The Groundwater Project

Groundwater in Peat and Peatlands

Peatand Peatlands_Book Cover June 2022
Publication year: 2023
Number of pages: 108

ISBN: 978-1-77470-015-0

Authors:

Jonathan S. Price: University of Waterloo, Canada
Colin P.R. McCarter: Nipissing University, Canada
William L. Quinton: Wilfrid Laurier University, Canada

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Last Update: 13 November 2023
Released: 24 March 2023

Spanish Translation by Elizabeth Naranjo

Released: May 31 2024

Description

Peatlands are wetlands with soil comprised of undecomposed remains of plants that accumulate in such a way that both responds to and controls the flux and storage of surface water and groundwater, as well as controlling runoff to downstream ecosystems. Water tables are generally at or near the surface for much, or all, of the year.

Peatlands strongly influence global climate because they are the largest global terrestrial store of carbon.

Depending on the setting, peatlands develop into distinct forms that peatland scientists generally categorize as bogs, fens, and swamps with peat soils. Bogs have accumulated sufficient peat depth, mostly due to the abundance of Sphagnum mosses, that they become topographically isolated and receive water only via precipitation, thus shed surface water and groundwater. Bogs can have a typically sparse cover of stunted trees. Fens and peat swamps generally receive water and constituent dissolved ions from adjacent mineral terrains, although flow directions may reverse. As with bogs, the quantity and quality of incoming water controls the function and structure of their plant community and, therefore, their soil properties including the ability to store and transmit groundwater. Fens generally have a steadier supply of water than swamps, and thus a more stable water table that favors sedges and brown mosses, and sometimes trees. Swamps typically experience episodic water exchange; thus, their water table varies, which is more favorable for woody vegetation.

In peatlands, more recently formed, less decomposed soils occur in the upper layers – these newer soils can have extremely high porosity (≤95%) and are typically more permeable (saturated hydraulic conductivity up to 10-1000 m/d), whereas soils deeper than 0.3 – 0.5 m generally have low hydraulic conductivity (≤0.5 m/d). Consequently, there is transmissivity feedback that exacerbates surface and groundwater flows when the water table is particularly high.
Understanding the hydrology and water quality is key to effective land management where peatlands are common on the landscape.

Contents

1 INTRODUCTION

2 GROUNDWATER CONTROLS ON PEATLAND FORM AND FUNCTION

2.1 Hydrogeomorphic Setting and the Categorization of Peatland Systems

2.2 Swamps

2.3 Fens

2.4 Bogs

2.5 Peatland Complexes

2.6 Regional Processes

3 PEAT: A POROUS MEDIUM

3.1 Saturated Zone Properties and Processes

3.2 Unsaturated Zone Properties and Processes

4 TRANSPORT OF SOLUTES

4.1 Transport in Peat

4.2 Transport in Peatlands

5 CONTAMINATION in PEATLANDS

5.1 Atmospheric Pollutants as Contaminant Sources

5.2 Direct Pollutants as Contaminant Sources

5.3 Non Aqueous Phase Liquids (NAPLs)

6 PEATLAND DISTURBANCE

6.1 Peatland Drainage

6.2 Peat Harvesting and Restoration

6.3 Climate Change

6.4 Peatland Wildfires

7 NUMERICAL MODELING IN PEAT AND PEATLANDS

7.1 Numerical Flow and Transport Models

7.2 Challenges of Numerical Modeling

8 METHODS AND APPROACHES

8.1 Well and Piezometer Installation and Use

8.2 Sampling Peat

8.3 Parameterization of Peat

8.3.1 Hydraulic Conductivity
8.3.2 Water Retention
8.3.3 Bulk Density and Porosity
8.3.4 Specific Yield and Drainable Porosity

9 WRAP-UP SECTION AND RESEARCH NEEDS

10 EXERCISES

11 REFERENCES

12 BOXES

Box 1 Height of Domed Peatlands

Box 2 Permafrost Peatlands

Box 3 Tropical Peatland Hydrology

Box 4 Van Genuchten Mualem (VGM) Variables and Parameters

Box 5 Mobile Water Porosity and Solute Transport

Box 6 Mercury in Peatlands

13 EXERCISE SOLUTIONS

14 NOTATIONS

15 ABOUT THE AUTHORS

Interview with Authors