Software and Systems Engineering Standards: Verification and Validation of Sy...
GROUNDWATER MODELING SYSTEM
1. Groundwater Modeling System
Presented by
Chandra Vanshi Thakur(17WM60R07)
Shyam Mohan Chaudhary(17AG62R13)
Visuto Khatso(17AG62R14)
Rajnish Singh(17AG62R18)
2. UTILITY OF THE MODEL
• Comprehensive graphical user environment for
performing groundwater simulations.
• provides tools for every phase of a simulation
– site characterization,
– model development,
– calibration,
– post-processing and
– visualization.
3. GMS CAN BE DOWNLOADED FROM
https://www.aquaveo.com/downloads
co
Contains all core
components, all tools
of site characterization,
additional models and
ARC-GIS extensions
4. MODEL FRAMEWORK
• Several numerical models are currently supported in
GMS.
• MODFLOW
– MODFLOW is a 3D, cell-centered, finite difference,
saturated flow model developed by the USGS.
– The governing equation (partial-differential flow
equation) can be approximated by replacing the
derivatives with finite differences.
5. continued…
Governing Groundwater flow equation
The saturated flow modeling is based transient on the three-
dimensional Darcy equation
where Kxx, Kyy, Kzz are the hydraulic conductivity along the x, y
and z axes ,
h is the hydraulic head,
Q represents the source/sink terms, and
S is the storage coefficient
9. INPUT DATA REQUIREMENTS
• Base map.
• Boundary conditions.
• Rainfall and evaporation data for the entire study
area.
• Groundwater level to define the initial and boundary
condition and for calibration and validation.
• Aquifer properties.
• Groundwater abstraction data.
10. INPUT DATA REQUIREMENTS
• The input file formats
– ASCII files (.TXT, .ASC, .DAT),
– MS Access Database files (.MDB),
– MS Excel files (.XLS),
– ESRI Point files (.SHP),
– USGS DEM files (.DEM),
– ESRI grid files (.GRD)
– http://india-wris.nrsc.gov.in/
– https://www.ncdc.noaa.gov/cdo-web/
– http://www.indiawaterportal.org/met_data/
11. OUTPUT DATA
• Hydraulic Heads
• Drawdown
• Flow rates
• Mass Balance
• Iteration information.
• The velocity vectors, path lines, water table contours,
concentration contours can be seen in 2D or 3D
according to the selection.
14. EXTRA AVAILABLE DATA
• Vertical anisotropy (Kh/Kv)
– Layer 1 = 10
– Layer 2 = 5
• Grid size : 22860 m x 22860 m.
• Cell size : 1524 m x 1524 m.
• Grid consists of 15 rows and 15 columns.
• Top layer wells: 12 with discharge 12230 m3/day each
• Middle layer wells: 2 with discharge 12230 m3/day each
• Bottom layer well: 1 with discharge 0.15 m3/day
15. EXTRA AVAILABLE DATA
• LAKE : Constant head
boundary on the left.
(first two layers) (30 cells)
• Starting heads will be set
equal to zero
• Steady state solution will
be computed.
DRAIN
16. MODELING WITH GRID APPROACH
• Units
• Creating the Grid
• Creating the MODFLOW simulation
• Assigning IBOUND values directly to cells
• LPF package
• Recharge Package
• Drain Package
• Well Package
• Checking and saving the simulation
• Running MODFLOW
• Viewing the solution
• Zone Budget
• Conclusion
83. PROBLEM STATEMENT
• Since the groundwater there has been severely
contaminated by salinization, most water for agricultural
purposes is drawn from the river.
• Effective strategies for both management and protection
of groundwater resources are required to avoid future
irreversible environmental impacts, such as depletion
and deterioration of groundwater quality.
84. OBJECTIVES
• To employ MODFLOW within the framework of the
GMS to study the groundwater processes of the
hydrogeological system of Bou-Areg unconfined
aquifer
• To perform particle tracking in the aquifer using
MODPATH inside GMS framework .
85. METHODOLOGY
STUDY AREA
• The plain of Bou-Areg is located on the Mediterranean coast
of northeastern Morocco.
• The coastal plain of Bou-Areg covers 160 km2.
• The waters of the lagoon are very salty, with average salinity
levels between 37 g/l and 42 g/l during the past thirty years.
• The climate of the study area is semi-arid to humid. Average
annual precipitation is around 346 mm.
86.
87. Data preparation
• Analysis of pumping tests.
– The Neuman and Theis solutions are applied to obtain
hydraulic conductivity (1.1 × 10−6 to 5 × 10−4 m/s)
storage coefficient (1.30 × 10−4 and 3 × 10−2)
Vertical anisotropy (3 to 15)
The water balance technique is used to estimate the recharge
(9.2 × 106 m3/year)
R=P−Q −RET −ΔW
Mod el s etu p
• finite-difference model grid (500 m x 500 m) 28 rows and 53 columns.
• layer one thickness between 5 and 11 m.
• layers two and three, which are each 25 m thick.
95. CONCLUSIONS
• The results of the model calibration show reasonable
agreement between observed and calculated water
levels for the observation wells.
• The horizontal hydraulic conductivity, obtained from the
model calibration, ranges between 3 × 10−4 and
2 × 10−6 m/s.
• The model aquifer is more sensitive to recharge than to
hydraulic conductivities and storativity.
• The MODPATH results show that migration of pollutants
from the upstream of the aquifer towards the lagoon is
very slow and could attain the Bou-Areg lagoon in 1000
years.
96. FUTURE SCOPE
• Since MODFLOW is based on FORTRAN
programming language which is generally
sophisticated, so attempts should be made to
code the MODFLOW in user friendly language
• Since GMS involves the use of various models
flow, transport and optimization, A DSS should
be generated to assist and help decision makers
in decision making process