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Student Seminar Series

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Name of the Speaker Mr. Abhishek Chakraborty
Title of the Seminar Influence of Irrigation on Soil Carbon Fluxes for a Semi-arid Agro-ecosystem of India
Date &Time 31st July 2019 – Monday – 4.00 PM
Venue Lecture Hall, ICWaR

With the increasing population of India, not only is there a growing stress on the water resources of the country but also there is a need to increase the crop yield throughout the nation. Due to these reasons, there is a pressing need to switch to water-saving irrigation practices in the water-stressed climates of semi-arid dryland ecosystems of India. The transformation from flood irrigation to drip and sprinkler irrigation is one such method by which the water- use efficiency of irrigation systems has increased. Also, to cater to the needs of increasing population, there is a requirement to increase the crop yield by either intensifying irrigation or switching to high yielding varieties of crops. These transformations are expected to play a huge part in change in carbon fluxes from soils of these regions. Soil is the largest terrestrial carbon sink and plays an important role in carbon sequestration. Crop production through irrigation and fertilization results in the greenhouse gas emission from the soil to atmosphere. It is expected that a drip or sprinkler irrigation system would have a greater carbon footprint than a conventional flood irrigation system. This is partially attributed to the carbon emission during their manufacturing and partially to the heterogeneous and under saturated state of soil. There is a definite gap in understanding the soil carbon fluxes from the irrigation fields of semi-arid ecosystems in India. In this seminar, I wish to discuss a few methods by which the soil carbon fluxes from a heterogeneous agro-ecosystem of India present in the semi-arid climate can be addressed.

 


Name of the Speaker Mr. Biswajit Panda
Title of the Seminar Authigenic clay mineral formation by reverse weathering: Impact on global climate and heavy metal cycling in large water bodies
Date &Time 7th July 2019 – Monday – 4.15 PM
Venue Lecture Hall, ICWaR

Weathering of continental silicate rock consumes  and supply cation to oceans and thereby modulating both climate and sea water chemistry (Raymo et. al., 1988). A series of secondary reactions dominate the transport of these cation from the weathering site to their point of release in oceans. These secondary reactions which lead to the formation of authigenic clay minerals thus acts as a controller of cation flux to the oceans (Misra and Froelich, 2012). The neoformed clays within the fluvial and oceanic system act as a sink for the soluble cation, thus playing a significant role in the global riverine and oceanic elemental budgets. The release of  due to clay mineral formation is in contrast to silicate weathering that acts as a net sink of  and is hence, termed Reverse weathering (Mackenzie and Garrels, 1966). Reverse weathering not only plays a critical role in the geochemical cycling of elements it also modulates the global carbon cycle. In this seminar I am going to discuss some aspects of reverse weathering and the ways to study the same in Indian riverine systems where in recent years heavy metal concentration have been on the rise because of anthropogenic activity.

 


Name of the Speaker Mr. Walter Samuel
Title of the Seminar Physical and Geochemical Characteristics of the Brahmaputra River Basin
Date &Time 9th May 2019 – Thursday – 4.15 PM
Venue Lecture Hall, ICWaR

The Brahmaputra River suffers a dramatic change in elevation before it enters India along the eastern syntaxis where it exhumes large amounts of sediments which it eventually deposits along the plains of Assam and Bangladesh. This river system is one of the largest in the world with a high specific discharge and experiences several long-duration floods during monsoon, causing enormous damage to infrastructure, agriculture and livelihood of the inhabitants of low-lying areas in the flood plains. Physical studies carried out on the Brahmaputra river basin have utilised a single hydrological model to simulate the daily discharge. Relying on a single model often leads to predictions that capture some phenomena at the expense of others. Multi-model ensemble hydrological simulation has been an effective method for improving simulation accuracy. Geochemical characteristics related to the major ion chemistry and radioisotope systematics in this river have been previously studied, but none of these studies has focussed on using geochemistry to study flood events that occur annually in the Brahmaputra. The aim is to simultaneously dwell on the physical and geochemical characteristics of the river basin. This enables one to address and investigate questions based on geochemical attributes that may otherwise not be answered using a purely physical modeling approach.

 


Name of the Speaker Ms. Reshma Mohan T.
Title of the Seminar Modelling of Membrane Bioreactors:
Hydrodynamic and Biokinetic models
Date &Time 6th March 2019 – Wednesday – 4.15 PM
Venue Lecture Hall, ICWaR

Abstract: The world is currently in a highly water stressed situation, with 844 million people around the globe with no access to clean water. By 2050, it is estimated that 5.7 billion people in the world will have to live in areas  plagued by water scarcity (UN, 2013). The availability of safe drinking water in sufficient quantity is directly linked with how wastewater is managed. In India, about 38671 MLD of untreated sewage is discharged into waterbodies rendering these water sources unfit for use. To prevent contamination of natural water bodies and to achieve water sustainability, there is a need to value wastewater for its potential rather than discard it. Membrane bioreactor (MBR) has emerged as one of the leading technologies for treatment of both municipal and industrial wastewater due to efficiency in producing high quality effluents. There have been several modelling studies focusing on the biological processes and the hydrodynamics aspects of membrane bioreactor. Biokinetic models including the Activated sludge models, Hybrid models and integrated models is used to understand and capture the complexities of the biological processes in MBR. The Hydrodynamic models including Computational Fluid dynamics models (CFD) focus on MBR system design and optimization. A multiphase CFD model is developed to investigate the efficiency of the aeration system in the Membrane Bioreactor. The turbulence in the Bioreactor is modeled using k-є model and the diffusion of oxygen in water from aeration system is modeled using species transport model. The developed CFD model is also validated using existing literature experimental results.


Name of the Speaker Ms. Tresa Mary Thomas
Title of the Seminar Monsoon low pressure systems and
stochastic risk analysis
Date &Time 30th January 2019 – Wednesday – 4.15 PM
Venue Lecture Hall, ICWaR

Every year India suffers from floods triggered by Monsoon Low pressure Systems (LPS), which cause disastrous effects at many locations in the country. In the past, a few studies developed procedures for identifying genesis points of LPS and algorithms for tracking their propagation. They were used on various reanalysis products to determine tracks of LPS originating in the Indian subcontinent. But none of those procedures are proven to be effective in predicting the interannual variability of LPS frequency observed by India Meteorological Department (IMD). Questions also arise on the subjectivity involved in the manual procedure (based on pressure charts) considered by IMD for detection of LPS tracks. Inconsistency also exists in future projections of these systems by various studies. Results obtained from investigations performed on different approaches to examine these issues would be presented.


Name of the Speaker Ms. Sneha Santy
Title of the Seminar Impact of Climate change on Water quality for Ganga river
Date &Time 31st   October 2018 – Wednesday – 4.00 PM
Venue Lecture Hall, ICWaR

Abstract: Climate change will have significant effects on fresh water quality due to increase in river temperature and changes in magnitude of stream flow. Other major factors affecting water quality are the point and non-point sources of pollution which include industrial & municipal sewage discharge and agricultural runoff. Due to climate change, there can be deterioration of water quality even if the effluent discharged is within permissible limits. Objective of the study is to quantify the response of water quality due to climate change, and to identify hotspots of pollution in the Ganga River. Water quality analysis is carried out using a water quality model QUAL2K. The impact of climate change is assessed using 2 methods: hypothetical scenarios of temperature & stream flow and temperature outputs of GCMs for various RCP scenarios as input to water quality model.


Name of the Speaker Mr. Siva Naga Venkat Nara
Title of the Seminar Spatio-temporal variations of runoff and baseflow components using isotopic methods
Date &Time 28th  November 2018 – Wednesday – 4.00 PM
Venue Lecture Hall, ICWaR
Abstract: The quantification of runoff and base flow components of hydrograph in terms of water fluxes and chemical composition is an important issue in catchment hydrology. Particularly in a riverine system contribution of hydrograph components depends on the initial state of the various hydrological reservoirs and on the characteristics of the hydrological input (precipitation). Baseflow reacts slowly to precipitation and is usually associated with water discharged from groundwater storage. By separating the baseflow (pre-event water) from the stream discharge the contribution of surface and groundwater can be quantified using stable isotope tracers.
The stable isotopes of water namely 18O and 2H, which are part of the water molecule, are typically considered in the hydrological investigations owing to their spatio-temporal variations resulting from isotope fractionations along different phase changes of water cycle and diffusion. Various atmospheric processes such as advection, condensation and evaporation directly impact the composition of stable water isotope, which consequently influence the groundwater isotopic composition. As a part of the Isotope Hydrograph Separations (IHS), study has been done for Kabini catchment by applying end member mixing analysis (EMMA) to quantify the pre-event water and event water.