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Date Permissions Signed

2-21-2018

Date of Award

Winter 1990

Document Type

Masters Thesis

Degree Name

Master of Science (MS)

Department

Geology

First Advisor

Kelsey, H. M.

Second Advisor

Talbot, James L.

Third Advisor

Easterbrook, Don J., 1935-

Abstract

Three types of groundwater systems occur within glacial sediments in a 10 mi2 (25 km2) area near Sumas, Washington: an unconfined sand and gravel aquifer, a confined sand and gravel aquifer, and a generally unproductive clay aquitard. Water levels in the area were mapped from measurements of wells and points along stream courses in October 1988 and March 1989. The water-level configurations for the two aquifers roughly parallel surface topography. Water level maps were used to estimate direction of groundwater flow, which is generally to the southeast in the unconfined aquifer and to the northeast in the confined aquifer. Water level measurements made within the clay aquitard indicate that most water horizons are perched and water level is controlled by the surface topography of the clay. The highest water levels throughout the study area occur during the spring, following high precipitation during winter months. Water levels vary seasonally in response to changing recharge and discharge conditions. Recharge is principally by direct precipitation onto surficial units. Discharge is to streams, drainage ditches and springs and by pumping. Hydrostratigraphic cross-sections were made using data from well drillers' lithologic logs, existing geologic maps, and field exposures. Five hydrostratigraphic units were delineated based on porosity, permeability, geographic location, and lateral extent of the hydrostratigraphic horizons. By using hydrologic properties associated with water-bearing units and hydraulic gradients measured from water-level maps, average linear velocities within the aquifers were estimated at 4.0 gal day-1ft-2 in the confined aquifer and 7.4 to 120 gal day-1ft-2 in the unconfined aquifer.

Type

Text

Keywords

Goundwater systems, Groundwater flow, Hydrostratigraphy

DOI

https://doi.org/10.25710/34zp-wa92

Publisher

Western Washington University

OCLC Number

1032829559

Subject – LCSH

Groundwater--Washington (State)--Sumas Region; Aquifers--Washington (State)--Sumas Region; Geology--Washington (State)--Sumas Region; Geology, Stratigraphic

Geographic Coverage

Sumas Region (Wash.)

Format

application/pdf

Genre/Form

masters theses

Language

English

Rights

Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this thesis for commercial purposes, or for financial gain, shall not be allowed without the author's written permission.

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