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Acadian Pontchartrain (ACAD) Groundwater Studies

NAWQA Ground-Water Study Design

Focuses on assessing the water-quality conditions of major aquifers with emphasis on the quality of recently recharged ground water associated with present and recent human activities... (USGS, Circular 1112)
Types of Studies:
Land-Use Studies (LUS)
Intermediate scale spatially and directed toward the effects of human activities on ground-water quality
Sub-Unit Surveys (SUS)
Large spatial scale and broadly characterizes ground-water quality across the Study Unit
Flow-Path Study (optional)
Local scale, tracing of water movement

General Objectives

Land-use Studies:
to examine natural and human factors that affect the quality of shallow ground water that underlies key types of land use.
Sub-Unit Surveys:
to supplement existing data in providing a broad overview of ground-water quality in each Study Unit

Well Selection Strategies

Land-Use Study: Sub-Unit Survey:

ACAD NAWQA Ground-Water Studies

Land-Use Studies: Sub-Unit Surveys:

Rice Land-use Study - Purpose

To provide a comprehensive assessment of the concentrations and distribution of water-quality constituents in recently recharged shallow ground water (<20-30 years) associated with the most significant land use in the Study Unit.

Rice Land-use Study - Design

  1. Randomly select 30 well sites in the rice growing areas
  2. Drill and install 30 monitor wells according to State Regulations and NAWQA guidelines
  3. Sample these 30 monitor wells for the constituents listed in USGS Circular 1112, (typically sampled only once)

Rice Land-use Study - Status

Sub-Unit Surveys: Chicot Aquifer and Chicot-equivalent Aquifer - Purpose

To provide a broad assessment of the water-quality conditions of the most important present and future ground-water resources of the Study Unit.

Sub-Unit Survey Aquifer Selection Approach

The first step in the design of the SUS is to divide the ground-water resource of interest into aquifer subunits. This is based primarily on identification of major hydrogeologic settings.

Ground-water withdrawals in the Study Unit area

Sub-Unit Survey - Design

  1. Select 30 well locations in each aquifer (60 total) using Jon Scott's grid-based random selection program
  2. Sample existing wells (domestic), typically sampled only once
  3. Contact well owners for permission to sample these wells
  4. 5 wells sampled to date

Example Sub-Unit Survey site grid

Groundwater well drilling:
Rob Fendick and Roland Tollett drilling groundwater well at Bluebonnet
Swamp Preserve in Baton Rouge, LA.

Typical monitor well installation:
Example groundwater well in rice field in southwestern Louisiana.

Typical Groundwater Well construction:
Diagram showing parts of a groundwater well.

Landuse/Landcover survey for the ACAD groundwater studies

  1. Obtain black and white aerial photo's and topographic map for each well location.
  2. Draw 50 and 500 meter radius circle around well.
  3. Describe landuse within these circles.
  4. Send data to Central Processing Group in Mississippi to be digitized and compiled.


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