plantation/ agriculture with urban expansion contribute to an increase in streamflow. As per the water availability and vulnerability assessment, the Aghanashini basin was classified under the extremely vulnerable sector, Gurupura and Varahi basins under the low vulnerable sector for water scarcity. The thesis is an attempt to study the LULC comprehensively on the impact on rivers of the Western Ghats of India and is an effective tool in understanding the hydrological impacts and adopting strategies to counter the impacts of LULC and CC.Item Exploring the Hydraulic Performance of Conical Pile Head Breakwater – An Experimental Investigation(National Institute Of Technology Karnataka Surathkal, 2023) H S, Arunakumar; U., Pruthviraj; Shirlal, Kiran G.Conventional pile breakwater is a pervious structure built using prismatic circular piles and it has been proven to provide partial protection efficiently. Increasing the size of the pile breakwater in the vicinity of the free surface increases its hydraulic efficiency, as most of the wave energy is concentrated there. In the present study, the conventional pile breakwater model is modified by widening the cross-sectional area of the piles at the surface level in a conical shape termed as conical pile head breakwater (CPHB). The influence of the dimensionless structural parameters such as relative diameter (D/Hmax), relative height (Y/Hmax), relative clear spacing (b/D) and relative clear spacing between rows of CPHB (B/D) on the hydraulic performance is comprehensively explored through physical model studies. The hydraulic performance of the model includes wave transmission (Kt), wave reflection (Kr) and energy dissipation (Kd) coefficients. The study is carried out under monochromatic waves of varying wave height (0.06 m to 0.16 m) and wave period (1.4 s to 2 s) at different depths of water (0.35 m, 0.40 m and 0.45 m). For single-row non-perforated CPHB, the structural configuration of D/Hmax = 0.4, Y/Hmax = 1.5 and b/D = 0.1 have emerged as the best performing model for which a smaller value of Kt of 0.66 is obtained along with Kr of 0.22 and Kd of 0.72. Further, the investigation is carried out to determine the influence of the second row of similar piles arranged in a staggered manner. For two rows of CPHB, B/D of 0.4 is the optimum spacing, which provided a minimal Kt of 0.58 with Kr of 0.24 and Kd of 0.79. The addition of a second row of piles with a similar configuration reduces the Kt by a maximum of 12.34% compared to a single row of CPHB. However, from the construction point of view, driving two rows of piles at a closer spacing in the field may give rise to technical issues and practical difficulties such as disturbance of neighbouring piles, altering soil bearing capacity, equipment manoeuvring and restricted access for construction and maintenance personnel due to the limited space. iTo ward off such possibilities, an effort is made to enhance the functionality of single row of CPHB structure by introducing perforations to encourage energy dissipation. The influence of perforations on the performance of the perforated CPHB is comprehensively investigated through physical model studies. The effect of perforations and their distribution around the pile head (Pa), percentage of perforations (P) and size of perforations (S/D) on the wave attenuation characteristics are evaluated to arrive at an optimum configuration. A minimum Kt of 0.58 associated with Kr of 0.26 and Kd of 0.78 is obtained for an optimum configuration of Pa = 50%, P = 19.2% and S/D = 0.25 at a water depth of 0.45 m. This result compares exceptionally well with that of two rows of CPHB. Overall, providing the perforations is found to be effective in enhancing the wave attenuation capability by up to 12.4%. The Kt of the proposed CPHB is about 19 to 35% lesser than that of the perforated hollow pile breakwater under matching test conditions. To ascertain the suitability of an open-source software REEF3D in CPHB modelling, selected cases of CPHB are numerically simulated and the results are validated with the experimental data. For non-perforated CPHB, the numerical results are under predicted for Kt (less than 4%) and over predicted for Kr and Kd (less than 9%). For the perforated CPHB, the variation is slightly higher (up to 12%) compared to the non-perforated structure. Validation of the numerical results with the experimental data shows that REEF3D produces reliable results with acceptable RMSE values. In addition, a set of empirical equations is derived using the data fitting technique for quick prediction of Kt and Kr of CPHB. The empirical equations estimate the Kt and Kr values quite accurately with a high coefficient of determination (R2 ≥ 0.90). The overall performance of the CPHB is found to be promising and therefore, may be considered as one among the host of measures for the purpose of wave energy damping necessary for various shore/nearshore applications.Item Studies on Caisson Type Breakwater – A Physical and Numerical Approach(National Institute Of Technology Karnataka Surathkal, 2023) V., Kumaran; ., Manu; Rao, SubbaThe design and construction of coastal structures such as breakwaters, at greater water depths is rapidly increasing as a result of the increasing draught of large vessels and off-shore land reclamations. Vertical caisson-type breakwaters may be the best alternative compared to ordinary rubble mound breakwaters in larger water depths, in terms of performance, total costs, environmental aspects, construction time and maintenance. To fulfil the functional utility and impact of the structure on the sea environment, it is necessary to study the hydraulic performance of such breakwaters. In the present project, the hydrodynamic performance of caisson breakwater with various geometric configurations are studied in detail. In the first phase, a physical model approach is carried out extensively to study the stability of toe protection for vertical caisson breakwater. The determination of the size of the toe armour units and their cross-section for the stable design are investigated. The applicability of the Brebner and Donnelly (Coast Eng Proc 1: 24, 1962) design curve for depth-limited conditions is validated for a certain fixed relative foundation depth (d1/d). In the second phase, an investigation of the non-perforated caisson type breakwater is performed considering different wave conditions. The variation of dynamic wave pressure, wave force, wave run-up, and wave reflection are determined for this structure. The maximum wave force on the caisson breakwater is calculated from measured pressure values and is compared with the wave forces calculated by Goda’s and Sainflou wave theories. The comparison of results illustrate that the Goda’s formula provides a good estimation of wave force distribution compared with the experimental findings. In the third phase, a numerical model of caisson breakwater is developed to study its performance using the computational fluid dynamics (CFD) approach using Ansys- Fluent and validated the same using experimental data. In the fourth phase, the experimental investigations are carried out on non-perforated vertical wall breakwater with the presence of a vertical and horizontal slotted barrier. In the fifth phase, the perforations (i.e 8 %, 10%, 13%, 15%, 20%) are introduced in the front face of the caisson breakwater to analyse the hydraulic performance to arrive at better perforations in reducing the wave forces, wave reflection and wave runup.Item Performance Evaluation of Vertical Porous Screen In A Sloshing Tank By Analytical and Experimental Investigation(National Institute Of Technology Karnataka Surathkal, 2023) Bhandiwad, Mallikarjun S; B M, DodamaniLiquid participation in the vessels or tanks is called as sloshing. The sloshing dynamics in the tank is a complicated phenomenon. Dynamics of sloshing mainly include transient motion of liquid, resonant condition, linear and nonlinear motion, frequency shift phenomenon etc. Therefore, it attracts many researcher and scantiest to study the dynamics of liquid motion in the tanks. Due to its complex and significant phenomenon that has many engineering applications. Stability of sloshing tank and stability of moving vehicles or/and structures coupled with sloshing tank are most concern. In view of fact of sloshing in the tank for many engineering application, it is important to control and/or reduce the liquid participation in the sloshing tank and achieve a required level damping. The damping in tank include viscous effect of liquid in the tank, wave- tank interaction, and wave motion in the baffled tank. For this purpose, one such system is the liquid (water) tank with flow damping device. Many researchers have investigated the sloshing dynamics in the tank with solid and porous baffles in order to control and/or reduce the wave elevations in the sloshing tank. The varying types solid baffles in the sloshing tanks are used to reduce the hydrodynamic action (force and pressure) on tank walls and reduce the weight penalty and cost. Similar to the solid baffles, the porous baffles with varying porosities are also being used in the sloshing tank not only to control hydrodynamics action but also used to enhance the required level damping in the tank. The perforation in the baffles generally include slat type configuration with horizontal and vertical arrangement with respect flow direction. In the porous baffled tank, the dynamic of sloshing includes wave-baffle interaction associated with linear and nonlinear phenomenon. The wave- structures (baffles) interaction is dependent in tank geometry, liquid fill level, type of excitation, flow through baffles, and most importantly drag, loss, and inertia coefficients. The tank with varying porous baffled with optimum liquid fill level in the tank are mainly designed as a Tuned Liquid Damper (TLD) to reduce the structural vibrations. In this regard, many researchers have been working on sloshing dynamics in the tanks to construct the damping in the tank with porous baffles and appropriate liquid fill level. And, the screen drag coefficient is an important parameter to consider to study the dynamic of liquid sloshing the porous baffled tank, iThe liquid free surface in most important, where the wave energy is concentrated during liquid motion and first resonant mode of sloshing in the tank is an important factor for structure-TLD interaction problems. On this basis, using fully extended porous baffles from tank bottom may result in increased wave baffles interaction inducing larger sloshing attenuation near the resonant modes. Hence, the concept of using circular hole perforation in the baffle is comprehended for the advancement of porous baffles in the sloshing tank. In the present study, free surface elevations, sloshing force, and energy dissipation of the porous baffle in the rectangular sloshing tank are examined by both analytical and experimental program. The three varying porosity is adopted for porous baffles in the sloshing study. To concerns of first resonant mode in the sloshing tank, the porosity of 4.4%, 6.8%, and 9.2% are adopted for the baffles. Initially, the gravitational flow test is planned and conducted to study the flow phenomena through porous baffles, and documented the drag coefficient variation for all porous baffles based on the Reynold numbers. Secondly, the linear second-order ordinary differential equations for sloshing dynamics in the rectangular tank were solved using Newmark’s beta method and obtained the analytical solutions for liquid sloshing with and without baffles in the tank following the procedure similar to Warnitchai and Pinkaew (1998) and Tait (2008). The porous baffle loss coefficient is an important parameter to study the baffle’s performance in the tanks. Hence, the two analytical models based on porous baffle loss coefficients were formulated for rectangular sloshing tanks with porous baffles. The analytical model-1 includes both Reynold’s number and porosity dependent loss coefficient, whereas model-2 includes porosity dependent and independent of Reynold’s number. The model's test results were validated with a series of shake table experiments under sway motion at different excitation frequencies which cover up to the first four sloshing resonant modes. In the third stage, experiment shake table tests are performed to validate analytical model results. Initially the test includes rectangular clean tank with varying liquid fill level to study the effect of liquid fill level in the sloshing tank. Considered small, medium, high, and liquid fill in the tank based on tank height (H) which include iiaspect ratio (ratio of static liquid depth to tank length) of 0.163, 0.325, and 0.488 respectively. In the experiment test series, the sloshing with varying fill level subjected to seventeen different excitation frequencies which are include first five resonant mode of liquid sloshing in the tank and the tank driven by sway amplitude (A/L) of 0.0075. Further, the shake table tests are performed for porous baffled tank. In the test series, initially the tank with two baffle condition were considered. In the tank the two baffles are positioned at 0.33 distance of tank length from both end walls. And tank with single baffle case, the baffle positioned at centre of the tank length. The response of free surface elevation and sloshing force variations in the tank analytical models were compared with the experiment's test results. In the two porous baffled sloshing tank under the range of sway excitations, the response of wave motion and sloshing force by both analytical and experimental tests results exhibit the resonant frequency shift phenomenon which is provoked by the low-level porosity of screens (4.4% and 6.8%) in all three fill levels. As porosity of baffle increases (9.2%), the secondary peak start appearing near the first resonant mode along with secondary peak at third resonant mode of sloshing tank. The analytical results matched with shake table test results with a quantitative difference near the first resonant frequency. It is found that Reynolds number dependent porous baffles in the sloshing tank significantly reduce the sloshing elevations in the tank compared to Reynolds number independent one. As a result, Reynold’s number and porosity dependent loss coefficient for porous baffles was found to be more effective. In the case of tank with single porous baffle condition, the analytical model fails to exhibits the exact resonant phenomenon near the secondary resonant excitation mode. but, experiment rest results show the exact resonant frequency shift phenomenon in the tank with centrally positioned porous baffle.Item Studies on Wave Interaction with Composite Breakwater System(National Institute Of Technology Karnataka Surathkal, 2023) K.R., Athul Krishna; Karmakar, DebabrataIn the present study, gravity wave dissipation due to the composite breakwater system consisting of porous structure with different configurations of vertical barriers, pile-rock porous structure with vertical barriers, multiple porous structure and barriers, submerged porous plate with bottom-standing and surface piercing porous structure, submerged porous structure with fully-extended barrier and submerged plate, and stratified porous structure backed by stepped obstacle is investigated under the assumption of small amplitude wave theory. The numerical investigation is performed using eigenfunction expansion method and orthogonal mode-coupling relation. The comparative study on specific structural configurations is performed using the physical model test to validate the numerical and experimental investigation. Further, validation of the numerical result is also performed with the results available in the literatures. Darcy’s law is incorporated for the flow through porous media and the porosity factor of the structure is introduced using the complex porous effect parameter. The composite breakwater system is studied for various parameters such as relative water depth, porosity of structure and barrier, structural thickness to wavelength ratio, water depth to wavelength ratio, submergence depth of the plate and gap between the structure and barrier. The study for the wave transformation due to submerged porous plate coupled with porous structure noted that, the wave damping due to the submerged porous plate backed by surface- piercing porous structure is more as compared to the submerged porous plate backed by the bottom-standing porous structure. In addition, the study on the coupled porous structures and submerged plate illustrates that, the increasing width of the fully-extended porous structure improves the performance of the breakwater system. The study on the stratified porous structure with stepped obstacle and porous block illustrates that the presence of the stratified structure decreases wave transmission and efficient wave attenuation can be easily achieved. The wave force acting on stratified structure is noted to be decreased if the structure is combined with wider surface-piercing porous blocks. Further, the presence of stratified porous structure combined with porous block helps in creating a tranquil zone in the leeside of the structure. The proposed study exhibits an informative result for the wave energy attenuation by different configuration of composite breakwater system which can be designed and implemented in coastal and harbour regions for achieving the tranquility.Item Physical Model Studies on Breakwaters with Geotextile Sand Container Armour Units(National Institute Of Technology Karnataka Surathkal, 2023) Elias, Tom; Shirlal, Kiran G.Breakwaters are essential constructions providing tranquillity to ports and harbour structures when natural protection is lacking. Traditionally, these massive structures are constructed using natural rocks weighing tonnes. In the present scenario, obtaining huge natural rocks is cumbersome and non-eco-friendly. Harnessing the advantages of geotextile sand containers (GSCs), numerous submerged breakwaters and shoreline protection structures have been constructed worldwide. But an emerged breakwater structure with geotextile armour units, capable of replacing the conventional structures, is rarely discussed. A 1:30 scaled, monochromatic wave flume physical experimentation is carried out as a preliminary investigation to test the feasibility of using GSCs as breakwater armour units. The structural design of the GSC breakwater evolved based on a comprehensive literature survey. Single-layer GSC breakwater structures armoured with sand-filled units differing in size and fill percentage (named Bag 1, Bag 2, Bag 3 and Bag 4 ) are investigated in the initial stage. Studies on hydraulic performance (wave runup, rundown and reflection) and stability of GSC breakwater are carried out to analyse the efficiency of the structure against the wave conditions of the Mangaluru coast. The study revealed that the reflection coefficient (Kr) for GSC structures could range from 0.26 to 0.69. Additionally, reducing GSC fill percentage from 100 to 80 is found to be more effective (up to 64%) in reducing reflection, runup and rundown rates than altering GSC size. As far as stability is concerned, the best-performing single-layer configuration comprising Bag 3 could withstand wave heights up to 2.7 m in the prototype. The effect of armour unit size and sand fill ratio on the stability of the structure is analysed, and it is concluded that changing the sand fill ratio from 80% to 100% shot up the structural stability to a maximum of 14%. Increasing bag size also resulted in increased stability by up to 8%. Stability curves for all tested configurations are projected as the significant research outcome and can serve as a practical guideline for coastal engineers in designing GSC breakwaters. It's efficacy to be used as the armour units of breakwaters motivated to advance further in GSC research by adding a second GSC layer to the breakwater model. These double- layered breakwater models with different placement modes are tested for its hydraulic iiiperformance and stability. Double layer placement showed 45 to 52% less Kr than single- layer placement and 38 to 42% lesser than the conventional breakwater, owing to its higher porosity. It is observed that the stability of the structure increased by up to 17% when supplemented with double layers. Structure tends to be stable with increasing armour unit size and fill percentage. Larger bags stacked in double layers is found to be the most stable configuration. 80% filled, slope parallel placement exhibited the least stability. Double layer placement with Bag 3 is found to be stable up to a wave height of 0.132 m on the model scale, which is 3.96 m in the prototype. Stability nomograms for all the tested double-layer GSC breakwater cases are obtained from physical experimentation. In the last stage, a pilot study is conducted by filling cement and sand to GSC units of the best-performing models from the above experiments. When GSC breakwaters are filled with sand and cement, up to 43% increased stability is observed with a considerable decrease in wave runup, rundown and reflection. As a result, cement-sand-filled GSC units can be suggested as a possible alternative to sand-alone-filled units where vandalism has to be countered.Item Flood Susceptibility Modelling Using Remote Sensing – Machine Learning Approach and Optical Water Quality Analysis of Vembanad Lake System In Kerala, India(National Institute Of Technology Karnataka Surathkal, 2023) K. S. S., Parthasarathy; Kundapura, SubrahmanyaWetlands are essential ecosystems that play a significant role in mitigating the impacts of climate change. Wetlands store large amounts of carbon and help to regulate the climate by reducing the amount of carbon dioxide in the atmosphere. They also help to reduce the impacts of extreme weather events, such as floods and hurricanes, by absorbing and retaining water. However, wetlands are also vulnerable to the effects of natural and anthropogenic factors, which can alter their hydrology and lead to the loss of wetland habitats. It is crucial to protect and preserve wetlands to maintain their vital role in mitigating the impacts of climate change. The wetland functions, commodities, and services are lost due to upland land use activities. Hence, accurate and up-to-date information on the upland regions around wetlands is essential. The present research considers the Vembanad Lake System (VLS) in Kerala, India, which is specifically affected by challenging issues to its health and survival. The study area faces threats like encroachment and climate change resulting in floods and alteration in the precipitation patterns. Further, the lake system is endangered by the deteriorating quality of incoming water. Thus, the overall spatio-temporal analysis is critical in protecting and managing water resources in the study region. Anthropogenic activities result in a massive Land Use and Land Cover (LULC) change, and it has become a prominent issue for decision planners and conservationists due to inappropriate growth and its effect on natural ecosystems. As a result, the change in LULC for the short term, i.e., within a decade, is carried out using three Machine Learning (ML) approaches, Random Forest (RF), Classification And Regression Trees (CART), and Support Vector Machine (SVM), on the Google Earth Engine (GEE) platform. When comparing the three techniques, SVM performed poorly at an average accuracy of around 82.5%, CART being the next at 87.5%, and the RF model being good at an average of 89.5%. The RF outperformed the SVM and CART in almost identical spectral classes, such as barren land and built-up areas. As a result, RF- classified LULC is considered to predict the Spatio-temporal distribution of LULC transition analysis for 2035 and 2050. This analysis was conducted in Idrisi TerrSet software using the Cellular Automata (CA) - Markov chain analysis. The model's efficiency is evaluated by comparing the projected 2019 image to the actual 2019 iclassified image. The model efficiency obtained was good, with more than 94.5% accuracy for the classes except for barren land, which might have resulted from the recent natural calamities and the accelerated anthropogenic activity in the study area. Floods have claimed the lives of countless people and caused significant property damage, putting their livelihoods in jeopardy. The study area faced adverse mishappening during the 2018, 2019, and 2021 floods due to the torrential rainfall events. Estimations of flood-inundated areas are prepared from 2018, 2035, and 2050 LULC maps. The extent of flood inundation during the 2018 floods and the possible flood inundation region for the projected LULC in 2035 and 2050 are determined. From the analysis of the 2018 classified image, 14.7 km2 of built-up area was found inundated during the year 2018 floods. The scenario of the 2018 flood event is used to quantify the flood that may occur and inundate the projected LULC 2035 and 2050 scenarios. It is found that the flood will affect about 19.87 km2 and 23.32 km2 of the built-up region, majorly for the 2035 and 2050 projected scenarios, respectively. The goal of this research is to construct effective decision tree-based ML models such as Adaptive Boosting (AdaBoost), RF, Gradient Boosting Machines (GBM), and Extreme Gradient Boosting (XGBoost) for integrating data, processing and generating flood susceptibility maps. Eighteen conditioning parameters, including seven categorical and eleven numerical data, are used for flood modelling using ML. These seven categorical data are converted into 50 numerical data, resulting in a total input data of 61. The Recursive Feature Elimination (RFE) is utilized as the feature selection technique, and 22 layers are chosen to feed into the ML models to generate the flood susceptibility maps. The efficiencies of the models are evaluated using Receiver Operating Characteristic – Area Under Curve (ROC-AUC), F1 score, Accuracy, and Kappa. According to the results obtained, all four ML models demonstrated fairly good performance. However, XGBoost fared well in terms of the model's metrics. The ROC-AUC values of XGBoost, GBM, and AdaBoost for the testing dataset are 0.90, whereas 0.89 for RF. The accuracy varied significantly among the four models, with XGBoost scoring 0.92, followed by GBM (0.88), RF (0.87), and AdaBoost (0.87). The resulting flood susceptibility map can be utilized for early mitigation actions during future floods and for land use planners and emergency managers, assisting in reducing flood risk in regions prone to this hazard. iiWater quality is one of the essential parameters of environmental monitoring; even a slight variation in its characteristics may significantly influence the ecosystem. The water quality of Vembanad Lake is affected by anthropogenic effects such as industrial effluents and tourism. The optical parameters representing water quality, such as diffuse attenuation (Kd), turbidity, Suspended Particulate Matter (SPM), and Chlorophyll-a (Chl-a), are considered in this study to evaluate the water quality of the Vembanad Lake. As this lake is regarded as of ecological importance by the Ramsar Convention and has faced severe concerns over recent years, there was a substantial change in the water quality during the lockdowns of the COVID-19 pandemic. This research aimed to examine the change in water quality using optical data from Sentinel-2 satellites in the ACOLITE processing software from 2016 to 2021. The analyses showed a 2.5% decrease in the values of Kd, whereas SPM and turbidity show a reduction of about 4.3% from the year 2016 to 2021. The flood and the COVID lockdown had an impact on the improvement in the quality of water from 2018 to 2021. The findings indicated that the reduction in industrial activities and tourism had a more significant effect on the improvement in the water quality of the lake. There was no substantial change in the Chl-a until 2020, whereas an average decrease of 12% in Chl-a values was observed throughout 2021. This decrease can be attributed to the reduction in the lake's Hydrological Residence Time (HRT). The outcome of this research depicts augmentation of the change in the LULC pattern and its prediction, future flood-inundation regions, flood susceptibility mapping, and the lake's water quality. The findings of this research work will be a valuable reference to help the government and Non-Government Organisations (NGOs) during strategic planning.Item Analysis of Influence of Land Use Land Cover and Climate Changes on Streamflow of Netravati Basin, India(National Institute Of Technology Karnataka Surathkal, 2023) Jose, Dinu Maria; G S, DwarakishMassive Land Use/Land Cover (LULC) change is a result of human activities. These changes have, in turn, affected the stationarity of climate, i.e., climate change is beyond the past variability. Studies indicate the effect of LULC change and climate change on the hydrological regime and mark the necessity of its timely detection at watershed/basin scales for efficient water resource management. This study aims to analyse and predict the influence of climate change and LULC change on streamflow of Netravati basin, a tropical river basin on the south-west coast of India. For future climate data, researchers depend on general circulation models (GCMs) outputs. However, significant biases exist in GCM outputs when considered at a regional scale. Hence, six bias correction (BC) methods were used to correct the biases of high-resolution daily maximum and minimum temperature simulations. Considerable reduction in the bias was observed for all the BC methods employed except for the Linear Scaling method. While there are several BC methods, a BC considering frequency, intensity and distribution of rainfall are few. This study used an effective bias correction method which considers these characteristics of rainfall. This study also assessed and ranked the performance of 21 GCMs from the National Aeronautics Space Administration (NASA) Earth Exchange Global Daily Downscaled Projections (NEX-GDDP) dataset and bias-corrected outputs of 13 Coupled Model Inter-comparison Project, Phase 6 (CMIP6) GCMs in reproducing precipitation and temperature in the basin. Four multiple-criteria decision-making (MCDM) methods were used to identify the best GCMs for precipitation and temperature projections. For the CMIP6 dataset, BCC-CSM2-MR was seen as the best GCM for precipitation, while INM-CM5-0 and MPIESM1-2-HR were found to be the best for minimum and maximum temperature in the basin by group ranking procedure. However, the best GCMs for precipitation and temperature projections of the NEX-GDDP dataset were found to be MIROCESM-CHEM and IPSL-CM5A-LR, respectively. Multi-Model Ensembles (MMEs) are used to improve the performance of GCM simulations. This study also evaluates the performance of MMEs of precipitation and temperature developed by six methods, including mean and Machine Learning (ML) techniques.The results of the study reveal that the application of an LSTM model for ensembling performs significantly better than models. In general, all ML approaches performed better than the mean ensemble approach. Analysis and mapping of LULC is essential to improve our understanding of the human-nature interactions and their effects on land-use changes. The effects of topographic information and spectral indices on the accuracy of LULC classification were investigated in this study. Further, a comparison of the performance of Support Vector Machine (SVM) and Random Forest (RF) classifiers was evaluated. The RF classifier outperformed SVM in terms of accuracy. Finally, the classified maps by RF classifier using reflectance values, topographic factors and spectral indices, along with other driving factors are used for making the future projections of LULC in the Land Change Modeler (LCM) module of TerrSet software. The results reveal that the area of built-up is expected to increase in the future. In contrast, a drop in forest and barren land is expected. The SWAT model is used to study the impacts of LULC and climate change on streamflow. The results indicate a reduction in annual streamflow by 2100 due to climate change. While an increase in streamflow of 13.4 % is expected due to LULC change by the year 2100 when compared to the year 2020. The effect of climate change on streamflow is more compared to LULC change. A reduction in change is seen in the streamflow from near to far future.Item Streamflow Forecasting Using Wavelet Coupled Soft Computing Techniques and Fuzzy Logic-Based Approach for Stream Water Quality-Quantity Assessment(National Institute Of Technology Karnataka Surathkal, 2023) S, Shruti Kambalimath; Nandagiri, LakshmanHydrologic time series is a collection of timely recorded variables such as streamflow, temperature, evaporation, etc. over a period of time. Forecasting of such time series necessarily aid future predictions based on past records as well as filling of missing data or extension of available data. Accurate and timely forecasting of hydrologic time series can be a great aid for various applications in water resources planning and management. During the last few decades, several types of stochastic models have been proposed as well as developed for modeling hydrological time series and generating synthetic stream flows. Some of such stochastic models are autoregressive (AR), Moving Average (MA), Autoregressive Moving Average (ARMA), and Autoregressive Integrated Moving Average (ARIMA). In contrast to the analytical models, soft computing methods learn from past records and require limited input parameters. These techniques are very useful in cases where there are limitations in terms of data availability. The collection of techniques under Soft Computing renders low-cost solutions to imprecisely formulated problems and attempt to mimic the behavior and learning ability of human beings into computers. One such soft computing technique is “Fuzzy Logic”. We have developed three soft computing models to forecast daily streamflow time series for different lead times for Malaprabha sub-basin in Karnataka state of India. The performance of Support Vector Machine (SVM), Adaptive Neuro-fuzzy Inference System (ANFIS), and Fuzzy models to forecast daily streamflow is tested for 1-day, 3-days and 5-days ahead forecasts. The results indicate that the performance of the models significantly decreases with an increase in lead times. The models show high R2values for 1-day ahead streamflow forecasts, whereas it is low for 3 and 5-days lead time. It is necessary to provide a powerful tool to reduce the noise in the data so that accuracy of the model is increased. Wavelet transformer is one such powerful tool used to decompose the data set into different scales. The wavelet method effectively decomposes the original time series in to sub-series at different resolution levels there by facilitating denoising of the data. In this research work, discrete wavelet transform is coupled with the fuzzy logic method to improve the accuracy of the forecast. The iperformance of all the three models significantly increased when the wavelet is coupled, especially for longer lead times such as 5 days. The Wavelet coupled fuzzy (WT-fuzzy) model outperformed Wavelet coupled ANFIS (WT-ANFIS) and Wavelet coupled SVM (WT-SVM) models. However, WT-ANFIS performed better than WT- SVM.Longer lead time forecasts find applications in flood forecasting and evacuation programs. This research aims at improving the efficiency of forecasting models especially for longer lead times such as 3 days and 5 days which are crucial times for undertaking quick flood evacuation measures. The second phase of this research is stream water quality-quantity modeling. Water quality and quantity are the two aspects that are interrelated and hence should be studied together within an integrated framework. In today's world, demand for water essentially takes into account both quality and quantity aspects for various uses of water. Having a sufficient accessible quantity of water becomes meaningful only if this quantity of water is acceptable in terms of its quality. This study aims at studying the role of the quantity of water in determining its quality along with the other quality parameters. The Water Quality Index (WQI) is an efficient tool which can describe the status of water by translating a large amount of data in to a single value. The results in this study indicate that streamflow can be considered as one of the inputs to determine the WQI.Item A Remote Sensing and Machine Learning Based Framework for the Assessment of Spatiotemporal Water Quality Along the Middle Ganga Basin(National Institute Of Technology Karnataka Surathkal, 2023) S K, Ashwitha; H, RameshUnderstanding the changes in surface water quality over time and space necessitates an examination of spatiotemporal water quality data. This data can be used to identify pollution sources, monitor changes in water quality, and assess the effectiveness of management and conservation efforts. Furthermore, spatiotemporal surface water quality assessment can forecast future water quality trends, allowing for precise decision-making and conservation. Overall, spatiotemporal water quality assessment is critical in protecting and managing water resources. Various multivariate statistical and machine learning techniques are used in this study to determine the river water quality status and comprehend the spatiotemporal pattern along the Middle Ganga Basin in Uttar Pradesh. The study was carried out for 14 years (2005-2018), with 20 Water Quality Parameters (WQPs) collected monthly and covering spatially from up-stream to downstream Ankinghat to Chopan respectively (20 monitoring stations under Central Water Commission, Middle Ganga Basin). The temporal dissimilarity of river water quality is established by applying the Spearman non-parametric correlation coefficient test (Spearman r). A significant p-level (0.0000) is observed for temperature within the season with a Spearman r of -0.866. Besides that, the parameters EC, pH, TDS, T, Ca, Cl, HCO3, Mg, NO2+NO3, SiO2, and DO strongly correlated with the season (p < 0.05). The K-means clustering algorithm temporarily classified the 20 monitoring stations into four clusters based on the similarity and dissimilarity of WQPs. Box and Whisker plots were generated based on these clusters to study water quality trends along individual clusters in different seasons. PCA was applied to screen out the most dominating WQPs causing spatial and seasonal variations from a large data set. Seasonally, the three PCs chosen explained 75.69% and 75% of the variance in the data. With PCs >0.70, the variables EC, pH, Temp, TDS, NO 2+NO3, P-Tot, BOD, COD, and DO have been identified as the dominant pollutants. The applied RDA analysis revealed that LULC has a moderate to strong contribution to WQPs during the monsoon season but not during the non-monsoon season. Furthermore, dense vegetation is critical for keeping water clean, whereas agriculture, barren land and build-up area degrade water quality. Besides that, the findings suggest the relationship between WQPs and LULC differs at different spatial scales. The istacked ensemble regression model is applied to understand the model's predictive power across different clusters and scales. Overall, the results indicate that the riparian scale is more predictive than a watershed and reach scales. As a further part of this work, an integrated use of remote sensing, insitu measurements, and machine learning modelling is used better to understand the water quality status along the study region. In this context, a remote sensing framework based on the Extreme Gradient Boosting (XGBoost) and Multilayer Perceptron (MLP) regressor with optimized hyperparameters to quantify the concentrations of different WQPs from the Landsat-8 satellite imagery is developed. Six years of satellite data from upstream to downstream Ankinghat to Chopan (20 stations under Central Water Commission (CWC), Middle Ganga Basin) are analysed to characterise the trends of dominant physicochemical WQPs across the four identified clusters. A significant coefficient of determination (R2) in the range of 0.88- 0.98 for XGBoost and 0.72-0.97 for MLP was generated using the developed XGBoost and MLP regression models. The bands B1- B4 and their ratios are found to be more consistent with the WQPs. Meanwhile, the performance matrix RMSE for the parameters SiO2 and DO for all clusters for the XGBoost method is determined to be superior to MLP. Indeed, these findings show that a small number of insitu measurements is sufficient to develop reliable models for estimating the spatiotemporal variations of physicochemical and biological WQPs. As a result, Landsat-8 models could aid in the environmental, economic, and social management of any body of water.