# HydroGeoSphere

This is an instructional guide to conducting numerical simulations in the groundwater modelling software known as HydroGeoSphere (HGS).

## Introduction

HydroGeoSphere is a three dimensional control-volume finite element groundwater model, and is based on a rigorous conceptualization of the hydrologic system consisting of surface and subsurface flow regimes. The model is designed to take into account all key components of the hydrologic cycle. For each time step, the model solves surface and subsurface flow, solute and energy transport equations simultaneously, and provides a complete water and solute balance.
Please note that the content of this Wikibook consists of Chapter 5 of the complete HydroGeoSphere User Manual (Release 1.0). For consistency, references are labelled as shown in the complete manual, and some refer to content that is currently only available there.

## Contents

* General
** File Process Control Options
** Units and Physical Constants
** Preprocessor Considerations
*** Array Dimensioning
* Problem Identification
* Grid Generation
** Simple Grids
** Interactive Block Grids
** 3-D Random Fracture Generator for Block Grids
** 2-D Random Fracture Generator
** Interactive 3-D Mesh Generator
*** Defining a 2-D Mesh
*** 3-D Mesh Generation
*** Adding a New Layer
*** Elevation Instructions
** Tetrahedral Element Grids
** Axisymmetric Flow
** Reading an Existing 3-D Grid
** Manipulating the 3-D Grid
** Grid Projection
** Ending Grid Generation
* Selecting Mesh Components
** Selecting Nodes
** Selecting Segments
** Selecting Faces
** Selecting Inclined Faces
** Selecting Elements
* Simulation Control Options
** General
*** Finite-Difference Options
*** Matrix Solver
** Timestep Control
*** Adaptive Timesteps
** Saturated Flow
** Variably-Saturated Flow
*** Newton Iteration Parameters
** Discrete Fracture Flow
** Surface Flow
** Transport
** Density-Dependent Flow and Transport Solution
*** Relative Concentration as Primary Variable
*** Absolute Concentration and Temperature as Primary Variables
*** Salt Mass Fraction as Primary Variable
** Heat Transfer
** Inactive Elements
* Initial Conditions
** Subsurface Flow
** Surface Flow
** Transport
*** Solute Definition
*** Travel Time Probability
*** Heat Transfer
* Boundary Conditions
** General
** Type
*** Specified Head
*** Specified Flux
*** Seepage
*** Free Drainage
*** Potential Evapotranspiration
*** Specified Flowrate
*** River Flux
*** Drain Flux
*** Surface Loading
*** Hydromechanical Stress
*** Pore Water Freezing and Thawing
*** Surface Flow
*** Snowmelt
** Node and Face Sets
** Time-Varying Inputs
*** Interpolation
*** Intermittent Conditions
** Constraints and Tecplot Options
*** Nodal Flux Head Constraints
*** Tecplot Output
** Transport
*** Specified Concentration
*** Specified Mass Flux
*** Specified Third-Type Concentration
*** Thermal Energy
*** Imported from GMS
*** Immiscible Phase Dissolution Source
*** Zero-Order Source
* Materials and Material Properties
** General
*** Defining a New Zone
*** Saving and Retrieving Element Zone Numbers
*** Defining New Zones Using ARCVIEW Files
*** Defining New Zones Using GridBuilder .GEN Files
*** Selecting Zones
*** Modifying Zoned Properties
** Saturated Subsurface Flow
*** Porous Medium
*** Discrete Fractures
*** Dual Continuum
*** Wells
*** Tile Drains
*** Channel Flow
*** Cutoff Walls
*** Imported from FRACTRAN
** Variably-Saturated Subsurface Flow
*** Porous Medium
*** Discrete Fractures
*** Dual Continuum
*** Functional Constitutive Relationships
*** Tabular Constitutive Relationships
** Surface Flow
** Evapotranspiration
** Transport
*** Porous Medium
*** Discrete Fractures
*** Dual Continuum
*** Surface Runoff
* Output
** Grid
*** GMS
*** GRID BUILDER
*** TECPLOT
*** IBM Data Explorer (OPENDX)
** Flow Solution
*** Observation Wells and Points
*** Fluid Mass Balance
** Surface Flow Hydrographs
** Transport
*** Observation Wells and Points
*** Solute Mass Balance
*** Flux-Averaged Concentration at a Well
*** Travel Time Probability
    References