When working to a software you should try its design at best, then write your code with or without an IDE and finally check and test your code. Let’s for the moment skip the check and test question which has its own development and concentrate on the first phases of your work. Your design was good but your coding goes trough various modifications and, sometimes, you get lost. That is the time to use a Version Control System, a tool that allows you to recover older versions of your code and track your code history. This is what summarizes this nice and free course on Coursera. A VCS is a highly recommended tool even if you work alone. there are many of VCSs but here we concentrate our attention on Git, the free and open source VCs designed and implemented by Linus Torvalds also knows as the initial developer of the Linux OS and maintainer of its kernel. If you are one who prefer to read books, there is at least one open book on Git, and you can find it here. Otherwise, the Coursera videos are certainly worth to be seen. Coursera does not only introduces Git but also Github, but we will be back on it later. An interesting short introduction to both Git and Github can be found in this short tutorial. However, if you want to face the topics orderly, please first complete the video lectures.

My reflections and notes about hydrology and being a hydrologist in academia. The daily evolution of my work. Especially for my students, but also for anyone with the patience to read them.

## Friday, October 30, 2020

### Use Git and Github

## Thursday, October 22, 2020

### On putting plants in hydrological models in practice

The work of Concetta D’Amato Ph.D. started with joining together a reasonable evapotranspiration model with a solid infiltration model building a virtual lysimeter.

### Freezing soil requires new algorithms

Assuming you have got the physics right and you wrote the right equations, which is not given for granted when you deal with freezing soils, you have to solve the equations. This paper, deals with this last topic: given the freezing soil equation it implements a new algorithm to solve it. This algorithm was invented by Casulli and Zanolli in their 2010 paper. They called it nested Newton, we renamed it NCZ from Newton-Casulli-Zanolli. It was implemented for solving Richards equation which present a spiky term called hydraulic capacity, that poses serous challenges to the convergence of the solver. We extended here to a new equation with the same type of terms. In fact all equations that involve phase transitions have terms of this type.

To someone a new algorithm for integration of some equation can seem a minor achievement but, while in some type of simulation, the numerical errors of traditional methods can be somewhat constrained, in most of the simulation they do not and tend to increase up to a point that any prediction either quantitative or qualitative becomes useless. Obviously our case has an enormous effect when dealing with simulations of permafrost areas under the threat of climate change. If this introduction makes you curious, you can find the the preprint at The Cryosphere page, by clicking on the Figure above.

Reference

Casulli, Vincenzo, and ZANOLLI. 2010. “A Nested Newton-Type Algorithm for Finite Colume Methods Solving Richards’ Equation in Mixed Form.” *SIAM Journal of Scientific Computing* 32 (4): 2225–73.

Tubini, Niccolò, Stephan Gruber, and Riccardo Rigon. “A Method for Solving Heat Transfer with Phase Change in Ice or Soil That Allows for Large Time Steps While Guaranteeing Energy Conservation.”

## Sunday, October 18, 2020

### It's time to revise the GIUH

- Rigon, Riccardo, Marialaura Bancheri, Giuseppe Formetta, and Alban de Lavenne. 2016. “The Geomorphological Unit Hydrograph from a Historical-Critical Perspective.” Earth Surface Processes and Landforms, EGU Reprint Series, 41 (1): 27–37

- Rigon, R., P. D’Odorico, and G. Bertoldi. 2011. “The Geomorphic Structure of the Runoff Peak.” Hydrology and Earth System Sciences 15 (6): 1853–63.

- D’Odorico, P., and R. Rigon. 2003. “Hillslope and Channel Contributions to the Hydrologic Response.” Water Resources Research. https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2002WR001708.

- Rinaldo, Andrea, Alessandro Marani, and Riccardo Rigon. 1991. “Geomorphological Dispersion.” Water Resources Research 27 (4): 513–25.

**However, the theory has some limitations. Its applicability is based on the:**

- assumption that the rainfall is uniformly distributed (but C. Cudennec and coworkers were able to generalize it, see review paper)

- the river network is dynamic (e.g. https://www.erc-dynet.it/publications/ or previous studies by M. Marani, Biswal and coworkers)

- Bancheri, Marialaura, Francesco Serafin, and Riccardo Rigon. 2019. “The Representation of Hydrological Dynamical Systems Using Extended Petri Nets (EPN).” Water Resources Research 55 (11): 8895–8921.

- Rigon, R., and M. Bancheri. n.d. “On the Relations between the Hydrological Dynamical Systems of Water Budget, Travel Time, Response Time and Tracer Concentrations.”

Another remark regards that once upon a time I was looking and satisfied with discharge, now I try to check the water and the energy budget and, therefore, the overall budget. Let’s see what comes next and if I am able to close the circle. For who is still interested to implement a GIUH solver, please look at here.

## Thursday, October 15, 2020

### Save the date ! The GEOframe Winter School 2021 (GWS2021)

Compared to what was done in the past courses, there will be more practice and a more detailed work on evapotranspiration and rainfall-runoff. It will be much more focused on exercises and on getting the water budget performed under various hypotheses on models' structure.

Due to COVID-19/COVID-SARS-2 the lectures and the work will be limited to, at most, 10 people in presence but it will be possible to follow the class remotely either synchronous online and asynchronous online (we’ll use a “blended” type of teaching based on Zoom). There is no fee or subscription for the asynchronous classes (and no personal support, just the support coming through the geoframe users mailing list). Synchronous classes with no personal support though require subscription and the payment of a small fee of 10 Euros or (for Italians) a subscription to the Italian Hydrological Society.

**However, who requires a certificate of participation, and want personal support, must pay a fee (150 euros). Getting the certificate will be subject to present a report and an analysis of a catchment performed with the GEOframe tools. Tourists are welcomed but obviously real learning requires exercise and some effort.**

**Instructors will be**

- Prof. Riccardo Rigon, Ph.D. (GS)
- Prof. Giuseppe Formetta, Ph.D. (GS)
- Ing. Marialaura Bancheri, Ph.D. (GS)
- Ing. Niccolò Tubini, Ph.D. candidate
- Ing. Concetta D’Amato, Ph.D student

**Participants**

**Topics:**

**Homework to do before the School**- Installations and introduction to the Object Modelling System Infrastructure and Jupyter**Homework -**Radiation for Hydrologists**Day 1**- Hydrologic Response Units delineation and treatment of spatial features**Day 2**- Interpolation of hydrometeorological datasets**Day 3**- Exercise with your own catchments under instructors supervision**Day 4 -**Evaporation and Transpiration with GEOframe-Prospero**Day 5 -**Modelling lumped models with GEOframe-ERM**Day 6**- Adding features to your modellingg with ERM**Day 7**- Looking forward

**Subscriptions for having credits for this class and support can be obtained all year long after January 15, 2021: ****please visit https://webapps.unitn.it/form/en/Web/Application/winterschool/GEOframeWS2021 and compile the form ****or write to abouthydrology@gmail.con with subject: GWS2021 if you need more information. After payment of the fee you can have individual support and gain the participation certificate if you setup and perform an exercise with the GEOframe tools. You can do it on a your own catchment or we can provide you with a catchment and the required data. **

### How snowy are the Alps ?

A recent preprint was submitted to The Cryosphere were a large group of colleagues scientists analyzed the snow precipitation in more than 2000 gauges all over the Alps. This research is not only important for assessing the effects of climate change but also will be a benchmark to other more local studies on snowfall.

I think it could be a good reading for many, therefore I am sharing its information here. By clicking on the Figure you download the paper.

## Friday, October 9, 2020

### Introducing the Extended Petri Net using an example

This is, in my intention, gentle introduction to the Extended Petri Net on which we wrote a paper recently. That is the definitive reference on the topic. However, a presentation can smooth out some difficulties that the constraint a paper imposes do not allow. So, below, please find the presentation, bu clicking on the Figure.

## Thursday, October 8, 2020

### Snowdrops

to waken again, to feel

in damp earth my body

able to respond again, remembering

after so long how to open again

in the cold light

of earliest spring--

afraid, yes, but among you again

crying yes risk joy

in the raw wind of the new world.

## Thursday, October 1, 2020

### WATZON seminar series - I

The Project WATZON has almost finished the first year of work. It was a troubled year, since the COVID-19 pandemic and we could not meet and do the field work required. However, we learn to use better the resources Internet brought to us. Upon the initiative of Paolo Nasta we started a series of on-line conferences on the tools and topics of the project. He is providing in these days seminars about the use of Hydrus-1D, a leading software for estimating infiltration by using Richards equation. He accepted his material to be uploaded on my VIMEO WATZON Channel.

To interested people, Paolo suggest the following material

Lecture 1: Introduction to Hydrus-1D - First part

- Please download this file https://www.pc-progress.com/en/Default.aspx?h1d-lib-isotope
- Replace the computational module. You need to replace these two exe files in the Hydrus folder. For example, for me (Paolo Nasta) is C:\Program Files (x86)\PC-Progress\Hydrus-1D 4.xx
- download the Stumpp's example and run it. Stumpp data here.

*In the attached Excel file I extracted Fig.6 from the Stumpp's paper. In this exercise we consider only delta18O transport. First of all, we all need to measure delta18O for each rainfall event. This is quite unfeasible. But...we need to sample rainfall as much as we can in order to make reliable interpolation of delta18O contents in ech daily rainfall episode! Stable isotopes of water are reported in the delta notation as the δ-content (‰), which is a relative deviation from the international standard V-SMOW (Vienna-Standard Mean Ocean Water). Mostly, the δ-content is negative. It is not possible to calculate with negative “concentrations” in HYDRUS-1D, and therefore, the user has to add an arbitrary value to all isotope data for the simulations (input and observation data). Do not take the absolute values though!*

In the PRIN WATZON activities, we sample the isotope concentration in the rainfall (very frequently!), plant, soil (at different depths) and groundwater table sporadically (it means every two weeks hopefully). So we use rainfall-isotope conc. as input.

We use the other sporadic isotope concentrations (in soil, plant, groundwater) as observation data for inverse modeling in Hydrus-1D. In inverse modeling we optimize the unknown parameters related to water flow (vG parameters, Feddes parameters) and solute transport (dispersivity, solute root uptake etc.).

Once we get the optimized parameters, we can have fun and run long-term simulations with known precipitation, known rainfall-isotope and calculate soil residence time, or travel times from rainfall to transpired water or to groundwater in each site. Please, let me know. I think it is getting quite clear so far."

In the PRIN WATZON activities, we sample the isotope concentration in the rainfall (very frequently!), plant, soil (at different depths) and groundwater table sporadically (it means every two weeks hopefully). So we use rainfall-isotope conc. as input.

We use the other sporadic isotope concentrations (in soil, plant, groundwater) as observation data for inverse modeling in Hydrus-1D. In inverse modeling we optimize the unknown parameters related to water flow (vG parameters, Feddes parameters) and solute transport (dispersivity, solute root uptake etc.).

Once we get the optimized parameters, we can have fun and run long-term simulations with known precipitation, known rainfall-isotope and calculate soil residence time, or travel times from rainfall to transpired water or to groundwater in each site. Please, let me know. I think it is getting quite clear so far.