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GroMoPo Metadata for Bangkok Basin groundwater age model


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Created: Feb 07, 2023 at 7 p.m.
Last updated: Feb 07, 2023 at 7:01 p.m.
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Abstract

A study was undertaken to understand the groundwater flow conditions in the Bangkok Basin, Thailand, by comparing 14 C-based and simulated groundwater ages. 14 C measurements were made on about 50 water samples taken from wells throughout the basin. Simulated ages were obtained using 1) backward-pathline tracking based on the well locations, and 2) results from a three-dimensional groundwater flow model. Comparisons of ages at these locations reveal a large difference between 14 C-based ages and ages predicted by the steady-state groundwater flow model. Mainly, 14 C and 13C analyzes indicate that groundwater in the Bangkok area is about 20,000 years old, whereas steady-state flow and transport simulations imply that groundwater in the Bangkok area is 50,000-100,000 years old. One potential reason for the discrepancy between simulated and 14C-based ages is the assumption in the model of steady-state flow. Groundwater velocities were probably greater in the region before about 10,000 years ago, during the last glacial maximum, because of the lower position of sea level and the absence of the surficial Bangkok Clay. Paleoflow conditions were estimated and then incorporated into a second set of simulations. The new assumption was that current steady-state flow conditions existed for the last 8,000 years but were preceded by steady-state conditions representative of flow during the last glacial maximum. This transient paleohydrologic simulation yielded a mean simulated age that more closely agrees with the mean 14 C-based age, especially if the 14C-based age corrected for diffusion into clay layers. Although the uncertainties in both the simulated and 14 C-based ages are nontrivial, the magnitude of the improved match in the mean age using a paleohydrologic simulation instead of a steady-state simulation suggests that flow conditions in the basin have changed significantly over the last 10,000-20,000 years. Given that the valid age range of 14 C-dating methods and the timing of the last glacial maximum are of similar magnitude, adjustments for paleohydrologic conditions may be required for many such studies.

Subject Keywords

Coverage

Spatial

Coordinate System/Geographic Projection:
WGS 84 EPSG:4326
Coordinate Units:
Decimal degrees
Place/Area Name:
Thailand
North Latitude
14.4844°
East Longitude
100.8257°
South Latitude
13.3452°
West Longitude
100.4013°

Content

Additional Metadata

Name Value
DOI 10.1007/s100400050083
Depth
Scale 10 001 - 100 000 km²
Layers 6-10 layers
Purpose Groundwater resources
GroMoPo_ID 87
IsVerified True
Model Code MODFLOW
Model Link https://doi.org/10.1007/s100400050083
Model Time
Model Year 1996
Model Authors W. Sanford, S. Buapeng
Model Country Thailand
Data Available Report/paper only
Developer Email
Dominant Geology Unconsolidated sediments
Developer Country USA
Publication Title Assessment Of A Groundwater Flow Model Of The Bangkok Basin, Thailand, Using Carbon-14-Based Ages And Paleohydrology
Original Developer No
Additional Information
Integration or Coupling None of the above
Evaluation or Calibration Unsure
Geologic Data Availability

How to Cite

GroMoPo, D. Kretschmer (2023). GroMoPo Metadata for Bangkok Basin groundwater age model, HydroShare, http://www.hydroshare.org/resource/c49dcbca0e604ddd9aedf7246201070a

This resource is shared under the Creative Commons Attribution CC BY.

http://creativecommons.org/licenses/by/4.0/
CC-BY

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