Soumendra Bhanja

Oak Ridge National Laboratory | ORNL · Computational Sciences and Engineering Division

In summer (pre-monsoon) of recent years, low water level among the last few decades, has been observed in several lower Indian reaches of the Ganges (or Ganga) river (with estimated river water level depletion rates at the range of -0.5 to -38.1 cm/year between summers of 1999 and 2013 in the studied reaches). Here, we show this Ganges river deplet...

A conversion of the global terrestrial carbon sink to a source is critically dependent on the microbially mediated decomposition of soil organic matter (SOM). We have developed a detailed, process-based, mechanistic model for simulating SOM decomposition and its associated processes, based on Microbial Kinetics and Thermodynamics, called the MKT mo...

Groundwater use in India has been in the limelight in recent years due to its intensive and apparent unsustainable use that poses threats to water security, drinking water supply and food production. Here, we present estimates of usable groundwater storage, for the first time, at the state-level across all of India using both in situ and satellite-...

The natural carbon dioxide (CO2) emission from the ecosystem, also termed as the ecosystem respiration (Reco), is the primary natural source of atmospheric CO2. The contemporary models rely on empirical functions to represent decomposition of litter with multiple soil carbon pools decaying at different rates in estimating Reco variations and its pa...

Central India faces a freshwater shortage due to its diverse terrain, sudden change in precipitation patterns and crystalline rock covered subsurface. Here, we investigate the patterns in terrestrial water storage anomaly (TWSA) over the last two decades, and also study the influence of the COVID-19 lockdown on TWSA in the drought-prone regions of...

Agriculture-sourced, non-point groundwater contamination (e.g., nitrate) is a serious concern from the drinking water crisis aspect across the agrarian world. India is one of the largest consumers of nitrogen fertilizers in South-Asia as well as in the world but groundwater nitrate lacks critical attention as a wide-scale drinking water pollutant i...

The 2020 COVID-19 pandemic has not only resulted in immense loss of human life, but it also rampaged across the global economy and socio-cultural structure. Worldwide, countries imposed stringent mass quarantine and lockdowns to curb the transmission of the pathogen. While the efficacy of such lockdown is debatable, several reports suggest that the...

The rapid decline of groundwater levels (GWL) due to pervasive groundwater abstraction in the densely populated (~1 billion) Indus-Ganges-Brahmaputra-Meghna (IGBM) transboundary river basins of South Asia, necessitates a robust framework of prediction and understanding. While few localized studies exist, three-dimensional regional-scale characteriz...

Ecosystem respiration (Reco) and its components, the autotrophic respiration (Ra) and soil respiration (Rs) are the essential indicators of the global carbon cycle. They are represented as functions of either temperature or soil moisture, or a combination of both in the widely-used Earth System Models (ESMs). Thus, it is difficult to evaluate the i...

Abstract: Watersheds in cold regions provide water, food, biodiversity and ecosystem service. However, the increasing demand for water resources and climate change challenge our ability to provide clean freshwater. Particularly, watersheds in cold regions are more sensitive to changing climate due to their glaciers’ retreat and permafrost. This rev...

Groundwater plays a major role in human adaptation and ecological sustainability against climate variability by providing global water and food security. In the Indus-Ganges-Brahmaputra-Meghna aquifers (IGBM), groundwater abstraction has been reported to be one of the primary contributors to groundwater storage variability. However, there is still...

The rapid groundwater depletion and the deterioration in groundwater quality in the major aquifers around the globe due to anthropogenic stress and natural causes have raised serious concerns over the usable groundwater resources worldwide. While the rapid depletion is attributed to pervasive groundwater abstraction for agriculture, industrial, and...

Groundwater security is a crucial component of the sustainable development in South Asia due to various population-linked issues. The region hosts almost one-fourth of the global population within less than 5% of the global land area. Prevailing groundwater depletion issues would lead to public health as well as food security concerns if goes uncon...

Due to unavailability of consistent income data at the sub-state or district level in developing countries, it is difficult to generate consistent and reliable economic inequality estimates at the disaggregated level. To address this issue, this paper employs the association between night time lights and economic activities for India at the sub-sta...

Groundwater and surface water support all of the human water needs. However, due to climate change, the extent and properties of permafrost and seasonally frozen grounds are changing in cold regions. This can substantially impact on both groundwater and surface water resources. We present here the decade-scale change in groundwater and surface wate...

Worldwide, >2 billion people (~1/3 world population), mostly living in economically stressed areas of Africa and South Asia, still do not have access to basic sanitation, and ~1 billion still practice open defecation. Water pollution due to open defecation may primarily be linked to economy, and other factors such as social and hygiene practices, l...

The water and food security of South Asia is embedded in the groundwater resources of the transboundary aquifer system of Indus-Ganges-Brahmaputra-Meghna (IGBM) rivers, which has been subjected to diverse natural and anthropogenic triggers. Thus, understanding the relative importance of such triggers in groundwater level change and developing a pre...

Soil heterotrophic respiration (RH) is a crucial component of the atmospheric carbon dioxide (CO2) budget, as RH accounts for ∼10 times more CO2 than burning fossil fuels. However, modelling of RH is primarily based upon empirical/semi-empirical approaches. Here, we developed a mechanistic model based on microbial kinetics and thermodynamics proces...

India has been the subject of many recent groundwater studies due to the rapid depletion of groundwater in large parts of the country. However, few if any of these studies have examined groundwater storage conditions in all of India’s river basins individually. Herein we assess groundwater storage changes in all 22 of India’s major river basins usi...

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Globally, ~1 billion people, mostly residing in Africa and South Asia (e.g. India), still lack access to clean drinking water and sanitation. Resulting, unsafe disposal of fecal waste from open-defecation to nearby drinking water sources severely endanger public health. Until recently, India had a huge open-defecating population, leading declining...

The scarcity of groundwater storage change data at the global scale hinders our ability to monitor groundwater resources effectively. In this study, we assimilate a state‐of‐the‐art terrestrial water storage product derived from Gravity Recovery and Climate Experiment (GRACE) satellite observations into NASA's Catchment land surface model (CLSM) at...

Normalized Difference Vegetation Index (NDVI) is widely used as an efficient indicator of vegetation cover. Here we assess the possibility of using NDVI as an indicator of groundwater storage. We used groundwater level (GWL) obtained from in situ groundwater observation wells (n > 15,000) in India in 2005–2013. Good correlation (r > 0.6) is observe...

This study explores the uncertainties in terrestrial water budget estimation over High Mountain Asia (HMA) using a suite of uncoupled land surface model (LSM) simulations. The uncertainty in the water balance components of precipitation (P), evapotranspiration (ET), runoff (R), and terrestrial water storage (TWS) is significantly impacted by the un...

Quantifying soil carbon dioxide (CO2) emission is a crucial step for estimation of global greenhouse gas budget. NaturalsoilCO2 emissionmodellingischallengingtoincorporateinteractionsamongthemultiplechemical,physical and biological processes. Most of the available agroecosystem models are based on carbon and nitrogen pool assumptions, where each po...

Soil respiration is a crucial source of carbon dioxide (CO2) in the atmosphere. The underlying processes involved are multifaceted, sequential chemical reactions associated with the conversion of soil organic carbon to CO2. In this paper, we present a mechanistic, biogeochemical model to simulate soil CO2 emissions considering the microbial and seq...

More than quarter of underprivileged global population, who lack access to basic sanitation and clean drinking water, live in India. Consequently, every year, millions suffer with enteric diseases from drinking faecal-contaminated groundwater. The UN Sustainable Development Goal lists access to safe water and basic sanitation for all by 2030, as th...

Groundwater recharge sustains groundwater discharge, including natural discharge through springs and the base flow to surface water as well as anthropogenic discharge through pumping wells. Here, for the first time, we compute long-term (1996–2015) groundwater recharge rates using data retrieved from several groundwater-level monitoring locations a...

Global hydrological and land surface models are increasingly used for tracking terrestrial total water storage (TWS) dynamics, but the utility of existing models is hampered by conceptual and/or data uncertainties related to various underrepresented and unrepresented processes, such as groundwater storage. The gravity recovery and climate experimen...

Over the past decade, the issue of diminishing groundwater resources in India has garnered significant concern worldwide. Indian groundwater abstraction may be ascribed as the “largest groundwater abstraction in human history”. However, our recent studies have identified replenishment of groundwater storage at regional scale in parts of southern an...

Groundwater is one of the most important natural resources for economic development and environmental sustainability. In this study, we estimated groundwater storage in 11 major river basins across Alberta, Canada, using a combination of remote sensing (Gravity Recovery and Climate Experiment, GRACE), in situ surface water data, and land surface mo...

Groundwater recharge sustains groundwater discharge, including natural discharge through springs and base flow to surface water as well as anthropogenic discharge through pumping wells. Here, for the first time, we compute long-term (1996–2015) groundwater recharge rates using data retrieved from several groundwater level monitoring locations acros...

Present projections of climate change scenario show an increase in global temperature and CO2 content, which have indirect impacts on surface water flow, but rainfall has direct impacts on surface run-off and groundwater storage system. This study investigates the effect of climate change on aquifer storage and surface run-off, and interactions wit...

In recent years, intense abstraction of groundwater has led to depletion in groundwater storage (GWS) in India, the second most populous country in the world. In this chapter, we demonstrate our work on estimating groundwater storage over India by using data from the Gravity Recovery and Climate Experiment (GRACE) satellite mission to study long-te...

Large number of people in the globe depends on groundwater as a major source of freshwater. Here, we provide present-day regional-scale groundwater recharge rates in a major part of the Indian subcontinent. We have used a combination of ground-based observed water level data obtained from an intense network of observational wells, along with satell...

Groundwater is one of the most important natural resources for economic development and environmental sustainability. However, groundwater storage can be significantly affected by climate change through permafrost thaw, snowpack change, and glacier retreat in cold climate regions, and human activities due to over-use and over-extraction of resource...

The dwindling groundwater resource of India, supporting almost one fifth of the global population and also the largest groundwater user, has been of great concern in recent years. However, in contrary to the well documented Indian groundwater depletion due to rapid and unmanaged groundwater withdrawal, here for the first time, we report regional-sc...

This study investigates some of the benefits and drawbacks of assimilating Terrestrial Water Storage (TWS) observations from the Gravity Recovery and Climate Experiment (GRACE) into a land surface model over India. GRACE observes TWS depletion associated with anthropogenic groundwater extraction in northwest India. The model, however, does not repr...

Groundwater level measurements from 3907 monitoring wells, distributed within 22 major river basins of India, are assessed to characterize their spatial and temporal variability. Groundwater storage (GWS) anomalies (relative to the long-term mean) exhibit strong seasonality, with annual maxima observed during the monsoon season and minima during pr...

In this study, we tried to validate groundwater storage (GWS) anomaly obtained from a combination of GRACE and land-surface model based estimates, for the first time, with GWS anomaly obtained from a dense network of in-situ groundwater observation wells within 12 major river basins in India. We used seasonal data from more than 15000 groundwater o...

The Indian Sub-Continent is one of the most densely populated regions of the world, hosting ∼23% of the global population within only ∼3% of the world's land area. It encompasses some of the world's largest fluvial systems in the world (River Brahmaputra, Ganges and Indus Basins), which hosts some of the highest yielding aquifers in the world. The...

We analysed aerosol optical and physical properties in an urban environment (Kolkata) during winter monsoon pollution transport from nearby and far-off regions. Prevailing meteorological conditions, viz. low temperature and wind speed, and a strong downdraft of air mass, indicated weak dispersion and inhibition of vertical mixing of aerosols. Spect...

Groundwater resources are rapidly depleting in the developing countries like India, the second populous country in the world. A huge amount of groundwater has been abstracted in recent years (243 BCM during 2011-12) leading to depletion in groundwater storage (GWS) in India. In order to study long-term GWS change over parts of Indian subcontinent,...

Exponential increase in population triggers significant depletion in groundwater storage (GWS), particularly in the developing countries like India, due to the demands of irrigation and industry. Approximately, 70% of groundwater withdrawals worldwide are associated with irrigation. In order to study long-term GWS change over parts of the Indian su...