Indian Stations Research Articles

GPS: User Position Calculation Including Advanced Troposphere Delay Modeling

Objective of this project is to analyze and mitigate troposphere delays induced in GPS signals, which can result in very large position errors while estimating user position. The standard models currently present do not take into account all the various set of parameters or elements of the troposphere that can cause a significant delay. This project also includes study of troposphere propagation delays that improve the understanding of GPS signal propagation through the troposphere during irregular conditions. This characteristic is very important as it can play crucial role in real time surveying, navigation, precision farming and positioning for emergency services. Due to the tropical nature of the Indian climate the troposphere delay can be observed significantly in India sub-continent. In order to accurately estimate delay troposphere in real time conditions is taken into account, which are provided by the Indian meteorological department, by their automatic weather surveillance systems. GPS data for stations in India is obtained from CORS data for Bangalore, from where we obtain the observation and navigation files used in the calculations. Obtained data is processed and run through various algorithms like least squares satellite position calculation, error mitigation and ray tracing algorithms to mitigate troposphere and better estimate user position. Apart from these algorithms this project also includes a study on various concepts/formulas that help in using the forecasted real time data to be used in snell’s law to estimate delay as part of ray tracing techniques. All the code development in this project is done using MATLAB by math works and GUI is developed for an easier interface. For analysis purposes the data is analyzed with and without the advanced mitigation techniques to show the improvement in position estimation using advanced troposphere mitigation techniques.

Earth’s Atmospheric Dynamics and Temperature and Pressure Profiles Over a Low-Latitude Indian Station Using Different Remote Sensing Techniques – A Case Study

Background/objectives: Even after plenty of inclusive studies, the earth’s lower atmospheric dynamics and a few important atmospheric parameters (temperature and pressure, etc.) have not yet been completely understood, particularly over equatorial and low-latitude regions. Methods/analysis: An attempt is made here by effectively utilising various ground- and satellite-based remote sensing instrument (Doppler sodar) data over a typical low-latitude Indian station, i.e. Gadanki (13.45°N, 79.16°E), to understand different atmospheric dynamics, and the critical behaviors of temperature and pressure profiles as measured by radiosonde and COSMIC RO techniques are presented. Findings: Zonal, meridional and vertical winds measured using the Doppler sodar showed distinct diurnal and nocturnal variations; most importantly, the evolution of night-time boundary layer was observed. A one-to-one correspondence was seen between radiosonde measured and COSMIC RO measured temperature and pressure profiles. Applications/improvements: This study recommends that it is very much essential to use different available datasets from various remote sensing instruments to completely understand the earth’s atmospheric dynamics since various dynamical interactions play a role in dictating them directly and indirectly near the earth’s surface.Keywords: Low-latitude Station, Doppler Sodar, Radiosonde, COSMIC RO Technique, Atmospheric Dynamics, Nocturnal Boundary Layer

A multi-experiment approach to ascertain electromagnetic precursors of Nepal earthquakes

The experimental data obtained from three different techniques such as (i) subsurface VLF electric field measured with the help of a borehole antenna (ii) total electron content (TEC) of the ionosphere measured with a GPS receiver and (iii) VLF amplitude of subionospheric fixed frequency (f = 19.8 kHz) NWC (Naval Communication Station) transmitter signals monitored with SoftPAL receiver are analysed in relation to two major Nepal earthquakes occurred on 25 April (M = 7.8) and 12 May (M = 7.3), 2015. The VLF electric field data and fixed frequency VLF transmitter signal data are taken from Mathura and Agra stations in India whereas TEC data are taken from three IGS stations, one of which Lucknow (Lck3) is located in India and others Lhasa (Lhaz) and Wuhan (Wuhan) are located in China, all within 800 km from epicenters of two earthquakes except Wuhan which is located at about 2865 km. The results of the analysis indicate that while borehole and TEC data show anomalies in normal variations within 8–15 days prior to the earthquake of 25 April, the same occur within 5–7 days prior to the earthquake of 12 May. The subionospheric variations of VLF amplitude also show an anomaly 4 days before the later earthquake. Occurrence of these anomalies is examined critically in the light of local lightning and magnetic storms. However, these factors are not found to influence the data. A brief description of generation and propagation mechanisms of seismogenic emissions is also presented.

Design parameter modelling of solar power tower system using adaptive neuro-fuzzy inference system optimized with a combination of genetic algorithm and teaching learning-based optimization algorithm

Abstract Determining the optimal sizing of a solar power tower system (SPTS) with a thermal energy storage system is subject to finding the optimum values of design parameters including the solar multiple (SM), design direct normal irradiance (DNI) and thermal storage hours. These design parameters are determined for each station separately and have remarkable effects on the thermo-economic performance of the system. This paper aims to demonstrate how artificial intelligence (AI) techniques may play an important role in addressing the above-mentioned need and help determine the optimum design parameters for different stations. For this purpose, we developed a thermo-economic model of a 100 MW SPTS with a molten salt storage system for five stations (two stations in India, and one each in Bangladesh, Pakistan, and Afghanistan). A method-based AI is utilized in this paper to ascertain the design parameters of the system. Additionally, a novel hybrid method based on adaptive neuro-fuzzy inference system optimized with a combination of genetic algorithm and teaching-learning-based optimization algorithm (ANFIS-GATLBO) is employed. The input parameters are latitude, longitude, design point DNI and SM, while the annual energy produced, levelized cost of energy and capacity factor are the target variables. The results of the study show that although the annual energy produced by SPTS rises by increasing the SM and decreasing design point DNI, optimum design parameters should be determined by the economic factors. In addition, it was found that the ANFIS-GATLBO method used in this study successfully predicted the targets with a correlation coefficient close to 1.

Model order estimation methods for low frequency oscillations in power systems

Estimation of low frequency oscillation modes is important for taking remedial actions to ensure the small signal stability of the power system. This paper proposes three approaches to estimate the model order of low frequency oscillations using ringdown data from Phasor Measurement Units. The first approach uses a sequential cumulative sum test on the eigenvalues of the autocorrelation matrix of the signal data to estimate the model order. The second approach estimates the model order based on the eigenvalue contribution in the trace of the autocorrelation matrix. The third algorithm uses sum of squares of the eigenvalues to estimate the model order. All the methods are compared to ascertain their efficacy in estimating the model. The algorithms are tested on oscillation data obtained for WSCC 9 bus system simulated on RTDS and the field data from a generating station in India.

Experiences in discharge measurements at Small Hydropower Stations in India

As a part of Ministry of New and Renewable Energy (MNRE), Government of India programme for promoting small hydropower (shp) development, efficiency testing and performance evaluation of Small Hydro Power plants is mandatory for receiving financial incentives by plant developer. The task of efficiency testing and performance evaluation of shp plants was assigned by MNRE to Alternate hydro Energy Centre (AHEC) Indian Institute of Technology Roorkee in the year 2003 along with financial support to acquire the required instrumentation and develop expertise. Over 200 small hydro plants (SHPs) of different capacity (1–25 MW) as well as types viz dam toe based, run of river and canal fall based have been tested for efficiency and performance evaluation during the period 2005–2018 in different states of India as per IEC-60041, IEC-62006, ISO -1438-1 and ISO-748 to the extend feasible as per available resources and time. During efficiency testing of hydro plants, it has been found that discharge measurement is very challenging activity as the most of the plant owners did not provide the required space and provisions for mounting/fixing the instruments for discharge measurement. After commissioning of the plants it becomes extremely difficult to select the ideal/suitable locations and providing the provisions for mounting different measuring instruments. Various problems observed during discharge measurement are discussed in this paper and may be helpful for testing in future.

An improved model based on the support vector machine and cuckoo algorithm for simulating reference evapotranspiration.

Reference evapotranspiration (ET0) plays a fundamental role in irrigated agriculture. The objective of this study is to simulate monthly ET0 at a meteorological station in India using a new method, an improved support vector machine (SVM) based on the cuckoo algorithm (CA), which is known as SVM-CA. Maximum temperature, minimum temperature, relative humidity, wind speed and sunshine hours were selected as inputs for the models used in the simulation. The results of the simulation using SVM-CA were compared with those from experimental models, genetic programming (GP), model tree (M5T) and the adaptive neuro-fuzzy inference system (ANFIS). The achieved results demonstrate that the proposed SVM-CA model is able to simulate ET0 more accurately than the GP, M5T and ANFIS models. Two major indicators, namely, root mean square error (RMSE) and mean absolute error (MAE), indicated that the SVM-CA outperformed the other methods with respective reductions of 5–15% and 5–17% compared with the GP model, 12–21% and 10–22% compared with the M5T model, and 7–15% and 5–18% compared with the ANFIS model, respectively. Therefore, the proposed SVM-CA model has high potential for accurate simulation of monthly ET0 values compared with the other models.

Measurement of environmental radiation and analysis of microdosimetric spectra of cosmic rays during the 35th expedition to Indian station Bharati, Antarctica

Tissue equivalent proportional counter (TEPC) model HAWK FWAD-3 was used for the evaluation of absorbed dose, dose equivalent rate (ḢTEPC) and microdosimetric spectra measured (i) in the mixed radiation fields formed mainly by cosmic rays onboard aircraft during the flights between Mumbai and the Indian station Bharati (Progress air base), two polar flights at Antarctica, and (ii)ground level environmental radiation field at locations situated in three continents, namely Antarctica, Africa and Asia with different latitudes. The study also includes evaluation of absorbed dose rate, dose equivalent rate of cosmic rays and terrestrial radiation using active detectors namely RADEYE-G and BERTHOLD Rem counter. An effort was made to compare the measured dose equivalent rate by TEPC for the commercial flight routes to Antarctica with the values calculated by the software code EPCARD and a good agreement was observed. The 35th expedition to Bharati, Antarctica showed higher values of dose equivalent at the pole (Larsemann Hills region, 69°24′37.60″S, 76°11′01.70″E) than the world average for an evaluation period of six months during summer.

Cloud fraction retrieval and its variability during daytime from ground-based sky imagery over a tropical station in India

Total Sky Imager (TSI) is operated at a high altitude station in the Western Ghats of the Indian sub-continent from June 2012 to June 2013. The TSI image content is classified as clear, thin and thick clouds using red-blue ratio (RBR) threshold technique and then cloud fraction (CF) is retrieved. An algorithm is proposed to improve the accuracy of CF retrieval, by adapting the methodologies used in earlier studies and new developments are suggested in sections of the validation of clear sky image and the aerosol correction factor. Time series of thin, thick and total CF are constructed for each day at 5 min interval. These measurements at high temporal resolution are first of their kind over a tropical station in India. Both thick and thin CFs showed high temporal variability. The transition from one season to another season also showed distinct CF variability. Monthly mean CF showed a mono model distribution in the winter months (December and January) and a bimodal distribution in the pre-monsoon months (March, April, May) including February. During the monsoon season (JJAS) about 90% CF is observed throughout the day. The post-monsoon months (October, November) show a bimodal distribution with one peak in the morning hours and another peak in the afternoon hours. Unlike thin CF, total and thick CFs showed almost similar variability. The comparison of CF retrieved from MODIS (Terra and Aqua) and TSI showed a good correlation for overcast sky conditions, while partial cloudy skies showed less correlation due to the effect of satellite viewing angles. Such continuous measurements of CF at high temporal resolution are essential for cloud radiative forcing studies.

Examination on the Influence Area of Transit-Oriented Development: Considering Multimodal Accessibility in New Delhi, India

As Indian cities adopt the concept of transit-oriented development (TOD), concerns have arisen regarding the applicability of TOD standards formulated in developed countries in the Indian context. This study aims to estimate the TOD influence areas in New Delhi by examining the last mile connectivity patterns of passengers on the Delhi Metro Railway (DMR). Questionnaire surveys conducted on the last mile connectivity reveals use of various access modes for metro stations in India, although current research only considers walking and cycling to be universal forms of access. Therefore, this study focuses on the DMR’s multimodal accessibility to investigate the last mile distance of each mode. In order to offset the rounding errors of reported distance, a heaping model and multiple imputation (MI) were employed to improve the accuracy of the reported distance. Afterward, distance decay analysis and receiver operating characteristic (ROC) curves were used to determine the thresholds of last mile distances. The findings show that the influence area differs across travel modes and increases in the order of walking, informal transit, buses, and private transport, respectively.

Monitoring the largest North Korean nuclear explosion 2017, through Indian Seismological Network

Seismological characteristics of the North Korean largest nuclear test of September 2017 have been examined using the data of the In− dian Seismological Network. Full waveform modelling of the ground motion data of Indian stations for this nuclear test shows 16% isotropic component, 47.5% DC and 35.8% CLVD components. The Indian stations being located about 3500 to 5000 km away from the source, gave lesser isotropic component as compared to that from the nearby stations around the North Korean test site. This is attributed to the rapid attenuation of the high frequencies emitted from the source. Its average body wave magnitude, mb from the Indian stations broadly agrees with that reported by worldwide data. It was found that the surface wave magnitude of this test in North Korea was large as com− pared to those from the Kazakistan and Nevada nuclear tests for almost similar mb. It is hypothesized that more powerful fusion pro− cess in the nuclear test could result in larger tectonic slip.

Evaluating the variability, transport and periodicity of particulate matter over smart city Bhubaneswar, a tropical coastal station of eastern India

Air pollution has become a matter of concern over Indian mega-cities. In the present study, we analyse the variation of particulate matter (PM) (PM10 and PM2.5) over Bhubaneswar (20.18°N, 85.50°E, 45 above MSL), which is a coastal Indian station, and the state capital of Odisha. Variation of meteorological parameters (i.e. air temperature, humidity, wind speed, and wind direction) over the station shows low winds originating and transported mainly from land areas during post-monsoon and winter, and from the Bay of Bengal during pre-monsoon and monsoon seasons. The site, in general, has evident diurnal variations of meteorological parameters and PM, other than monsoon season. In addition to surface observations at the site, 48-h back trajectory calculation by HYSPLIT model and the study employs potential source contribution function analysis for precise identification of the transported pollution areas for different seasons.

A review on the upper atmospheric sodium observations from India: Insights

This review article briefly brings out the historical development of atmospheric sodium (Na) measurements over India and the importance of coordinated measurements with multiple techniques to address physical processes in the Earth's upper atmosphere. These measurements were initiated in the early 1970s by observing Na airglow emission intensities with broad band airglow photometer from Mt. Abu, a low-latitude hill station in India. Considerable amount of night-to-night variations in nocturnal emission intensities of the Na airglow were observed. Later, investigations regarding the dependence with the magnetic activities from the equatorial and low latitudes were carried out and double-humped structures in the nocturnal variation of intensities were reported. With the advent of Na lidar at Gadanki around 2005, the measurements of atmospheric neutral Na atom concentration became possible and more frequent occurrences of sporadic Na layers over the magnetic low latitude station compared to other latitudes were detected indicating the role played by electrodynamics. Later, a possible relationship between E-region field aligned plasma irregularities and the concentration of neutral Na atoms was investigated using coordinated measurements of VHF radar and Na lidar. Further, simultaneous measurements with Na lidar and a narrow band airglow photometer with narrow field of view brought out the importance of coordinated observation wherein the characterization of gravity waves could be carried out and also revealed the importance of collisional quenching due to ambient molecules in the Na airglow emission processes. In addition, combining the ground based measurements of Na lidar and meteor wind radar along with satellite measurements made possible to hypothesize the over-turning Kelvin–Helmholtz billow in the Na layer manifests “C-type” or inverted lambda shape structures in the height-time-concentration map of neutral Na atoms. This review paper presents a synoptic view mostly based on the previously reported observations of Na airglow emission, Na lidar and coordinated Na airglow and Na lidar observations from the Indian sector and highlights the importance of simultaneous measurements of mesospheric Na and its emissions along with satellite-borne measurements to address interesting geophysical processes in the Earth's upper atmosphere.

Techno-economic optimization of an off-grid hybrid renewable energy system using metaheuristic optimization approaches – Case of a radio transmitter station in India

Development of hybrid renewable energy system has become a challenging task considering the intermittencies of renewables and multi-dimensional designing aspects (for example technical and economic aspects) of such hybrid systems. Although there are many investigations on the development of hybrid renewable energy systems, the investigations of useful models or effective methods are only a few. Metaheuristic algorithms are gaining much popularity in the optimization of complex systems like hybrid renewable energy system for their ability to give quick, accurate, and optimal solution. The objective of the present study is to obtain a techno-economic optimal design of an off-grid hybrid solar photovoltaic/biogas generator/pumped hydro energy storage/battery system with the help of metaheuristic optimization techniques for a radio transmitter station in India. Performances of two such techniques – water cycle algorithm and moth-flame optimization that have become popular in recent time are evaluated and compared with Genetic Algorithm, which was used as a benchmark metaheuristic in previous studies on hybrid renewable energy system. The objective function is a minimization of total net present cost subject to design constraints. A detailed modeling strategy has been elaborated for the optimization problem. A sensitivity analysis based on loss of load probability type reliability criteria is carried out to investigate the feasibility of the proposed design. The results show that both the considered metaheuristics are effective in finding the optimal design; however, water cycle algorithm has marginally better design solution than the other two algorithms. The optimal configuration by the water cycle algorithm is found to have solar photovoltaic panel area of 548.67 m2 (size 69.2 kW), biogas generator size of 16 kW, battery bank of 21 units, converter size of 30 kW, and upper reservoir volume of 2081.5 m3 with a total net present cost of $0.813 million. Further, on comparing the results with literature, it is found that the present metaheuristic optimization has resulted in an effective hybrid renewable energy system design with a lower techno-economic cost.

Seasonal, annual, and interannual variability in MLT quasi-two-day waves over the low-latitude region Kolhapur (16.8°N; 74.2°E)

This study presents the quasi-two-day wave (Q2DW) characteristics of the mesosphere and lower thermosphere (MLT) region obtained by taking hourly mean values of horizontal wind velocities for 4 years (August 2013–July 2017) through continuous measurements using a medium-frequency (MF) radar (operating frequency – 1.98 MHz) located at the low-latitude Indian station Kolhapur (16.8°N; 74.2°E). The MF radar located at Kolhapur was upgraded in 2013, and these results of Q2DW have been reported for the first time after upgrading. The present study investigated variability in seasonal, annual, interannual, and solar indices of Q2DWs traveling in zonal (EW) and meridional (NS) components in the MLT region. The Q2DW activity is observed to be stronger during austral summer (January–February) (EW = ∼5 m/s and NS = ∼8–10 m/s) than during boreal summer (June–July) (EW = ∼5 m/s and NS = ∼6–8 m/s). The Q2DW amplitudes are larger in the meridional component than in the zonal one. A strong semiannual oscillation (SAO) has been observed in Q2DWs, with peak during January–February and June–July. In addition, small enhancement is seen in meridional Q2DW in October (∼5–6 m/s). It is observed that the entire spectrum (40–60 h) measured between 86 and 94 km contributes to the SAO amplitudes during January–February and June–July, whereas the waves measured between 42 h and 52 h contribute to enhancement in October similar to that reported elsewhere. In general, the Q2DW amplitude shows large interannual variability. The easterlies developed in the global circulation model in Northern hemisphere during May intensify up to around summer solstice. Q2DW activity peaks during westerly shear zone and intensifies with time at a lower thermospheric altitude (above 90 km). Small positive correlations (r = 0.2 for sunspot number and r = 0.1 for 10.7 cm solar flux) have been observed between Q2DW amplitudes and solar activity.

Investigations of vertical wind variations at a mountain top in the Himalaya using Doppler Lidar observations and model simulations

Hight-resolved observations of vertical winds remain nearly non-existing over the Himalayas, despite of anticipated crucial role of vertical motions in transporting pollution across the Himalayan hills. The present study analyze the vertical wind observations from surface to 1 km above ground level over Manora Peak (29.4° N; 79.5° E; 1958 m amsl) in the Himalaya performed using a Doppler Lidar during the Ganges Valley Aerosol Experiment (GVAX). Vertical wind exhibited a pronounced diurnal variability at Manora Peak comprising of upward motions during the daytime (05–10 UT) and downward motions during nighttime typical of a mountain-valley system. Mean vertical wind speeds are observed to be varying from −0.8 to +0.8 ms−1 during the study period with a variance of 0.1–1.5 m2s-2, which is attributed to the thermally driven turbulence. Mean vertical winds are observed to be stronger in the Doppler Lidar profiles above Manora Peak (−0.8 to 0.8 ms−1) as compared to near surface measurements at this station using an ultrasonic anemometer (−0.4 to 0.4 ms−1), and low altitude stations in India. Daytime vertical wind speeds are observed to be higher during pre-monsoon (0.81 ms−1), as compared to post-monsoon (0.24 ms−1) and winter (0.33 ms−1). Average Black Carbon (BC) concentrations are significantly higher during strong upward vertical winds, which indicates efficient transport of polluted air mass from low-altitude regions to the Himalaya. Weather Research and Forecasting (WRF) model reproduces the observed diurnal pattern in the vertical wind at the observation site however the model underestimates the variability.

Measurements of radon (222Rn) and thoron (220Rn) exhalations and their decay product concentrations at Indian Stations in Antarctica

During the 33rd summer expedition to the two Indian Stations at Antarctica, Bharati and Maitri, radon and thoron progeny concentrations in indoors and outdoors were measured along with radon (222Rn)/thoron (220Rn) exhalation rate measurements of soil samples, radionuclide content and 222Rn emanation coefficient. This investigation was based on the reports of the higher gamma radiation levels reported around these stations. The results will give an estimate of the radioactivity level as well as the total dose received by personnel carrying out long-term measurements at these stations. Radon and thoron progeny concentrations were measured using direct radon and thoron progeny sensors (DRPS and DTPS). The soil radionuclide content was measured using HPGe gamma spectrometry while radon/thoron exhalation rates were measured using the accumulation method by scintillation radon/thoron monitor. In contrast to a higher radiation field and radioactivity content, studies showed the radon/thoron exhalation rates and progeny concentration to be similar to that measured in normal background areas of other parts of the world. This could be attributed to the ice deposits and the larger atmospheric dispersion, and also to the soil nature which is mainly loamy sands with low clay content contributing to a lower emanation. The results are discussed.

Surface PM2.5 Estimate Using Satellite-Derived Aerosol Optical Depth over India

ABSTRACT Concentrations of fine particulate matter (PM2.5) that exceed air quality standards affect human health and have an impact on the earth’s radiation budget. The lack of round the clock ground-based observations from a dense network of air quality stations inhibits the understanding of PM2.5’s spatio-temporal variability and the assessment of its health and climate effects. Aerosol optical depth (AOD) values retrieved from satellite based instruments can be used to derive surface PM2.5 concentrations. This study integrates Moderate Resolution Imaging Spectroradiometer (MODIS) AOD retrievals and simulations from the Weather Research and Forecasting Model coupled with Chemistry (WRF-Chem) to determine the ground-level PM2.5 concentrations at a 36 km resolution across India. WRF-Chem simulations provide the factor relating the AOD with the PM2.5. Satellite-derived PM2.5 mass concentrations are compared with the available ground-based observations across India for the year of 2011. The results show a correlation between the satellite-derived monthly PM2.5 estimates and the ground-based observations for 15 stations in India with coefficients of 77% and diurnal scale coefficients varying from 0.45 to 0.75. The best estimations of PM2.5 mass concentrations on a spatio-temporal scale across India address various environmental issues.

Long term observations on stable isotope ratios in rainwater samples from twin stations over Southern India; identifying the role of amount effect, moisture source and rainout during the dual monsoons

The dominant factor that controls the rainwater isotope ratios in the tropics is believed to be the local or instantaneous rainfall amount. This notion was challenged in several recent observations indicating that the stable ratios in rainwater are controlled by other factors such as source water composition and intensity of convective activity. Since amount effect is the basis for paleoclimate reconstruction of rainfall it is important to develop comprehensive knowledge about it at different time scales. Here we investigated the relationship of rainwater δ18O with the local or instantaneous rainfall amount at different time scales at two Indian stations, Thiruvananthapuram (TRV) and Bangalore (BLR), for four years covering the dual monsoon systems [Indian Summer Monsoon (ISM) and Northeast Monsoon (NEM)]. It was observed that the seasonal variations are more pronounced over BLR due to its continental location in the central Southern peninsular India, compared to TRV which is a coastal station. Isotopically enriched samples were found during seasonal high temperature and low relative humidity at the respective stations. The intra-event observations indicated that the ‘amount effect’ at the intra-event scale was significant due to post-condensation evaporation, which was supported by low d-excess values and its inverse correlation with rainfall amount. The correlation between event based δ18O and local rainfall amount for both the stations was weak (r = 0.2 and 0.3) whereas the isotopic signature was sensitive to the convective activity during the monsoon period. Significant negative spatio-temporal correlations of δ18O over the moisture convergence regions were obtained with proxies of convective activity over parts of the Arabian Sea as well as over the regions of moisture pathways associated with synoptic scale disturbances from the Bay of Bengal. We observed that the correlation pattern varies with the seasonal changes of moisture source and transport pathways during the periods of ISM and NEM.

Physical, chemical and geotechnical characterization of fly ash, bottom ash and municipal solid waste from Telangana State in India

Utilization of fly ash, bottom ash and municipal solid waste in the field of geotechnical engineering necessitates determination of its physical, chemical, morphological and engineering properties. This paper presents detailed physical, chemical and geotechnical characterization of fly ash, bottom ash and municipal solid waste from Telangana State in India. Fly ash and bottom ash samples were collected from Kakatiya thermal power station in India. Municipal solid waste (MSW) sample was collected from Borabanda municipal dump site in the city of Hyderabad, India. From the experimental results, it is noticed that specific gravity of fly ash, bottom ash and municipal solid waste were found to be 1.86, 1.77 and 2.2 respectively. Presence of quartz and mullite; quartz, mullite and calcium carbonate; and quartz and corundum are found to be predominant in fly ash, bottom ash and MSW respectively. The peak friction angle of fly ash, bottom ash and municipal solid waste were found to be 37.02°, 33.77° and 35.23° respectively. Permeability characteristics of fly ash, bottom ash and municipal solid waste were observed to be 1.01E−04 cm/s, 2.01E−04 cm/s and 1.16E−04 cm/s respectively. From the observation of experimental results, it can be concluded that fly ash, bottom ash and municipal solid waste from Telangana state are effective material to be used as backfill material, filter material and embankment construction.