Flood Forecasting Methodology in Alberta

Evan Friesenhan, M.Eng., P.Eng Alberta Environment and Sustainable Resource Development

March 17, 2014

River Forecast Team Mandate

• To provide Albertans with information related to current and future river or river ice conditions to enable Albertans to make decisions related to water supply, and emergency response planning.

– Real-time flow forecasting and support to partners (public, provincial staff, Municipal Emergency Managers, Industry, Provincial Parks, National Parks, Prairie Provinces) – Near real-time data quality management; enter WSC and Provincial field measurement; assist in prioritized field maintenance of monitoring network – Daily Natural Flow Forecasting – Water Supply

RFC Flood Operations Methodology Open Water Forecasting Operations - General • Primary river flooding concerns are caused by: – Significant rainfall events and significant rain on snow events • Based on weather and river conditions, the River Forecast Centre will enter 24 x 7 operations to provide forecasting services as required • Rotation period: mid-March to mid October • Typical Critical Time Period: mid-May to mid-July

Waiparous Creek 2013 Red Deer River 2013 (June 20th and 21st) Highwood River upstream of High River 2013 Open Water Forecasting Operations - Data Quality Assurance

• 400+ Hydrometric stations – 146 model forecast points • 630 Meteorological stations (~300 FIRES)

Elbow River at Bragg Creek 2013

AESRD Temporary Station – Medicine Hat 2013 Elbow River below Glenmore Reservoir 2013 2013 Flood Monitoring Network

• 110 Hydrometric and 179 Meteorological stations under constant review – 208 Hydro and ~300 Met in the 5 effected basins • Constantly refining forecasts for 63 different forecast locations • 13 hydro gauges lost/destroyed at various forecast points in the Bow, Oldman and Red Deer basins; another 13 had equipment, erosion, damage issues

Open Water Forecasting Operations - Weather Forecasts

• Alberta Environment and Sustainable Resource Development (ESRD) – Fire Weather Office – twice daily briefings; duty forecaster • Environment Canada – Regional and Global models, Significant Weather Discussions issued by the Prairie and Arctic Storm Prediction Center, NOAA – Modeling and Guidance, Unisys, Intellicast, Weather Network, etc River Forecast Centre Event Operations: Stage 1 – Anticipation of Major Storm

• Discuss weather forecast and model results, assess basins for areas of concern • Allocate RFC staff to support 24/7 Operations • Notify GOA water managers and support teams, as well as municipal authorities with an identified flood sensitivity • Due to uncertainty surrounding weather model results, advisories are not typically issued until rain is on the ground and the storm centre and its path are identified • Information in FYI email’s (internal), Forecaster’s Comments

Sheep River at Black Diamond 2013

River Forecast Centre Event Operations: Stage 1 – Anticipation of Major Storm (2013)

• Saturday June 15th: Related initial forecast of large system with a very good moisture feed to OIB managers and City of Calgary. Forecast was still very general with no specific high intensity location. (100mm storm total basin wide, 200mm locally due to convection very possible). • Monday June 17th: Started to contact monitoring groups and municipalities prone to flooding (prepared them for the likelihood of a 2005 type event). • Tuesday June 18th: Most recent weather models forecast amounts of 100 mm over 48 hr period, locally up to 150 mm for the Bow basin. Runoff model runs completed based on Bow basin averages of between 75mm and 125 mm (48 hour weather forecast total) with 50 mm as maximum 12 hour total. Forecasted inflows to Ghost Reservoir are provided to the City of Calgary and TAU

River Forecast Centre Event Operations: Stage 2 – Flood Event

• Alert internal and external clients – Directly call municipal emergency managers and water managers – Flood Watches or Flood Warnings via Alberta Emergency Alert – Local Authorities, Media • Quantitative Forecasts – Time and peak flow rate range • Continuous support to emergency management groups, public, comm. • Continue to provide situational updates • 24x7 operations: QA/QC, data monitoring field coordination, alerts, comments, FYI email’s (internal).

Red Deer River near Sundre 2013 River Forecast Centre Event Operations: Stage 2 – Flood Event (2013)

• As rain fell, flood advisories were issued Wed night and early Thursday morning. • Morning weather model runs showed that the storm was still expected to bring rain for the next 36 hours. • On average, the Elbow, Sheep and Highwood River basins received 12 hour totals of between 115 and 140 mm; approx 1.5 times the 1:100 year value. Numerous locations in the Bow also received 100 mm over the first 12 hour period (nearly the forecasted total over a 48 hour period) • Typical large system rainfall rates are between 3 and 5 mm/hr; 2013 - 10 to 20 mm/hr for a continuous 14 hours. • Up to 250 mm rain fell in 24 hours in some locations

Courtesy of South Saskatchewan Region River Forecast Centre Event Operations: Stage 2 – Bow River Advisories • High Streamflow Advisory – 5:50 am Thursday June 20, 2013 • Flood Watch – 8:45 am Thursday June 20, 2013 – By 8:45 am weather forecast was blown, and new forecast indicated 50 mm more precipitation for the day – Bow basin had received up to 120 mm in a 12 hour period • Flood Warning – 12:45 pm am Thursday June 20, 2013 – The intensity of the rainfall caused many small ungauged creeks to activate contributing more flow downstream of Canmore and upstream of the Ghost Reservoir. Our models are calibrated based on historical events, and there were no historical events with such large local contributions to flow along the middle Bow. Field information along with the updated weather forecast was used to adjust the flood forecast model to better forecast the inflows into the Ghost Reservoir. – Based on the inflow forecast and communications with the City of Calgary, and not knowing if Ghost Reservoir could attenuate any of the flood peak, a flood warning was issued. • 4:00 pm Thursday June 20, 2013 – TAU indicated likelihood that 1700 m3/s outflows were likely. This information was passed onto the City of Calgary • 6:40 pm City of Calgary orders Bowness and Sunnyside evacuation

River Forecast Centre Event Operations: Stage 2 – Flood Event (2013)

2000 56 mm in first 12 hr of event (2005) 0

1800 23 hrs from centroid of precipitation to 5 peak flow at Calgary (787 m3/s) (2005) 1600 10 1400 15 Significant rainfall started ~ 8 pm June 19, 2013 in the Bow

1200 Basin 20 /s) 3 m ( 1000 120 mm in first 12 hr of event (double of 2005) 25

Flow 800 7 hrs from centroid of precipitation to flow peak of 2005 30

600 3 35

23 hrs until peak flow of 1700 m /s from centroid of (mm/hr) snowmelt / Rainfall precipitation 400 40 Flood warning issued 4 hrs after centroid of precipitation 200 45

0 50 0 10 20 30 40 50 60 70 80 90 100 Hours into rainfall event

Bow at Calgary (2013 event) Bow at Calgary (2005 event) Precip (2013) Precip (2005) River Forecast Centre Event Operations: Stage 2 – Flood Event (2013)

1200 0

10 1000

20 1995 800 30 2005

600 40

Flow (m³/s) 2013 - Hourly flow at Highwood River below Little Bow Canal

2013 - Hourly flow at Highwood River at Diebels 50 (mm/hr) Input Moisture 400 Ranch Hourly Rainfall at Highwood FIRES station - 2013

Hourly Snowmelt from snow pillows 60

200 70

0 80 17-Jun 18-Jun 19-Jun 20-Jun 21-Jun 22-Jun 23-Jun

**all numbers are preliminary Communication Flow:

•Coordinates Municipal response to flooding • Interacts with POC. AEMA, Regions (WMS, MD’s,SK,BC,FD’s, WTP) MD’s - EOC •discuss operations Industry

• system coming (scenario runs) • issued advisory Public • provide actionable info • contact is continuous until end • field info

Infrastructure Ops ESRD Management FYI RFC (Executive, WMO, Regions) (Dam Safety) • system coming • issued advisory • discuss operations • RFS Management – FYI – • messaging known thresholds - • concerns Communications/BN/AR’s

Media FRCC GOA - POC (lead by ASERT) •Coordinates ESRD’s response to flooding •Coordinates GOA’s response to flooding • Interacts with POC • Interacts with FRCC and EOC

2014 Projects

• RFS Managed Contracts – Lessons Learned and Partner Engagement Workshops – Mar 2014 – Performance Measures – May 2014 – Weather Forecast Uncertainty Project – May 2014 – Event Reviews (Oldman/Red Deer) – May 2014 – Precip/Runoff Temporal Variability Study

• Environment Canada Collaboration – Converting gridded weather model data to model input/web interface

Medicine Hat WSC shack: High water mark and 5500 m³/s predicted level est. 2014 Projects Cont’d

• Partnerships and Working Groups – FloodNET – NSERC – Flood/Modeling Research – letter of support – AI-IEEE, WaterSMART– Flood Forecasting Workshop – UBC/Canmore: Canmore Statistical Forecast Model Research Project – City of Calgary: River Flood Mitigation Program - Event Forecasting • WISKI Alarm Manager – Rainfall Intensity Alarms

Drumheller 2013 Alberta Rivers Mobile App

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