Mr. Wang-chun WOO Scientific Officer, Hong Kong Observatory - - PowerPoint PPT Presentation
Mr. Wang-chun WOO Scientific Officer, Hong Kong Observatory wcwoo@hko.gov.hk Ir. Jason H.Y. WONG Senior Engineer, Drainage Services Department jasonwong@dsd.gov.hk Weather Bulletins Local Weather Forecasts 9-day Weather Forecasts SWIRLS
Scientific Officer, Hong Kong Observatory
wcwoo@hko.gov.hk
Senior Engineer, Drainage Services Department
jasonwong@dsd.gov.hk
Local Weather Forecasts 9-day Weather Forecasts
2-hour Rainfall Nowcast https://maps.weather.gov.hk/ocf/index_e.html
Weather Radar Automatic Rain Gauges
Z = a R b
20 30 40 50 60 5 7 9 11 13 15 17 19 21 dBZ dBG
Latest Radar Image Previous Radar Image Forecast Radar Image By Semi- Lagrangian Advection Motion Field By Variational Optical Flow
Products
(Updated every 15 minutes)
Past Hour Past 24 Hours / Today /
Yesterday / Daily
Dissemination Channels:
HKO Internet Website Weather TV Programme Weather Panels
On Website On Smart Phone App
Malaysia Zhuhai South Africa Macao India
SWIRLS Nowcast System
Wetland at Shuen Wan Optimization of Penstock Operation Kai Tak River Improvement Works Early Rainstorm Alert System
Diamond Hill Wong Tai Sin Tsz Wan Shan San Po Kong Kowloon City Kai Tak
Catchment Area 10.8 km2 (Approx. 60 nos. of Victoria Park)
Kai Tak River - Project Background
DSD Upstream and Midstream Section – 1.1km CEDD Downstream Section – 1.3km
Tolo Harbour Effluent Export Scheme (THEES)
Tai Po Sewage Treatment Works Shatin Sewage Treatment Works
Tolo Harbour Kai Tak River
July 2010 June 2018
Kai Tak River - Improvement on Drainage Capacity
15
10
Kai Tak Development Area Tai Shing Street
Deepening riverbed by 1 metre Construct 400m long box culvert Bottlenecks
Deepened riverbed
Construct 400m long box culvert
6m width, 3.2m height
Choi Hung Road
Original riverbed
Concrete blocks for temporary flow diversion
Kai Tak River - Difficulties on River Improvement Works
During construction, original drainage capacity of river must be maintained Most of the works are highly susceptible to weather
Completed box culvert Works site flooded in adverse weather
Suspend discharging treated effluent
River bed deepening works to be carried out
HKO - 9-day Weather Forecast
Kai Tak River - Weather Information and Forecast
HKO - Weather Radar Image HKO - Regional Weather Forecast
Real-time Raingauge data
Calibration of radar reflectivity using real-time raingauge measurements Calculation of coming 6 hours rainfall intensity
Kai Tak River - Early Rainstorm Alert System
Generation of raw data in grid
HKO’s “SWIRLS” Nowcasting System 天文台「小渦旋」臨近預報系統
“SWIRLS” - Short-range Warning of Intense Rainstorms in Localized Systems
Kai Tak River - Early Rainstorm Alert System
Kai Tak River - Early Rainstorm Alert System
Kai Tak River - Early Rainstorm Alert System
Monitor the change of predicted rainfall intensity Send out alert SMS when more than 20% of catchment area exceeds 30mm/hr
Gratings removed during heavy rainstorm
Kai Tak River - Early Rainstorm Alert System
Once alert SMS was received
23
Kai Tak River - 24-hour Real Time Monitoring System
39
Send SMS flood alert messages to nearby shops when the river water level hits the alert level
Alert level
Water level sensor
2015 2016 2017 2018
Start to apply “Early Rainstorm Alert System”
Kai Tak River Improvement Works have been completed without flooding since 2015
Last flooding incident on 26.9.2015
Completion of Kai Tak River
Ha Tei Ha (wetland) Penstock
EXISTING STREAM NEW CULVERT EXISTING CULVERT
Application of SWIRLS to Penstock Operation Optimization at Shuen Wan
Pumping Station
Culvert
Shuen Wan Penstock - Original Operation Mode of Penstock
Penstock opens when tidal level < +2.1mPD Penstock closes when tidal level higher than +2.1mPD
Penstock Penstock
When water level of river is higher than +2.1mPD, flood water overspills to by-pass box culvert connected to pumping station for discharging to sea Penstock
Pumping Station
Shuen Wan Penstock - Original Operation Mode of Penstock
Wetland in dry condition Wetland in wet condition
Shuen Wan Penstock - Original Operation Mode of Penstock
Penstock operation relied on tide level only
Design Philosophy
Objective:
Increase water backflow into the wetland without compromising flood protection standard
mode of penstock
Design Concept
heavy rainstorm
SWIRLS nowcasting system
Shuen Wan Penstock – Design Philosophy
“SWIRLS” Nowcast Local Raingauges Weather Warning Signals Define Weather Condition - Rainy or non-rainy days ?? Define Trigger Level Sea Level > Trigger Level?
Penstock Close Penstock Open
No
Yes
Shuen Wan Penstock – Design Philosophy
Forecast in any grid > 10mm/hr Actual Rainfall depth > 10mm/hr Any warning signal issued
Normal Sunny Highest Trigger Level (+2.75 mPD) “SWIRLS” / Rain Gauges / Warning Signals Normal Rainy (Wet) Original Trigger Level (+2.10 mPD) Reserve sufficient storage capacity, without compromising flood risk Non-rainy Days Shorten penstock closing period Rainy Days Normal Rainy (Dry) Higher Trigger Level (+2.35 mPD) Wet Soil Dry Soil
Shuen Wan Penstock - Mechanism of Enhanced Operation Mode
Shuen Wan Penstock - Comparison of Operation Mode of Penstock
Previous
mode Enhanced
mode Total operation time reduced by 90% as compared to previous operation mode +2.1mPD +2.1mPD
tide level Penstock closed when tide above +2.1mPD Penstock only closed in rainy days
Shuen Wan Penstock - Comparison of Water level at Wetland
Previous operation mode Enhanced operation mode
最高潮水位 +2.37mPD 最高潮水位 +2.31mPD 濕地水位 +1.89mPD 濕地水位 +2.18mPD Highest tide
Water level at wetland
Tidal level Water level at wetland
Highest tide
Water level at wetland
Shuen Wan Penstock - Condition of Wetland after Enhancement Works
Seawater ingression can be
Flood protection standard can be maintained
Wetland and all living habitats can be preserved