In the MAP newsletter 7 the RAPHAEL (Runoff and Atmospheric Processes for flood HAzard forEcasting and controL) project was presented (Ranzi, 1997). The project’s objectives, the study areas (Lago Maggiore and Ammer watershed) and the partnership, with a significant presence of MAP groups were summarised there. Since then this partially EU-funded project officially started and in February 1999 the first year of activity was completed. Coupled hydro- meteorological models are being tested to improve flood forecasts in complex and trans-national mountain watersheds. Four relevant flood episodes have been selected for the Ticino- Toce (TT) watershed, in the Lago Maggiore area:
TT1: 22.09 - 25.09 1993 Brig,
TT2: 11.10 - 14.10 1993,
TT3: 03.11 - 06.11 1994 Piedmont,
TT4: 27.06 - 30.06 1997,
and three in the Ammer watershed area, in the Bavarian Alps, with a small upper part in Austria:
A1: 16.07 - 20.07 1993,
A2: 27.08 - 30.08 1995,
A3: 17.07 - 20.07 1997.
Two of the Lago Maggiore events (TT1 and TT3) are well known in the MAP context, and within RAPHAEL relevant additional information have been collected: physiogeographic, hydrological (streamflow and reservoir levels) and meteorological data that are not distributed by the standard operational networks of hydrometeorological monitoring services are now available. For example in Fig. the 24 hours accumulated precipitation over the Lago Maggiore area during September 24 1993, computed on the basis of 120 raingauge data, provides some indications on the effect orography plays in the precipitation enhancement. The local precipitation maxima are close to steep mountain barriers, indeed. Altitude only, however, is not able to explain the spatial variability of data, as is shown in Fig. 2
Unfortunately, until now, the data providers have posed strict limitations to the data distribution and efforts are now being taken by the project s partners to have the authorisation for the data distribution, outside the project also. As soon as this problem will be solved, a link between the RAPHAEL and the MAP web site will be established and instructions for getting the authorised data will be accessible from there. In the next months the MAP community is deeply involved in the preparation of the MAP-SOP. Since the Lago Maggiore MAP target area includes one of the Raphael target areas the information collected during the project could be of some help for the preparation of the experiments and for the interpretation of their results.
Figure 1. Daily (24 September 1993) precipitation for the TT1 (Brig) event. The white
squares represent the position of the surface meteorological stations in the Ticino-Toce
area. Only for a few of them precipitation data have not been collected within the Raphael
project. The white line represents the Ticino at Mio-rina (6599km 2 ) watershed boundary.
Meteorological fields for some of the seven events have been simulated by the SM, BOLAM, MC2 and the NH meteorological models. Hydrological models are using the simulated precipitation fields as well as raingauge and radar data as input for modelling rainfall-runoff processes. The preliminary results are promising. For example, a test event was created using 120h of data obtained from output of sample runs of MC2 (Benoit at al. 1997) for the Brig case. The 72h accumulated precipitation terminates on September 25, 1993 1800 UTC; the MC2 mesh used was 10km and re-initialisation occurs every 24h (i.e. 3 independent 30h runs have been spliced together, with removal of initial periods). The streamflow hydrographic simulated using the WATFLOOD (Kouwen et al., 1996) model forced by the MC2 precipitation simulation was then compared to the measured values (Fig. ) at the stream gauge at Candoglia, above Mergozzo (Longitude: 08°25’19" Latitude: 45°58’27"). Additional events will be modelled in the future. At the same streamgauge station encouraging results have been provided by coupling, for instance, the BOLAM (Buzzi et al., 1994) meteorological model with the hydrological flood model developed by the team of the Polytecnico di Milano.
Figure 2. Altitudinal variability of the daily precipitation from 22 September 08
through 23 September 08 UTC and from 23 September 08 through 24 September 08 UTC 1993
(Brig case) in the Ticino Toce area.
Another interesting aspect that is resulting from the first projects activities is the problem of the standardisation of, for instance, land-use and soil classification in different European countries. For instance the land use as derived from satellite-based classification in the Italian, south-westerly part of the Ticino-Toce area marks a contrast with the Swiss land-use data derived from the Arealstatistik data base. A similar result, although not so evident, is shown by the soil permeability map processed with the contribution of the University of Munich on the basis of field and laboratory measurements and existing maps prepared by the ETH and the University of Brescia.
So, a question arises: should we expect different hydrological responses in the Italian and Swiss catchments due to different surface properties or due to differences in the classification systems? These and other problems are addressed when dealing with transnational watersheds as those selected within RAPHAEL. The collaborative participation of six end-users is giving us the feeling that our research might be really useful, some day, both for science and applications: if this will not be the case, we can still say that we have tried to do our best to reach this objective!
Figure 3. Simulated streamflow at the stream gauge at Candoglia (above Mergozzo in the
Toce valley) from WATFLOOD using test event.
Benoit, R., M. Desgagné, P. Pellerin, S. Pellerin, S. Desjardins and Y. Chartier, 1997: The Canadian MC2: a semi-Lagrangian, semi-implicit wide-band atmospheric model suited for fine-scale process studies and simulation. Mon. Wea. Rev., 125, 2382-2415.
Buzzi, A., M. Fantini, P. Malguzzi and F. Nerozzi, 1994: Validation of a limited area model in cases of Mediterranean cyclogenesis: surface fields and precipitation scores. Meteorol. Atmos. Phys., 53, 137- 153.
Kouwen, N., F. Seglenieks, E.D. Soulis, R. Benoit, J. Mailhot, P. Pellerin, V. Lee, M. Danard, and W.C. Chin, 1996: Modelling Large Watersheds with Numerical Weather Data. Scientific Meeting of the Canadian Geophysical Meeting, Banff, Alberta, May 5-9, 1996. Abstract No. 26.
Ranzi, R., 1997: The RAPHAEL Project. MAP Newsletters, edited by G. Mayr and S. Bader, Innsbruck, 7, pp. 9-11.
