Assessing Dual-Polarization Radar Estimates of Extreme Rainfall during Hurricane Harvey

Abstract Hurricane Harvey hit the Texas Gulf Coast as a major hurricane on 25 August 2017 before exiting the state as a tropical storm on 29 August 2017. Left in its wake was historic flooding, with some locations measuring more than 60 in. (150 cm) of rain over a 5-day period. The WSR-88D radar (KHGX) maintained operations for the entirety of the event. Rain gauge data from the Harris County Flood Warning System (HCFWS) was used for validation with the full radar dataset to retrieve daily and event-total precipitation estimates for the period 25–29 August 2017. The KHGX precipitation estimates were then compared with the HCFWS gauges. Three different hybrid polarimetric rainfall retrievals were used, along with attenuation-based retrieval that employs the radar-observed differential propagation. An advantage of using a attenuation-based retrieval is its immunity to partial beam blockage and calibration errors in reflectivity and differential reflectivity. All of the retrievals are susceptible to changes in the observed drop size distribution (DSD). No in situ DSD data were available over the study area, so changes in the DSD were interpreted by examining the observed radar data. We examined the parameter space of two key values in the attenuation retrieval to test the sensitivity of the rain retrieval. Selecting a value of α = 0.015 and β = 0.600 provided the best overall results, relative to the gauges, but more work needs to be done to develop an automated technique to account for changes in the ambient DSD.

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A pilot operational flood warning system in Andalusia (Spain): presentation and first results

Hydrology and Earth System Sciences Discussions ◽

10.5194/hessd-8-10425-2011 ◽

2011 ◽

Vol 8 (6) ◽

pp. 10425-10463 ◽

Cited By ~ 2

Author(s):

P.-A. Versini ◽

M. Berenguer ◽

C. Corral ◽

D. Sempere-Torres ◽

A. Santiago-Gahete

Keyword(s):

A Priori ◽

Warning System ◽

Rain Gauge ◽

Flow Measurements ◽

Radar Rainfall ◽

Flood Warning ◽

Flood Alert ◽

First Results ◽

Flood Warning System ◽

Rainfall Runoff Model

Abstract. The Guadalhorce Basin is located in Andalusia (South of Spain). Its floods have historically represented a major hazard for the city of Málaga. In 2008 it has been decided to implement a pilot operational flood warning system (GFWS) with the aim of analyzing the capability to minimize the risk to people, and economic activity, as well as for guiding water resources management. The system is oriented to provide distributed warnings based on rainfall accumulations and discharge forecasts. Rainfall accumulation maps are generated according to the interpolation of rain gauge measurements and weather radar rainfall maps whereas discharge forecasts are computed using a distributed rainfall-runoff model. Due to the lack of flow measurements, the model was calibrated a priori in most of the basin area. The performance of the system has been tested on two recent rainfall events which caused many inundations. First results show how the GFWS performed well and was able to forecast the location and timing of flooding. It demonstrates that a simple model and a rough calibration could be enough to issue valuable warnings. Moreover, the European Flood Alert System (EFAS) forecasts have been used to prevent from the flood several days in advance. With low resolution and long anticipation, EFAS appears as a good complement tool to improve flood forecasting and compensate for the short lead times of the GFWS.

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Application of the HBV hydrological model in a flash flood case in Slovenia

Natural Hazards and Earth System Science ◽

10.5194/nhess-10-2713-2010 ◽

2010 ◽

Vol 10 (12) ◽

pp. 2713-2725 ◽

Cited By ~ 29

Author(s):

M. G. Grillakis ◽

I. K. Tsanis ◽

A. G. Koutroulis

Keyword(s):

Hydrological Model ◽

Flash Flood ◽

Warning System ◽

Weather Forecast ◽

Radar Data ◽

Added Value ◽

Distributed Hydrological Model ◽

Flood Warning ◽

Forecast Models ◽

Flood Warning System

Abstract. An atmospheric depression passed over northwest Slovenia on 18 September 2007 producing precipitation that exceeded 300 mm/d and a 100-year return period runoff in Zelezniki tributary. The resultant flash flood in the study area, which consisted of five basins, was simulated with the conceptual distributed hydrological model HBV (Hydrologiska Byråns Vattenbalansavdelning). The model was calibrated and validated with past rainfall – runoff events with satisfactory results producing values of Nash – Sutcliffe coefficient between 0.82 and 0.96. The validated model was applied to the flash flood case with stream gauge failure, driven by spatiotemporal precipitation produced by a set of rain gauges and radar data. The model delivered satisfactory results on three out of five basin outlets while the other two had stream gauge failure during the event. The internal basin dynamics of the most affected area in Zelezniki, was successfully tested in eight of its sub-basins by comparing the peak discharges with the ones evaluated by the slope-conveyance method during a detailed intensive post event campaign. The added value of this method is in the reduced uncertainty in peak discharge estimation and event interpretation and in an effective flash flood warning system for the study area when it is combined with radar nowcasts and operational high resolution short range weather forecast models.

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Feedback structure and EFAS flood warning verification for the rivers in the northwestern Russian Federation

Hydrometeorological research and forecasting ◽

10.37162/2618-9631-2020-4-96-109 ◽

2020 ◽

Vol 4 ◽

pp. 96-109

Author(s):

A.V. Romanov ◽

◽

M.V. Yachmenova ◽

Keyword(s):

Russian Federation ◽

Forecast Accuracy ◽

Warning System ◽

General Description ◽

System Quality ◽

Flood Warning ◽

Forecast Lead Time ◽

Feedback Structure ◽

The Russian Federation ◽

Flood Warning System

Based on the example of flood warning data provided by EFAS for the territory of Northwestern Administration for Hydrometeorology and Environmental Monitoring in 2018-2020, the structure of the systematized issues of the EFAS portal is analyzed. The issues determine a feedback for the year-round monitoring of the accuracy of flood forecasting using the LISFLOOD base model, as well as its calibration. Several most important feedback sections are highlighted, that allow improving significantly a procedure for the quantitative and qualitative differentiated assessment of short- and medium-range flood forecasts. Using the results of the numerical analysis, a general description of the EFAS flood warning system quality and the prospects for the participation of the Russian Federation in it are given. Keywords: flooding, hydrological forecasts, forecast lead time, feedback, forecast accuracy

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