Thursday, April 28, 2022

Resolving the water budget of a complex carbonate basin in Central Italy with parsimonious modelling solutions

Placed at the center of the Mediterranean, the Apennines chains provide a critical water supply for people living in the Italian Peninsula. Yet, the quantification of water resources in this region is challenging given that the different components of the water cycles (i.e., snowmelt, evapotranspiration, and subsurface water recharge) are highly variable in space and time due to the specificity of the climate, the reforestation trend, and the complex landscapes and geology. In this study, we investigated the challenging hydrological river regime of a complex carbonate basin with significant external (and partially karst) groundwater contribution – the Upper Nera basin – affected by recent important seismic sequences.

When dealing with such type of basins, the generic approach to delineate the basin boundaries based on the geomorphology of the area can lead to questionable results potentially yielding significant water budget imbalances. Therefore, both (hydro)geological and hydrological features have to be considered for understanding the challenging hydrological behavior of these basins.Here we proposed a specific analysis of precipitation-runoff time series corroborated with hydro-geological survey to obtain information on basin response time and the true contribution area of the basin. We applied the extreme versatility of the
GEOframe-NewAge modeling system to simulate the significant fraction of external groundwater contribution by embodying hydrogeological information of the area obtained by surveys and the hydrological analysis in a conceptual reservoir approach. We validated the model against in situ discharge observations and with remote sensing information of evapotranspiration and snow.
We show that the model (tested with several hydrological signatures and a new conceptual evaluation based on an empiric probability function) performs relatively well in reproducing the different water balance components and that the upper river basin is significantly impacted carbonate rock river discharge (i.e., up to 85% in proportion to the total discharge for some stations) coming from outside the geomorphological boundary of the basin. Yet, the groundwater recharge effects on the river, gradually attenuates at the outlet of the basin (Visso station)You can access the preprint by clicking on the Figure above.

Tuesday, April 26, 2022

DARTHs 4 Bern (A seminar)

So what are DARTHs ? I provided various material that starts from:

I provide here the slides as pdf by clicking on the image above. Bern University gave me the occasion to trying a further summary in a presentation which is on my VIMEO channel here

Monday, April 11, 2022

Snow droUghts predictioN in the Alps: a changing climate assessmEnT: SUNSET PRIN Project

Reduced mountain snowpack, i.e. a “snow drought”, due to rising temperatures or changes in precipitation amount has critical implications on water resources availability. Ongoing climate change may influence the frequency and severity of snow droughts. SUNSET aims to develop an integrated methodology to assess the impact of climatic variations and changes on snow droughts and on the seasonal low flows in the Italian Alps. To meet this objective, SUNSET develops based on two main scientific advances. The first advance are the Convection-Permitting Models (CPM) for climate simulations, with improved topographical features, physical representation of mountain‐precipitation interactions, and avoided errors from convective parameterizations. A second recent advance is the availability of improved multi-objective calibration strategies for hydrological-snowpack models which permit reliable simulations of both snow pack evolution and runoff variability. With SUNSET, a modelling chain linking bias-corrected Convective Precipitation Modelling (CPM) and Regional Climate Models (RCM) outputs as well as state-of-the art hydrological models will be developed and exploited to quantify changes in the frequency and severity of snow droughts through the end of the current century. The project focuses on two broad study areas in the Western and Eastern Italian Alps, where a set of catchments with detailed process observations are available.

SUNSET is based on two types of data: i) 20-to-30 years time series of validated catchment precipitation-temperature-discharge data from the network of twelve project study basins; ii) process data, collected in previous projects which will help improving the hydrological model validation. The past dataset includes observations from MODIS and Sentinel-1 that are functional to provide correct snow cover areas and snow water equivalent data.

Climate simulations will be based on 12-member CPM and RCM ensembles from the FPS-CORDEX project available for 3 time slices (historical, 1996-2005; near future, 2041-2050; far future, 2090-2099) for the extreme climate change scenario, i.e. RCP8.5. RCM outputs from CORDEX will also be considered to evaluate the added value of CPM compared to coarser resolution models and to investigate the climate change signal under different scenarios which are not available in CMP simulations, i.e. RCP4.5 (six-member RCM ensembles) versus RCP8.5 (six-member RCM ensembles. Hydrological models are part of an expandable system called GEOframe developed along the last 15 years and have already a setup for most of the study basin network.

SUNSET will communicate and disseminate the project results to a wide audience of residents in the two study areas and beyond through collaborations with Local Authorities. SUNSET will test, archive, document, and keep track of versions of the research code and software using open-source software and data protocols and accessible documentation.

By clicking on the above Figure you can access the full proposal. 
Finally we've got the project!