Adaptation of pressurized irrigation networks to new strategies ofirrigation management: Energy implications of low discharge andpulsed irrigation

This paper analyzes the consequences of adopting new on-farm irrigation management strategies (lowdischarge rates, long irrigation times and high frequencies) in an existing on-demand and sectorizedpressurized irrigation system in eastern Spain. The sectorized behavior of the network was analyzedusing two criteria: (i) the operating sectors obtained in a first stage by arranging the hydrants dependingon their altitude respecting the pumping station and (ii) the operating sectors obtained by means ofan optimization process. The Simulated Annealing combinatorial metaheuristic optimization techniquewas employed to find the best solution. Random on-demand patterns were generated using a Montecarlosimulation. The hydraulic requirements of the network were analyzed in every scenario by the Epanet2.0 engine. The effect on energy consumption, power requirements and energy costs was assessed takinginto account the electricity tariff billing structure. It was found that reductions in emitter discharge (qe)and Energy consumption (E)-Energy Cost (EC) savings are not inherently related to each other. Certainamounts of E and EC could be saved when the number of sectors and operating time parameters wereproperly selected. Pulsed irrigation in the current scenario showed an energy saving potential of 10.67,6.43 and 6.99% for power capacity, E and EC, respectively.The study has been partially funded by the IMPADAPT project (CGL2013-48424-C2-1-R) with Spanish MINECO (Ministerio de Economia y Competitividad) and Feder funds.Garcia-Prats, A.; Guillem Picó, S. (2016). Adaptation of pressurized irrigation networks to new strategies ofirrigation management: Energy implications of low discharge andpulsed irrigation. Agricultural Water Management. 169:52-60. https://doi.org/10.1016/j.agwat.2016.02.023S526016

Influence of pore-scale heterogeneity on the precipitation patterns in Microbially Induced Calcite Precipitation (MICP)

The principle of tailoring material properties to improve the mechanical behaviour of soils through compaction or cement grouting dates to the 60s. The increasing trends of urbanization worldwide require new solutions for the development of resilient and sustainable infrastructures. During the past decades, a new field has emerged, pushing the boundaries of ground improvement towards new frontiers. This is no other than the field of biogeotechnologies, which is commonly referred to the biomediated soil improvement technology Microbially Induced Calcite Precipitation (MICP) or biocementation. MICP harnesses microbial activity that facilitates the formation of calcium carbonate precipitates that fill the pores and can improve the mechanical properties of the soil. Despite significant steps towards the characterization and application of MICP, less is known about the effect of the available pore network of various base materials on the MICP process. This is considered to be fundamental towards understanding and addressing precipitation inhomogeneities, which result from flushing porous media with bacterial suspensions and calcifying solutions to induce the formation of biocementing binders. The present thesis focuses on the effect of pore-scale heterogeneity on the precipitation patterns and deposition in MICP. Observations at the pore-scale were coupled to macroscale observations of chemical reaction efficiency and permeability. This multi-scale approach was achieved with the use of experiments in meter-long microfluidics and time-lapse microscopy. By means of this novel experimental setup that encompassed periodic pressure measurements, and an image processing algorithm that was developed in the context of this thesis, the spatiotemporal evolution of MICP along distance of the treated medium and the resulting permeability change were investigated. By applying the same MICP injection strategy in triplicates in the two microfluidic replica of homogeneous and heterogeneous porous media of same porosity, the results revealed that despite a similar bacterial distribution across the whole chip, the chemical reaction efficiency was higher in the heterogeneous than the homogeneous porous medium. This higher chemical reaction efficiency in the heterogeneous porous medium stems from a combination of higher number and slightly higher average size of crystals, as well as a higher precipitation rate in the heterogeneous than the homogeneous porous medium. Through a second set of experiments, the effect of pore network heterogeneity on the deposition of calcite during MICP in glass bead columns that comprised of three distinctive granulometries of increasing gradation, namely a uniform, poorly-graded and well-graded one was investigated. The analysis was conducted by combining bench-scale experiments with chemi-cal monitoring, micro-computed tomography and numerical simulation of absolute permeability using the reconstructed 3D volumes. Collectively, the results suggested distinctive precipitation patterns in porous media that were subjected to the same MICP treatment due to their intrinsic structure.LM

ΑΡΙΘΜΗΤΙΚΗ ΕΠΙΛΥΣΗ ΤΗΣ ΤΡΙΣΔΙΑΣΤΑΤΗΣ ΑΞΟΝΟΣΥΜΜΕΤΡΙΚΗΣ ΔΙΗΘΗΣΗΣ ΣΕ ΑΚΟΡΕΣΤΟ ΕΔΑΦΟΣ

In the present study we present and discuss the numerical solution of the equation of three-dimensional axisymmetric infiltration of water in homogeneous unsaturated soil. On the surface of the soil a constant pressure head is being applied in horizontal circular surface area of ratio Ro. The mathematical model consists of the differential equation of flow that describes the physical problem and the necessary initial and boundary conditions. The solution is obtained by the finite difference method. The alternation direction and implicit (A.D.I.) numerical method that was used for the solution of the flow equation gave results that were verified with the maintenance of the soil water volume balance in very satisfactory levels. In addition, due to the strong nonlinearity of the flow equation, the stability of the numerical solution was verified by the computer results.Στην παρούσα μελέτη παρουσιάζουμε και συζητούμε την αριθμητική επίλυση της εξίσωσης της τρισδιάστατης αξονοσυμμετρικής διήθησης του νερού σε ομογενές ακόρεστο έδαφος. Στην επιφάνεια του εδάφους εφαρμόζεται νερό με σταθερό φορτίο πίεσης σε οριζόντιες κυκλικές λεκάνες ακτίνας Ro. Το μαθηματικό ομοίωμα αποτελείται από τη διαφορική εξίσωση ροής που περιγράφει το φυσικό πρόβλημα και τις απαραίτητες αρχικές και οριακές συνθήκες. Η επίλυσή του γίνεται με τη μέθοδο των πεπερασμένων διαφορών. Η πεπλεγμένη μέθοδος των εναλλασσόμενων διευθύνσεων (A.D.I) που χρησιμοποιήθηκε για την επίλυση της εξίσωσης ροής έδωσε αποτελέσματα τα οποία επαληθεύθηκαν με τη διατήρηση σε πολύ ικανοποιητικά επίπεδα του ισοζυγίου όγκου του εδαφικού νερού. Επίσης λόγω της ισχυρής μη γραμμικότητας της εξίσωσης ροής η ευστάθεια της αριθμητικής λύσης ελέγχθηκε στα αποτελέσματα που έδωσε ο ηλεκτρονικός υπολογιστής

ANALYSIS OF LOCAL INFILTRATION FROM : 1. SURFACE POINT SOURCE OF TRICKLE IRRIGATION. 2. SURFACE LINE SOURCE OF TRICKLE IRRIGATION.

Στην παρούσα μελέτη παρουσιάζεται η ανάλυση της τοπικής διήθησης από : α. σημειακή και β. γραμμική επιφανειακή πηγή στάγδην άρδευσης σε τρία ομογενή ακόρεστα εδάφη και για διάφορες παροχές εφαρμογής. Το μαθηματικό μοντέλο αποτελείται από τη διαφορική εξίσωση ροής που περιγράφει τα φυσικά προβλήματα και τις απαραίτητες αρχικές και οριακές συνθήκες. Για την αριθμητική επίλυση της εξίσωσης ροής χρησιμοποιήθηκε η πεπλεγμένη μέθοδος των εναλλασσόμενων διευθύνσεων (Α.D.I). Η σύγκλιση τού αριθμητικού σχήματος λόγω έλλειψης αναλυτικής λύσης επαληθεύεται με τη διατήρηση σε πολύ ικανοποιητικά επίπεδα του ισοζυγίου όγκου του εδαφικού νερού.In the present study it is presented the analysis of local infiltration from : a. surface Point source and b. surface line source of trickle irrigation in three homogeneous, unsaturated soils using various wetting rates. The mathematical model consists of the differential equation of flow that describes the physical problems and the necessary initial and boundary conditions. The Alternating Direction Implicit Method (A.D.I) was used for the numerical solution o¥ the {low equation. The convergence of the numerical scheme, due to lack of an analytical solution, is verified by the maintenance of the soil water volume balance in very satisfactory levels

THE EFFECT OF DISCHARGE RATE AND APPLIED IRRIGATION DEPTH ON SOIL MOISTURE DISTRIBUTION IN IRRIGATION FROM SURFACE POINT SOURCE

Στην παρούσα εργασία παρουσιάζεται η τοπική διήθηση από επιφανειακή πηγή στάγδην άρδευσης, λαμβάνοντας υπόψη την εξάτμιση του νερού από την επιφάνεια του εδάφους καθώς επίσης και τη μύζηση του εδαφικού νερού από τις ρίζες. Το φυσικό φαινόμενο προσομοιώνεται με ένα μαθηματικό μοντέλο αξονικής συμμετρίας. Η διαφορική εξίσωση που το περιγράφει επιλύεται αριθμητικά με τη πεπλεγμένη μέθοδο εναλλασσόμενων διευθύνσεων. Η εφαρμογή του μοντέλου γίνεται σε μια από τις δώδεκα εδαφικές κλάσεις της U.S.D.A. (Schaap and Leij, 1998). Επίσης χρησιμοποιούνται δύο παροχές σταλακτήρων (2 και 4 l/h) και δύο δόσεις άρδευσης (18 και 30 mm).In the present paper is presented the local infiltration from surface point source, taking into consideration the evaporation of water from the soil surface as well as the water extraction by roots. The physical phenomenon is simulated with the help of a mathematical model of axial symmetry. The differential equation that describes it is solved numerically with the Alternating Direction Implicit method. The implementation of the mathematical model took place against one of the twelve USDA soil classes (Schaap and Leij, 1998). Also, it were used 2 discharge rates (2 and 4 l/h) and two applied irrigation depths (18 and 30mm)