Manabendra Saharia, Ph.D. student in CEES/ARRC, won 1st place in the graduate student poster contest at the Society of Environmental Journalism (SEJ) 25th Annual Conference. The conference was held in Norman, Oklahoma from October 7th-11th, 2015. Manab’s poster focused on his work to identify the basins in the US with the fastest rainfall-runoff response.
On the evening of May 23rd into the early morning of May 24th, 2015 the Blanco River in Texas experienced a significant flooding event resulting in the closure of I-35 north & southbound near the city of San Marcos, TX. There were also multiple high-water rescues in the area including helicopter rescues of victims trapped in houses. The Hays County jail in Texas was also evacuated due to threatening flood waters. The FLASH development system was running for this event producing products forecasting & monitoring the flooding in near real time.
Traditional rainfall based products including the rainfall accumulation and the ratio of rainfall to flash flood guidance highlight a large area northwest of San Marcos for flooding impacts. The storm system produced 6-8″ of rain over the region to the northwest resulting in exceedance of flash flood guidance by 160-180%.
The FLASH hydrologic model based products correctly show the heavy rainfall being concentrated into the rivers and the downstream flooding impacts in San Marcos resulting from the heavy rainfall to the northwest of the region.
- This was a very heavy rainfall event that was captured well by MRMS radar-only estimates
- The flash flood guidance product indicated significant exceedance over threshold values, but the areas of concern were limited to the headwaters of the Blancos river
- The distributed hydrologic model forecasts better refined the threat area to the Blancos river and provided several hours of lead time
- This event clearly highlights the need to account for overland flow and routing, displacing the impacts well downstream of the causative rainfall
The MRMS-FLASH system, running in a real-time demonstration mode for several years now, performed admirably for the recent flash flooding events in Oklahoma and Texas. The MRMS-FLASH system runs in a completely automated fashion ingesting quantitative precipitation estimates every 5-minutes from the MRMS mosaic of NEXRAD data. The FLASH hydrologic modeling system subsequently produces 6-hour forecast hydrographs for everywhere across the CONUS.
On evening of May 25th, 2015 the city of Houston, Texas experienced a serious flash flooding event. MRMS precipitation estimates indicate that the western portions of the city experienced 6-8″ of rainfall.
The ratio of precipitation to flash flood guidance shows exceedance values of 100-140% over this area, however some of the USGS stream gauges reporting flash flooding (blue triangles) and the flash flood local storm reports (brown circles) fall outside of this region. This product is important because it is equivalent to the main tool operational NWS forecasters have available for flash flood monitoring and prediction.
The Coupled Routing and Excess Storage (CREST) distributed hydrologic model, a part of the MRMS-FLASH hydrologic modeling suite, generates maps of streamflow and unit streamflow (cubic meters per second per square kilometer) every 15 minutes. Comparisons between the observations of flash flooding and the maps of unit streamflow show a good correspondence between areas of high unit streamflows and flash flooding.
The MRMS-FLASH suite of hydrologic models are able to correctly identify areas of flash flooding thanks to the incorporation of
- Stream & overland routing
- Modeling of impervious surfaces
Published: December 23, 2014 by CRC Press
Radar Hydrology: Principles, Models, and Applications provides graduate students, operational forecasters, and researchers with a theoretical framework and practical knowledge of radar precipitation estimation. The only text on the market solely devoted to radar hydrology, this comprehensive reference:
- Begins with a brief introduction to radar
- Focuses on the processing of radar data to arrive at accurate estimates of rainfall
- Addresses advanced radar sensing principles and applications
- Covers radar technologies for observing each component of the hydrologic cycle
- Examines state-of-the-art hydrologic models and their inputs, parameters, state variables, calibration procedures, and outputs
- Discusses contemporary approaches in data assimilation
- Concludes with methods, case studies, and prediction system design
- Includes downloadable MATLAB® content
Flooding is the #1 weather-related natural disaster worldwide. Radar Hydrology: Principles, Models, and Applications aids in understanding the physical systems and detection tools, as well as designing prediction systems.
“This is the first book on radar hydrology written by hydrologists. Whereas the excellent knowledge of radar technology by the authors permits an adequate coverage of the principles of rainfall rate estimation by radar, their hydrological background allows them to provide a unique message on the benefits (and on the remaining challenges) in exploiting radar techniques in hydrology. … In a clear and concise manner, the book combines topics from different scientific disciplines into a unified approach aiming to guide the reader through the requirements, strengths, and pitfalls of the application of radar technology in hydrology—mostly for flood prediction. Chapters include excellent discussion of theory, data analysis, and applications, along with several cross references for further review and useful conclusions.”
The final report on the inaugural Hazardous Weather Testbed Hydro experiment has been released. The report details how the experiment was run, configuration details for AWIPS2, conclusions from the experiment and recommendations for future iterations of the experiment. Thanks again to all of our participants!
Website hosting MRMS, FLASH, and NOXP products: http://wdssii.nssl.noaa.gov/web/wdss2/products/radar/iphex.shtml
More information about IPHEX can be found here: http://iphex.pratt.duke.edu
And here: http://pmm.nasa.gov/IPHEx
The award is selected by the NWA Weather Analysis and Forecasting Committee. The poster, A CONUS-wide analysis of flash flooding: simulations, warnings, and observations, identifies regional trends in the frequency of flash flood observations in NWS Storm Data, flash flood warnings, and flash flood guidance. His co-authors are J.J. Gourley (NOAA/OAR/NSSL), Yang Hong (OU), Zac Flamig (OU), and Ed Clark (NOAA/NWS). The recognition includes $125 and complimentary membership in the NWA for 2014.