Radar‐based flood forecasting in small catchments, exemplified by the Goldersbach catchment, Germany

Ehret, Uwe; Götzinger, J.; Bàrdossy, András; Pegram, Geoff

doi:10.1080/15715124.2008.9635359

Cited by 42 publications

(25 citation statements)

References 3 publications

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“…It is characterized by merging operational rainfall radar data with rain gauge data as well as disdrometer data to characterize droplet sizes and vertical rain radar that have been installed within the Attert catchment at three meteosites. These data are combined: (a) by means of data assimilation into the soil-vegetation-atmosphere model system WRF-NOAH-MP (Skamarock et al, 2008;Schwitalla and Wulfmeyer, 2014) and (b) by a geo-statistical merging originally proposed by Ehret et al (2008) for improving quantitative precipitation estimates. During radiation-driven conditions horizontally averaged sensible and latent heat fluxes are observed by means of a scintillometer and airborne thermal remote sensing that yields spatially highly resolved data on leaf temperature and soil surface temperature at different time slices.…”

Section: Experimental Designmentioning

confidence: 99%

HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

Zehe

Ehret

Pfister³

et al. 2014

Hydrol. Earth Syst. Sci.

100

103

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Abstract. According to Dooge (1986) intermediate-scale catchments are systems of organized complexity, being too organized and yet too small to be characterized on a statistical/conceptual basis, but too large and too heterogeneous to be characterized in a deterministic manner. A key requirement for building structurally adequate models precisely for this intermediate scale is a better understanding of how different forms of spatial organization affect storage and release of water and energy. Here, we propose that a combination of the concept of hydrological response units (HRUs) and thermodynamics offers several helpful and partly novel perspectives for gaining this improved understanding. Our key idea is to define functional similarity based on similarity of the terrestrial controls of gradients and resistance terms controlling the land surface energy balance, rainfall runoff transformation, and groundwater storage and release. This might imply that functional similarity with respect to these specific forms of water release emerges at different scales, namely the small field scale, the hillslope, and the catchment scale. We thus propose three different types of "functional units" -specialized HRUs, so to speak -which behave similarly with respect to one specific form of water release and with a characteristic extent equal to one of those three scale levels. We furthermore discuss an experimental strategy based on exemplary learning and replicate experiments to identify and delineate these functional units, and as a promising strategy for characterizing the interplay and organization of water and energy fluxes across scales. We believe the thermodynamic perspective to be well suited to unmask equifinality as inherent in the equations governing water, momentum, and energy fluxes: this is because several combinations of gradients and resistance terms yield the same mass or energy flux and the terrestrial controls of gradients and resistance terms are largely independent. We propose that structurally adequate models at this scale should consequently disentangle driving gradients and resistance terms, because this optionally allows Published by Copernicus Publications on behalf of the European Geosciences Union. E. Zehe et al.: HESS Opinions: Thermodynamic reinterpretation of the HRU conceptequifinality to be partly reduced by including available observations, e.g., on driving gradients. Most importantly, the thermodynamic perspective yields an energy-centered perspective on rainfall-runoff transformation and evapotranspiration, including fundamental limits for energy fluxes associated with these processes. This might additionally reduce equifinality and opens up opportunities for testing thermodynamic optimality principles within independent predictions of rainfall-runoff or land surface energy exchange. This is pivotal to finding out whether or not spatial organization in catchments is in accordance with a fundamental organizing principle.

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Section: Experimental Designmentioning

confidence: 99%

HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

Zehe

Ehret

Pfister³

et al. 2014

Hydrol. Earth Syst. Sci.

100

103

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“…Since an important fraction of the uncertainty of hydrological predictions is due to the uncertainty of the input rainfall observations and forecasts, radar-based ensemble nowcasting systems are increasingly used as inputs for flood and sewer system modeling (e.g., Ehret et al, 2008;Silvestro and Rebora, 2012;Silvestro et al, 2013;Xuan et al, 2009Xuan et al, , 2014. At longer forecast ranges, the NWP ensembles are also exploited for uncertainty propagation into hydrological models (see Roulin and Vannitsem, 2005;Thielen et al, 2009;Schellekens et al, 2011).…”

Section: Introductionmentioning

confidence: 99%

Development and verification of a real-time stochastic precipitation nowcasting system for urban hydrology in Belgium

Foresti

Reyniers

Seed

et al. 2016

Hydrol. Earth Syst. Sci.

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Abstract. The Short-Term Ensemble Prediction System (STEPS) is implemented in real-time at the Royal Meteorological Institute (RMI) of Belgium. The main idea behind STEPS is to quantify the forecast uncertainty by adding stochastic perturbations to the deterministic Lagrangian extrapolation of radar images. The stochastic perturbations are designed to account for the unpredictable precipitation growth and decay processes and to reproduce the dynamic scaling of precipitation fields, i.e., the observation that largescale rainfall structures are more persistent and predictable than small-scale convective cells. This paper presents the development, adaptation and verification of the STEPS system for Belgium (STEPS-BE). STEPS-BE provides in realtime 20-member ensemble precipitation nowcasts at 1 km and 5 min resolutions up to 2 h lead time using a 4 C-band radar composite as input. In the context of the PLURISK project, STEPS forecasts were generated to be used as input in sewer system hydraulic models for nowcasting urban inundations in the cities of Ghent and Leuven. Comprehensive forecast verification was performed in order to detect systematic biases over the given urban areas and to analyze the reliability of probabilistic forecasts for a set of case studies in 2013 and 2014. The forecast biases over the cities of Leuven and Ghent were found to be small, which is encouraging for future integration of STEPS nowcasts into the hydraulic models. Probabilistic forecasts of exceeding 0.5 mm h −1 are reliable up to 60-90 min lead time, while the ones of exceeding 5.0 mm h −1 are only reliable up to 30 min. The STEPS ensembles are slightly under-dispersive and represent only 75-90 % of the forecast errors.

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“…The kriging with a radar based error correction (KRE), which is also known as 'conditional merging' The merged rainfall using this method combines the interpolated rain gauges using the Ordinary Kriging (OK) method and the spatial variability of radar data (Ehret et al 2008). The steps of CM are first to interpolate the rain gauge observations using OK to estimate the best linear unbiased rainfall field at all ungauged locations.…”

Section: Kriging With a Radar Based Error Correctionmentioning

confidence: 99%

“…Next, radar pixels at gauge locations are extracted from the radar rainfall field and the values at other locations are interpolated using OK. Subsequently, the deviation C between the observed and interpolated radar rainfall field is calculated from the following equation (Ehret et al 2008). …”

Section: Kriging With a Radar Based Error Correctionmentioning

confidence: 99%

“…The radar domain for each of the four cases of the merged areas has also been extracted from radar network. For each case, the merging of the daily radar and the rain gauge data has been performed for extreme rainfall in the period of 1 st April 2007-28 th February 2009, by using two well-known geostatistical interpolation methods: conditional merging (Ehret et al 2008) and KED (Verworn & Haberlandt 2011). The performance of the merged data is assessed using rain gauge observations inside the study area (in the real world situation, no gauges are available in the study area.…”

Section: Introductionmentioning

confidence: 99%

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Exploration of an adaptive merging scheme for optimal precipitation estimation over ungauged urban catchment

Fadhel

Rico‐Ramirez

Han

2016

Journal of Hydroinformatics

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General rightsThis document is made available in accordance with publisher policies. Please cite only the published version using the reference above. Full terms of use are available: http://www.bristol.ac.uk/pure/about/ebr-terms ABSTRACTMerging raingauge-radar data improves the accuracy of precipitation estimation for urban areas. Since the rain gauge network around the ungauged urban catchment is fixed, the relevant research question is about the optimal merging area that produces the best rainfall estimation inside the catchment. To answer this, an incremental radar-gauge merging performed by gradually increasing: the distance from the centre of the study area, the number of merging gauges around it and the radar domain. The proposed adaptive merging scheme is applied to a small urban catchment in west Yorkshire, Northern England for 118 extreme events from 2007 to 2009. The performance of the scheme is assessed using four experimental raingauges installed inside the study area. The result shows that there is indeed an optimum radar-gauge merging area and consequently there is an optimum number of rain gauges that produce the best merged rainfall data inside the study area. Different merging methods produce different results for both classified and unclassified rainfall types. Although the scheme was applied on daily data, it's applicable to other temporal resolutions.This study is of important value for other studies such as urban flooding analysis, since it provides improved rainfall estimation for ungauged urban catchment.

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Radar‐based flood forecasting in small catchments, exemplified by the Goldersbach catchment, Germany

Cited by 42 publications

References 3 publications

HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

HESS Opinions: From response units to functional units: a thermodynamic reinterpretation of the HRU concept to link spatial organization and functioning of intermediate scale catchments

Development and verification of a real-time stochastic precipitation nowcasting system for urban hydrology in Belgium

Exploration of an adaptive merging scheme for optimal precipitation estimation over ungauged urban catchment

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