Assessment of different rainfall products in flood simulations

Özkaya, Arzu
Floods happening due to heavy rainfall are one of the most widespread natural hazards. To predict such events, accurate rainfall products and well calibrated hydrologic models are essential especially in urban settlements for life savings. With the objective of assessing the rain detection potential of rainfall data products, several hourly rainfall datasets are used as forcing inputs in two hydrologic models. Physic based distributed model, WRF-Hydro, and conceptual based lumped model, HEC HMS, are used to simulate the three catastrophic flood events those occurred in Terme Basin in Samsun. For the calibration of both models, gauge data belonging to 22nd November 2014 flood event are used. Furthermore, stream network density effect in rainfall-runoff modeling is investigated in WRF-Hydro model. In model evaluations, two different flood events with different rainfall datasets are used. The datasets contain weather radar data and satellite rainfall estimates from Hydro-Estimator (HE) as nowcasting products; Weather Research and Forecasting Model (WRF) precipitation data as a forecasting product and gauge-based data. Among these datasets bias correction is applied to the weather radar data by using Kalman Filtering and their use in flood modeling is also evaluated in the simulations. Results show that all products have different limitations and potentials depending on the rainfall type. Among them, the HE product generally indicates poor performance in the simulations in this basin. Whereas, gauge data located in close proximity to the study area is good at representing the flood peak occurrence time but has a weakness in the flood magnitude estimation. WRF precipitation data are superior in detecting the rain with some time inaccuracy but as a forecasted product it can be useful as an early warning system to take initial precautions. Bias corrected radar data using the gauging stations in close proximity to the studied one has an affirmative effect on results especially in frontal rainfall type. Results of the models show that both models are generally close to each other in representing hydrograph shape and peak time. The average value of correlation (r) and root mean square error (RMSE) for all events and rainfall products indicate that WRF Hydro (0.61 for r, 62.6 m3/s for RMSE) showed a slightly better success compared to the HEC HMS (0.59 for r, 67.6 m3/s for RMSE). However, one of the flood event that has mainly convective origin makes the difference between the models. In this event, WRF-Hydro model presents the physical-based model’s ability in showing hydrograph peak discharge and time to peak accurately. The overall results indicate that the use of well calibrated hydrologic model with rainfall data that compound of calibrated radar, WRF precipitation forecast and observations in ungauged or poorly gauged areas can help to take necessary precautions against flooding and provide benefit in saving life and property. 


Analyses of flood events using regional hydrometeorological modeling system
Önen, Alper; Yücel, İsmail; Department of Civil Engineering (2013)
Extreme rainfall events and consequent floods are being observed more frequently in the Western Black Sea region in Turkey as climate changes. In this study, application of a flood early warning system is intended by using and calibrating a combined model system. A regional-scale hydro-meteorological model system, consisting of Weather Research and Forecasting (WRF) model, NOAH land surface model and fully distributed NOAH-Hydro hydrologic models, is used for simulations of 25 heavy-rainfall and major flood...
Drought analysis using CORDEX simulations over the mediterranean climate regions of Turkey
Poyraz, Anıl Yıldırım; Yücel, İsmail; Department of Civil Engineering (2018)
Drought has been a significant result of climate change that causes variance on precipitation regimes. Mediterranean region is one of the hotspots of the world in this respect. Dry summers and rainy winters -the characteristic of this climate type- makes this region more vulnerable to the effects of climate change. Hence, it is important to monitor drought considering the increasing population and economic facilities in the regions that are under Mediterranean climate conditions in Turkey. This study aims t...
WRF-Hydro Model Application in a Data-Scarce, Small and Topographically Steep Catchment in Samsun, Turkey
Ozkaya, Arzu; Akyürek, Sevda Zuhal (2020-05-01)
Floods due to heavy rainfall are one of the most frequent and widespread natural hazards. Rainfall is one of the key variables in flood modeling. For topographically steep catchments, flood modeling requires accurate rainfall sources in both time and space. The objective of this study is to compare different rainfall sources in physics-based distributed hydrologic model, (Weather Research and Forecasting) WRF-Hydro, in a data-scarce, small and topographically steep catchment. For this purpose, the model was...
Analysis of the 2007 and 2013 Droughts in Turkey by NOAH Hydrological Model
Bulut, Burak; Yılmaz, Mustafa Tuğrul (2016-10-01)
Analysis of drought, which is classified as a natural disaster, is globally considering the damage it gives. As a result detection of its characteristics is essential for understanding and reducing the effects of this natural disaster and for imminent prediction. In this study, soil moisture estimates obtained from NOAH hydrological model and normalized difference vegetation index obtained from MODIS observations are used to analysis the recent droughts in Turkey. With the utilization of these parameters th...
Analysis of drought events in North Cyprus
Khan, Sana; Akıntuğ, Bertuğ; Sustainable Environment and Energy Systems (2019-9)
Drought is a temporary climatic condition which arises due to lack of precipitation. It has become an important natural phenomenon for North Cyprus due to its semi-arid climate and with vulnerabilities culminating as a result of climate change there is a dire need to keep a good track of such extreme climate events for sustainable water resource management. The island is facing serious water shortages, and for Mediterranean region climate change impacts on water resources has become a pressing issue, hence,...
Citation Formats
A. Özkaya, “Assessment of different rainfall products in flood simulations,” Ph.D. - Doctoral Program, Middle East Technical University, 2017.