The new call for the 2019 doctoral position is out. I am interested in topic "D1/D2 - Agricultural, Environmental and hydro-meteorological sciences and engineering”. There are a few available doctoral grants which will be given to a selection of applicants, according to the rule specified in the call. I am interested in students who wants actively collaborate to the WATZON Prin Project. So please peruse the WATZONE project's pages to write your personal project which the appllication requires.
Overview of the state of art of our topic
Plants water-use strategies are driven by plant functional traits (PFT) (examples are leaf size, toughness and longevity, seed size and dispersal mode, canopy height and structure, capacity for nitrogen fixation) (Mitchell et al., 2008) and in recent years, plant-physiology studies provided an increasingly detailed knowledge of plants behaviour (Schymanski and Or, 2017), but only some of them started to be inserted in ecohydrological models (e.g. Fatichi et al., 2016). Models simulating plant-hydraulic processes are still rare and confined to specific studies (Hölä et al., 2009; Mackay et al., 2015; Nikinmaa et al., 2014). Other studies account explicitly for topographic attributes and lateral water and mass exchanges (Ivanov et al., 2008; Shen et al., 2013; Tague et al., 2013), but their treatment of plant processes is often oversimplified (Zhou et al., 2013). In mountain terrain, even the effect of plot-scale (0.01-0.1 km2) spatial variability of the energy fluxes is still largely not understood (Rollinson and Kaye, 2015) notwithstanding pioneering stud- ies which account for various feedbacks are available, which show that vegetation productivity and water use do not change linearly through spatial gradients (Niedrist et al., 2016). Research questions addressed
How specific plant water-use strategies can be implemented in hydrological models ?,
Which is the relative role of biotic (PFT) versus abiotic (soils, topography, climate) processes in determining the spatial and temporal variability of ET and soil water?
Which is the right level of complexity necessary in models to upscale R3 results from plants to catchments?
How to take advantage of a combination of advanced multi-sensor, multiscale observations to constrain eco-hydrological models and improve their spatial accuracy?
How to leverage recent theories of transport to implement the solutes dynamics in plants ?
The candidate will take care of implementing, besides the code, the appropriate procedures for continuous integration of the evolving source code, and s/he will be also asked to maintain a regular rate of commits to the common open platform. Despite these conditions, and being free and open source, the code will be intellectual property by the coder. This will be guaranteed also by the components-based infrastructure offered by OMS3, which allows to better define the contributions of anyone. The implementation part will be followed, accompanied by testing activities, either for mathematical consistency, and for physical consistency with experiments and field measurements. The Ph.D. student is intended to produce, besides working and tested codes, also at least three papers in major journals (VQR Class A), of which, at least one as first Author. All the code developed will be done in Github (or similar platform), inside the GEOframe community and will be Open Source according to the GPL v3 license.
The candidate will take care of implementing, besides the code, the appropriate procedures for continuous integration of the evolving source code, and s/he will be also asked to maintain a regular rate of commits to the common open platform. Despite these conditions, and being free and open source, the code will be intellectual property by the coder. This will be guaranteed also by the components-based infrastructure offered by OMS3, which allows to better define the contributions of anyone.The implementation part will be followed, accompanied by testing activities, either for mathematical consistency, than for physical consistency with experiments and field measurements.The Ph.D. student is intended to produce, besides working and tested codes, also at least three papers in major journals (VQR Class A), of which, at least one as first Author. Duration of the doctoral studies is three years.
Further information of the policies of the research group can be found:
We had financed (small financial support indeed) a PRIN project called WATZON (WATer mixing in the critical ZONe: observations and predictions under environmental changes). It was reborn on the ashes of the Water MIX and PRECISE projects and its short description is:
"Sustainable land and water resources management is inextricably linked to a detailed knowledge of water availability in the critical zone (CZ), which is the thin outer layer of the Earth extending from the top of the tree canopy to the bottom of water aquifers, and that controls water quality and quantity, sustaining human activity. The CZ is experiencing ever-increasing pressure due to growth in human population and water demands, and changing climatic conditions. Understanding, predicting and managing intensification of water use and associated economic services in the CZ, while mitigating and adapting to rapid climate change and biodiversity decline, is now one of the most pressing societal challenges of the 21st century. Vegetation is a fundamental element of the CZ, as connects water from different storages in the subsurface zone with water in the lower atmosphere, therefore regulating water fluxes among different compartments of the CZ. Several studies in the last years have examined water mixing processes in the soil-vegetation-atmosphere system. However, because of the large spatio-temporal variability of subsurface water movement and the capability of plants to access water from both deep and shallow sources, and the resulting highly-complex feedbacks in water exchanges between vegetation and other ecohydrological compartments, fundamental scientific questions on the effect of vegetation on the hydrological cycle, especially under different climatic forcing and land-use conditions, remain unanswered. The main objective of the project WATZON (WATer mixing in the critical ZONe: observations and predictions under environmental changes) is to advance the understanding of water mixing in the CZ by investigating ecohydrological processes of water exchange between vegetation and surface and subsurface water compartments.
Specifically, the project aims at:
assessing the description of water mixing process across the CZ by using integrated high-resolution isotopic, geophysical and hydrometeorological measurements from point to catchment scale, under different physiographic conditions and climate forcing;
testing water exchange mechanisms between subsurface reservoirs and vegetation, and to assess ecohydrological dynamics in different environments by coupling the high-resolution data set from different CZ study sites of the project consortium with advanced ecohydrological models at multiple spatial scales;
developing a process-based conceptual framework of ecohydrological processes in the CZ to translate scientific knowledge into evidence to support policy and management decisions concerning water and land use in forested and agricultural ecosystems.
The project objectives will be achieved by integrating different methodological tools, such as environmental tracers (isotopes of hydrogen and oxygen), advanced geophysical measurements and detailed ecohydrological models, to develop an interdisciplinary and holistic comprehension of ecohydrological dynamics under different climatic forcing and land use conditions.
The project will create a new network of study sites in Italy (Critical Zone study sites) representative for different climatic, physiographic and vegetation conditions in the Mediterranean area, including grassland, forested and agricultural ecosystems. High-resolution and detailed experimental data and observations will be collected in a consistent way across all study sites in order to identify water pools potentially involved in ecohydrological water exchanges and fine-study root water uptake dynamics. The high-quality data collected in the field and the experimental results will serve as a basis to implement and apply new-generation, robust, reliable and realistic ecohydrological models aiming at assessing water mixing and exchange mechanisms between subsurface reservoirs, vegetation and atmosphere at the root-plant scale and the stand and catchment scale. Models will be used also to develop scenario-based projections for assessing the impact of land-use change on ecosystem services under different climatic and environmental conditions.
In addition to the foreseen significant advancement of scientific research on water mixing processes in the CZ, the other main impact of WATZON will regard the communication with stakeholders and interaction with the civil society. Involvement of the most relevant stakeholders (e.g., water agencies, river basin authorities, reclamation and irrigation districts, government agencies for forest management and protection, national parks, municipalities and regional councils) will allow to translate the acquired scientific knowledge into practices to support effective and sustainable land and water resources management across a variety of climate and physiographic settings.
WP3 will use data and experimental results provided by the activities to test, implement and apply robust, reliable and realistic (R3) ecohydrological models aiming at assessing water mixing and exchange mechanisms between surface, subsurface reservoirs, vegetation and atmosphere within the CROSSes. Particularly, the models will be applied at three main scales: i) the scale of the roots-stems-leaves apparatus, to analyse vegetation water uptake dynamics and their possible switches over time; ii) the stand and iii) catchment scale, to examine how plant water use affects streamflow generation within different ecohydrological regimes. The starting set of models for the project is composed by GEOtop-dv, JGrass-NewAge (JN), now called GEOframe.
Task 3.1.This task will model ecohydrological processes. Soil water flow will be modelled through 3D Richards equation, with improved parameterizations of soil water retention curves, hydraulic conductivity and treatments of hydraulic conductivity. Interaction between water and roots will be implemented. New schemes of plants hydraulics will be implemented to obtain the partition between evaporation and transpiration. Energy and the carbon budget will be modeled to properly constraint the transpiration production. Tools for accounting for water age, and tracers concentration, will be coupled to the new modules of GEOtop and GEOframe. New gridding and numerics will be devised to mimic the experiments and measurements domains.
Task 3.2. This task will couple field data and ecohydrological models at the root-stem-plant volume scale. Along with the 3D simulations, 1D models will be used. Fluxes will be analysed both in time domain and estimating residence and travel time to cope with tracers at integrated soil-plant scale. These results will be compared with those identified by isotope data and geophysical measurements in project's catchments.
Task 3.3. This task will couple field data and ecohydrological models at the stand and catchment scale. New models of plants communities functioning based on plant functional traits and optimality principles will be introduced, along with the more mechanistic ones. The model results will be compared in CRitical zOne Study Sites –(CROSSes) 2, 4, 5 and 6 against isotope data.
WP3 provide the following deliverables.
Deliverable 3.1: New improved components of the models GEOtop and GEOframe and their documentation at the end of each project’s year (version +1,+2,+3).
Deliverable 3.2: Case studies will be provided for all the experimental sites, using the various versions of the model components. All the material for the simulation will be provided to the research community online by Open Science Framework.
Please find the presentation by clicking on the figure above. Presentation is thought as a sequence of hints to topics I will eventually define better, after having heard what the other participants will say before me. The schedule of the meeting, held at Bocconi University in Milan today is here.
2019 -05-24 - Lab work on infiltration (Richards 1d)
Richards 1d material: Downloading the material at the Github place you get also the documentation. The presentation in /Materials. The Notebook are in the directory /Jupyter_Notebook. Look first at the Notebook "README"
Francesco Serafin is not anymore a Ph.D. student bu a doctor! His work concerned mainly the structure of the Object Modelling System Version 3 especially in two directions: improving the researchers modelling experience and improving the end users experience. You can learn directly from his video how.
The defense had a more than forty minutes of presentation and the same period of discussion. In order, you can find below, the presentation, the YouTube video of the the defense and the discussion (the latter in Italian).
The presentation (by clicking on the Figure):
The Video of the defense
Francesco Serafin Defense 2019-05-10 - YouTube
The Discussion (In Italian)
Discussion at Francesco Serafin Defense 2019-05-10 - YouTube
In many papers that deal with semi-distributed hydrological modelling, it is argued about the models structure, a topic which becomes even more relevant when people talks about uncertainty and attribute to the model structure an error that is named epistemic error. But what is the model structure is rarely discussed in depth. Butts et al. (2004) discusses in an interesting way what this means, citing the book by K. Beven (GS). They said: Beven (2000) breaks down the development of a hydrological model into the following steps:
The Perceptual model: deciding on the processes
The Conceptual model: deciding on the equations
The Procedural model: developing the model code
Model calibration: getting values of parameters
Model validation: confirming applicability and accuracy
Evidently, the concepts that are relevant for defining what a model structure is are the first two: "The selection of specific perceptual and conceptual models determines the model structure. " Model structure includes a whole range of choices and assumptions made by the modeller either explicitly or implicitly in applying a hydrological model. Examples of different model structures include:
different process choices and descriptions
coupling of the processes
representations of the spatial variability-zones, grids, sub-catchments, etc.
element scale and sub-grid process representations including distribution functions, different degrees of lumping, effective parameterisation, etc.
interpretations and classifications of soil type, geology land use cover, vegetation, etc.
There is a great variety of models and mathematical approaches to cope with the above issues. For limiting the discussion, let’s assume to concentrate on those models which are implemented as systems of ordinary differential equations. These models differs, in practice for:
the number of equation (let’s called them places according to our classification of such systems)
the interactions between places (represented by the relative adjacency matrix)
the form of fluxes laws
In particular, point (1) above deals both with the number of processes and the discretisation of the landscape in hydrologic units in space (called representative elementary watersheds REW, e.g. Reggiani et al., 1999 or Hydrologic response units, HRUs, Burges and Kampf, 2008). A recent tradition tried to build a heuristic about how to select appropriately these elements (e.g. Clark et al., 2011; Fenicia et al., 2011, Fenicia et al., 2014, Fenicia et al., 2016) which constitute an interesting reading. Once hydrologic heuristics are applied, we find with the nude set of equations, and it could be interesting to see if there exist methods that can discover and classify the main properties of the dynamical systems which depends on their structure. This problem, indeed, has received a lot of attention in system and control theory (see for e.g. Ljung, 1999 and references therein), mostly to autonomous linear systems.
Some of the aspects, in this case is the discover of T-invariants and P-invariants, or, in a less obscure language, of loops and set of correlated quantities that remains globally (i.e. their sum) stationary (i.e. Gilbert and Heiner, 2006). Other aspects regards reachability, i.e. the prior understanding if a certain distribution of the state variables can be obtained. All these aspect are well dealt within traditional books in system and control theory. Unfortunately the resulting structure of hydrological models is usually non-autonomous (the system are open) and non-linear. All aspects that make investigations more complicate, but probably not unfeasible. A lot of digging in literature and research is necessary though.
At recent EGU General Assembly in Vienna, Daniele Penna was invited to give a talk on recent developments of tracers hydrology. He was so kind to share with me the pdf of his slides, that you can find below by clicking on the Figure.
Below, I am inserting the main paper cited. (Work in progress)
Thomas Dunne (GS) came to Trento one year and a half for research with a colleague. In the ocasion he gave a seminar on his research about Amazonas river that I recorded. I had the permission of posting it after the publishing of a paper that was under submission at that time.
Now the paper is accepted and I've got the permission to go ahead. The seminar is very enjoyable anf you will like it.
Here it is the video
(uploading on YouTube)
Below the Discussion.
Tom Dunne at Trento talking about his research on Amazonas - YouTube
Since 10 year, the Saturday after the EGU meeting, Guenter Bloeschl (GS) organizes at TU Wien a meeting of hydrologists called the Wien Hydrology Symposium. This year among the guest there was Thomas Dunne (GS) who talked about fluvial geomorphology. Tom is universally known for his work as hydrologist and geomorphologist (both of them) and students will realize that saturation excess mechanism of overland flow formation take its name from him as Dunnian runoff. Here you can find a picture of him with my own representation of "his" process.
My draw is also here below for free usage (I have also the image for the Hortonian runoff though).