Arc Hydro groundwater data model: a data model for groundwater systems within ArcGIS AWRA Specialty Conference Geographic Information Systems (GIS) and Water Resources III May 2004

Geographic data models Conceptual Model – a set of concepts that describe a subject and allow reasoning about it Mathematical Model – a conceptual model expressed in equations Data Model – a conceptual model expressed in a data structure Geographic Data Model – a data model for describing and reasoning about the world A model is a simplification of reality

Hydrologic information system “ combination of geospatial and temporal hydrologic data and hydrologic models that supports hydrologic practice, science and education” (Maidment, 2004)

Arc Hydro surface water A data model for representing surface water systems

Describing the hydrologic cycle

1.Support representation of regional groundwater systems. 2.Support representation of site scale groundwater studies. 3.Enable the integration of surface water and groundwater data. 4.Connect to groundwater modeling software. Data model goals Objective Extend the Arc Hydro data model to include a representation of groundwater systems.

Regional groundwater systems Usually the horizontal scale >> vertical scale Modeled as 2 dimensional flow

Site scale groundwater studies Characterization of Savannah River Site in South Carolina Usually model 3D flow to study mass transport Important to establish a 3D model of the system

Integration of surface water and groundwater information Geographic relationship between the surface and groundwater elements Need to represent movement of water between the surface and subsurface

Connection to groundwater models Data model = Database Model input Model outputs

Integration of surface water and groundwater models

Data model framework Objects from geologic maps Raster catalog to represent geologic formations and parameter distribution Features describing groundwater systems Raster catalog to represent water related parameters Features used in relation with modeling Table that describes hydrogeologic units and their properties Describes surfaces

Groundwater feature dataset Aquifer (2D Polygons) BoreLine (3D line)GeoSection (3D polygon) Wells (points) GeoVolume (Multipatch) Objects that are used to describe groundwater systems

Outcrop Downdip

Geologic objects Geologic formations Geologic structures (fault, fold, scarp ) Geologic contacts Describe objects from geologic maps or other geologic data

GeoRasters TransmisivityHydraulic conductivity GeoRasters: Distribution of properties Define boundaries of hydrogeologic units Top of formationFormation base Raster ID DescriptionUnits 1Transmisivitym 2 /day 2Hydraulic conductivity m/day 3Formation topM 4Formation basem Raster catalog GeoRasters are usually constant over time Woodbine aquifer, Texas

TransmisivityHydraulic conductivityFormation Top Formation base Woodbine aquifer, Texas

HydroRasters HydroRasters describe water related properties Potentiometric surfaceSaturated thickness Contaminant concentration Raster ID DescriptionUnitsTime 1Potentiometric surface mMay Saturated thickness mJune ConcentrationMg/LiterJuly 2003 Can change over time

HydroRasters HydroRasters describe water related properties Potentiometric surfaceSaturated thickness Raster IDNameDate/Time 1Potentiometric surface_MayMay Potentiometric surface_JuneJune Potentiometric surface_JulyJuly 2003 Can change over time Potentiometric surface

Potentiometric surface Contaminant concentration

Modeling elements 3 dimensional models Connection to modeling tools: enable the preparation of model inputs and communication of model outputs 2 dimensional models

Finite difference meshFinite element mesh

Hydrogeologic unit HGU IDHGU CodeFormationReference 11Sand 28Red Clay 323Bouldery till Hydrogeologic unit table Describes the hydrogeologic unit and links together the spatial representations

Hydrogeologic unit HGU IDHGU CodeFormation 11Sand 28Red Clay 323Bouldery till Hydrogeologic unit table GeoArea BoreLineGeoSectionGeoVolume

Construction of a hydrogeologic unit example Neuse Basin North Carolina ~280 km 80 km

Coastal aquifer system * From USGS, Water Resources Data Report of North Carolina for WY 2002 Section line Beaufort Aquifer

Defining the control volume This control volume is the boundary of the river basin down to a specified depth Next step - Describe the subsurface within this control volume

Boundaries of aquifers Map view of the aquifers

3D view of the aquifers and the control volume Aquifer top elevation interpolated from contour maps

Beaufort aquifer A display of the water quality zones in the aquifer Outline of the Neuse River Basin

Hydrostratigraphy information North Carolina Division of Water Resources website Hydrostratigraphy from boreholes in the Beaufort boundary

Hydrostratigraphy attributes Attributes of the borehole describe the hydrostratigraphy at varying depths Beaufort aquifer top Elevations above mean sea level Land surface elevation Castle Hayne confining layer top Castle Hayne aquifer top Beaufort confining layer top

3D view of the information Start from a 2D point (X, Y) with attributes describing the Z dimension Conceptual description of the subsurface Beaufort aquifer top Elevations are feet above mean sea level Land surface elevation Castle Hayne confining layer top Castle Hayne aquifer top Beaufort confining layer top

Transform into 3D lines The HydroID relates the vertical description of hydrogeologic units back to the borehole point Hydro ID = 66

Transform into 3D lines Given the X and Y coordinates and the Z coordinate for the hydrogeologic units, 3 dimensional lines can be generated to represent the hydrostratigraphy within the borehole

Interpolate to create a model of the subsurface Cross sections, fence diagrams Interpolating to create cross section views

Interpolate to create a model of the subsurface Creating solid models Beaufort confining layer Beaufort aquifer Using external models we can compute the volume of the solids

Apply sources and sinks Sources and sinks drive the water movement through the control volume Recharge / Discharge areas USGS wells

Analysis Once we have a model of the subsurface we can look at interaction between control volumes and how water will move between them Recharge zones Streams

3 dimensional groundwater model example Savannah River Site South Carolina Savannah River Site Radioactive waste burial ground

Conceptual model horizontal dimension General head boundaries Package Streams Radioactive burial ground

Conceptual model vertical dimension 5 layers in the conceptual model Zone IIB2 “Water Table” “Tan Clay” 180 Zone IIB1 “Barnwell / McBean” 130 “Green Clay” 125 Zone IIA Gordon aquifer 50 (feet)

Conceptual model vertical dimension 5 layers in the conceptual model Zone IIB2 “Water Table” “Tan Clay” 180 Zone IIB1 “Barnwell / McBean” 130 “Green Clay” 125 Zone IIA Gordon aquifer 50 (feet)

GIS representation of the horizontal dimension Represent the horizontal properties of the surface within ArcMap Each cell is 100 meters by 100 meters 1600 m 3000 m

Create a 3 dimensional representation of the model Can generate a 3D model in ArcScene Vertical dimension ~ 75 meters Each cell in the 2D representation is transformed into a 3D object (Multipatch) Control volume for the model domain

Views of the subsurface Once a solid model is constructed we can generate views of the subsurface Cross section along streams intersecting the model domain

Cell2D Cell3D

Surface water groundwater interaction example Brazos River Texas 1Site 1 1Simonton 1Wallis

Cross sections and profile lines Describe the 3 dimensional shape of the channel

3D view of the channel 3 dimensional description of the channel and the water within it

Interaction of river with subsurface

Questions ??