Modeling of Flow and Transport in Groundwater Systems M. Sekhar Department of Civil

Engineering Indian Institute of Science

RESOURCE ASSESSMENT

CM

SWAT MODFLOW

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SWAT MODFLOW

BIO

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INTEGRATED MODELING

SUSTAINABLE MANAGEMENT

CONTAMINANT MIGRATION

Groundwater discharge variationsGroundwater discharge variations

~ 1000 km~ 1000 km22Lower Lower Kabini Kabini BasinBasin

Sustainable Groundwater Management Under Climatic & Anthropogenic Effects Sustainable Groundwater Management Under Climatic & Anthropogenic Effects

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Water table fluctuation & Chloride mass balance methods

Cumulative Rainfall Departure & Groundwater Levels

CRD

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Soil Moisture Retrieval & Modeling Using Assimilation MethodsSoil Moisture Retrieval & Modeling Using Assimilation Methods

Data used: 29th April 2005 – 29th March 2007

Numerical models for simulating profile soil moisture in soils using improved inversion (e.g. GLUE) and assimilation models (e.g. ensemble Kalman filter) are needed to characterize the land-surface fluxes under various soil cover conditions. Soil moisture prediction in plots for various crop types is developed. Near-surface soil moisture retrieval using ENVISAT satellite at watershed scale is under cropped areas is in progress. Field scale experiments to use future micro-wave Indian satellite (RISAT) are being developed.

Example: Simulations in soil plots with grass cover for understanding the evaporation and recharge fluxes

Numerical modeling for stochastic analysis of flow and Numerical modeling for stochastic analysis of flow and reactive solute transport in heterogeneous porous mediareactive solute transport in heterogeneous porous media

Scale dependent dispersivityB

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33--D problemD problem

Plume

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LandfillLandfill

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LandfillLandfill

Stochastic FEM

Modeling of the effect of contaminant sources in groundwater is needed to predict the development of the plume characteristics.

The random field modeling is required for analyzing the effect of heterogeneity in parameters (e.g. hydraulic conductivity, dispersivity, sorption and decay coefficient)

3-D stochastic flow and transport models are developed for analyzing the prediction uncertainty of concentration plumes due to the combined effect of randomness of system parameters and the input source conditions.

Stochastic Modeling of Flow Conditional to Watershed Investigations Stochastic Modeling of Flow Conditional to Watershed Investigations

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Blue colour = Top clay layer (Blue colour = Top clay layer (RegolithRegolith))Green to yellow colour = Weathered rock (Green to yellow colour = Weathered rock (Fissured zoneFissured zone))Red colour = Fresh or fractured rockRed colour = Fresh or fractured rock

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Hydrogeochemical Modeling – Theoretical & Field ApplicationsHydrogeochemical Modeling – Theoretical & Field Applications

3D Reactive Transport Model with equilibrium geochemical reactions (HYDROS)

Example: Sulphide mineral oxidation and transport of oxidation products from pyrite ore mine tailing dump

Multi-component transport of solutes in soil and groundwater system require modeling the geochemical reactions arising from the water-rock/sediment interactions.

A multidimensional numerical model (HYDROS) based on the finite volume method for the multi-component equilibrium reactive solute transport is developed, which combines the transport model with equilibrium speciation module MINTEQA2 (US geological survey).

HYDROS is evaluated and compared with the MINTOX simulations used to model the metal mobility in aquifers impacted by acid mine tailings discharge.

HYDROS is then applied to the case study of the transfer of transition metals with organic colloids in the swamp groundwater of the experimental Nsimi watershed, representative of the humid tropical ecosystem of the South Cameroon Plateau.

Research Areas & Future InterestsResearch Areas & Future Interests Groundwater resources assessment under climatic variations and

anthropogenic effects using numerical models, statistical tools and

field studies.

Retrieval of near surface soil moisture through radar remote

sensing (SAR) and estimation of profile soil moisture using

modeling and assimilation at watershed scale.

Stochastic modeling of flow and reactive solute transport in

heterogeneous porous media. Theoretical investigations and field

scale experiments.

Integrated geochemical and hydrological studies in tropical regions

using experimental watersheds.

Publications pertaining to the slidesPublications pertaining to the slides

Chaudhuri, A. and Sekhar, M. (2007) Stochastic finite element method for analysis of transport of nonlinearly sorbing solutes in 3-D heterogeneous porous media. Water Resources Research, 43, W07442.

Soumya, B., Sekhar, M., Riotte, J. and Braun, J.J. Non-linear regression model for spatial variation in precipitation chemistry for South India. Atmospheric Environment (In Press).

Mangiarotti, S., Sekhar, M., Javeed, Y., and Mazzega, P. Spatio-temporal analysis of groundwater dynamics due to climatic variability and land use changes. Hydrological Processes (Accepted).

Descloitres, M., Ruiz, L., Sekhar, M., Legchenko, A., Braun, J.J., Mohan Kumar, M.S. and Subramanian, S. (2007) Characterization of seasonal local recharge using Electrical Resistivity, Tomography and Magnetic Resonance Sounding. Hydrological Processes, doi. 10.1002/hyp.6608.

Sekhar, M., Braun, J. J., Hayagreeva Rao, K. V., Ruiz, L., Viers, J., and Dupre, B. (2007) Hydrogeochemical modeling of organo-metallic colloids in the Nsimi experimental watershed, South Cameroon. Environmental Geology (In Press).

Sekhar, M., Rasmi, S.N., Javeed, Y., Gowrisankar, D., and Ruiz, L. (2006). Modeling the groundwater dynamics in a semi-arid hard rock aquifer influenced by boundary fluxes, spatial and temporal variability in pumping/recharge. Advances in Geoscience, Hydrological Sciences (ed) Park, N., V. 4, p. 173-181