Large-Scale Hydrological and Sediment Modeling in Nested Domains under Current and Changing Climate

SMHI investigated how well can large scale models predict runoff and sediment concentrations in a recent scientific publication. The comparison of historical simulations for three nested model domains (global, continental, and national) found that simulated sediment concentrations varied considerably among the nested models in spatial patterns, whereas runoff values were more similar. For indicators of future change, variables that were calibrated directly provided more consistent message than those derived from other model outputs. These results are important for DIRT-X applications as the cross-scale analyses give a better understanding and quantification of impacts and uncertainties in climate impact assessments.

Read more: https://ascelibrary.org/doi/10.1061/%28ASCE%29HE.1943-5584.0002078

Global distribution of sediment concentrations from WW-HYPE
Figure 2. Global distribution of sediment concentrations partly follows the distribution of runoff at a first look. However, closer examination shows low sediment concentrations present in areas of both low and medium runoff (e.g., northern Europe and Asia).

 

Modelling Workshop

The modelling workshop was organized by the Leibniz Universität Hannover (LUH) and gathered around 11 research partners during one and a half day of joint work. It was held 28-29 September online via Zoom. 

The main purpose was to identify the interfaces among models that constitute the modelling chain of each study case: Banja, Gepatsch and Orust/Tjörn. Moreover, a special emphasis was given to the potential output variables produced by each model, which serve as input variables for the subsequent model in the chain.

This allowed us to understand the actions needed to study the propagation of uncertainties from selected model parameters (Task 2.2 ”Targeted model experiments”) through the modelling chain. Although the final uncertainty analysis will be carried out by LUH, the active participation of all involved modellers helped to understand uncertainties in the modelling chain. The final results will be published in D2.1 ” Report on uncertainty in climate impact models”.

Example of the Banja modelling chain and involved variables.

Excursion to the Gepatsch Reservoir

In the beginning of September, seven members of the project group visited the Gepatsch Reservoir Study area in the Upper Kaunertal Valley in Tyrol, Austria. The two-day excursion offered insights into the location, topography and landcover of the study area as well as the operating principle of the reservoir and its diversions. 

During those two days, in total three different water intakes were visited: the Verpeil intake (right), the Pitzbach intake (below left) and the Taschachbach (below right). 

1) At the Verpeil intake, which is a part of the diversion “Kaunertal East”, the working principle of the intake setup was explained.
pic2_flushing_pitzbach_kschneider_website
2) At the Pitzbach intake, the group watched the flushing of the sediment from the desilting chamber to the riverbed, after probing the amount of bedload trapped in the desilting chamber.
pic3_arch_dam_sschwindt
3) The Taschachbach intake differs from the others: instead of the Tyrolean Weir and the desilting chamber, the coarse sediment is trapped in a basin behind an arch dam.

The first stop at the reservoir was the gate valve tunnel, before we went up to the lake (below, left). After a short stroll over the dam crest, were we could enjoy the view over the reservoir to the glaciers, we went below ground again. The exploration tunnel on the western side of the reservoir partly collapsed some years ago, due to a slow downward movement in the slope above. This sliding movement of the mountain is permanently observed with extensometers installed to the tunnel wall (below, right), in order to detect any accelerations in the sliding process and eventually prevent the initiation of a landslide.

Our next stop took us to the measurement stations of Gepatsch Alm and Weissee (below, left), before we went up to the glaciers, chasing the last sunrays. Overlooking the remaining ice masses and the surrounding mountain slopes we could clearly see the consequences of climate change. Snowless areas and foil covered patches of snow bear witness of the glacier retreat and melting permafrost (below, right). The now uncovered rock faces and fields of loose scree gave us an impression of the sediment amounts which will inevitably be transported to the reservoir in the next decades. This moment demonstrated again the importance of our project and the need for an adapted management strategy based on profound research outcomes.

Many thanks go out to Dr. Johannes Schöber and Franz Eiter from the TIWAG, for taking their time to show us around and providing us with helpful information.

the measurement stations of Gepatsch Alm and Weissee.
Snowless areas and foil covered patches of snow on the glacier

Online Dirt-X General Assembly

The DIRT-X General Assembly was held online, 17-18th June 2020.

The project partners gave an overview of the progress in different activities during the first project year, found synergies in the case studies, planned upcoming work in climate impact evaluations, and discussed new knowledge and scientific discoveries made in the project so far.

The highlights from the meeting were:

  • Research into hydrological modelling, sedimentation, bed load and coastal zone processes in the case studies has begun and the most suitable approach for each study depends strongly on the quality of the input data. The intensity of heavy rainfall events, which cause soil erosion to a high degree, cannot, but must be represented in precipitation data with accurate spatio-temporal resolution.
  • Bias adjustment of climate data to local conditions is mostly completed. The case studies should be able to test the impact of changing climate by the end of the year
  • E-HYPE, SMHI’s large scale hydrological model was linked to UU’s energy model. The model is being refined to better represent erosion and sediment transport processes at the continental scale. The calibration of the global sediment model was completed soon after the GA.
  • The European power system model has been set up and configured (based on an overview of basic socio-economic assumptions per SSP narrative at MS level, considered implication of future land use and sectoral water withdrawal &consumption at grid cell level).

This was also the first time the project partners met with the newly established DIRT-X project Advisory Board and received feedback from external experts represented on the Board.

Participants online at the Dirt-X General Assembly in June, 2020

A short quiz on the project case studies, and a virtual tour around Europe to visit various ‘favourite reservoirs’ of project members were held to enjoy some social time with everyone.

For more information on the DIRT-X project description, visit  https://dirtx-reservoirs4future.eu/project-description/

DIRT-X Kick-Off

Team photo

Across Europe, there are thousands of larger and smaller water reservoirs with an important role for drinking water supply, hydropower, environment, and recreation. In a new project lead by SMHI, researchers are going to look into the impact on the water reservoirs from climate change and changing socioeconomic conditions.

At the end of September (30 September – 1 October 2019) , 18 researchers from five countries met in SMHI in Norrköping to start and coordinate the project.

Read more in this article.