Dhanya C T

Indian Institute of Technology Delhi | IIT Delhi · Department of Civil Engineering

Standardized Precipitation Index (SPI) is one of the frequently used meteorological drought indices. However, the time-varying characteristics observed in the historical precipitation data questions the reliability of SPI and motivated the development of nonstationary SPI. To overcome some of the limitations in the existing nonstationary drought in...

Future climate projections are a vital source of information that aid in deriving effective mitigation and adaptation measures. Due to the inherent uncertainty in these climate projections, quantification of uncertainty is essential for increasing its credibility in policymaking. While quantifying the uncertainty, often the possible dependency betw...

The goal in this commentary is to share the development of the NASA Applied Science pre‐launch protocol called the Early Adopter Program (EAP) that is designed to build user‐readiness of planned satellite Earth observing missions proactively and before the launch. Here we focus in particular on the Surface Water and Ocean Topography satellite missi...

Sub-daily precipitation is projected to intensify more rapidly with global warming, that in turn may lead to frequent disasters such as flash floods, landslides, etc. However, the precipitation projections from Global Climate Model (GCMs) are known to be highly uncertain, with an increasing magnitude at finer spatio-temporal scales. Hence, realisti...

Aim of this work is the assessment of the individual and combined impacts of land use land cover change (LULCC) and inter-decadal climate variations (CV) on the water and energy cycles over India, given extensive land use land cover change over the last decades. In this study, we quantify the contributions of LULC and CV on changes in the water and...

Over the last two decades, several data sets have been developed to assess flood risk at the global scale. In recent years, some of these data sets have become detailed enough to be informative at national scales. The use of these data sets nationally could have enormous benefits in areas lacking existing flood risk information and allow better flo...

Environmental flows play a major role in terms of quantity and quality for sustainable riverine ecosystems (Brisbane Declaration, 2007). Environmental Flows (EFs) have a variety of impacts in different regions of the world, including fisheries and other aquatic life, assimilative capacity, drinking water security, agriculture, transportation, navig...

A realistic assessment of drought onset is paramount for the effective development of various risk management strategies at the more intense later stages of drought propagation. Such assessments are primarily governed by the methodological sophistication of the drought indicators employed, leading to their consistent modifications. The initial domi...

The state of Assam, primarily in the Brahmaputra basin, is one of the most flood-prone states of India, with devastating floods occurring every year. Rapid urbanization in the floodplains and inadequate water management have further exacerbated the human and infrastructural exposure to floods. Despite efforts in organizing relief camps and setting...

The overwhelming increase and variations in the extreme rainfall events demand the use of a nonstationary Intensity-Duration-Frequency (IDF) curve for the design and management of water resource infrastructure. Generally, nonstationary IDF curves were developed by incorporating the trend in the distribution parameter using Generalized Extreme Value...

The hydrological impact of many expensive investments on watershed interventions remains unquantified due to lack of time series data. In this study, remote sensing imagery is utilized to quantify and detect vegetation cover change in Magera micro-watershed, Ethiopia, where sustainable land management interventions have been implemented. Normalized...

A realistic evaluation of drought onset is inevitable for the effective implementation of mitigation strategies. Meteorological droughts indicating the onset of drought propagation, are usually quantified through unbiased indices that consider the month-wise magnitude variations in historical climatic variables, while completely ignoring their intr...

The conventional error decomposition schemes of satellite-based precipitation products (SPPs) suffer from significant drawbacks such as misrepresentation of hit bias (H) component and magnification of random error, which limits their accuracy in deducing reliable conclusions. We propose a novel error decomposition technique by disintegrating the to...

Ensuring water security considering the near- and far-future climatic and socio-economic uncertainties, is one of the grand global challenges. In developing countries, supply-side management like the construction of new dams, rehabilitation and augmentation of the existing water resources and supply infrastructure are the widely adopted solutions....

Floods are a recurrent natural phenomenon in the Brahmaputra basin, India’s one of the major river basin. The government employed flood mitigation strategies that have mainly been focused on structural measures that involve the construction of dams, embankments, dykes, and anti-erosion structures. Consequently, the economic investments in Flood Pro...

The assessment of climate and land-use transformations upon the hydrologic response is crucial for decision-makers to accomplish various adaptation strategies. The Regional Climate Models (RCMs) have been extensively employed to study the impact of climate change on various hydrologic components. However, these climate models are subjected to a lar...

The quantity and quality of water flow in a river may significantly change from its normal condition between a reservoir and downstream, thus paving the way for drastic changes in the riverine ecosystem. Any disruption in the river's natural flow regime can alter the entire river ecosystem and socio-economic activities. Environmental flows are main...

The conventional hydrological modeling framework with a traditional streamflow-alone calibration approach is often challenged with the difficulty of accurately simulating the extreme flow conditions. This study explores the possibility of improving the simulation of extreme hydrological events by incorporating the antecedent soil saturation conditi...

The risk of flood and drought is strengthening due to future intensification of precipitation extremes and such intensification is more rapid for sub-daily precipitation extremes which can cause flash flood and prompt landslides. Despite this fact, the credibility of projections from general circulation models (GCMs) in sub-daily precipitation extr...

The study focuses on climate change impacts on the environmental flow indicators from hydrologic method point of view using IWMI’s Global Environmental Flow Calculator and Indicators of Hydrologic Alteration. It also discusses how the changes in flow magnitude and duration of annual extreme conditions, timing of annual extreme water condition, freq...

The existence of fewer gauging sites along with sparse network of rain gauges make the monitoring of floods difficult, especially over regions characterized with hydrologic heterogeneity. The availability of observations from satellite sensors makes it possible to study hydrological behaviour of such under-observed river basins. In this study, we e...

Decision trees are ideally suited for handling huge datasets and modelling non-linear relationships between different variables. Given the relationship between precipitation and bias may be very complex and non-linear, bias-correction of satellite precipitation is a challenge. We examine the applicability of Classification and Regression tree (CART...

Conventional Contingency Table (CT) compares the simulated/remotely-sensed dataset with observed dataset based on the frequency of rainfall events detected. However, while drawing comparison, it overlooks the variability in the rainfall intensity of Hit events (rainy events detected by both simulated and observed dataset). We propose to expand the...

Drought quantification is carried out by indicators like (1) Standardized Precipitation Index (SPI) and (2) Standardized Precipitation Evapotranspiration Index (SPEI), which encompass the historical characteristics of meteorological variants (precipitation and temperature). The behavioral pattern of these variables has changed significantly due to...

Conventional hydrological modeling frameworks being focused on the overall water balance of the hydrological system are challenged with the difficulty of accurately simulating the hydrological extremes. The availability of antecedent soil saturation observations from satellite sensors could be incorporated to simulate the hydrological extremes more...

The behavioral pattern of temperature and precipitation govern the characteristics (intensity, frequency, and duration) of meteorological drought. The present meteorological drought indices like the Standardized Precipitation Index (SPI) and the Standardized Precipitation Evapotranspiration Index (SPEI) function on a historical inter-comparison of...

This poster is a preliminary part of the larger project on "Integrated Groundwater Model to Investigate the Anthropogenic Influence on Hydrological Fluxes". The authors have made an attempt to re-evaluate the history of groundwater depletion in the Ganga Basin, India through an analysis of the past twenty years groundwater level data and past hundr...

Dynamic behavior of extreme rainfall characteristics heightened by the abrupt warming of the environment has affected the sustainability of the existing water resources systems and infrastructure, which were designed employing the traditional ‘stationary’ assumption. Here, we propose a realistic and efficient framework to detect non-stationarity in...

Any significant change in climate is known to have a significant impact on crop production and human resources, which are generally difficult to quantify. In the present study, two indices are defined: (i) refined growing season (GS) characteristics and (ii) transition period, based on the annual cycles of diurnal temperature extremes, to unravel a...

This study aimed to estimate water quality–based minimum environmental flow (Eflow) of a river under the impact of different plausible scenarios. The water quality model QUAL2K was deployed to simulate levels of dissolved oxygen (DO) and biochemical oxygen demand (BOD) in a river during the dry season. Hypothetical scenarios of pollution were gener...

Hydrology in a Changing World: Challenges in Modeling https://link.springer.com/book/10.1007/978-3-030-02197-9 This book offers a comprehensive overview of the challenges in hydrological modeling. Hydrology, on both a local and global scale, has undergone dramatic changes, largely due to variations in climate, population growth and the associated...

Various reanalyses have been utilized in numerous climate related researches around the globe, however, there exists considerable biasedness in these products, especially in precipitation and temperature data. The ability of these reanalysis products to simulate the precipitation and temperature patterns is observed to be satisfactory at global sca...

Predictability of climate variables is known to be limited to few days up to few weeks due to the inherent chaotic nature and resulting sensitivity to initial conditions. However, such generalization of limited predictability is cautioned because of the highly nonlinear nature and the known influence of localized causal factors on many climate vari...

River flooding has been causing extensive losses to life and property, which is a serious concern worldwide. To minimize these losses, suitable planning and management practices are required for the floodplain mapping. Flash floods occur almost every year in the deltaic region of Brahmani and Baitarani river basins in India, during the monsoon seas...

Floods in India are one of the most common natural disaster due to the irregularities in monsoon. The water generated from these floods causes huge damage to the lives and property, and, hence optimal water management has emerged as a major issue that concerns every member of our society. Over the past few decades, water professionals have made tre...

A river water quality management model under average climatic conditions may not be able to account for the extreme risk of low water quality which is more prominent under an increase in river water temperature and altered river flows. A modeling framework is developed to assess the risk of river low water quality extremes by integrating a statisti...

Abstract: Water resources management and modelling studies are often constrained by the scarcity of observed data, especially of the two major variables i.e., precipitation and temperature. Modellers, hence, rely on reanalysis datasets as a substitute; though its performance heavily vary depending on the data availability and regional characteris...

Effective management of floods in densely populated urban areas poses a great challenge. Computer modeling plays an important role in appropriate management of urban drainage systems. In this study an effort has been made to develop an efficient urban drainage model in which hydraulic results obtained from the developed SWMM model have been linked...

Regionalization of rainfall or delineation of a region into areas having similar rainfall characteristics is useful for many hydrologic applications and water resources management. In this study, we aim to regionalize India into regions having similar rainfall and climatic characteristics using self-organizing maps (SOM), an artificial neural netwo...

The vital demand of reliable climatic and hydrologic data of fine spatial and temporal resolution triggered the employment of reanalysis datasets as a surrogate in most of the hydrological modelling exercises. This study examines the performance of four widely used reanalysis datasets: ERA-Interim, NCEP-DOE R2, MERRA and CFSR, in reproducing the sp...

Different reanalyses have been applied widely for various climate-related researches around the globe. However, the skill of these reanalyses to simulate the precipitation patterns at regional scales needs to be carefully assessed due to their known susceptibility to significant biases and inability to capture extremes, especially over complex clim...

Understanding the evolution of Diurnal Temperature Range (DTR), which has contradicting global and regional trends, is crucial because it influences environmental and human health. Here, we analyse the regional evolution of DTR trend over different climatic zones in India using a non-stationary approach known as the Multidimensional Ensemble Empiri...

Rising global temperatures are causing increases in the frequency and severity of extreme climatic events, such as floods, droughts, and heat waves. We analyze changes in summer temperatures, the frequency, severity, and duration of heat waves, and heat-related mortality in India between 1960 and 2009 using data from the India Meteorological Depart...

Different hydrological models provide diverse perspectives of the system being modeled, and inevitably, are imperfect representations of reality. Irrespective of the choice of models, the major source of error in any hydrological modeling is the uncertainty in the determination of model parameters, owing to the mismatch between model complexity and...

The negative impacts of climate change are expected to be felt over wide range of spatial scales, ranging from small basins to large watersheds, which can possibly be detrimental to the services that natural water systems 10 provide to the society. The impact assessment of future climate change on hydrologic response is essential for the decision m...

The negative impact of climate change is felt over wide range of spatial scales, ranging from small basins to large watershed area, which can possibly outweighs the benefits of natural water system. General Circulation Models (GCMs) has been widely used as an input to a hydrological models (HMs), to simulate different hydrological components of a r...

Environmental flows (Eflow, hereafter) are the flows to be maintained in the river for its healthy functioning and the sustenance and protection of aquatic ecosystems. Estimation of Eflow in any river stretch demands consideration of various factors such as flow regime, ecosystem, and health of river. However, most of the Eflow estimation studies h...

Calibration is the most critical phase in any water quality modelling process. This study proposes a sequential calibration methodology for any water quality model using reach-specific estimates of model parameters, which would aid in the improved prediction of river water quality characteristics. The proposed methodology accounts for the heterogen...

Accurate estimates of monsoonal rainfall at daily time scales are essential inputs for various water-related sectors such as drought and flood forecasting, crop and water management for agriculture etc. To serve this purpose, a variety of rainfall products, especially the gauge based products which serve as the ground-truth for other derived rainfa...

The increase in drought, flood, diseases, crop failure etc. in the recent past has created an alarm amongst the researchers. One of the main reasons behind the intensification of these environmental hazards is the recent revelation of climate change, which is generally attributed to the human induced global warming, represented by an increase in gl...

Water distribution systems have become immensely complex due to ever increasing water demand and sporadic availability of water at the sources. Generally, water management issues are handled through human intervention, which naturally leads to incompetent trial and error procedures. Moreover, the non-linear system dynamics and sequential pumping op...

Subsurface movement of water within the alluvial formations of Ganga Basin Systemof North and East India, extending over an area of 1 million km2,was simulated using Visual MODFLOW based transient numerical model. The study incorporates historical groundwater developments as recorded by various concerned agencies and also accommodates the role of s...

The Storm Water Management Model (SWMM) has been an effective tool for simulating floods in urban areas, but has been seldom applied for river systems. In this study, a geographic information systems-based SWMM model was developed to authenticate the model's viability as a streamflow simulator for modeling floods in the Brahmani river delta. The mo...

Modeling of extreme events and its dynamic behavior have always been an intriguing topic. Increase in the magnitude and frequency of extreme events has widely been reported in recent decades, which is attributed to abrupt changes in climate. Numerous studies on extreme Indian monsoon characteristics, using a coarse resolution data set, have pointed...

The climate impact studies in hydrology often rely on climate change information at fine spatial resolution. Downscaling is a practice for obtaining local-scale hydrological variables from regional-scale atmospheric data that are provided by General Circulation Models. Among two downscaling methods, Statistical Downscaling is taken into account, as...

American Geophysical Union (AGU-2015), San Francisco, USA, December 14-18, 2015.

American Geophysical Union (AGU-2015) San Francisco, USA, December 14-18, 2015.

American Geophysical Union (AGU-2015), San Francisco, USA, December 14-18, 2015.

A case for incorporating requirements of water quality and water quantity under climate change in estimating environmental flow (Eflow) is presented. Despite the developments in Eflow assessment technologies worldwide, such studies are given little attention in practice. Eflow estimates for a given river stretch need to be modified accounting the p...

Extreme events though occur rarely, have adverse impact on water resources management. Rarity often limits the application and efficiency of models in simulating these events. Recent revelation of rapid climate change further aggravates this issue. Water resources planning and management demands holistic analysis and modelling of extreme events con...

Soil moisture is the source of water for evapotranspiration over the continents and it participates in both energy and water balance of the earth. Soil moisture participates in the energy cycle by managing the partitioning of the energy budget into latent and sensible heat, there by influencing the hydrological cycle. But to better understand the i...