Predictability of flash flooding in sloping dutch catchments (Rur, Niers and Swalm Rivers) : master thesis

Wasim, Syeda Khushnuma (author), Weerts, Albrecht (mentor), Den Toom, Matthijs (mentor), Rusjan, Simon (co-mentor)

The Dutch province Limburg is characterized by sloping terrain and is therefore prone to serious damages during flash floods. This was also the case for the July 2021 flood event. The study focuses on a detailed hydrological analysis and the generation of deterministic flood forecasts of the tributaries of the Meuse River in Limburg (i.e. Rur, Niers and Swalm rivers). For hydrological modeling, the wflow_sbm model was used which is a distributed hydrological model and its parameters were estimated with the Iterative Hydrography Upscaling (IHU) method and from Pedo Transfer Functions (PTFs). The horizontal hydraulic conductivity fraction (KsatHorFrac) parameter for the Rur catchment was calibrated to generate deterministic forecasts. Due to the significant difference between the observed and the simulated discharges of the Niers and Swalm catchments it was not possible to calibrate their hydrological models. Probable reasons for this difference can be the effects of ground water abstractions for pit mining and other purposes, frequent mowing management in the Niers catchment etc. Therefore forecasts were generated only for the Rur catchment by coupling the wflow model with Delft-FEWS. The forecasts generated using the DWD ICON dataset showed substantial error when compared to the observed discharge. However, for the flood event of 2021, the model predicted high flows 5-6 days ahead of the flood. There was a large overestimation of the peak for the forecast in downstream of the Rur catchment. The sensitivity of the forecast performance by changing KsatHorFrac was also analysed in the end. The findings of the study show several scopes of improvements in the wflow hydrological modeling and flood forecasting of the Meuse tributaries. Future studies based on these recommendations could aid in providing a more accurate flood prediction in this region.

• Language: English
• Keywords: civil engineering, master thesis, flash floods, sloping catchments, flood forecast, hydrological model
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: FGG - Faculty of Civil and Geodetic Engineering
• Place of publishing: Ljubljana
• Publisher: [S. K. Wasim]
• Year: 2022
• Number of pages: IX, 63 str., [5] str. pril.
• PID: 20.500.12556/RUL-141729
• UDC: 556.16.044:627.152.3(043.3)
• COBISS.SI-ID: 123971843
• Publication date in RUL: 06.10.2022

Secondary language

• Language: Slovenian
• Title: Napovedljivost poplav na hudourniških prispevnih območjih vodotokov Rur, Niers in Swalm na Nizozemskem : magistrsko delo

Abstract

Območje Limburga na Nizozemskem z relativno strmo topografijo terena je med poplavami julija 2021 utrpelo veliko poplavno škodo. Magistrska naloga se osredotoča na podrobne hidrološke analize in izdelavo deterministične napovedi poplav pritokov reke Meuse na območju Limburga (prispevna območja rek Rur, Niers in Swalm). Za potrebe hidrološkega modeliranja je bil uporabljen prostorsko distribuiran hidrološki model wflow_sbm, parametri modela so bili ocenjeni z metodo Iterative Hydrography Upscaling (IHU) in s pomočjo Pedo Transfer Function (PTF). Parameter horizontalne hidravlične prevodnosti (KsatHorFrac) v hidrološkem modelu prispevnega območja reke Rur je bil umerjen in na podlagi tega so bile izdelane deterministične hidrološke napovedi. Zaradi znatnih razlik med opazovanimi in simuliranimi pretoki rek Niers in Swalm ni bilo mogoče detajlno umeriti hidroloških modelov za prispevni območji teh dveh rek. Najverjetnejši vzroki za ugotovljena razhajanja med merjenimi in modeliranimi pretoki so velike količine odvzete vode za različne rabe ter izvaje regulacijskih in vzdrževalnih del v strugi reke Niers. Zato so bile hidrološke napovedi izdelane za prispevno območje reke Rur z združeno uporabo modelov wflow in Delft-FEWS. Hidrološke napoved, ustvarjena z uporabo nabora vhodnih hidrometeoroloških podatkov iz baze DWD ICON, so se izkazale kot precej nenatančne. Navkljub slabšim rezultatom simulacij je bil model sposoben za poplavni dogodek, ki se je zgodil leta 2021, napovedal visokovodne razmere 6 dni pred dejanskim pojavom poplavnega dogodka. Simulirane vrednosti pretoka so bile precenjene predvsem v spodnjem delu prispevnega območja reke Rur. Na koncu smo analizirali tudi občutljivost hidroloških napovedi na spremenjene vrednosti parametra KsatHorFraca. Izsledki študije nakazujejo možnosti izboljšav pri hidrološkem modeliranju z uporabo programa wflow in napovedovanju poplav hudourniških pritokov reke Meuse. Nadaljnje študije, ki temeljijo na naših ugotovitvah, bi lahko zagotovile natančnejšo napoved poplav v obravnavani regiji.

• Keywords: gradbeništvo, magistrska dela, VOI, hudourniške poplave, hudourniška območja, napovedi poplavnih dogodkov, hidrološki model