Hydraulic conductivity and porosity of soil/saprolite cores in Dead Run watershed, Baltimore County, MD USA


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Owners: Claire WeltyJohn J. Lagrosa IV
Type: Resource
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Created: Jan 30, 2023 at 4:17 a.m.
Last updated: Jun 26, 2023 at 3:01 a.m.
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Abstract

Soil/saprolite cores were collected at eight hilltop locations in the headwater area of Dead Run watershed in Baltimore County, MD, and evaluated for hydraulic conductivity and total porosity. The lithology consists of Mount Washington Amphibolite (mafic rock) transitioning to the Potomac Group of the Fall Zone. Cores were collected using an AMS 10.2 cm-diameter steel auger bucket, in increments of about 15 cm, to depth of refusal. The length of the soil cores ranged from 1.4 m to 6.5 m. Each ~1200 cm3 sample was evaluated in the laboratory for hydraulic conductivity (K) using a UMBC/CUERE-designed falling-head permeameter and the Hvorslev equation. For each of 180 samples, 6 measurements were taken and corrected to a water temperature of 20˚C. Average K values ranged from 10-9 to 10-5 m/sec, with a geometric mean of 4.9x10-7 m/sec and an lnK variance of 2.7. The pattern of hydraulic conductivity varied with depth. K decreased by ~ 1-2 orders of magnitude to a depth of about 0.5 m. As the soil transitioned to saprolite, K values then increased by 1-2 orders of magnitude to depths of 2 - 2.5 m. For longer cores, a decrease in K values of 1-2 orders of magnitude was observed below 2.5 m, followed further zonal order-of-magnitude increases/decreases over 1-2 m depths. Results illustrate pronounced zonal heterogeneity of hydraulic conductivity for this system. As observed at other field sites, hydraulic conductivity values were log-normally distributed. Total porosity was determined on the same samples using a Teros 12 soil moisture sensor. Four measurements were taken. Average total porosity ranged from 0.31 to 0.53, with a mean of 0.45 and variance of 0.0016. Total porosity generally decreased with depth (0.1 – 1m), followed by an increase and then leveling off to a relatively constant value with depth. The zonal heterogeneity of total porosity was most prominent from 1-2 m, as opposed to hydraulic conductivity, which exhibited zonal heterogeneity with greater depths for longer core samples.

Coverage

Spatial

Coordinate System/Geographic Projection:
WGS 84 EPSG:4326
Coordinate Units:
Decimal degrees
Place/Area Name:
Woodlawn, MD
North Latitude
39.3388°
East Longitude
-76.7143°
South Latitude
39.2837°
West Longitude
-76.7675°

Temporal

Start Date: 06/01/2021
End Date: 12/31/2022
Leaflet Map data © OpenStreetMap contributors

Content

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Related Resources

This resource belongs to the following collections:
Title Owners Sharing Status My Permission
Dead Run Data Collection Claire Welty · John Lagrosa IV  Discoverable &  Shareable Open Access

Credits

Funding Agencies

This resource was created using funding from the following sources:
Agency Name Award Title Award Number
National Science Foundation Collaborative Research: Network Cluster: Urban Critical Zone processes along the Piedmont-Coastal Plain transition 2012340
National Science Foundation Frameworks:Collaborative Proposal: Software Infrastructure for Transformative Urban Sustainability Research 1931283

Contributors

People or Organizations that contributed technically, materially, financially, or provided general support for the creation of the resource's content but are not considered authors.

Name Organization Address Phone Author Identifiers
John J. Lagrosa IV Center for Urban Environmental Research and Education at the University of Maryland, Baltimore County Maryland, US

How to Cite

Richards, M., M. McWilliams, C. Welty (2023). Hydraulic conductivity and porosity of soil/saprolite cores in Dead Run watershed, Baltimore County, MD USA, HydroShare, http://www.hydroshare.org/resource/76eb5c3cac6d4996ba8eb620a6d7948d

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

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

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