The HYDRATE network of hydrometeorological observatories:

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1 The HYDRATE network of hydrometeorological observatories:. taking stock, looking ahead Marco Borga University of Padova Department of Land and Agroforest Environments

2 Outline HYDRATE-NHO: what? HYDRATE-NHO: why? HYDRATE-NHO: how? HYDRATE-NHO: some findings What worked well? Even better if Future perspectives

3 HYDRATE-NHO: What? AIM: To increase understanding of hydrometeorological processes leading to Flash Floods, by improving Flash Flood observations. Establishment of six instrumented Hydrometeorological Observatories, with focus on Flash Flood observations. FF are locally rare phenomena. We need to observe flash floods where they happens in a wide region! Observatories: instrumented (radar+hm networks) large geographical areas (about km2 area wide), sufficiently large to have a good probability of observing flash-flood events. Over HOs, operational and research observation systems are implemented to attain high space-time resolution.

4 HYDRATE-NHO: What?

5 HYDRATE-NHO: Why? Space-time scales of flash floods Space-time characters of FF-leading storms in Europe ( ) Fronts MCS Convective Radar Cell detection Rain gauge networks for monitoring floods

6 HYDRATE-NHO: How? Development of a flash flood observation methodology The principles: To benefit from the density and the quality of the radar coverage as well as from dense rain and river gauging networks in order to collect physical variables. To collect complementary information from field investigations carried out during the days following the event (hazard and vulnerability).

7 HYDRATE-NHO: How? post-event analysis - 1 Data Flood traces Witnesses accounts

8 HYDRATE-NHO: How? post-event analysis - 2 River sections survey Use of hydraulic models for peak Q estimation

9 HYDRATE-NHO: some findings Development of Spatial Moments of Catchment Rainfall to organise, scale and analyse event observations Analysis of rainfall spatial variability by using flow path as geometry: DR,n = A 1 w(u )τ (u ) n da A where: w(u ) = R(u ) A 1 R(u )da A where: R(u) = rainfall at location u A = catchment area τ = response time from location u to the catchment outlet If R is uniform and n=1, we have: D1 = A 1 τ (u )da A 29 may 2009

10 HYDRATE-NHO: some findings Development of Spatial Moments of Catchment Rainfall to organise, scale and analyse event observations Example (Sesia 2002): For this basin and storm event (statistics computed on cumulated rainfall): D1* = 1.27 D2* = 0.65 Use of statistics computed on cumulated rainfall fields, to predict the impact of averaging the space rainfall on flood modelling.

11 HYDRATE-NHO: some findings Development of Spatial Moments of Catchment Rainfall to organise, scale and analyse event observations

12 Fella (2003)

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14 Sesia (2002)

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16 Feernic (2005)

17 HYDRATE-NHO: some findings Impact of rainfall systematic spatial variability on flash flood response modelling A key question in hydrology is how spatial variability in rainfall can be represented and aggregated in flood response models. So far, attention has been focused on the random spatial variability. No attention at all on the rainfall systematic variability. Δt adimens ionale [routing ] 1 0,8 0,6 0,4 F ella 0,2 0-0,20,80 B iella02 0,90 1,00 1,10-0,4-0,6 Norma liz ed time dista nc e 1,20 1,30 S imones ti

18 HYDRATE-NHO: some findings Impact of rainfall systematic spatial variability on flash flood response modelling A key question in hydrology is how spatial variability in rainfall can be represented and aggregated in flood response models. Expected behaviour

19 HYDRATE-NHO: some findings Impact of rainfall systematic spatial variability on flash flood response modelling A key question in hydrology is how spatial variability in rainfall can be represented and aggregated in flood response models.

20 HYDRATE-NHO: What worked well? Sampling different European hydroclimatic regions Bringing together scientists from a wide range of disciplines Significant infrastructure that normally would be beyond the scope of funding for EU projects Wide access to data sources to support project The added value from ongoing findings from others working in the catchment area common to your project A real bonding between some interdisciplinary teams

21 HYDRATE-NHO: Even better if Some infrastructure was not appropriate for the projects. Some were installed assuming certain project activities. Some were installed in nonideal locations. Better design needed at the start. Some tasks were common to many activities. A small number of key start up activities would have been useful to develop the conceptual models and formulate key questions. It took a long time to fully appreciate the problems being tackled by teams in other disciplines. More time needed? The demands on the Catchment Service Teams were too great. More realistic tasks need to be set. Access to some key data was problematic during the project lifetime. A commitment to delivery is needed.

22 HYDRATE-NHO: Future perspectives HYDRATE was funded for 3 years, although it is stated These 'flagship' sites will provide the basis for long-term monitoring, needed to define natural variability and responses to flash flood in a changing environment. Attempts to secure longer term funding through EU failed. Other attempts are now being made. The European Union current programme of research funding indicates hydrological observatories as area of funding in the near future. HYDRATE and other European initiatives in this area are likely to develop partnerships. HYMEX