All. 3 del disciplinare

		     Consiglio Nazionale delle Ricerche

		             PROGRAMMA SHORT – TERM  MOBILITY – ANNO 2008

Proponente:			
Prof. Lucio Ubertini	

Fruitore:
Prof. Muthiah Perumal	

Istituto di afferenza:
Indian Institute of Technology Roorkee Dept. of Hydrology	

Istituzione ospitante: 
Istituto di Ricerca per la Protezione Idrogeologica (CNR-IRPI)  	

Dipartimento: numero di codice

1	

Titolo del programma:
Improved  real-time flood forecasting models using simplified routing methods	

Obiettivi (3-4 righe)
To apply simplified routing methods for flood forecasting purposes along river channels, 	
located in Upper-Middle Tiber river basin, by assimilating hydrometric data in real-time.	

Attività da svolgere (max 10 righe)
To investigate the capability of the variable parameter routing methods, especially the variable 	
parameter Muskingum methods and the multilinear models for replacing the traditional routing	
methods based on linear theory as used in the currently available real-time flood forecasting	
methods. The success of such investigation will enable the introduction of improved flood	
 forecasting methods which are efficient and less cumbersome for field use.	

Descrizione del progetto (2000 – 4000 battute)
Real-time forecasting of river flows is an important problem of operational hydrology. For all practical purposes flood flows are treated as one-dimensional gradually varied unsteady flows and they are governed by the Saint-Venant equations. But the operational use of the Saint-Venant equations is severely hindered by several factors such as high computational skill, requirement of large amount of river geometry data and knowledge of initial and boundary conditions under unsteady conditions (Szollosi-Nagy and Mekis, 1988). Real-time flood forecasting models need to be simple and not data intensive for quick and numerical error free estimation of flood flows. To achieve these characteristics, linear deterministic models such as the kalinin-Milyukov model have been employed as basic hydrological model in many of the operational forecasting models of large basins (WMO, 1983). The real-time use of such forecasting models based on linear theory results in significant forecasting errors which exhibit strong persistence of the error series (Szollosi-Nagy and Mekis, 1988). This characteristics of the error series clearly demonstrate that the linear hydrologic model, such as the Kalinin-Milyukov model, employed in the forecasting model is inadequate to capture the inherent variability of the flood propagation process being modeled. To overcome this deficiency, generally, the parameters of the hydrologic model are upgraded in real-time by employing algorithms such as Kalman filter for estimating the revised paprameter estimates at every forecasting time level (Szollosi-Nagy and Mekis, 1988)This process of upgrading the parameters of the hydrologic model implies the unsuitability of the linear model to model the non-linearity of the flood propagation process and suggests the use of a hydrologic model that is capable of modeling the nonlinearity of the hydrological process being modeled, though in a less cumbersome manner.
Recently this researcher has studied independently (Perumal, 1992, 1994a, 1994b, 1994c), along with other researchers (Perumal and Ranga Raju, 1998a, 1998b, 1999; Perumal et al., 2001; Perumal and Sahoo, 2007; Perumal and Sahoo, 2008) and with the researchers of CNR-IRPI, Perugia ( Perumal et al., 2007a; Perumal et al., 2007b; Perumal et al., 2008a; Perumal et al., 2008b; Perumal et al., 2008c) a number of simplified models which are derived from the Saint-Venant equations and capable of varying the model parameters in a physically based manner by linking the parameters with channel and flow characteristics. The above studies have clearly demonstrated the capabilities of these models to handle the nonlinearity of the routing process in a more efficient manner than the currently used simplified models such as the Kalinin-Milyukov method widely used in eastern European countries. Further the models studied by the researcher and his co-workers have been developed from theoretical considerations and their ability to route floods have been verified by simulating hypothetical floods and using the floods of a reach of Tiber River. It is argued that the use of a simplified flood routing model accounting for the nonlinear flood wave propagation characteristics is more desirable to reduce the model error in any real-time flood forecasting model instead of using a simple linear routing model that results in large error and, subsequently, minimizing this error using a cumbersome parameter updating algorithm such as the Kalman filter  (Szollosi-Nagy and Mekis, 1988)
During this researcher’s visit to CNR-IRPI, Perugia, it is proposed to initiate the investigation on the capability of the variable parameter routing methods, especially the variable parameter Muskingum methods and the multilinear models which have been studied by this researcher along with the researchers of the CNR-IRPI, Perugia, for replacing the traditional routing methods based on linear theory as used in the currently available real-time flood forecasting methods. The success of such investigation will enable the introduction of improved flood forecasting methods which are efficient and less cumbersome for field use.	
References	
Perumal, M. (1992) Multilinear Muskingum flood routing method. Journal of Hydrology. 133: 259-272.	
Perumal,M. (1994a) Hydrodynamic derivation of a variable parameter Muskingum method- Part 2: Verification. Hydrological Sciences- Journal of IAHS. 39(5): 443-458	
Perumal,M. (1994b) Hydrodynamic derivation of a variable parameter Muskingum method- Part 1:Theory and solution procedure. Hydrological Sciences-Journal of IAHS. 39(5):431-442.	
Perumal,M. (1994c) Multilinear discrete cascade model for channel routing. Journal of Hydrology. 158: 135-150 	
Perumal,M. and Ranga Raju,K.G. (1998a) Variable-parameter stage-hydrograph routing method II : Evaluation. Journal of Hydrologic Engineering, ASCE. 3(2): 115-121 	
Perumal,M.and Ranga Raju,K.G. (1998b) Variable-parameter stage-hydrograph routing method I: Theory, Journal of Hydrologic Engineering, ASCE. 3(2): 109-114 	
Perumal, M. and Ranga Raju, K.G. (1999) Approximate convection-diffusion equations. Journal of Hydrologic Engineering, ASCE. 4(2): 161-164 	
Perumal, M., O'Connell, P.E., and Ranga Raju, K.G. (2001) Field applications of a variable-parameter Muskingum method. Journal of Hydrologic Engineering, ASCE 6(3):196-207.	
Perumal, M., and Sahoo, B. (2007), Applicability criteria of the variable parameter Muskingum stage and discharge routing methods, Water Resources Research, American Geophysical Union (AGU), Vol. 43(5), W05409, doi: 10.1029/2006WR004909, 1-20.	
Perumal, M., and Sahoo, B. (2008), Volume conservation controversy of variable parameter Muskingum-Cunge method, Journal of Hydraulic Engineering, ASCE, 134(4),ISSN-0733-9429/2008/4-1.	
Perumal, M., Moramarco, T., Sahoo, B., and Barbetta, S. (2007a) A methodology for discharge estimation and rating curve development at ungauged river sites, Water Resources Research, American Geophysical Union, Vol. 43(2), W02412, doi: 10.1029/2005WR004609, 1-22.	
Perumal, M., Moramarco, T., and Melone, F. (2007b), A caution about the multilinear discrete lag-cascade model for flood routing, Journal of Hydrology, Elsevier Publications, Vol. 338, doi:10.1016/j.jhydrol.2007.02.022, 308-314.	
Perumal, M., Moramarco, T., Sahoo, B., and Barbetta, S. (2008a), Multilinear diffusion analogy model for streamflow routing, iEMSs 2008 International congress on Environmental modeling and software, Integrating Sciences and Information Technology for Environmental Assessment and Decision Making, 4th Biennial meeting of iEMSs, July, to be organized in Barcelona (submitted).	
Perumal, M., Moramarco, T., Sahoo, B., and Barbetta, S. (2008b), Rating curve development at ungauged river sites using the variable parameter Muskingum discharge hydrograph routing method (submitted to Journal of Hydrology, Elsevier publications)	
Perumal, M., Moramarco, T., Sahoo, B., and Barbetta, S. (2008c), Multilinear Muskingum stage routing method considering floodplains (submitted to Journal of Hydrologic Engineering, ASCE)	
Szollosi-Nagy, A. and Mekis, E. (1988), Comparative analysis of three recursive real-time river flow forecasting models: deterministic, stochastic, and coupled deterministic-stochastic, Stochastic Hydrology and Hydraulics, 2, 17-33.	
WMO (World Meteorological Organization) (1983), Guide to hydrological practices, Vol. 2, 4th ed., Geneva: WMO Publ. 168.	

Il Proponente
     Prof. Ing. Lucio Ubertini