GEOtop (PDE based) vs NewAGE (ODEs based)

This is a the oster we'll present at Tübingen on April 5 during the 2018 Hydromod Conference. It argues about process-based modelling and lumped modelling, intending that the first type of models solve partial differential equations (PDEs), the second (ODEs).

Clicking on the figure above you can access the pdf of the file and read the Q-codes, if you like. Q-codes refers to other posts in abouthydrology. Therefore as an alternative you can browse the blog for them.

Making a good poster

Everybody fight for having an oral presentation at conferences. However, a poster is often not a bad idea. A poster is like a resume. His scope is not to tell everything about your work, but to attract potentially interested people from who you can have nice conversations, learn something, start a collaboration. To get the general idea of an award winning poster, give a close look to the poster below, that is part of a dedicated page on Nature.

A less traditional layout is the one of the poster to which I dedicated the first post of this year. Finally informative guidelines by:

• Nature journal
• Cornell Center for Material Research
• Liverpool University
• Colin Purrington's templates
• McDermott poster story

Obviously, it is assumed that you have something to tell (but this is another topic). 

Designing storm waters managements systems

We are arrived then to design a storm water management system. Which are the requirements ? Which are the typical case studies ? Which are the tools for making the right estimations ? These lectures start to give an answer.

Criteri di progettazione delle Fognature pluviali

Esempi di due interventi di progettazione e/o riprogettazione delle fognature pluviali

Criteri di dimensionamento speditivo delle reti di fognatura pluviale (Parte I)

Criteri di dimensionamento speditivo delle reti di fognatura pluviale (Parte II)

Criteri di dimensionamento speditivo delle reti di fognatura pluviale (Parte III)

Using the linear reservoir model to infer the maximum discharge of a hydraulic network

Ancora sul calcolo del diametro interno (speditivo) dei tubi di fognatura

A short introduction to precipitation and precipitation statistics

I am sharing here the videos of my lectures, in Italian, about precipitations. They were performed during my today class of Hydrology, whose main site is here. More material on precipitations can be found in this old post.

Precipitation: a short introduction

Statistical properties of precipitation on the ground

The concept of return period

Intensity-Duration-Frequency curves (and return period again)

Gumbel distribution function

Interpolating Gumbel with the moments method

Interpolating Gumbel with the maximum likelihood method

Interpolating Gumbel with the minimum squares method

Illustrating the Pearson's test

A deeper explanation of Pearson's test (and a little of hypothesis testing)

Alternative videos for some of the topics are available here.

The Generalised extreme value distribution

Some on statistic of extreme precipitations

These are the lectures that regard the interpolation of Intensity-Duration-Frequency (IDF) curves to rainfall estreme datas. It is covered a  little of theory which will be subsequently used to practically interpolate some data sets. These lectures are part of the class of Hydraulic Constructions and Hydrology held at the University of Trento.

Intensity-duration-frequency curves definition

The Gumbel distribution

Moments method

Maximum likelihood

Minimum squares

Open Science Frameworks 4 Italians

For enjoinment of my students, I prepare some slides and and gave a brief introduction to the Open Science Framework in Italian that can be of help for anyone.

The slides can be found here.

Using the slides I gave this talk.

However, I also make a short practical presentation.

They obviously do not substitute the much more comprehensive YouTube in English

and the quite extensive help.

Water viscosity

“Viscosity is a property of the fluid which opposes the relative motion between the two surfaces of the fluid that are moving at different velocities. In simple terms, viscosity means friction between the molecules of fluid. When the fluid is forced through a tube, the particles which compose the fluid generally move more quickly near the tube's axis and more slowly near its walls; therefore some stress (such as a pressure difference between the two ends of the tube) is needed to overcome the friction between particle layers to keep the fluid moving.” (Source Wikipedia)

One relevant point for us is that water viscosity changes with temperature in a non neglibile way between -10 and 40 centigrades, temperature that many soils can across easily in different seasons: this table shows how much. A model for water viscosity in a large range of temperatures is given by Kestin et al. [1978], which can be used in models.
Viscosity is actually so important that an entire website is dedicated to its experimental values of viscosity: viscopedia. Same information can also be read from this other informative website about water as a substance.
Viscosity variation is usually forgotten in hydrological modelling and the fact that water travels two times faster (at least) in summer than in winter is usually forgotten in any model of runoff production. It is probably time that we incorporate such effects in our modelling of infiltration, and for what regards me, in our numerical integrator of Richards equation.
When dealing with infiltration, in hydrologically realistic contexts, papers by Constanz and coworker are a standard reference, starting from Constantz [1981], Ronan et al, 1998, and Costantz and Murphy [1991]. Papers citing them are also interesting (here the Scopus list) and cover quite recent works too. We can identify two issues (the usual ones): first it is necessary to understand how viscosity variation affects equations of flow, secondly how these affect a heterogeneous landscape.
Grifoll et al (2005), in analysing the problem of water vapor transport, independently if you like or not their solutions, contains the right equations, and can be an help to write yours.
A related question is if temperature alters also the soil water retention curves. This problem is faced by a recent paper by Roshani and Sedano [2016] but it is still clearly an open problem.

I did not start really reading these papers. However, here it is their list below.

• Constantz, J. (1981). Temperature Dependence of Unsaturated Hydraulic Conductivity of Two Soils. Soil Sci. Soc. Am. J., 46, 466–470. 
• Constantz, J., & Murphy, F. (1991). The temperature dependence of ponded infiltration under isothermal conditions. Journal of Hydrology, 122, 119–128.. 
• Grifoll, J., Gastó, J. M., & Cohen, Y. (2005). Non-isothermal soil water transport and evaporation. Advances in Water Resources, 28(11), 1254–1266. http://doi.org/10.1016/j.advwatres.2005.04.008
• Hopmans, J. W., & Dane, J. H. 1986). Temperature Dependence of Soil Hydraulic Properties. Soil Sci. Soc. Am. J., (50), 4–9. 
• Jaynes, D. B. (2002). (1990) Temperature Variations Effect on Field-Measured Infiltration, 1–8. 
• Kestin, J., Sokolov, M., & Wakeham, W. A. (1978). Viscosity of Liquid Water in the Range -8 C to 150 C. J. Phys. Chem. Ref. Data, 7(3), 941–048. 
• Ronan, A., Prudic, D., Thodal, C., & Constantz, J. (1998). Field study and simulation of diurnal temperature effects on infiltration and variably saturated flow beneath an ephemeral stream. Water Resources Res., 34(9), 2137–2153. 
• Roshani, P., & Sedano, J. Á. I. (2016). Incorporating Temperature Effects in Soil-Water Characteristic Curves. Indian Geotechnical Journal, 46(3), 309–318. http://doi.org/10.1007/s40098-016-0201-y