Wetland Hydroperiod Monitoring in the Credit River Watershed

Acknowledgements:

We wish to thank numerous internal and external specialists for their expertise and continued support toward this project.

The purpose of the Wetland Hydroperiod Monitoring study is to improve our understanding of hydrologic structure and function of wetlands and to understand wetland sensitivity to hydrological, anthropogenic and climate change impacts.

This initiative will assist with:1. Future land-use planning2. Impact assessment3. Wetland restoration initiatives and 4. The evaluation of the wetland integrity in the watershed.

This project builds upon CVC’s existing Terrestrial Monitoring Program which currently studies the structure, function and composition of floral and faunal communities within the Credit River Watershed, but currently has limited capabilities to draw conclusions about the hydrology within wetlands. Data from this project will be paired with current Terrestrial Monitoring data to identify linkages between hydrological function to trends observed in floral and faunal indicators.

Wetland hydroperiod monitoring sites are located at a subset of terrestrial monitoring wetland plots. Siteswith the following characteristics are being selected:

• Deciduous swamps with either mineral or organic substrates

• Homogenous vegetation community structure• Located on either CVC or public property • Preferably isolated or palustrine wetland communities

Sites are also being selected for effectiveness monitoring. Effectiveness monitoring is an approach for monitoring pre- and post-development impacts on natural features. Sites for effectiveness monitoring will be selected from wetland communities that are currently subject to the greatest development pressures projected to occur in the area within the next 10 years.

These communities include: • Green Ash Mineral Deciduous Swamps• Black Ash Mineral Deciduous Swamps and • Freeman and Silver Maple Deciduous Mineral Swamps.

1.0 BACKGROUND

2.0 SITE SELECTION

PRELIMINARY FIELD INVESTIGATIONS

• Wetland evaluations

• Ecological Land Classification (ELC) and

• Soil test pits and/or cores.

MONITORING FREQUENCY

• From April to November (from thaw to freeze)

• Ground water and surface water loggers record hourly

• Soil moisture loggers record at 10 minute intervals (to capture rapid hydrologic changes)

3.0 MATERIALS AND METHODS

In order to relate hydrologic data to vegetation, hydrologic monitoring equipment are placed in close proximity to the vegetation monitoring plots. Three permanent hydrologic stations will be installed in each of the wetlands located at the 40m transect post, the 10m transect post and in an adjacent upland community.

Equipment Quantity Configuration

Surface water data logger 2 One each at the 10m and 40m stations.

Monitoring wells coupled with data loggers

4

Two wells, one shallow (35cm slotting from 10cm below the surface) and one deep (slotted up to 2m from 10cm below the surface) each at 10m and 40m station.

Soil moisture probes coupled with data loggers

variable

One nest of probes at 10m, 40m and upland stations with 3-5 probes at predetermined depths.Number of probes and installation depths determined according to where soil conditions are not permanently saturated within the rooting zone.

Barometric pressure gauge 1A barometric pressure gauge will be placed in an inconspicuous location within the wetland.

Piezometers coupled with data loggers

6+

At least two nested piezometers (1m and 2m deep, screened 15cm) at each of the three stations. Additional piezometers may need to be installed where soil textures are variable enough to influence water movement.

EQUIPMENT AND CONFIGURATION

PRELIMINARY GROUND WATER AND SURFACE WATER RESULTS

4.0 PILOT SITE: KEN WHILLANS WETLAND

TERRESTRIAL COMMUNITIES

The terrestrial monitoring plot encompasses two ELC community types:

• The first 20m of the plot are located in a Willow Mineral Thicket Swamp (SWT2-2)

• The last 30m of the plot is classified as a Freeman Maple Mineral Deciduous Swamp (SWD3-3).HYDROPERIOD EQUIPMENT

1. Diurnal Fluctuations

Temporal fluctuations in groundwater are witnessed daily and seasonally. The fluctuations indicate the influences of water uptake by vegetation and the subsequent transpiration occurring during daylight hours. Diurnal fluctuations seem to be affected by actively growing vegetation and precipitation events.

2. Significant Rainfall Event Influences Groundwater

The observed rapid response of the piezometer to rainfall suggests the mineral substrate (silty very fine sand and loam) are highly transmissive. During some rainfall events, the soil becomes saturated and the groundwater level rises above ground surface.

3. Similar Groundwater Signatures

Ground water levels recorded in piezometers and monitoring wells have almost identical hydrologic signatures.

4. Soil Moisture and Groundwater Recharge

4a. A combination of:

• Unsaturated soil conditions

• High evapotranspirationpotential and

• Interception by plants

reduce groundwater recharge and corresponding water table response to precipitation events.

4b. During periods of:

• Saturated soil conditions and

•Low evapotranspiration,

water table levels rise and may contribute to surface water storage.

Eva Szecsenyi

Water Resources Technician, ESzecsenyi@creditvalleyca.ca

0.25

0.27

0.29

0.31

0.33

0.35

0.37

0.39

0.41

0.43

0.45

12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 12:00 0:00 12:00

Time

Dep

th (

m)

Ken Whillans Wetland Monitoring Well Installation Details

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

40m Station DeepMonitoring Well

40m Station ShallowMonitoring Well

10m Station DeepMonitoring Well

10m Station ShallowMonitoring Well

De

pth

(m

)

* The ground surface is located at 0m for all monitoring wells.

Ken Whillans Wetland Piezometer Installation Details

-2

-1.5

-1

-0.5

0

0.5

1

1.5

2

2.5Upland 2mpiezmeter

Upland 1mpiezometer

40m Station 2mpiezometer

40m Station 1mpiezometer

10m Station 2mpiezometer

10m Station 1mpiezometer

WetlandMonitoringProgram

Piezometer

De

pth

(m

)

* The ground surface is located at 0m for all piezometers.

Piezometer and Monitoring Well Groundwater Levels

-0.6

-0.5

-0.4

-0.3

-0.2

-0.1

0

0.1

0.2

07-Dec-11

08-Dec-11

09-Dec-11

10-Dec-11

11-Dec-11

12-Dec-11

13-Dec-11

14-Dec-1

1

Date

Dep

th (

m)

2m Piezometer 1m Piezometer Shallow Well

Deep Well Ground

Wetland Hydroperiod Equipment

10m Station- Ken Whillans Wetland

-0.7-0.6-0.5-0.4-0.3-0.2-0.1

00.10.20.30.40.50.60.70.80.9

15-Aug-1

1

04-Sep-1

1

24-Sep-1

1

14-Oct

-11

03-N

ov-11

23-N

ov-11

13-Dec-

11

Date

De

pth

(m

)

-45

-40

-35

-30

-25

-20

-15

-10

-5

0

Pre

cip

ita

tio

n (

mm

)

2m Piezometer Ground Water Level Surface Water

Ground 1m Piezometer Ground Water LevelShallow Well Ground Water Level Deep Well Groundwater Level

Incremental Precipitation

Precipitation Source: Environment Canada (2011). Credit River at Boston Mills

1 4a.

24b.

3