T.I. Eldho

• B.Tech, M.Tech, Ph.D., PDF
• Indian Institute of Technology Bombay

In-situ bioremediation is a cost-effective aquifer restoration technique based on microbial degradation of organic groundwater contaminants into harmless substances. Simulation Optimization (SO) models aids in the effective design of field bioremediation process by determining optimal rates and locations of pumping and injection wells. However, mos...

The Pump and Treat (PAT) is an effective remediation technique for the alleviation of pollutants such as industrial effluents and chemicals from the groundwater. This technique involves the extraction of groundwater from one or more pumping wells for the treatment above the ground surface. Remediation of contaminated aquifers is a tedious and resou...

In this study, a linked simulation optimization (SO) model is presented for identification of groundwater contaminant sources. The SO model consists of two steps namely, simulation and optimization. The simulation step entails developing a groundwater contaminant transport model in which the advection–dispersion-reaction equation (ADRE) is solved f...

The present study illustrates an experimental investigation of flow hydrodynamics in the vicinity of a submerged circular pier across various submergence levels under only current and wave–current combined flow conditions. The instantaneous velocity data are collected using particle image velocimetry for three distinct frequencies of waves to deter...

Floods cause devastating effects on the economy and risks to life and property. The climate change impacts might be most severe in developing countries like India because of the poor capacity to adapt to climate variability. The flood in August 2018 in the Southern state of India, Kerala is an eye-opener to take consolidated efforts in land-use pla...

Around 30% of the world’s population lacks access to safe water despite being a critical factor that modulates the complex dynamics of ecosystems and societies. Efficient technologies to purify water to potable form are either inaccessible or economically not viable for the majority. Water poverty and scarcity can be potentially exacerbated by the...

In this study, the simulation–optimization (SO) model is used to identify the aquifer parameters (flow and transport parameters) of a confined aquifer. The unknown parameters are obtained by comparing the observed and the simulated values. The meshless local radial point interpolation method (LRPIM) is used for the purpose of simulation of groundwa...

Hydrological models are widely used to estimate and forecast streamflow for various applications. Given the inherent uncertainties in these models, there is a pressing need to enhance the current state of the modelling strategies. Historically, hydrological models showed significant improvement through soil moisture (SM) assimilation. Particularly,...

The waves and currents can frequently be observed together near the coastal region such as estuaries. The presence of wave modifies the flow around the structures like bridge pier near the sea. A clear understanding of turbulent flow filed in such conditions will be very much helpful in the economical and optimal design of the pier. This study expe...

Satellite precipitation estimates play a crucial role in water resources management by providing valuable data on rainfall patterns and distribution over large areas. However, satellite precipitation estimates have errors due to both the inherent uncertainties of the retrievals and how the estimates are used. In this study, we quantify the effect o...

This study delves into the potential impacts of climate change on meteorological and hydrological droughts in the Western Ghats region of South India, a large and humid tropical region. Utilizing three drought indices—the Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), and Standardized Runoff Inde...

Meshless methods are efficient tools in prediction of fate of groundwater contamination. In these methods, the choice of amount of discretization in space and time affects the accuracy of solution and computational time. Peclet number is a controlling parameter of such numerical transport simulation models and is the measure of space discretization...

Most of the studies on local scour considered the equilibrium condition for peak flow. However, it is very rare that steady peak flow run for sufficiently long duration to achieve the equilibrium state. In this study, the effect of flow unsteadiness on the hydrodynamics and the local scour around a cylindrical pier over a gravel bed was investigate...

An understanding of natural degradation of multiple reactive contaminants in the aquifers is essential before designing the monitoring or remediation programs for polluted aquifers. Since such reactive contaminants are ubiquitous, a number of research works has been performed in the past three decades for the modelling of multi-species reactive tra...

The Western Ghats (WG) in South India is a biological hotspot with a cluster of small river basins and heterogeneous climate and vegetation patterns, and it is categorized under the water stress region by Central Water Commission (CWC). This study aims to evaluate the effects of climate change and land use/land cover (LULC) transformations on water...

The effect of climate change (CC) variation results in considerable changes in hydrology leading to large-scale socio-economic impacts. Further studies demonstrate that long-term climate change in the river basins is giving rise to frequent hydro-meteorological extremes such as floods and droughts. In this study, the future CC impacts on a river ba...

The land use/land cover (LULC) and climate change have detrimental impacts on the water balancing component (WBC) of a river basin, especially in the humid tropical regions. The aim of this study is to assess changes in the past, present, and future WBCs by analyzing the individual and combined impacts of both climate as well as LULC changes using...

The evaluation of climate change impacts on hydrology using Global Climate Models (GCM) and emission scenarios is incomplete, without quantifying the uncertainty associated with it. As the uncertainties play a significant role in such analysis, it is important to quantify them in order to develop productive management and decision-making capabiliti...

In this study, the hydrometeorological impacts of climate change in the Upper Godavari River basin in India are quantified for historical and future periods using a well-calibrated hydrological model H08. The study provides a quantitative assessment of various hydrological fluxes projected for the future that are useful in water resource planning a...

An accurate estimation of aquifer parameters is important for effective groundwater management and future scenario prediction. These parameters are mostly obtained through different time-consuming and cumbersome field pumping tests. The inverse problem is a recently developed widely accepted mathematical approach to obtain the representative optima...

Groundwater flow modeling plays an important role in managing the groundwater resources. Several numerical models have been used to model the groundwater flow in hypothetical and field aquifers. These models can predict future groundwater level in an aquifer system using the available groundwater information and incoming/outgoing water into it for...

To tackle the groundwater flow issues, numerical approaches like the finite difference method and the finite element method are frequently utilized. The pre-processing portion of these traditional methods involves the usage of elements or a grid to solve the issue. Pre-processing or re-meshing process consumes more time and computationally complex....

Land use and land cover change (LULC) has significant impact on hydrologic response at the river basin/watershed level. Quantitative assessment of LULC impacts on runoff generations on river basin scale is important for water resources development and impact assessment of extreme events. Based on the historical LULC changes, the future LULC can be...

We here propose a two-step approach-based simulation-optimization model for multi-objective groundwater remediation using enhanced random vector functional link (ERVFL) and evolutionary marine predator algorithm (EMPA). In this study, groundwater flow and solute transport models are developed using MODFLOW and MT3DMS. The ERVFL network is used to a...

Landuse landcover (LULC) and climate change have significant hydrological impacts, especially in humid tropical regions. Cautious planning and development based on early preparedness can result in LULC patterns that may improve the well-being of human beings and ecosystem. This demands significant knowledge related to the climatic and hydrological...

The general circulation models (GCMs) and emission scenarios (RCP 4.5 and 8.5) have proven to be significantly functional in evaluating the impacts of climate change (CC) on hydrology, although their performance and accuracy varies on a regional scale. The objective of the present study is to evaluate the performance of five CMIP5 GCMs (CanESM2, BN...

Groundwater contamination is a major problem and it can be contaminated by natural or manmade activities. Contaminant sources cannot be identified promptly after a contamination event due to slow groundwater movement in aquifers. To limit the further spread of the plume and to take appropriate remedial measures, it is essential to determine the rel...

Contaminants in groundwater may enter through various sources which are required to be identified for informed decision-making regarding remediation. In early stages of contamination of an aquifer, the sources of contamination are generally unknown. To estimate the unknown release histories at potential sources, the governing equations of contamina...

This study investigates the local scour around the cylindrical pier mounted on a gravel bed for low coarseness ratio (d/d50), which is defined as the ratio of pier diameter d to the median particle size (d50) of the bed material. Experimental study was conducted in a flume with varying pier diameter and flow conditions. Effect of flow depth on the...

The objective of this study is to explore the higher-order turbulence statistics of flow and turbulent length scales around a complex pier (CP) and compare the results with that of a simple pier (SP). The velocity data were recorded in a laboratory flume using Particle Image Velocimetry (PIV). The PIV data were analyzed to estimate the velocity flu...

In-situ bioremediation is a cost-effective technique to eliminate petroleum hydrocarbons from groundwater. In previous studies, this has been mostly applied under the approximation of a homogeneous porous medium, even though in reality aquifers are often characterized by significant heterogeneities. Here, different heterogeneous and equivalent homo...

Catchment hydrological response to anthropogenic change is quite extensive. Especially, surface runoff is highly dependent on various human-induced activities like urban sprawl, construction of dams, modern agricultural practices, etc. Hence, understanding its impact is highly essential. In this study, a heterogeneous river basin called Bharathapuz...

Adsorption plays a vital role in contaminant transport in groundwater. Generally, a local equilibrium assumption is used in which the retardation factor is derived from aquifer material and contaminant type. However, for problems involving faster seepage velocities, this assumption becomes invalid and the mass transfer between mobile and immobile o...

It is widely known that land use/land cover (LULC) changes significantly alter watershed hydrology and sediment yields. The impact, especially on erosion and sedimentation, is likely to be exacerbated in regions dominated by high rainfall patterns such as monsoons. This study analyzed the hydrological responses of LULC changes in terms of streamflo...

In this paper, two meshless methods, namely, a weak form Meshless Local Petrov Galerkin (MLPG) method, and Meshless Weak Strong (MWS) form method, obtained by combining MLPG with a strong form Radial Point Collocation Method (RPCM), are presented for simulation of advection-dispersion-reaction phenomena of the contaminants in the porous media. The...

Groundwater can be contaminated by natural or manmade activities. The quality of groundwater is affected by increased levels of contaminants in effluents from industries, pesticides from agriculture, septic systems, landfills, leakage from fuel tanks, toxic chemical spills, etc. There are various methods available for numerical modeling of contamin...

In the last few decades, due to intense anthropogenic activities, global warming and related climate change issues are being reported frequently in different parts of the world. The impacts due to global warming and climate change have proven to be damaging and calamitous for the natural flow and balance of the hydrological cycle throughout the pla...

This study proposed a novel combination of a meshfree simulator with the covariance matrix adaptation evolution strategy (Mfree-CMA-ES) to construct a simulation-optimization (SO) model for accurate estimation of aquifer parameters. In most regional aquifer systems, minimal temporal fluctuations are observed throughout the year. Therefore, the wide...

The effects of landuse/landcover (LULC) and climate change on hydrology and soil erosion processes are of major concern, especially in the humid tropics. In this study, an evaluation of these changes is performed in a humid tropical catchment (Vamanapuram river basin, India) using a physically based distributed model, SHETRAN. The past landuse maps...

Due to climate change, growing demand with increasing population and environmental pollution, the management of water resources is crucial for its sustainable use. In computer simulations, traditionally, the problem domain is discretized using grid/mesh-based methods such as Finite Difference Method (FDM), Finite Volume Method (FVM), and Finite Ele...

We herein propose two-step approach based simulation-optimization models for groundwater remediation using enhanced random vector functional link (ERVFL) and evolutionary marine predator algorithm (EMPA). The weighted least square method is used to improve the robustness of the ERVFL network, where weights are computed using the kernel density esti...

Environmental changes owing to anthropogenic activities and global warming are of growing concern globally due to its detrimental effects. Effective monitoring of environmental changes requires data that can be extracted through application of geospatial technologies such as remote sensing (RS) and Geographic Information system (GIS). Hydrological...

Meshless methods are potential substitutes to the conventional finite difference and finite element methods (FDM and FEM) and have the advantage of alleviating the meshing and remeshing process of these mesh-/grid-based methods. The strong and weak form-based meshless techniques, though efficient in groundwater studies, have their limitations. The...

Hydro-climatologic processes are analyzed in climate models to predict future climate data. These data are used in the hydrological model to predict the hydrological behavior of watersheds which are very helpful in water resource management. In this study Soil and Water Assessment Tool (SWAT) is used with statistically downscaled General Circulatio...

High computational requirement of physically based fully distributed hydrological models (PDHM) constrains the use of all available general circulation models (GCMs) to assess climate change impacts. Here, an approach of ensembling GCMs using clustering based on future climatological variables was compared with model democracy while using a PDHM, S...

Droughts are the major natural disasters affecting water availability leading to social, economic, and environmental challenges. Due to climate variability, investigation of climate change impact on droughts is of vital importance for sustainable societal and ecosystem functioning. Western Ghats, a humid tropical region of India is selected as a ca...

A reliable flow simulation is essential for better groundwater management. However, the complex flow behavior cannot be simulated by analytical methods and numerical models are often required. The Finite Difference and Finite Element Methods (FDM, FEM) are the most common and reliable numerical methods for groundwater studies. These methods require...

A meshless simulation model based on the radial point collocation method (RPCM) is developed in this study to simulate contaminant transport in heterogeneous aquifers with nonlinear adsorption. The nonlinear adsorption is represented using popularly used Langmuir’s isotherm. The nonlinear governing equation of the contaminant transport is solved ut...

The West Flowing River Basins from Tadri to Kanyakumari (WFRB-2), India, is a highly complex hydrological system witnessing hydrological extremes frequently. In this study, the impacts of climate/Land Use Land Cover (LULC) changes on hydrology in WFRB-2 are investigated on a 0.25° spatial scale for a historic (1979–2018) time period. Six major rive...

Groundwater contaminant sources identification and parameter estimation using the simulation-optimization (S/O) approach require numerous runs of the computationally expensive simulation model through the optimization algorithm. The computational cost can be effectively reduced by using a surrogate model which can accurately approximate the simulat...

Wakes and higher-order turbulence around circular cylinders of different diameters are investigated using particle image velocimetry measurements. The cylinder Reynolds number (Re d) is defined by the depth-averaged velocity, cylinder diameter, and kinematic viscosity. The influence of Re d on third-order moment of velocity fluctuations, turbulent...

Plastic-derived pollutants are hazardous and pervasive in the environment, and their detection is a challenge due to observational constraints of various dimensions. Physical, chemical, thermal, and spectroscopic methods are extensively used to identify microplastics in environmental systems, but fundamental challenges exist in the isolation and an...

Groundwater flow problems are generally solved using analytical or numerical methods. Though analytical solutions are exact and preferable, they are not available for complex field problems. Hence numerical methods such as Finite Element and Finite Difference methods are used to solve complex groundwater problems. These conventional mesh/ grid-base...

Land use-land cover change (LULC) has considerable impacts on hydrologic response at the river basin/ watershed level. Quantitative assessment of LULC impacts on runoff generations on river basin scale is important for water resources development and impact assessment of extreme events. Based on the historical LULC changes, the future LULC can be p...

COVID-19 has wreaked havoc throughout the planet within a short time frame, inducing substantial morbidity and mortality in the global population. The primary procedures commonly used to manage the pandemic can produce various environmental pollutants, primarily contaminants of emerging concern such as plastics, chemical disinfectants, and pharmace...

In this study, the local scour and the associated flow hydrodynamics around a complex pier with rectangular pile-cap at three different pile-cap elevations are investigated. The pile-cap elevations were selected with respect to the initial sand bed, such that the pile-cap was unexposed (case I), partially exposed (case II), and fully exposed (case...

The estimation of the impacts of climate change on hydrology at the local level comprises various sources of uncertainty. Especially, global climate models (GCMs) are found to be one of the major sources of uncertainty at the local level and it is important to identify for robust water resource planning and management. Therefore, this study demonst...

The forest-agricultural landscapes of the humid tropics are transforming in their physical and socio-cultural spaces. Even though the processes of landscape transformation are highly contextual, their drivers, impacts and implications fan out across multiple scales from the local to the global. In the present study, the processes of landscape chang...

Plastic particles have become ubiquitous in various environmental compartments, with the atmosphere being the least explored of these. Furthermore, the way atmospheric plastics affect terrestrial biological systems has not been evaluated to the same extent as for aquatic ecosystems. Plastics are even found in human lungs, and hence their adverse ef...

This study investigates the turbulent flow characteristics around a complex pier (CP) with an elliptical pile-cap to understand the mechanics of the flow responsible for current-induced scour. The velocity data are recorded using an acoustic Doppler velocimeter for a Reynolds number of 67 745. This study gives mean velocities in different horizonta...

Estimation of the expected maximum scour depth is very crucial at the design stage of a bridge. In India, for design of a bridge pier, the guidelines given by the Indian Road Congress (IRC) code is generally followed. The IRC equation is generally used to estimate the mean scour depth with a factor of safety of two to obtain the maximum design scou...

The world is facing an unprecedented time owing to the ongoing COVID-19 pandemic. The research community is racing to find a solution to contain the outbreak, leading to the proposals of many possible routes of the virus transmission and its dynamics. The Indian sub-continent experiences the monsoon season that leads to heavy rainfall and flooding...

Understanding the complex groundwater flow behaviour is of utmost importance for a better and quicker management of groundwater. A thorough study of flow behaviour can be attained by modeling. Numerical simulation models have been proven to be an effective means of modeling of groundwater. The state-of-art meshfree simulation models, demonstrated i...

Groundwater is the largest source for freshwater which plays an important role in the hydrological cycle. The pollution of groundwater is on the rise due to various natural and anthropogenic sources such as landfills, agricultural lands, and underground waste storage facilities etc. These pollutants can be subjected to reactions depending on the co...

Circular piers are most commonly used for bridges around the world. Depending on the width of the bridge, single or multiple piers are provided. When the number of piers is more than one, the scour pattern around the pier is affected by the mutual interference and the formation of the horseshoe vortex system around each pier. The mutual flow interf...

In this study, we assess the soil erosion susceptibility at the sub-basins scale using remote sensing data with the integration of the Geographical Information System (GIS) for the Netravati river basin in Western Ghats, India. The Cartosat digital elevation model was used for the calculation of morphometric parameters, and Landsat satellite images...

Wakes and higher-order turbulence around circular cylinder of different diameters are investigated using particle image velocimetry measurements. The cylinder Reynolds number (Red) is defined by the depth averaged velocity, cylinder diameter and kinematic viscosity. The influence of Red on third-order moment of velocity fluctuations, turbulent kine...

Remotely sensed (RS) observations are becoming prevalent for hydrological model calibration in sparsely monitored regions. In this study, the parameter uncertainty associated with a hydrological model calibrated with RS evapotranspiration (ET) and soil moisture (SM) is investigated in detail using a Markov chain Monte Carlo (MCMC) approach. The dai...

Locating the sources of the contaminant in groundwater is crucial for efficient remediation design and water resources management. Source identification in groundwater is challenging as an aquifer is only perceived as contaminated when contamination is measured in one of the observation wells. Amongst the available techniques, the simulation-optimi...

Inverse modelling is a powerful technique for estimating unknown variables in groundwater problems which are essential for water resource management. Simulation-optimization (SO) models are generally used for solving inverse problems in groundwater. In this approach, the optimization model, which is linked externally with the simulation model, iden...

This experimental study was aimed at investigating the maximum scour depth around a complex bridge pier with oblong pile-cap at three different elevations with respect to the sand bed. The clear-water scour experiments were performed in a recirculating flume where the pile-cap was unexposed, partially exposed and fully exposed to the flow. The resu...

Hydrologic models are important tools for accurate water resource assessment. Distributed models are commonly used for this purpose as its output provides detailed information about catchment hydrology. High data requirements and complex structure limit the application of the distributed models at the majority of locations. In comparison, conceptua...

In this study, a meshless simulation model based on the element-free Galerkin method (EFGM) is proposed for the coupled simulation of groundwater flow and contaminant transport (GFCT) in the two-dimensions. EFGM discretizes the governing GFCT equations using the Galerkin integral approach and shape functions generated through the moving least squar...

Groundwater flow and transport models are essential tools for the management of groundwater resources. Estimation of aquifer parameters in the simulation models is of prime importance for accurate assessment of water availability, the fate of contaminants and remediation. In this study, the flow and transport parameters of a confined aquifer are de...

Groundwater flow and contaminant transport are complex phenomena which require partial differential equations to be solved numerically throughout the problem domain. Finite Difference method (FDM) and Finite Element method (FEM) based models are traditionally employed for these simulations. These methods suffer from certain instabilities due to the...

In this study, the impacts of land use/land cover (LULC) and climate change on the streamflow and sediment yield were investigated for the Payaswani River Basin, Western Ghats, India. The LULC was determined using Landsat images, and climate data were procured from five general circulation models for representative concentration pathway (RCP) 4.5 (...

In this paper, the meshless element-free Galerkin method (EFGM) based coupled model is developed to simulate the groundwater flow and multispecies reactive transport coupled with sequential decay reactions in unconfined aquifers. The use of moving least squares (MLS) approximation in approximating the head and concentration vari- ables in EFGM tend...