Saturday, March 31, 2012

Judea Pearl Won the Turing Prize

I came to across Judea Pearl book: Causality: models, reasoning and inference in the search for understanding the subtleties of the Bayesian approach to statistics (and statistics in general).  I am  still  studying, and trying hard to understand how his findings can improve my approach to research in Hydrology.   I think that this Turing Prize he got was well deserved, and I did this post  for others to join the list of admirers of his work.

 In his site, videos, tutorial and other good food for thinking, and  "Causal Inference in Statistics: An Overview", Statistics Surveys 3 (2009): 96--146 [Free PDF], a must read for whom interested.^1

^1 For who captured by his work, it could be interesting to give a look to the TETRAD Project.

Wednesday, March 28, 2012

Modelling catchment-scale shallow landslide occurrence by means of a subsurface flow path connectivity index

This paper extends the concept already introduced in  two previous papers on Hydrological Processes  and Earth Surface Processes and landforms. The idea pursued in the first was that hillslope processes can be conceptualized in order to obtain a topographic index useful for a simple hydrological modelisation of hillslopes. The second paper investigates the role of soil depth and push further the conceptualization, besides introducing some concept of self-organization in the production of instabilities. 

This third paper in row applies the theory above to a case in North of Italy, and tries finally to fill the gap between hillslope modeling and catchment analysis. The paper also introduces the concept of catchment connectivity, which is usually given for granted but it is, indeed, not always present, and build on previou work by Jeff McDonnell and collaborators and Stuart Lane.  Finally the paper investigates the hillslope stability of the basins above.

The model described, CISLAM is available as an OMS component here

Monday, March 26, 2012

Michi Lehning: Snow hot and cold, dangerous and beautiful, fragile and persistent

Michi Lehning is one of the leading scientists in  snow and avalanches, and related boundary layer meteorology, research.

He is co-author of  three very good pieces of software:
and several papers on the topics he is expert. Recently he worked on the uneven distribution of snow during storms that is very enlightening.  The last March 15, besides being hed of a group at WLSF (here his many projects),  he also became professor at EPFL-ENAC School.
I am writing this to advertise that  his opening lecture at EPFL can be watched and dowloaded here.

Wednesday, March 21, 2012

Open Topography

The site

hosts free LIDAR data, and tools contained in OpenTopography for their treatment. Data are usually provided in form of points clouds that can be subsequently treated with their tools to obtain DEMs, and in already treated DEMs. They also provide a ciberinfrastructure for the storage and delivery of those data that can be of interest for those who wants to manage professionally a data storage service.
Woth to note is that you can use the jgrasstools for manage them.

Thursday, March 15, 2012

Power Laws

Many non linear phenomena where shown to obey a power law. However, this paper shows that we could have inferred them improperly. The paper, I realize, is quite famous, since it gained over than 1000 citations according to Google Scholar (but I did not know it). ...

I gave it a look and it is actually very interesting. In fact, my good all power laws (e.g. Rigon et al.,  1996; Maritan et al., 1996; Rinaldo et al., 1998; Convertino et al., 2007) were a little different, since my exponents were all less than 1 (not greater than 1, as those treated in the paper): but I think that most of the result can be appropriately adapted.  There are also these weblog pages where there are further comments and a lot of information (maybe too much ?) by one of the authors.
For general information about statistics give a look here.

Snow Maps from GEOtop

Arpa Veneto (ARPAV), and Mountaineering s.r.l. a company founded by some of my former students have started an innovative service where our model GEOtop is used together with MeteoIO to produce snow maps.  Precisely maps of snow water equivalent, and snow height, at any the desired time step.  The overall product was named SnowMaps.

ARPAV provides the forcing hydrometeorological data, and  Mountain-eering  performs the simulations and produces the maps. In this first phase of the project maps are given any fifteen days. Only the last maps produced are available on-line, while older data can be requested from the Centro Valanghe di Arabba. Other institutions offer this kind service in the world, however, to our knowledge, if the first time that the product is given on a basis of a physical model.

The maps of snow height cover:
  • The whole Veneto
  • Comelico-Val d’Ansiei
  • Ampezzo
  • Cadore
  • Agordino-Zoldano
  • Alpago 
  • Prealpi bellunesi
  • Prealpi vicentine
  • Prealpi veronesi
and can be found here (click on vai alla mappa for the latest maps).  Reference in Eblish on GEOtop 2.0 used for these maps can be found in another post, or, in Italian, here.

The resolution of the maps is 250 meters.

Wednesday, March 14, 2012

A Science Initiative of the International Association of Hydrological Sciences

As you may know, the Prediction in Ungauged Basins (PUB) decade of the International Association of Hydrological Sciences (IAHS)is ending in 2012. After the success of PUB, IAHS is stimulating a public discussion to identify an appealing subject for a new science initiative for the decade 2013-2022.

A Task Force has been nominated to organize and moderate the above discussion, that is taking place in a public blog, at the internet address The blog already received several visits and comments, and a first summary of the discussion has been recently published.
Alberto Montanari invites everyone to contribute.

Saturday, March 10, 2012

A few historic papers on geomorphology from the Bill Dietrich collection

I did my Ph.D. on landscape evolution models, and at that time I collected, among other stuff, the papers that Bill Dietrich was used to distribute for reading to his students. Here the list of the historic (before 1980) papers in that group.

Gilbert, G.K., Report on the geology of the Henry Mountains (Utah): US Geographical an Geological, Survey of the Rocky Mountains Region, Washington D.C., 1877

Gilbert, G.K., The convexity of hilltops, Journal of Geology, 17(4), 344-350, 1909

Davis, W.M., The convex profile of badlands divides, Science, 20: 245, 1892

Horton, R. E. Erosional development of streams, and their drainage basins: hydrophysical approach to quantitative morphology, Bulletin of the Geological Society of America, 56: 275-370, 1945

Penck W., Morphological Analysis of landforms, London Macmillan, 1953

King, L.C., The uniformitarian nature of hillslopes, Trans. Edimburgh Geological Society, 17: 81-102, 1957

Culling, W.E.H. Analytical theory of erosion, Journal of Geology 68, 336-344, 1960

Hack, J.T., Interpretation of erosional topography in humid temperate regions, American Journal of Science, 258A: 80-97, 1960

Anhert, F.,  The role of the equilibrium concept in the interpretation of landforms of fluvial erosion and deposition, L'Evolution des Versants. Liege. Universite' de Liege, 23-14, 1967

Kirkby, M.J., Hillslope process-response models based on the continuity equation, Inst. British Geographers. Spec. Publ., 3:15-30, 1971

Smith, T.R., and F.P Bretherton, Stability and the conservation of Mass in Drainage Basin Evolution, Water Resources Research, 8(6): 1506-1529, 1972

For the longer series by Mike Kirkby look here.

A question a day ... about infiltration

One of my colleagues asked this morning the following:  I would like to insert in my model a module for infiltration and redistribution of water in soil. I obviously was thinking to a simple solution. For instance inspired by the paper by Iverson (2000) on which you work times ago. What do you suggest ?

My 2 C:

among the simplest solution I would use the Philip's one, or just a little more complicate, the analytical solution from D'Odorico et al., 2003. That solution derives from a linearization, and in the case you use variable precipitations, you must convolve the kernel solution with them, as indicated in the paper (the same as in the IUH). 

Increasing the complexity of what you could do, next step would be to numerically solve the Richards 1-D equation, and integrate this solution with a simple solution of the water table movement. For a rigorous derivation see the paper Cordano and Rigon, 2008. The model TRIGRS uses more or less this strategy. 
With Emanuele Cordano I also implemented a model for solving the Boussinesq equation with a rigorous and fast method. This could be a solution for the water table movements after infiltration, if you are not satisfied with steady state solutions ( This last one does not have yet a module for infiltration.

Other would suggest to use Green-Ampt solutions: but I do not see any advantage to use it with respect with the above ones. Perhaps some gain in speed but certainly no gain in clarity. Obviously the simpler the solution, more the parameters must be considered variables to be calibrated ex-post. The assumptions on which they (the parameters) are assumed constant are, in fact,  not really supported by reality, and made for being able to use analytical solutions. 

P.S. - Many in the past (And in the present) use the Curve Number or SCS method. This is a case of pure mimesis of the behavior of infiltration. However, when calibrated, and in certain conditions, the method "works". I hate solutions that just work, but this in particular works, in my opinion for two  reasons: someway it accounts for soil cover (when we usually say infiltration, in reality we have the coupling of interception,   through-flow and,  eventually, infiltration), and, besides, the introduction of an initial abstraction accounts for the fact that the lateral flow is triggered only when there is a little of water table over the bedrock  (, and

Tuesday, March 6, 2012

Hydraulic Constructions (Again another class I teach)

I finally decide to upload here also the material of my class of Hydraulic Construction. Is a little off-topic here but I realized that that was the simplest way for me to communicate and upload the work to my students. For who is interested, the course deals mainly with urban hydrology (sewer systems, culverts design and so on) and urban water supply. I apologize with the other readers, I promise that I will not pollute more the blog with other post of this kind, and now switch to Italian.

Per il materiale di costruzioni idrauliche gli studenti del primo anno della laurea magistrale facciano riferimento a questo sito. Le slides saranno caricate su SlideShare e disponibili a tutti (anche ad altri studenti) ma richiede di creare un account per il download. Come accade per tutte le cose che faccio, esse sono il prodotto del mio sforzo particolare ma anche di cose che ho "rubato" a colleghi vari. Spero di essere riuscito a dare ad ognuno i crediti che gli spettano. Ma nel caso qualcuno si sentisse non rappresentato adeguatamente, me lo faccia sapere e concorderemo le modalità perchè abbia pieno riconoscimento.

Qui di seguito i link al materiale

1 - Introduzione al Corso
2 - Introduzione alle Costruzioni Idrauliche e alle opere pubbliche
3-  Fognature Pluviali
4 - Acquedotti
5 - Fognature Nere
Postfazione al corso del 2012

Arrivato in fondo, mi rendo conto che avrei potuto fare alcune cose meglio. Questo è ovviamente sempre possibile. L'anno prossimo mi auguro sarà pronto e definitivo il lavoro di importazione di Trento_p e di Epanet all'interno di uDig e quindi il corso si modificherà di conseguenza (e dovremo completare la documentazione). Sarà una bella innovazione e un bel traguardo (per chi osa i programmi sono già oggi disponibili al sito dei Jgrasstools). A ben guardare non ho affrontato due temi importanti della ricerca acquedottistica: mi sono limitato ad introdurre la verifica delle reti "demand driven", mentre avrei potuto parlare anche delle verifiche "pressure driven". Inoltre non ho parlato della ricerca perdite, altro argomento di grande attualità. Questo per quanto riguarda gli acquedotti. Per quanto riguarda le fognature, certamente si sarebbe potuto parlare  degli scaricatori di piena, delle vasche di prima pioggia e di un utilizzo e complessivo della rete per la gestione in tempo reale della rete pluviale. Ma tutto non si può fare ... e questa è solo la prima parte perchè gli stessi studenti seguiranno un secondo corso in cui affronteranno più direttamente le problematiche della progettazione!
Per chi avesse avuto la pazienza di guardarsi il materiale, e soprattutto agli studenti: ogni suggerimento costruttivo è bene accetto.
Postfazione al corso 2013
Non avrei che da ripetere alcune delle cose dette lo scorso anno. Tuttavia, quest'anno siamo riusciti ad usare i Nettools. Immagino che il lavoro sia stato faticoso per gli studenti (ma anche per i docenti!) e sono certo che ci sarebbe voluto piu' tempo. Un ringraziamento va a Bilal senza il quale questo non sarebbe stato possibile (sia pure passando attraverso il lavoro di molti altri). Mi conforta l'esito della prova in itinere, che sembrerebbe dimostrare che piu' o meno (quasi) tutti hanno recepito le cose fondamentali, con una buona percentuale che ha compreso le cose ottimamente. Per me e' la migliore soddisfazione.
Postfazione al corso 2014

Quest'anno, aggiunti gli audio delle lezioni, ho la sensazione che il materiale sia giunto a maturità. Nello stesso tempo, ciò impone il cambiamento e il raffinamento di varie parti che sento di non aver sostenuto all'altezza. Con l'aiuto di Bilal e di Marialaura Bancheri abbiamo cercato di rendere più accurate le verifiche e di incentrarle molto di più sul fare. Una strada faticosa, ma che intendo proseguire e strutturare meglio anche il prossimo anno.
Voti Costruzioni Idrauliche 2016

Qui i risultati del compito in itinere. Se voleste vedere i compitini (o per qualsiasi altro motivo inerente al compito) contattatemi.
* - Qui trovate le slides su Trento_p (rivedute e corrette) preparate da Bilal.
** - Qui scaricate i voti della prima esercitazione e della prova scritta 2012
** - E qui quelli della prova scritta del 2013
*** - il 19 Giugno, la mattina  Bilal Adem Ismail riceve gli studenti.  L'aula sara' stabilita la mattina stessa.

^0  - Domande del test intermedio 2016

^1 - Sul sito di R si trovano varie risorse per imparare ad usare R. Un gruppo italiano di utenti di R è Rante e li' vi si trova anche un manuale introduttivo ad R.  Qui si trova una miscellanea di contributi in inglese.   I contributi ad R si susseguono così velocemente che ogni giorno ce ne sono di migliori. Quindi tenete d'occhio il web.

^1b - Qui il file SintesiPaperopoli

^2 - Trovate al link il file delle portate 1990-2005.txt  e il file della Pluviometria di Paperopoli (Unix/Mac o  MS-Windows) utilizzati a lezione.

^3 - I file relativi alla esercitazione in aula con Epanet. Qui.
Scripts di R usati a lezione

- Lezione 17-04-2013 (script) e (notebook)
- Gli script di R per calcolare le curve di possibilità pluviometrica di Paperopoli (scripts) sino al disegno delle curve
Esempi di relazione e materiale correlato

Una relazione sulle curve di possibilità pluviometrica
- Di Aaron Iemma (qui): in realtà bastava citare la teoria statistica, ma Aaron ha voluto essere qui un pò scholar. Buona anche perchè Aaron ha fornito una serie di script per riprodurre tutto quanto ha fatto, mutata mutandis (qui gli script).

Sunday, March 4, 2012

Challenges and Opportunities for the Hydrological Sciences

From Anne Jefferson blog:

"The “blue book” has been updated and you can read and download a pre-publication PDF on the National Academies’ website for free. I’ve just been listening to a CUAHSI webinar summarizing the report, and I was please to see that a lot of the questions I’m interested in were highlighted by the committee that updated the report. For instance, there was specific mention of urban hydrology (and how changes to flowpaths and quantity alter water quality), the co-evolution of hydrology, landscapes, and life, and the need to understand the controls on the low flow extent of streams. I’ll be reading sections of this report in coming months, and if you want to get a sense of the state of hydrologic science, you would probably do well to start here too"

I will probably join Anne's efforts in reading the report.