Machine Learning and Process Based Modelling

 I had the occasion to see a presentation given by Saman Razavi on this topic and I found it educative.  It can be found on YouTube and you can see it below. It contains a quick historical review and exemplify the different abilities of the two type of models. Therefore I decided to share it with you.

The example Dr. Razavi does in the projections is interesting but, wanting to reproduce it, how did he obtained the target future curve ?  Dott. Razavi also addressed to his recent paper that is the basis for the talk and where you can find further details.

References

Razavi, Saman. 2021. “Deep Learning, Explained: Fundamentals, Explainability, and Bridgeability to Process-Based Modelling.” Earth and Space Science Open Archive. Earth and Space Science Open Archive. https://doi.org/10.1002/essoar.10506045.1.

About realism in models of infiltration

The Italian Association of Agricultural Engineering is organizing a group of webinars covering the topics the Associate study and research. I could attend to the first seminar, held by Prof. Antonio Coppola (GS).

His seminar was about the realism of models in Agricultural Hydrology and some of their applications.

Under this title it is easy to find very superficial and boring stuff. Instead prof. Coppola contribution was very interesting alive and inspiring. Therefore I think is a must see for anyone who, working on the topic, understand Italian.  If you take the time to listen to it, you will not waste your time. The pdf of the slides by Professor Coppola can be found here.

Peter S. Eagleson

I learned from Twitter that Peter S. Eagleson passed away. It is impossible to list all his merits for Hydrology. The seeds of his research and teaching are pervasive in Hydrology.  

I share here what Ignacio Rodriguez-Iturbe said when Peter got his Horton Medal:

“It is indeed a great honor for me, and also a great pleasure, to present to you the 1988 recipient of the Robert E. Horton Medal, Peter S. Eagleson. Shortly after it became public that Pete was the winner of this year's medal, I commented to my wife that, although I had never given a citation for an AGU medalist, this was one I would really love to give. The reason is simple: there is no one in the world who better represents the standards of excellence that a hydrologist hopes to achieve and that hydrologists hope our discipline will attain than Peter Eagleson.

Peter S. Eagleson (on the right) and Ignacio Rodriguez-Iturbe (Princeton, 2012)

Pete did not start his research career in hydrology. In fact, his Ph.D. thesis in 1956 and his research up to 1965 were mainly in the field of sediment sorting and transport by waves on beaches. During this period he also investigated problems related to flow‐induced vibrations of plates. His research in these areas was extremely successful, producing three chapters in books and about 20 journal papers in addition to many technical reports and journal discussions. Indeed, Pete had made his mark in wave theory and sediment transport, but it was good fortune for our field that starting about 1964 his interest in hydrology overcame all his past experience and assured a reputation in the waves and sediment field, and thus he embarked on a new adventure—bringing into hydrology the scientific rigor that existed in more academically established disciplines. With his strong fluid mechanics background—he still teaches that subject to undergraduates at MIT—Pete was ideally suited to lead the field toward new problems and also toward new approaches to old problems . . . and this he did indeed! Just in 1967 he and his students published six papers, most of them in Water Resources Research, which had a strong, an almost immediate impact on the field of hydrology. Here was somebody who was tackling the modeling of overland flow with the scientific standards of fluid mechanics. At the same time, finally somebody had arrived in the field who, using techniques from signal analysis, produced criteria for the optimum density of rainfall networks. I did not know Pete at that moment, but I remember reading many times his paper on the optimum density of rainfall networks and feeling the excitement of the author's original mind at work. It is the same feeling one has when reading his 1972 classic paper on the dynamics of flood frequency, where for the first time the stochastic nature of flood is analytically tied to the physical‐dynamic characteristics of the basin response. This intimate linkage between the probabilistic aspects of the phenomena, so crucial to hydrology, and the dynamic modeling of the physical aspects of the processes has become the trademark of Peter Eagleson's research and has had a profound influence in the field. Probably nowhere is this mark more evident than in Eagleson's series of seven papers, “Climate, Soil and the Water Balance: A Framework for Their Analytical Coupling,” published in 1978 in Water Resources Research. These papers are a magnificent display of imagination and analytic strength which go directly to the heart of hydrology, culminating with the dynamics of the annual water balance of the basin scale. They constitute a standard reference in the field and in my opinion one of the most significant hydrologic contributions in the last 20 years. This research led to Eagleson's theory of ecological optimality in water‐limited soil‐vegetation systems and inspired follow‐up research in different parts of the world on this most important topic.”

• Eagleson Interview by Steve Burgess in 1997

The seven 1978 papers

•  Eagleson, Peter S. 1978a. “Climate, Soil, and Vegetation: 1. Introduction to Water Balance Dynamics.” Water Resources Research 14 (5): 705–12.
• ———. 1978b. “Climate, Soil, and Vegetation: 2. The Distribution of Annual Precipitation Derived from Observed Storm Sequences.” Water Resources Research 14 (5): 713–21.
• 
  
• ———. 1978c. “Climate, Soil, and Vegetation: 3. A Simplified Model of Soil Moisture Movement in the Liquid Phase.” Water Resources Research 14 (5): 722–30.
• 
  
• ———. 1978d. “Climate, Soil, and Vegetation: 4. The Expected Value of Annual Evapotranspiration.” Water Resources Research 14 (5): 731–39.
• 
  
• ———. 1978e. “Climate, Soil, and Vegetation: 5. A Derived Distribution of Storm Surface Runoff.” Water Resources Research 14 (5): 741–48.
• 
  
• ———. 1978f. “Climate, Soil, and Vegetation: 6. Dynamics of the Annual Water Balance.” Water Resources Research 14 (5): 749–64.
• 
  
• ———. 1978g. “Climate, Soil, and Vegetation: 7. A Derived Distribution of Annual Water Yield.” Water Resources Research 14 (5): 765–76.

Peter Germann's open book on preferential flow

Peter German (GS) first raised the issue of how preferential flow in soils due to preferential flow in a famous paper with Keith Beven (GS) in 1982, Macropores flow in soils. A benchmark paper from which uncountable studies followed. Now retired, he wrote a book entitled "Preferential flow: Stokes approach to infiltration and drainage".

Since 1982 there was a great debate on preferential flow modelling which is not yet concluded. Germann's book is evidently  a contribution from a protagonist of this story and he had the kindness to make it open. I am not sure about the content. Stokesian flows are those that happens when all acceleration is dissipated, so the subtitle is not very informative on the content. More detailed comments will arrive when I will have read it. For now you can get it by clicking on the Figure.

Richard Rotunno on the predictability of Storms

In these days we have here in Trento,  at my Department, Richard Rotunno (GS), a pleasant person and an outstanding scientist. His field of interest is meteorology and micrometeorology and, in particular, the evolution of storms.  Here in Trento he gave various seminars and in particular one  on the predictability of storms, which he permitted to share with you.

As usual, by clicking on the above image, you will be able to access the presentation. He cited some interesting papers that you will find below. On the butterfly effect, you can also see this my previous post, to which I think the literature cited by Richards add something important.

References (In the order in which they are cited)

• Charney, J.G; Fjörtoft, R and von Neumann, Numerical integration of the barotropic vorticity equation, Tellus, 2:4, 237-254, DOI: 10.3402/tellusa.v2i4.8607, 1950 
• Lynch, P., The origins of computer weather prediction and climate modeling” , J Comp Phys, doi:10.1016/j.jcp.2007.02.034, 2008 
• Thompson, P.D., “Uncertainty of Initial State as a Factor in the Predictability of Large Scale Atmospheric Flow Patterns”, Tellus IX, 1957 
• Lorenz, E.N., “The Predictability of a Flow which Possesses Many Scales of Motion” E. N. Lorenz, Tellus XX1, 1969 
• Palmer, T.N; Döring, A.; Seregin, G. The Real Butterfly Effect”. 27,9, R123, Nonlinearity 2014 
• Lilly, D.K., “Numerical Simulation Studies of Two-Dimensional Turbulence: II. Stability and Predictability Studies” Geophysical Fluid Dynamics, 4(1), 1972 
• Tennekes, H, Turbulent flow in two and three dimensions, Bull. Amer. Met. Soc., 59(1), 1978 
• Skamarock, W.C., Evaluating Mesoscale NWP Models Using Kinetic Energy Spectra, Monthly Weather Review, 2004 
• Patton, E.g. and Sullivan, P.P, Atmospheric stability influences on coupled boundary-layer-canopy turbulence, Journal of Atmos. Sci., https://doi.org/10.1175/JAS-D-15-0068.1, 2016 
• Falko, J., Insights into Atmospheric Predictability through Global Convection-Permitting Model Simulations, Journal of Atmos. Sci., https://doi.org/10.1175/JAS-D-17-0343.1, 2018

Floods in Alberto Viglione research

I had the honour to be in the committee that selected Alberto Viglione (GS) to become Associate Professor at Politecnico di Torino.  Alberto gave a nice seminar entitled "understanding and Estimating River Flood Hazards across Timescales" which covers some issues on flooding forecasting and variability in space-time.

I really appreciate his point of view which is different from mine and from which I can learn a lot, therefore I  asked him the permission to publish his presentation in my blog here. Please by clicking on the Figure above, find Alberto's presentation.

References

Archfield, S. A., R. M. Hirsch, A. Viglione, and G. Blöschl (2016), Fragmented patterns of flood change across the United States, Geophysical Research Letters, doi:10.1002/2016GL070590.

Barendrecht, M.H., A. Viglione and G. Blöschl (2017) A dynamic framework for
flood risk, Water Security, 1, 3-11, doi:10.1016/j.wasec.2017.02.001.

Blöschl, G., M. Sivapalan, T. Wagener, A. Viglione, and H. H. Savenije (2013b), Runoff Prediction in Ungauged Basins - Synthesis across Processes, Places and Scales, 484 pp., Cambridge University Press, ISBN:9781107028180.

Blöschl, G., et al. (2017), Changing climate shifts timing of European
floods, Science, 357 (6351), 588–590, doi:10.1126/science.aan2506.

Di Baldassarre, G., A. Viglione, G. Carr, L. Kuil, J. L. Salinas, and G. Blöschl (2013), Socio-hydrology: conceptualising
human-flood interactions, Hydrology and Earth System Sciences, 17, 3295–3303, doi:10.5194/hess-17-3295-2013.

Merz, R., and G. Blöschl (2008), Flood frequency hydrology: 1. Temporal, spatial, and causal expansion of information, Water Resources Research, 44, W08432, doi:10.1029/2007WR006744.

Salinas, J. L., A. Kiss, A. Viglione, R. Viertl, and G. Blöschl (2016), A fuzzy Bayesian approach to
flood frequency estimation with imprecise historical information, Water Resources Research, 52 (9), 6730–6750, doi:10.1002/2016WR019177.

Viglione, A., R. Merz, and G. Blöschl (2009), On the role of the runoff coefficient in the mapping of rainfall to flood  return periods, Hydrology and Earth System Sciences, 13 (5), 577–593, doi:10.5194/hess-13-577-2009.

Viglione, A., G. B. Chirico, R. A. Woods, and G. Blöschl (2010a), Generalised synthesis of space-time variability in flood response: An analytical framework, Journal of Hydrology, 394, 198–212, doi:10.1016/j.jhydrol.2010.05.047.

Viglione, A., G. B. Chirico, J. Komma, R. A. Woods, M. Borga, and G. Blöschl (2010b), Quantifying space-time dynamics of flood event types, Journal of Hydrology, 394, 213–229, doi:10.1016/j.jhydrol.2010.05.041.

Viglione, A., R. Merz, J. L. Salinas, and G. Blöschl (2013), Flood frequency hydrology: 3. A Bayesian analysis, Water Resources Research, 49 (2), 675–692, doi:10.1029/2011WR010782.

Viglione, A., G. D. Baldassarre, L. Brandimarte, L. Kuil, G. Carr, J. L. Salinas, A. Scolobig, and G. Blöschl (2014), Insights from socio-hydrology modelling on dealing with flood risk – Roles of collective memory, risk-taking attitude and trust, Journal of Hydrology, 518 (A), 71–82, doi:10.1016/j.jhydrol.2014.01.018.

Viglione, A. and M. Rogger (2015) Flood processes and hazards, Chapter 1.1 in: J.F. Schroder, P. Paron and G. Di Baldassarre (Eds.) HydroMeteorological Hazards and Disasters, Elsevier, pp. 3-33, doi:10.1016/
B978-0-12-394846-5.00001-1.

Viglione, A., B. Merz, N. V. Dung, J. Parajka, T. Nester, and G. Blöschl (2016), Attribution of regional flood changes based on scaling fingerprints, Water Resources Research, 52 (7), 5322–5340, doi:10.1002/2016WR019036

Anke Hildebrandt's recent research

If you are interested in the hydraulics of plants, you should give a look to the recent production of Anke Hildebrandt. Her production encounter my favor since she is able to put together experimental work and theoretical work on the thermodynamics of trees. A topic on which recently I became interested in. Relevant among her production is the work on hess: A thermodynamic fomulation of root water uptake which was awarded as one of the best paper of 2017 in HESS. No more comments. Just papers to read below. 

Recent papers

Van Stan, J. T., Norman, Z., Meghoo, A., Friesen, J., Hildebrandt, A., Côté, J.-F., et al. (2017). Edge-to-Stem Variability in Wet-Canopy Evaporation From an Urban Tree Row. Boundary-Layer Meteorology, 165(2), 295–310. http://doi.org/10.1007/s10546-017-0277-7

Guderle, M., Bachmann, D., Milcu, A., Gockele, A., Bechmann, M., Fischer, C., et al. (2017). Dynamic niche partitioning in root water uptake facilitates efficient water use in more diverse grassland plant communities. Functional Ecology, 32(1), 214–227. http://doi.org/10.1111/1365-2435.12948

Metzger, J. C., Wutzler, T., Dalla Valle, N., Filipzik, J., Grauer, C., Lehmann, R., et al. (2017). Vegetation impacts soil water content patterns by shaping canopy water fluxes and soil properties. Hydrological Processes, 31(22), 3783–3795. http://doi.org/10.1002/hyp.11274

Weisser, W.W., C. Roscher, S. Meyer, A. Ebeling, G. Luo, E. Allan, H. Beßler, R. Barnard, N. Buchmann, F. Buscot, C. Engels, C. Fischer, M. Fischer, A. Gessler, G. Gleixner, S. Halle, A. Hildebrandt, H. Hillebrand, H. de Kroon, M. Lange, S. Leimer, X. Le Roux, A. Milcu, L. Mommer, P. Niklaus, Y. Oelmann, R. Proulx, C. Scherber, M. Scherer-Lorenzen, S. Scheu, T. Tscharntke, M. Wachendorf, C. Wagg, A. Weigelt, W. Wilcke, E.-D. Schulze, B. Schmid, N. Eisenhauer. Biodiversity effects on ecosystem functioning in a 14-year grassland experiment: patterns, mechanisms, and open questions. Basic and Applied Ecology, doi: 10.1016/j.baae.2017.06.002. (link)

Zimmermann, A., Voss, S., Metzger, J. C., Hildebrandt, A., & Zimmermann, B. (2016). Capturing heterogeneity: The role of a study area’s extent for estimating mean throughfall. Journal of Hydrology, 542(C), 781–789. http://doi.org/10.1016/j.jhydrol.2016.09.047

Guderle, M., D. Bachmann, A. Milcu, A. Gockele, M. Bechmann, C. Fischer, C. Roscher, D. Landais, O. Ravel, S. Devidal, J. Roy, A. Gessler, N. Buchmann, A. Hildebrandt. Dynamic niche partitioning in root water uptake facilitates efficient water use in more diverse plant communities. Functional Ecology, doi: 10.1111/1365-2435.12948. (link)

Metzger, J. C., N. Dalla Valle, T. Wutzler, J. Filipzik, R. Lehmann, M. Roggenbuck, D. Schelhorn, J. Weckmüller, K. Küsel, K. U. Totsche, S. Trumbore, A. Hildebrandt. Tracing spatial variation of canopy water fluxes to the soil with high resolution data. Hydrological Processes. doi: 10.1002/hyp.11274 (link)

Arnold, S., Attinger, S., Frank, K., Hildebrandt, A. 2016. Assessing the structural adequacy of alternative ecohydrological models using a pattern-oriented approach. Ecological Modelling 316: 52-61. doi: doi:10.1016/j.ecolmodel.2015.08.003. (link)

Hildebrandt, A. A. Kleidon and M. Bechmann. A thermodynamic fomulation of root water uptake. Hydrology and Earth System Sciences. 20: 3441-3454, doi: 10.51947hess-20-3441-2016. (link)

Milcu, A., W. Eugster, D. Bachmann, M. Guderle, Ch. Roscher, D. Landais, O. Ravel, A. Gessler, M. Lange, A. Ebeling, W. Weisser, J. Roy, A. Hildebrandt, N. Buchmann. 2015. Plant species and functional diversity increase grassland productivity-related water vapour fluxes: a combined Ecotron and modeling approach. Ecology 97(8): 2044-2054. doi: 10.1890/15-1110.1 (link)


Renner, M., S. K. Hassler, T. Blume, M. Weiler, A. Hildebrandt, M. Guderle, S. J. Schymanski, and A. Kleidon. Dominant controls of transpiration along a hillslope transect inferred from ecohydrological measurements and thermodynamic limits, Hydrology and Earth System Sciences 20: 2063-2083. doi: 10.5194/hess-20-2063-2016. (link)

Fischer, C., Tischer, J., Roscher, C., Eisenhauer, N., Ravenek, J. M., Gleixner, G., Attinger, S., Jensen, B., de Kroon, H., Mommer, L., Scheu, S., Hildebrandt, A. 2015. Plant species diversity affects infiltration capacity in an experimental grassland through changes in soil properties. Plant and Soil. 397(1): 1-16, doi: 10.1007/s11104-014-2373-5 (link)

Guderle M. and Hildebrandt A. 2015. Using measured soil water contents to estimate evapotranspiration and root water uptake profiles - a comparative study. Hydrology and Earth System Sciences. 19: 409-425. doi: 10.5194/hess-19-409-2015 (link)

Bechmann, M., C. Schneider, A. Carminati, D. Vetterlein, S. Attinger, A. Hildebrandt. 2014. Parameterizing complex root water uptake models - the arrangement of root hydraulic properties within the root architecture affects dynamics and efficiency of root water uptake. Hydrology and Earth System Sciences. 18:4189-4206. doi: 10.5194/hess-18-4189-2014 (link)

Fischer, C., C. Roscher, Jensen, N. Eisenhauer, J. Baade, S. Attinger, S. Scheu, W.W. Weisser, A. Hildebrandt. 2014. How do earthworm, soil texture and plant composition affect infiltration in managed grasslands along a plant diversity gradient? PLoS ONE9(6): e98987. doi:10.1371/journal.pone.0098987. (link)

Leimer, S., Kreutziger, Y., Rosenkranz, S., Beßler, H., Hildebrandt, A., Oelmann, Y., Weisser, W., Wirth, C. Wilcke, W., 2014. Plant diversity effects on the water balance of an experimental grassland. Ecohydrology, doi: 10.1002/eco.1464. (link)

Carminati, A., C. L. Schneider, A. B. Moradi, M. Zarebanadkouki, D. Vetterlein, H.-J. Vogel, A. Hildebrandt, U. Weller, L. Schüler, and S. E. Oswald. 2011. How the Rhizosphere May Favor Water Availability to Roots. Vadose Zone Journal 10:988. doi: 10.2136/vzj2010.0113. (link)

Kalbacher, T., C. L. Schneider, W. Wang, A. Hildebrandt, S. Attinger, and O. Kolditz. 2011. Modeling Soil-Coupled Water Uptake of Multiple Root Systems with Automatic Time Stepping. Vadose Zone Journal 10:727. doi: 10.2136/vzj2010.0099. (link)

Alexandrov, G. a., D. Ames, G. Bellocchi, M. Bruen, N. Crout, M. Erechtchoukova, A. Hildebrandt, F. Hoffman, C. Jackisch, and P. Khaiter. 2010. Technical assessment and evaluation of environmental models and software: Letter to the Editor. Environmental Modelling & Software 26:328-336. doi: 10.1016/j.envsoft.2010.08.004. (link)

Dalton Prize 2017 to Dani Or

This is the video of Dani Or (GS) lecture for the prize he received at this year EGU Wien. Dani is an outstanding scientist and any of the things he does deserve attention and a reading. He talked about evaporation and others of his lectures were already linked in this blog.

Here below the video of the presentation of Dani.

Here his lecture (unfortunately a little out of focus, but still visible. I hope that there will be an official, professional record from EGU). You can find the PDF of the slides here.

Italian Hydrology 2016

I am summarising here what I saw that rised my interest in the Italian biennial meeting of Hydraulics, Hydrology and Hydraulic constructions. Obviously I followed just the hydrology section and missed the rest. Therefore I could have not seen some very fundamental in one of the other subdisciplines. Do not blame me !

As a general observation, I have to say that few are still really producing models. Many are using products from others notably: tRibs, WRF-Hydro, SWAT, among the foreign. Cathy, Topkapi-X and GEOtop among genuine Italian products were presented at the Conference. Many young people also work on remote and proximate sensing research, where they exploit the capabilities of the new tools (especially UAVs but also on traditional remote sensing). Some work on statistical and probability models.  Some on eco-hydrology. Many we know they work on groundwater, but almost no abstract was presented on the topic that dominated last century literature. Remote sensing is certainly a great topic but today I will not talk about.
In doing my choices I keep an eye on the three step conceptualisation of learning processes represented in figure. There is stuff that is completely mainstream and has the maximum of attention in these years, other on which interest is growing, and other that foresees the future of the discipline.

The Italian hydrological community, especially if we include the numerous those who live abroad, is pretty alive (at present the WRR, HESS, ADWR, PNAS have Italian Editors). However, did I see material changing the paradigms ? Let's see in my comments below.

So, my favourite (if you click on figures, you are redirected to the slides):

Statistics

Marco Marani (GS) and coworkers rethink the estreme value concepts, observinfg that Pearson's distributions are obtained as a limit of an infinite number of events. He proposed intermediate distributions, when the number of observations is limited. He, they, called these distributions "metastistical". This is, I think, good and pretty much necessary too. Authors assume that extremes are sampled from iid variables, while others, Jim Smith for instance, think that extreme events are sampled out from a separate population. Is there any method to infer it from data ?

Elena Volpi and coworkers discussed the idea of return period. Her statement is that statistical independence is not a requirement for obtaining the classical equation of return period (post coming soon).
This is inscribed in the old story of stochastic processes used as representation of phenomena that appear highly variable. The field needs some refreshment after the discovery of climate change. Volpi's et al. Has the merit to bring in some novelty. I was intrigued by the separation and relation between return period and waiting time.

In the same subfield I registered attention to copulas, as a means to move from a univariate dominated applications to multivariate.

Strangely not application in machine learning or pattern recognition which could be os some interest when coupled with complex time and spatially varying signals.

Eco-hydrology

Gabriele Manoli (GS) uses a simplified ABL theory to study the effects of vegetation on precipitations, and, in particular he sorted out the effects of vegetation ages. Some about the theory of ABL came from an evolution of thet good old model by John Albertson (GS) but the novelty here is that eco-hydrology enters in the merit of phenology-plants evolution. Conditions in which conclusions are drawn are pretty uniform (probably Durham forest can be considered a nice approximation of it). the problem of heterogeneity calls for a treatment made with a process-based model.

Nadia Ursino and Chiara Callegaro explore the formation of some vegetational patterns made possible by water availability in water-limited environments. 

Measures

Tuscia’s guys (Salvatore Grimaldi et al., GS) make a lot f interesting things, but here, I have chose their 100 square meters pluviometer. Details on on it, the paper, slides and poster are below.

Process-based modelling

We’ve got some good work by Giacomo Bertoldi (GS), but he is too close to me for me being neutral. I mention two works. One by Alfonso Senatore (GS) and coworkers. He uses WRF coupled with WRF-Hydro. I am not sure of the contents of the latter. The good and the new could be that there is one model that treats with very detail the interactions with the atmosphere (thanks to WRF) or should. If it is a real thing, I am envy, because it is one thing I believe we have to add to GEOtop.

Monica Piras showed various comparison between process based models. She and co-workers used the model “blindly” without giving direct judgement about the performances of each one. Anyway, it is apparent that models behave differently, and someone should be wrong. Interesting part of her presentaion was the mention to downscaling techniques, necessary to couple climate projections and hydrological models. Below, please find her presentation.

I did not mention travel time theories. We already talk about it extensively. Nothing especially new was presented that it is not already in my previous posts, just some incremental advancement.

On " How to make our models more physically-based"

These reflections came after having read the discussion paper of the same title by Savenije and Hrachowitz (S&H) on HESSD, and I offer them to your own thinking (their paper was very successful in rising my interest, then). So first, read the opinion paper.

The paper has some (a ?) very good point:

“In brief, our hydrological system is alive and has a strong capacity to adjust itself to prevailing and changing environmental conditions. Although most physically based models take Newtonian  theory at heart, as best they can, what they generally miss is Darwinian theory on how an ecosystem evolves and adjusts its environment to maintain crucial hydrological functions. If this active agent is not reflected in our models, then they miss essential physics. “

However, let me divagate on their concepts and ideas, and debate first, the concept of what Physics is (related to modern Hydrology). In the wide, general sense, Physics is the study of nature, however, it has codified during the last centuries, since Galilei, as a science that uses experiments to validate (I know the danger in using this verb) some theoretical issue about the behavior of some phenomena. One key aspect of Physics is the the word experiment, which means that we have something to measure (a physical quantity) and tools to do it (instruments). Repetition of experiments and confirmation of outcomes, and establishing (mathematical) relations among quantities, brings to laws, Physical laws. 

I am aware that each one of the words in the paragraph above would require a book to be dissected, analysed in its historical development, and in fact this was done.

Physics and or “Physical Sciences” have evolved to specialise people. Someones are inclined to work on the theory, others to design experiments. Theory, in turn, means that there is some formal (meaning following unambiguous rules to process statements and precise definitions) language that expresses relations among things, quantities, the latter being closely related to what is measurable (i.e. to the ability to build tools to detect something). The entanglement between theory and measures (or the possibility to do some measurement, even in a “virtual” or “thought” way, or with tools that are not existing but can be conceived) is inextricable. 

So when Peter Eagleson  claim for hydrology as a (separate) physical science, I believe he meant that  there was the technology for implementing measures and a “corpus” of “mathematics” to be able to process and forecast hydrological facts, and doing it properly. 

During its history, Physics has changed and enormously expanded its field of interest. Galilei started with the motion laws, and continued with planets, attitude that Newton brought to a first completion. Optics came in, then electricity, electromagnetism, quantum mechanics, quantum electrodynamics, chemistry, thermodynamics, to name a few areas. 

The lighthouse, were always the “mathematical” approach in describing the world, and repeatable experiments to confirm the findings, and development of mathematics and of measurements techniques went along with it.  Besides,  another reference were conservation laws: mass, momenta, and energy (charge, and so on). 

So we can say that hydrology is a physical science, for instance,  also because it uses mass conservation law. In this sense, any of models presented in the paper by S&H are physical.  However,  a judgment on their assertions can be obtained by asking which is their “mathematics” and what do they measure.  

To be fully respectable, we would expect that authors of a physical model were concerned also with momentum conservation and energy conservation, but actually, if we would add this requirement, almost no hydrological model would be a physical model^1.  

If we accept the beginning phrase, according to its Authors thinking, we should become more physical being more “Darwinian” too. However, Darwin was, as everybody knows,  a biologist^2, or better, maybe, a "natural scientist".  I believe the Authors are right when they claim it but Schroedinger, in his “What is life”, was more concretely a physicist facing biology and his claiming that the approach of Physics could be applied also to life offers a strong counterexample that the Physics approach can be applied to Natural sciences, maybe pushing beyond the present limits the actual science. His work was inspirational for many and can be inspirational even now for doing research in hydrology. With its obsolescence, it is a gigantic conceptual contribution, and I suggest my students to read it, to get the fundamentals of what arguing about Physics is.

Going to some detail, S&H seem to claim that the hydrosphere obeys a homeostatic behavior, which seems to self-regulate and affect earth as much as possible, to maintain the conditions that sustain life. This is reminiscent of the Gaia hypotheses^3.  The difference in scale from hillslope hydrology to the global earth should be taken into account though.  

Furthermore, I think we have some realistic hints that the system (Gaia) can be broken, and therefore, I believe, that the evolutionary conditions that the many claim to be a possible guide to build new paradigms of models are valid under the assumption of a certain degree of equilibrium, that is far from being evident in this climate change era. In other words, the hydrological cycle and the ecosystems could be out of balance.
In any case, homeostasis can exist if feedbacks, which physical models should be able to capture, exist. Where is the mathematics for doing it ? I am not sure that arguing by adding reservoirs could be enough to capture intertwined behaviors, but, I admit, they are a starting point (I already kind of wrote it).  Frankly, I think the way inaugurated by Ruddel and Kumar is much more visionary and we should push on that side of research, instead that sticking only with a trial and error (remove and put) guided by uncertain measurements and weak modeling abilities. IMO, future is in network mathematics not reservoirs assemblage.  

S&H cite Aristotele, and they have good reason for doing it. Our hydrology is, maybe,  a physical science but often we can just observe the phenomena, not control them, as Galileian experiments would require. So we are lame in our trials, and immersed in dim light, not exposed to the full splendor of the Knowledge. Statistics is necessary to to disentangle measures and observations. Causal relations are often less than obvious, and as all we know, "correlation does not mean causation". All this fuzzines makes the matter prone to exciting but ineffective narrative  that usually starts with the word “holistic” (BTW a word I like too) and continues by saying that “the whole is more than its parts” but  most of the time does not continue with a proper fomalisation of what  "holistic" is and how this damn “whole” can happen. So maybe, he was very wise Galilei when he said to his Aristotelian antagonists “Io stimo più il trovar un vero, benché di cosa leggiera, che 'l disputar lungamente delle massime questioni senza conseguir verità nissuna. ” (I like more to find a truth in a small subject than discuss long time of general subjects without obtaining anything”)

I think that an interesting working hypothesis is that "the whole is the sum of its parts and the interactions among the parts", and that part of the quality of the system, seen as a whole, derives from parts' interactions and feedbacks. A system is itself a quite unidentified entity, and its definition is certainly recursive, meaning that, most of the time, a system is a system of systems, and reality is “stratified”.  But having a "basic system" at some scale should be feasible.

Finally, where is falsification ? Falsification is certainly a characteristic of a scientific enterprise, and therefore of Physics. Certain theories seem to me missing of the precision needed to obtain a proper falsification, and S&H should be more convincing on that side. On the contrary, Pete Eagleason book, Dynamic Hydrology, probably the best book ever in Hydrology, after fourty five years is “all wrong”, the right sense of wrongness. That’s science, that’s Physics !

P.S. - Another attitude I would not spread (S&H are affected) is to see remote sensing as an “oracle” which gives the right answer without paying debts to uncertainty and unknownness. I already wrote about. 

NOTES:

^ GEOtop is one of the few notable exceptions.

^2 - I remind an ironic slides by Per Bak with written: "is biology too difficult for biologists ?" Here the worth of retaliation hits.

^3 About the Gaia hypothesis an eminent colleague said “ … Are they testable ? Are they useful ?“ (IMHO:  useful, they were …)

Ecological Feedbacks of desertification: Stability and Resilience of Ecosystem and Society in arid Environments

This includes the outstanding presentation given by Paolo D'Odorico (GS) at the 2015 GII Ph.D. days. Besides the topic in itself, which is very interesting, it shows that hydrology is an inclusive science that moves toward the science of environment including all the processes and interactions. This lecture, however, deals with the global scale.

Enjoy.

Paolo Benettin explaining his Ph.D thesis on travel time distributions and catchment hydrology

During the last days we had in Trento the GII 2015 Ph.D. days. Fourty two Italian students in water engineering and related topics gathered in Trento to show their work, and exchange ideas. Among them there were the three recently graduated that a GII committee selected as the best Italian thesis for the last year graduates, and among them, Paolo Benettin. Paolo (I was in the committee that approved his graduation) talked about: "Catchment transport and travel time distributions". In this thesis, besides developing some case studies he also tried to give  a  definitive arrangement to the theory of travel time distribution. The talk he gave is now on my youtube channel:

The presentation is also available on slideshare:

And finally his thesis can be downloaded from here:

Paolo Benettin, Catchment transport and travel time distributions: theoretical developments and applications, University of Padua, 2015

Use of this information requires proper acknowledgment of sources.

Four interesting papers on Hydrological modelling

I met the first time Martyn Clark in Fort Collins last summer. USGS scientist Stacey Archfield organised a meeting for modellers (to which I was not invited :-( ), and Martyn was part of the crew.
I did not his work up to recently. and after our meeting, he came out with three Water Resources Research Papers, that I am listing here for subsequent readings.

Clark, M. P., Kavetski, D., & Fenicia, F. (2011). Pursuing the method of multiple working hypotheses for hydrological modeling. Water Resources Research, 47(9), n/a–n/a. doi:10.1029/2010WR009827

Pablo A. Mendoza, Martyn P. Clark, Michael Barlage, Balaji Rajagopalan, Luis Samaniego, Gab Abramowitz and Hoshin Gupta, Are we unnecessarily constraining the agility of complex process-based models? , Water Resources Research, Volume 51, Issue 1, pages 716–728, January 2015

Clark, M. P., B. Nijssen, J. Lundquist, D. Kavetski, D. E. Rupp, R. A. Woods, J. E. Freer, E. D. Gutmann, A. E. Wood, L. D. Brekke, J. A. Arnold, D. Gochis, R. Rasmussen. 2015. A unified approach for process-based hydrologic modeling: Part 1. Modeling concept, Water Resources Research, doi:10.1002/2015WR017198.

Clark, M. P., B. Nijssen, J. Lundquist, D. Kavetski, D. E. Rupp, R. A. Woods, E. D. Gutmann, A. W. Wood, D. Gochis, R. Rasmussen, D. Tarboton, V. Mahat, G. Flerschinger, D. Marks. 2015. A unified approach for process-based hydrologic modeling: Part 2. Model implementation and case studies, Water Resources Research, doi:10.1002/2015WR017200.


A late addition, the technical note regarding this SUMMA stuff.

Luca Brocca interview on Research Gate

Luca Brocca recently was very much interviewed for one of his achievements about the use of remote sensing in hydrology. He had this smart idea of obtaining rainfall from soil-moisture data. His SM2RAIN is a simple algorithm for estimating rainfall from soil moisture data that you can find in his web page together with  other interesting stuff:

• MISDc Rainfall-Runoff Model (and MILc)
• Soil Moisture Model
• Neyman-Scott Rectangular Pulse Model
• FARIMA
• Satellite vs in situ soil moisture observations
• Long-term (1989-2012) soil moisture data set

The paper that generate a big wave was:

Soil as a natural rain gauge: Estimating global rainfall from satellite soil moisture data,  available here. He also had the honour of a Nature Research Highlight mention. All of this deserve mention by itself. However, he was so kind to mention me in this recent Research Gate Interview. Thank you Luca !

Ning Lu lectures on hillslope processes and (especially) stability, at the Summer School on Landslides

In 2013 University of Calabria organised a very interesting School on Landslide triggering (many thanks to Lino Versace, Giovanna Capparelli and Giuseppe Formetta).  I actually gave a hand to organised it, and  I also gave a lecture on Richards equation.  Waiting for the official post of the lectures at the school site (after which, I will remove my videos), I cannot wait anymore to have on-line the lectures by Ning Lu. He gave four talks taken out of his beautiful book, Hillslope Hydrology and Stability, written with Jonathan Godt, new coordinator of the USGS landslide hazards program, and former co-advisor of my Ph.D. student Silvia Simoni (her thesis here).  A must-watch for any guy in the field !

First talk: A brief conceptual history of soil hydrology and soil mechanics (from Chapter 6 of his book)

Second talk: About Steady infiltration (Chapter 3 of his book)

Third talk, part I: Strength of hillslope materials (Chapter 7 of his book)

Third talk, part II: Hydro-mechanical properties of hillslopes (Chapter 8 of the book)

https://www.youtube.com/watch?v=xokmTXgmTf8

Fourth talk, part I: Failure surfaces  (Chapter 9 the book)

Fourth talk, part II: Field based stability analysis (Chapter 10 of his book)

Naming things in hydrological models

Yesterday I could meet with Olaf David, Scott Peckham (update: Scott did a presentation on MBI at the OMS3 summer school in 2016). Scott is a well known scientists either among hydrological modellers than geomorphologists. In the first field because of his recent work on CSDMS project (and his own model Topoflow), in which he was one of the leader scientists, in the latter thanks to his work on river network topology and the construction of Rivertools, one of the best suite of tools for watershed delineation and analysis.

The reason to meet was friendship and just talking and exchanging  what we are doing, and the meeting, closed in one (actually two) of the small breweries of Fort Collins, was really successful. 

One of the recent things Scott is pursuing is to understand what models have inside, and the approach he took, was to categorise all the variables they contain, and define in a manner as clear as possible.  His efforts can be found and well described in here.

“CSDMS asks that contributed models should be provided with a Basic Model Interface (BMI) which includes mapping input and output variable names to CSDMS Standard Names and providing model metadata. …  A good introduction to the CSDMS Standard Names is provided by Peckham (2014). A somewhat outdated, high-level overview of the CSDMS Standard Names is also available as aPowerpoint presentation.”

Scott and coworkers did not forgot netCDF parallel effort with its CF convention, but he realised that the coverage of hydrology was poor, and he want to built the vocabulary from scratch. The effort, is by far not useful to his project, but also for other models and infrastructures. With our model GEOtop we started a parallel, and much more limited work, in identifying keywords related to hydrological quantities and to control the model’s workflow (see GEOtop’s manual), and I plan to provide soon a matching between CSDMS names and GEOtop names (and, I will repeat the operation inside my lectures, modifying my slides).

Having a common vocabulary for identify things in models would certainly make easier to choose names for quantities, even if, clearly the internal variable names should be shorter for practical purposes,   identify code chunks that treat the same phenomena. Also search model through the web would facilitate with standard names for search.

Here below a brief description of the whole Scott’s effort.

• Motivation

While it is always a good idea to use existing standards whenever possible, CSDMS discovered that other naming conventions, such as the CF Convention Standard Names were not well-suited to the needs of component-based modeling. This section explains our motivation for developing a new standard.

• Background and Purpose

This section provides some background and basic information about the CSDMS Standard Names.

• Examples

This section provides numerous examples of CSDMS Standard Names, organized by the main object under consideration and its parts or "subobjects".

• Basic Rules

The CSDMS Standard Names follow an object + quantity pattern with an optional operation prefix applied to the quantity part. This section provides the basic rules for constructing CSDMS Standard Names.

• Object Name Templates

This section provides a set of templates and rules for constructing the object name part of a CSDMS Standard Name.

• Quantity Name Templates

This section provides a set of templates and rules for constructing the quantity name part of a CSDMS Standard Name. Many quantity names include the name of aphysical process and information about constructing process names along with numerous examples are given on the CSDMS Process Names page.

• Operation Templates

This section provides a set of templates and rules for constructing the optional operation part of a CSDMS Standard Name.

• Model Metadata Names

This section provides information on CSDMS Model Coupling Metadata (MCM) files and provides standardized model/variable metadata names for units, ellipsoids, datums, projections, "how modeled" and assumptions. It links to an extensive set of CSDMS Assumption Names and includes An Example Model Coupling Metadata file.

• Current List of CSDMS Standard Names 

My CV and Five Papers that represent me

For who it may concern, I am posting my up-to-date CV here. It collects what I did,  and contains information already present here (where, in addition, you have a link to the papers).

For a shorter version of my CV, please take this.
If I would asked to choose five papers that more represent my work (and me), they would be not the most cited (among them), not those in Journals with the highest impact (well ... among them), and I would select probably:

• Rinaldo, A., A. Marani and R. Rigon, Geomorphological dispersion, Water Resources Research, 27(4), 513-525, 1991
• Rodriguez-Iturbe, I. , A. Rinaldo, R. Rigon, R. L. Bras, A. Marani and E.J. Ijjasz-Vasquez, Energy dissipation, runoff production, and the 3-dimensional structure of river basin, Water Resources Research, (28)4, 1095-1103, 1992.
• Rigon R., Bertoldi G e T. M. Over, GEOtop: A distributed hydrological model with coupled water and energy budgets, Journal of Hydrometeorology, Vol. 7, No. 3, pages 371-388, 2006
• M. Dall’Amico, S. Endrizzi, S. Gruber, and R. Rigon, A robust and energy-conserving model of freezing variably-saturated soil, The Cryosphere, 5, 469-484, 2011, doi:10.5194/tc-5-469-2011
• Formetta G., Antonello A., Franceschi S., David O., and Rigon R., Hydrological modelling with components: A GIS-based open-source framework, Environmental Modelling & Software, 5 (2014), 190-200

Obviously I did decent work also between 1992 and 2006. Enjoy!

For 5 more recent papers, representing the decade 2015 to 2024 please see here. 

Uncertainty and Information Theory

We all are persuaded that uncertainty is a big topic, in life but also, in hydrology. So important that many hydrologists dedicate their life to its estimation, in connection to hydrological processes. Uncertainty since it is uncertain also generate confusion, and some of tis literature is  confuse and confusing (I don't want to cite negatively anyone, but I could).
Whatever the case, one of the best talk I attended to at last Fall American Geophysical Union Meeting, was the invited lecture by Hoshin Gupta. Hoshin has an outstanding (really outstanding, I mean) carrier in finding calibration methods, indentifiability of parameters and understanding uncertainty in models. Recently (see for instance Gong et al., 2013) he started to apply concepts derived from information theory to hydrology.  BTW, you can find the pdfs of his AGU’s presentations here: on the necessity to apply information theory concept to evaluate models structural hypotheses, and another one about Information theory and Bayesian inference in hydrology (both with a lot of citations).

I never really understood why hydrologists do not use information theory  concepts. I-Theory is a well developed mathematica theory with a lot of tools, and could help to get out from the fuzziness around  the determination of uncertainty in models. Besides, using the concept of I-Theory information/uncertainty one can gain knowledge about the complexity of processes outputs and, possibly, infer something about the "complexity" of models required to mathematically account for it in a proper way (remind: "Everything should be made as simple as possible but not simpler").

Hoshin is not the only one that was attracted by information theory. In my occasional browsing of the topic, I also found some other interesting papers: the first one, by  Majda and Gershgorin, is concerned by climate models. This is encouraging, because climate models are certainly at least as involved as hydrological models are, and, if not, even more. A second is Weijs et al. (2013): this is concerned with time series: we compare time series, therefore knowing how much information is hidden in a time serie (at least with reference according to some encoding key) is certainly useful. For Wejis and van de Giesen, this paper is just a coming back to the topic (see also Weijs et al., 2010, and Weijs CV)

Another paper came from  Rudell (GS) on EOS remarkably highlighting that the I-Theory applications to hydrology attracted last year  many more people than use to be.
For making me feeling among the smarter, I  bought a book, by Mezard (see also, and GS) and Montanari (Andrea, not our colleague Alberto who also has quite a production on uncertainty: please see his website) which can be a further source of ideas and thoughts.

So far, I never actually read carefully any one of the papers (or the book), but excited at the idea to have time to do it in deep.

References

Gong, W., H. V. Gupta, D. Yang, K. Sricharan, and A. O. Hero III (2013), Estimating epistemic and aleatory uncertainties during hydrologic modeling: An information theoretic approach, Water Resour. Res., 49, 2253–2273, doi:10.1002/wrcr.20161.

Mézard, M. and Montanari, A. , Information, Physics, and Computation, Oxford University press, 2009

Majda, A. J.,  and Gershgorin, B., Quantifying uncertainty in climate change science through empirical information theory, PNAS, August 24, 2010, vol. 107,no. 34, 14958–14963

Ruddel, B.L, N. A. Brunsell and P. C. Stoy, Applying Information Theory in the Geosciences to Quantify Process Uncertainty, Feedback, Scale, Eos, Vol. 94, No. 5, 29 January 2013

 Weijs, S. V.;  Schoups, G.  and van de Giesen, N., Why hydrological predictions should be evaluated using information theory, Hydrol. Earth Syst. Sci., 14, 2545-2558, 2010, www.hydrol-earth-syst-sci.net/14/2545/2010/, doi:10.5194/hess-14-2545-2010

Weijs, S. V., van de Giesen, N. and Parlange, M. B., Data compression to define information content of hydrological time series, Hydrol. Earth Syst. Sci., 17, 3171–3187, 2013 www.hydrol-earth-syst-sci.net/17/3171/2013/ doi:10.5194/hess-17-3171-2013

Four academic brothers (of mine)

I have many academic brother since Andrea Rinaldo is very prolific in generating first class researchers. I have even more I consider the inheritance of Ignacio Rodriguez-Iturbe, my postdoc advisor at (that time at) Texas A&M Unversity. Of the many three agreed to send me the presentations they gave at the Honour doctorate of Andrea Rinaldo, and you can find them with a little comment here below. 

The older (of the three) brother, Marco Marani, from Padova University and Duke, presented a work on the soil-water-plants continuum. He emphasize the role of roots in modifying the soil water distribution, otherwise controlled by Darcy flows. However, he also studied and talked about the influence of the soil-plants-atmosphere continuum. The presentation is here. The couple of references cited are: Volpe et al., 2013 and Manoli et al., 2014. 

Gianluca Botter talked about the travel time distribution approach to catchment scale transport. A topic that intersects also the “old water paradox” querelle, but is, in general, pretty effective in getting the distribution of pollutants. This approach has a long story that put its roots, in Gedeon Dagan’s work, as well as in Rodriguez-Iturbe geomorphic unit hydrograph. Andrea own papers on Mass response function with Sandro Marani can also be considered at the foundations of this presentation. 

Among the reference, recent papers on the topic are Botter et al., 2010 and Benettin et al., 2013. The presentation is here

Enrico Bertuzzo (GS) covered instead the new topic of water borne  diseases and their spreading along rivers. The way Enrico and coworkers analysed the problem, certainly inherited many notions and ideas sprout the early studies on river networks structure by Andrea (I had a part in it), but also on recent and domain specific achievements and findings. In the presentation he cited just one paper, but the research outcomes on the topic are certainly copious and exciting. The presentation is here. 

Andrea D’Alpaos (GS)  talked about tidal networks, their formation, their shapes, their similarity or dissimilarity from river networks. All of it in a blend of equations, analysis in the field and lab experiments. Another fascinating topic that was started with Andrea.  The presentation is here.

Overall is interesting to judge the differentiation of topics and methods used by the authors, expressing that each developed his on research personality and attitude.

Stealing from Dennis Baldocchi ;-)

Dennis Baldocchi (GS) is one of the major contributors to studies of plant-atmosphere interactions.  Recently he also published a book on this topic, entitled Terrestrial Biosphere-Atmosphere Fluxes with Russell Monson (nice videos at his site).  I think the book is "must have" for hydrologists, even if after my first quick reading I realised that the approaches to some (more hydrological) topics perpetuate the "standard model" and interpretations of turbulence (but, it is a textbook!): full of up-todate-information  indeed^1.

 However, he also have the merit to put a lot of material in his group website, including slides and lectures. You can find them here:

• Plant-Ecosystem-Atmosphere Interactions (this apparently contains the material of the book)
• Advanced topics in biometeorology and micrometeorology 
• Ecosystem Ecology
• The Biosphere

Also available are some conferences talks which include videos. For instance:

• Estimating Evaporation everywhere

• Measuring and Interpreting Fluxes of Trace Gases Across Local and Global Networks:

• Scaling Information on 'Biosphere Breathing' from Chloroplast to the Globe. Microsoft eScience Workshop, Oct 2010, Berkeley, C
• Defend Science Presentation on Climate Change, April, 2006 Berkeley

^1 - Do not try to lear thermodynamics from here (look here instead). At least from chapter 2. Nothing especially wrong indeed, but very far from the clearness of my favorite books.