Large-scale uncertainty in river water levels for flood defence reliability

Type
PhD research

Duration
2017-2021

Persons involved
Matthijs R. A. Gensen, MSc. (PhD candidate)
Prof. dr. Suzanne J.M.H. Hulscher (Promoter)
Dr. Jord J. Warmink (Daily supervisor)

Funding of the project
NWO – STW

Summary of the research
This PhD project focusses on the modelling of water level uncertainty in river systems. Water levels determine the main dynamic load on the 1430 km river dikes. In January 2017, the new risk-based flood protection policy was adopted by the Dutch government. This policy implies that flood defence safety no longer depends on a single water level. Instead, the full range of possible water levels now control flood defence safety. This requires new insight in the probability of occurrence of water levels in the Dutch rivers. Large-scale river interventions have been carried out, but their hydraulic effects were studied only deterministically, in spite of inherent uncertainty. This uncertainty is dominated by the discharge distribution over the river branches at bifurcation points, which is in turn influenced by regulation structures, large-scale roughness of river branches due to bed form dynamics and river interventions. Knowledge of their effects on water levels is essential in future planning of river interventions for flood defence reliability.

The goal of this project is to quantify and reduce the water level uncertainty for the large-scale cumulative effects of interventions for a range of water levels to support more accurate and robust dike designs and improved management strategies for the river system. In this project, an idealized model based on the Rhine dimensions is setup to simulate the uncertainty in the discharge distribution over the branches. Uncertainty analysis methods are applied to quantify and propagate the main uncertainty sources to the water levels. This project focusses on the combined effect of natural processes and large-scale river interventions to improve river maintenance strategies.

This project is part of the All-Risk program: “Implementation of new risk standards in the Dutch flood protection program”. This program investigates flood risk and how measures such as flood defences can reduce this risk. The All-Risk program is a collaboration of of various universities (UT, TUD, RU, UU and WU), research institutes (NIOZ and Unesco-IHE) and a wide variety of users.

Keywords 
River modelling, uncertainty analysis, flood regulation structures, bed form roughness, river interventions, river management.

Other stakeholders
Stichting Toegepast Onderzoek Waterbeheer
Rijkswaterstaat
Deltares
HKV – Lijn in water
Natuurmonumenten
It Fryske Gea
Waterboard Vechtstromen
Waterboard Noorderzijlvest

More information
Matthijs Gensen 
Room Horst W202
Tel. +31 53 489 7881 
E-mail m.r.a.gensen@utwente.nl