Floods pose a costly threat to Norwegian society and climate change makes it likely that damage costs due to flooding will escalate in the near future. The duration of such flood events is of particular interest: a flood spread over, for example, three days instead of one can have a very different impact on society and ecology.
Understanding temporal scaling in floods—that is, the relationship between floods of different durations—is an important aspect of gauging flood risk on a regional level and is a topic that is undertreated in the literature.
Evidence suggests that in Norway, the statistical characteristics of floods vary across a temporal scale for some catchments but not others (see Figure 1). This master's thesis would provide hydrological reasoning for this discrepancy by comparing catchment properties to both collected data and model output.
The thesis will use a combination of hydrological and meteorological data as well as model output. Hydrological data is publicly available from NVE and meteorological data is publicly available from the SeNorge data product hosted by MET Norge.
Pre-existing rainfall-runoff models will be used as a hydrological model.
Proposed tasks:
- Extract time series of rainfall and snowmelt from SeNorge.
- Compile a dataset of observations of streamflow as well as modeled streamflow.
- Perform scaling analysis of the annual maximum flood and rainfall and snowmelt datasets by looking at ratios of appropriate summary statistics, such as in Figure (1).
- Use a hydrological model as a tool to investigate how model parameters affect scaling properties.
Desired skills:
- Coding knowledge in either R or Python
Fig. 1 Changes in statistical properties over increasing flood duration are plotted along with the 90% confidence band for 12 gauging stations in Norway. The null model (no change in statistical properties from the instantaneous flood duration) is shown as a red dashed line. The proposed Master's project would focus on identifying hydrologic differences between catchments that match the null model quite well (f.ex. Øyungen) and catchments that clearly deviate from the null model (f.ex. Gryta). | Click here for a bigger version of the picture.
References:
- Sorteberg, A., Lawrence, D., Dyrrdal, A. V., Mayer, S., and Engeland, K. (2018). Climatic changes in short duration extreme precipitation and rapid onset flooding - implications for design values. NCCS, (1).
- Gaál, L., Szolgay, J., Kohnová, S., Parajka, J., Merz, R., Viglione, A., and Blöschl, G. (2012), Flood timescales: Understanding the interplay of climate and catchment processes through comparative hydrology, Water Resour. Res., 48, W04511, doi:10.1029/2011WR011509.