• Basic mechanism for ice growth by Temperature (degree-day method)• Growth adjusted for ice thickness

Prediction of Ice out dates based on Ice model

𝑑𝑑ℎ𝑑𝑑𝑑𝑑

= −�𝐻𝐻𝑖𝑖𝑖𝑖𝜌𝜌𝜌𝜌

� (𝑇𝑇𝑚𝑚 − 𝑇𝑇𝑖𝑖)

• Basic mechanism for ice decay by temperature (degree-day method)

Ashton Ice Decay Method (1983)

Ice In and Ice Out Evaluation

Stochastic Climate Generator

Challenge:

Examined ~50 different distributions and selected the Wakeby distribution as the best fit for precipitation for use with the WGEN climate generator

Wakeby Distribution

Model Simulations (1000 realizations) compared against statistics from historical record (annual and monthly mean and std. deviations, annual maximum event, heavy precipitation

Daily Temperature Min, Mean, and Max fitted to a Beta distribution on a monthly basis. Simulated temperatures compared against statistics from the historical record

Historical daily evaporation developed from airport climate data (Temp, Rh, Solar Radiation, etc.) – Used Morton CRWE method for open water Evaporation and Penman-Monteith Method for land surface Evapotranspiration.

0

1

2

3

4

5

6

Jan 2018 Feb 2018 Mar 2018 Apr 2018 May 2018 Jun 2018 Jul 2018 Aug 2018 Sep 2018 Oct 2018 Nov 2018 Dec 2018 Jan 2019

Mon

thly

Tai

lings

Eva

pora

tion

(in)

Time

0

1

2

3

4

5

6

7

Jan 2018 Feb 2018 Mar 2018 Apr 2018 May 2018 Jun 2018 Jul 2018 Aug 2018 Sep 2018 Oct 2018 Nov 2018 Dec 2018 Jan 2019

Mon

thly

Lak

e Ev

apor

atio

n (in

)

Time

Snow Pack Accumulation and Melt• Model is based on a paper by Kokkoen (2006)• Basic mechanism for freezing and thawing is by temperature

(degree-day method)• Precipitation is proportioned between rain and snow based on the

daily minimum and maximum temperature• Snow density increases with the age of the snow pack• The Snowpack can hold liquid or frozen water in the pore spaces• As the pore spaces in the snowpack decrease (either through losses

from melt or ablation, or through densification), the ability to hold moisture decreases and snowmelt may be released.

• Liquid water in the snowpack may freeze and is stored as ice• Melt comes from snowpack first, ice last, ablation only from snow.• Model calibrated to nearby station with daily snowfall, snow water

equivalent, and snow depth data for several years

Open Water Ice Accumulation and Melt

𝑑𝑑ℎ𝑑𝑑𝑑𝑑

= �1𝜌𝜌𝜌𝜌�𝑇𝑇𝑚𝑚 − 𝑇𝑇𝑖𝑖

�ℎ𝑘𝑘 + 1𝐻𝐻𝑖𝑖𝑖𝑖

�

Developing Environmental Components for a Water Balance

Slight Warming Trend identified in the historical record and incorporated in the Stochastic Climate Model

Runoff and Streamflow

0.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1.8

Oct 2015 Jan 2016 Apr 2016 Jul 2016 Oct 2016

Stre

amflo

w (m

3/se

c)

Time

0

1

2

3

4

5

6

7

8

9

Cum

ulat

ive

Mea

sure

d St

ream

flow

(mill-

m3)

Measured Streamflow Calculated StreamflowCumulative Measured Streamflow Cumulative CalculatedStreamflow

• Runoff calculated using the AWBM model• Seasonal baseflow component from the shallow

groundwater included based on numerical groundwater model

• Ice up and ice out of the streams and lakes effectively delaying winter baseflow

• Routing runoff and spring freshet through the drainages required seasonal delay and attenuation components in addition to those in the AWBM model

Regional Water Balance Schematic

Ashton Ice Growth Method (1989)

0

10

20

30

40

Jan 2003 Jul 2003 Jan 2004 Jul 2004 Jan 2005 Jul 2005 Jan 2006 Jul 2006

His

toric

al S

now

pack

Dep

th (i

n)

Time

Historical Snowpack Depth Simulated Snowpack Depth

David Hoekstra and Brent ThieleSRK Consulting (US) Inc.

Need to develop a water balance to surround the traditional mine site-wide water balance to evaluate environmental impacts on a more regional scale.

Stochastic Climate Module needed to be defensible.

Regional scale model needed to include robust hydrologic components to simulate freezing/thawing of ice and attenuation of stream and lake flow.

Using a large regional data set, regressed multiple stations to fill in the data gaps and build a continuous record of historical climate for the site

Wakeby Probability Density for May

Wakeby Cumulative Probability for May

Wakeby Quantile-Quantile Plot for May

Simulated vs Historical Heavy Precipitation

Simulated vs Historical Maximum Annual Precipitation

Simulated vs Historical Monthly Means and +/- 1 or 2 Sigma

Simulated vs Historical Mean, Maximum and Minimum Annual Temperatures

Mean Annual Temperature Trend over Time

Streamflow Calibration

Snowpack Calibration

Synthetically Generated Evaporation

Project:A Feasibility Study for a Proposed Mine in the Great Lakes Region

Extrapolated data to develop a single record representative of the site

Station 1Station 2Station 3Station 4Station 5Station 6Station 7Station 8Station 9

Station 10Station 11Station 12Station 13Station 14Station 15Station 16Station 17Station 18Station 19Station 20Station 21Station 22Station 23Station 24Station 25Station 26Station 27Station 28Station 29Station 30Station 31Station 32Station 33Station 34Station 35Station 36Station 37Station 38Station 39Station 40Station 41Station 42Station 43Station 44Station 45Station 46Station 47Station 48Station 49Station 50Station 51Station 52Station 53Station 54Station 55Station 56Station 57Station 58Station 59Station 60Station 61Station 62Station 63Station 64Station 65Station 66Station 67Station 68

Looked for correlations to location

Being in a populous area of North America, many climate stations to choose from

Project Water Balance