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In ormation ources or Foo Forecast- ase Action E orts THE UNIVERSITY OF ALABAMA IN HUNTSVILLE Authors: Claire Nauman ([email protected]), Amanda Markert, Tim Mayer, Eric Anderson, Robert Griffin I May 2019 Thailand , ' :$ Drainag e Line . 4) Watershed Bo u ndary £ 20 -Year Return Period £ 10-Year Return Period __:.>'--~:-------...___ £ 2-Year Return Period (C) Screenshot of Streamflow Prediction Tool (SPT) stream segments. 350 300 ,;,250 - M E -200 " 0 - E 150 0 a, - t;j l 00 50 0 I SPT Historical Slreamflow Cambodia I 10/6/2013, 289 1 -S treamflow - Max Event I - 20-year Event 9/19/2013, 153 - 10-year Event 2-year Event 9/1/2013 9/15/2013 9/29/2013 10/13/2013 10/27/2013 (D) SPT historical streamflow at peak flows Sept-Oct, 2013 for a stream segment near Tonie Sap Lake. 1- z w I- >< w 0 0 0 _J LL ' ,. ,1· ,. • • , Water Extent • Pre-event • Event maximum D Province boundary N 100 A Kil o meters (A) Maximum flood extent observed by several satellite overpasses in Oct, 2013. (UNOSAT) +- V) 0 u (]) .._ 0 LL a Hi tRat e = -- a+ c False A larm Ratio = Extreme Event b a+b No Extreme Event Observed Extreme Event No Extreme Event a b C d (F) Contingency table and equations for evaluating forecast performance against in situ observations. - - M E - " 0 - E 0 a, - - "" SPT Forecast Slreamflow Oregon 500 400 300 200 100 HRES Mean Max - Std. Dev. Upper Std. Dev. Lower Min 20-yr (360.1 I I 0-yr (305.0) 2-yr (173.1 I Max. (365.4) 0--------------------------- 5/16/2019 5/18/2019 5/20/2019 5/22/2019 5/24/2019 5/26/2019 (E) Example of the SPT probabilistic forecast from May 15, 2019 for a stream segment in Oregon. Some ensemble runs cross the 2-yr, 10-yr, and even 20-yr return period thresholds. People Directly I- Aff ected u D 0 C 1,000 <( 0 ro 5,000 ~ , a, a... o_ I 0,000 ' o_ =o 60,000 N 100 •• A Kil ometers (B) People directly affected by flooding caused by monsoon rains Aug-Oct, 2013. (Desi nventar) Cambodia Floods Begin to Recede 18 OCTOBER. 2013 BY RICHARD DAVI ES IN ASIA Cambodia Floods Update 10 OCTOBER. 2013 BY RICHARD DA VI ES IN ASIA f g+ ® in w 39 Dead in Cambodia Floods 3 OCTOBER. 2013 BY RICHARD DAVI ES IN ASIA Floods in Cambodia 2 SEPTEMBER. 2013 BY RICHARD DAVI ES IN ASIA f., 8. ®in t f., 8. ®in Like much of South and South East Asia, Cambodia has been suffering from floods since the monsoon rains began. The flooding in Cambodia started in early August Since then 13 people have died and as many as 10,000 people have been displaced. The wo rst affected areas are Banteay Meanchey, Preah Vi hear, Kampong Thom, and Kratie. The floods have also damaged at least 20,000 hectares of rice paddy fields. The Head of Cambodia's Cabinet of the National Committee for Disaster Management (NCDM), said that 11 of the deaths were in north western Banteay Meanchey. The other 2 fatalities were in northern Kampong Thom. Floods are common in Cambodia during the monsoon season, especially as 85 per cent of the nation's land lies with in the lower Mekong basin. 2011 saw some of the worst instances of flooding the country has seen, and as many as 250 people lost their lives. Floods claimed the lives of 14 people in Cambodia in 2012. There is a fear that the flooding this year is worse. Mong Sam An, commune chief in Palhal, said , "It is much worse than August last year. Last year, these floods didn't come until September". (G) Flood impact, location, and onset date information from news sources reporting on the 2013 Cambodia flooding. e 0 n t in my In forecast-based action (FbA), decision-makers can define plans to automatically trigger action before an extreme event occurs utilizing forecast information. Gathering data from past events is an important part of developing these plans. We showcase here several different types of information that can be used for selecting an FbA program location and developing FbA early action protocols, using the 2013 Cambodia flood event as an example. Cambodia falls within the lower Mekong region, which frequently experiences flooding. To understand where an event has occurred, flood extents derived from models or observed by satellites (A) can be consulted. Disaster loss databases can provide information about the impact of the event (B). Flood models and in situ observations can provide information about the timing of peak flows. In selecting a forecasting system and determining a forecast trigger threshold (e.g. 80% chance of exceeding the 1 in 10 year streamflow), performance of forecasting systems, like the Streamflow Prediction Tool co-developed by SERVIR and Brigham Young University, can be evaluated through comparison with in situ observations like those of the Mekong River Commission (C, D, E, F). News articles can also provide information about the event's impact and timing (G). Forecast uncertainty is one of the greatest challenges for taking action based on a forecast. Probabilistic forecasts account for uncertainty by running a model several times with slight changes in initial conditions and parameters. Each model run is called an ensemble and the spread of the ensembles gives an indication of the probability (e.g. 80% of ensembles exceeded the 10-yr return period threshold) (E). By examining historical data, decision- makers can determine the optimal trigger thresholds, enabling action despite uncertainty. References and Service L ayer Credi t s: Davies, R. (20 13). Re t rieved from h tt p:/ /flood l is t .com/ Des lnventar. (n.d.). Ca1nbodia Directly Affected. Re t rieved May 2, 20 1 9, from h tt ps:/ /www.desinven tar.net/Deslnvent ar/index.j sp. E sri, HE RE, Garmin,© OpenS treet Map con tribut ors, and t he G IS u ser comm unity Hu mani t arian Da ta E xchange. (n.d.). Ca,nbodia Ad,n inistrative Boundari es. Re t rieved May 2, 20 1 9, from h tt ps ://da ta .humda ta .org/ da taset/ cam bodia -admin -l eve l-0- in t erna t iona l-bo undaries. Snow, A l an D., So uffront, Michael, Rae, Cu rt is, & Crawley, Shawn. (20 1 7, August 21 ). erdc -cm/ tet hysapp - st reamflow_predic tion_tool: l . l .0 (Version l . l .OJ. Zenodo. h tt p:/ /doi.org/ l 0.5281/zenodo.846347 UN OSAT. (n.d.). Oc t ober20 l 3 Fl ood Vec t ors [Map ]. Re t rieved May l , 20 1 9, from h tt p:/ /floods. unosat .org/ geo port al/ ca tal og/ search/ search.page https://ntrs.nasa.gov/search.jsp?R=20190027201 2020-06-03T05:21:19+00:00Z
