Subsurface Modelling in iMODJurong Island - SingaporeiMOD International Users DaysDelft International Software DaysDelft, 2nd of November 2016

Peter Vermeulen, Deltares

Project team

Public Utilities Board, Singapore’s National Water Agency: PUB

National University of Singapore: NUS

Delta Research The Netherlands: DELTARES

Project Initiator

Location: Singapore – Jurong Island

• Surface area: 716 km2; Population: 5,5 million; Annual rainfall: ≈ 2,3 meter !

Jurong Island

Location: Jurong Island

1973 1989 2009

9 km

8.5 km

HistoricalMaps

Subsurface Modelling – Sources

HardrockSilt Clay

Wet-East transects

Before 1980 After 2002

HardrockSilt Clay

Coral Landfill (sand)

0.0

Sea

Coral

Subsurface Modelling - Sources

Bathymetry is a combination of:• the seabed levels measured in 2002 using the Water Alliance data bank;• Seabed level on the 1992 topographic map of Jurong Island (source: Map

resource library, Geography Department of NUS).

509 boreholes were converted from PDF to IPF, the format that iMOD can read

Boreholes were provided by JTC (Jurong Town Corporation)

Subsurface Modelling - Sources

SOLID Tool functionalitiesInput sources:

• Cross-sections (e.g. with seismic/geologic images);

• Polygons with extent of interpolation;• Masks to define extent of thickness between

overlying interfaces;• Faults for sharp discontinuities of interfaces;• Points with depth of interfaces;• Kriging settings per interface.

Output:• IPF points for export to e.g. Surfer, GIS;• IDF files for each interface that are

consistent with depth

Subsurface Modelling – SOLID Tool

Landfill

Coral

SiltClay

Jurong Formation

Old IslandSubsurface Modelling – Cross-sections

Individual points along cross-section are used in interpolation. Interfaces can be deactivated if no

points on that particular interface can be identified.

With 26 cross-section the subsoil has been

constructed in 4 separate layers with 5 interfaces

Subsurface Modelling – Masks

Interface 1 DTM / Bathymetry

Interface 2 Landfill; 5 Silt

Interface 3 Coral

Interface 4 Clay

Subsurface Modelling – Kriging Settings

Do not interpolate interface 1Apply consistency adjustments

Clay layer

Land Fill Coral

Silt layer

Surface layer

Jurong Formation

Subsurface Modelling - Results

Subsurface Modelling – Results

3-D images of cross-sections, in combination with results of the SOLID

Layers stacked

3-D print of the Subsoil of Jurong Island

Subsurface Modelling – Results

iMOD Solid Tool – advantages:

• Multiply User access during construction;• Ability to generate realizations for different resolutions;• Export to other packages e.g. Surfer, GIS;• Display of images on cross-sections and 3-D visuals.

Subsurface Modelling – Results