Claudio Gandolfi

Improved plant resistance to drought is promoted by the root‐associated microbiome as a water stress‐dependent trait

Although drought is an increasing problem in agriculture, the contribution of the root-associated bacterial microbiome to plant adaptation to water stress is poorly studied. We investigated if the culturable bacterial microbiome associated with five grapevine rootstocks and the grapevine cultivar Barbera may enhance plant growth under drought stress. Eight isolates, over 510 strains, were tested in vivo for their capacity to support grapevine growth under water stress. The selected strains exhibited a vast array of plant growth promoting (PGP) traits, and confocal microscopy observation of gfp-labelled Acinetobacter and Pseudomonas isolates showed their ability to adhere and colonize both the Arabidopsis and grapevine rhizoplane. Tests on pepper plants fertilized with the selected strains, under both optimal irrigation and drought conditions, showed that PGP activity was a stress-dependent and not a per se feature of the strains. The isolates were capable of increasing shoot and leaf biomass, shoot length, and photosynthetic activity of drought-challenged grapevines, with an enhanced effect in drought-sensitive rootstock. Three isolates were further assayed for PGP capacity under outdoor conditions, exhibiting the ability to increase grapevine root biomass. Overall, the results indicate that PGP bacteria contribute to improve plant adaptation to drought through a water stress-induced promotion ability.

Coupled SVAT–groundwater model for water resources simulation in irrigated alluvial plains

Understanding the interaction between soil, vegetation and atmosphere processes and groundwater dynamics is of paramount importance in water resources planning and management in extensively irrigated alluvial plains. This is the case, for example, of the most important agricultural and industrial area in Italy, the Padana Plain, where intensive exploitation of groundwater for domestic and industrial supply coexists with massive diversions from surface water bodies, providing abundant irrigation to one of the most productive agricultural districts in Europe. The paper presents a simulation system which reproduces the hydrological processes relevant in alluvial irrigated plains. In particular, it allows the evaluation of the distribution of crop water consumption in space and time, as well as simulation of the interaction between recharge and groundwater dynamics. The simulation code is based on the coupling of two models: a conceptual vadose zone model and the groundwater flow model MODFLOW. Additional code was written to provide an interface which performs the explicit coupling in space and time between the two models. A geographical information system (GIS) manages the spatially distributed inputs, parameters and outputs of the system. An application of the package to a large irrigation district, of approximately 700 km2, located in the middle of the Padana Plain, is also discussed in the paper.

IDENTIFICATION AND ANALYSIS OF NATURAL CHANNEL NETWORKS FROM DIGITAL ELEVATION MODELS

The identification and analysis of natural channel networks from digital elevation models are discussed from the point of view of their environmental applications. An interactive, graphical software package that implements some of the most widely used techniques for the automatic recognition of channel networks and for the computation of some useful geomorphologic indices and functions is presented.

A coupled human‐natural systems analysis of irrigated agriculture under changing climate

Exponentially growing water demands and increasingly uncertain hydrologic regimes due to changes in climate and land use are challenging the sustainability of agricultural water systems. Farmers must adapt their management strategies in order to secure food production and avoid crop failures. Investigating the potential for adaptation policies in agricultural systems requires accounting for their natural and human components, along with their reciprocal interactions. Yet this feedback is generally overlooked in the water resources systems literature. In this work, we contribute a novel modeling approach to study the coevolution of irrigated agriculture under changing climate, advancing the representation of the human component within agricultural systems by using normative meta-models to describe the behaviors of groups of farmers or institutional decisions. These behavioral models, validated against observational data, are then integrated into a coupled human-natural system simulation model to better represent both systems and their coevolution under future changing climate conditions, assuming the adoption of different policy adaptation options, such as cultivating less water demanding crops. The application to the pilot study of the Adda River basin in northern Italy shows that the dynamic coadaptation of water supply and demand allows farmers to avoid estimated potential losses of more than 10 M€/yr under projected climate changes, while unilateral adaptation of either the water supply or the demand are both demonstrated to be less effective. Results also show that the impact of the different policy options varies as function of drought intensity, with water demand adaptation outperforming water supply adaptation when drought conditions become more severe.

Modeling water resources of a highly irrigated alluvial plain (Italy): calibrating soil and groundwater models

Modern and effective water management in large alluvial plains that have intensive agricultural activity requires the integrated modeling of soil and groundwater. The models should be complex enough to properly simulate several, often non-linear, processes, but simple enough to be effectively calibrated with the available data. An operative, practical approach to calibration is proposed, based on three main aspects. First, the coupling of two models built on well-validated algorithms, to simulate (1) the irrigation system and the soil water balance in the unsaturated zone and (2) the groundwater flow. Second, the solution of the inverse problem of groundwater hydrology with the comparison model method to calibrate the model. Third, the use of appropriate criteria and cross-checks (comparison of the calibration results and of the model outputs with hydraulic and hydrogeological data) to choose the final parameter sets that warrant the physical coherence of the model. The approach has been tested by application to a large and intensively irrigated alluvial basin in northern Italy.RésuméLa gestion moderne et efficace de l’eau dans les grandes plaines alluviales siège d’une agriculture intensive requiert la modélisation intégrée du sol et des eaux souterraines. Les modèles doivent être suffisamment complexes pour simuler correctement plusieurs processus souvent non linéaires, mais suffisamment simples pour être calibrés efficacement avec les données disponibles. Une approche de calibration pratique et opérationnelle est proposée, basée sur trois aspects principaux. Premièrement, le couplage de deux modèles construits sur des algorithmes bien validés, pour simuler (1) le dispositif d’irrigation et le bilan en eau du sol au sein de la zone non saturée et (2) l’écoulement d’eau souterraine. Deuxièmement, la résolution du problème hydrogéologique inverse avec la Méthode de Comparaison de Modèle pour caler le modèle. Troisièmement, l’utilisation de critères appropriés et de vérifications croisées (comparaison des résultats du calage et des sorties du modèle avec des données hydrologiques et hydrogéologiques) pour choisir les jeux de paramètres finaux qui garantissent la cohérence physique du modèle. L’approche a été testée par application à un vaste bassin alluvial intensément irrigué du Nord de l’Italie.ResumenEl manejo moderno y efectivo del agua en grandes planicies aluviales que tienen una intensa actividad agrícola requiere el modelado integrado del suelo y del agua subterránea. Los modelos deber ser lo suficientemente complejos como para simular correctamente varios procesos, a menudo no lineales, pero lo suficientemente simple para ser efectivamente calibrado con los datos disponibles. Se propone un enfoque práctico y operativo de la calibración, basada en tres aspectos principales. Primero, el acoplamiento de dos modelos construidos sobre algoritmos bien validados, para simular (1) el sistema de irrigación y el balance de agua en el suelo en la zona no saturada y (2) el flujo de agua subterránea. Segundo, la solución del problema inverso de hidrología de agua subterránea con el Método de comparación de modelos para calibrar el modelo. Tercero, el uso de criterios apropiados y controles cruzados (comparación entre los resultados de la calibración y las salidas del modelo con los datos hidrogeológicos e hidráulicos) para elegir el conjunto de parámetros finales que garanticen la coherencia física del modelo. El enfoque ha sido probado por su aplicación a una gran cuenca aluvial, intensamente irrigada en el norte de Italia.摘要在有密集型农业活动的大型冲积平原进行有效的现代水资源管理需要对土壤和地下水进行综合模拟。模型需要足够复杂,以模拟几种常见的非线性的过程,同时又要足够简单,能够采用现有数据进行校准。本文主要基于以下三个方面,提出了一个具备可操作性且符合实际的校准方法:1. 基于有效算法的两种模型的耦合,以模拟(1)非饱和带灌溉系统和土壤水平衡和(2)地下水流。2. 针对地下水文学的反演问题,采用比较法去校正模型。3.使用合适的准则和交互检验(根据水力和水文地质数据,比较模型的校准结果和模型输出结果)去选择最后的参数设置以确保模型的物理一致性。将该方法已经应用在意大利北部的一个大型密集灌溉冲积平原中进行ResumoUma moderna e eficaz gestão da água nas grandes planícies aluviais com atividade agrícola intensiva requer uma modelação integrada do solo e das águas subterrâneas. Os modelos devem ser suficientemente complexos para simular adequadamente vários processos, muitas vezes de caraterísticas não-lineares, mas suficientemente simples para serem adequadamente calibrados com os dados disponíveis. Neste artigo é proposta uma abordagem para calibração baseada em três aspetos principais. Primeiro, o acoplamento de dois modelos construídos sobre algoritmos bem validados, para simular (1) o sistema de rega e balanço hídrico do solo na zona não saturada e (2) o fluxo de águas subterrâneas. Segundo, uma solução do problema inverso da hidrologia subterrânea, baseada no Método de Comparação do Modelo para calibrar o modelo. Terceiro, o uso de critérios adequados e validações cruzadas (comparação dos resultados de calibração com as saídas do modelo com dados hidráulicos e hidrogeológicos), de modo a selecionar o conjunto final de parâmetros que garantem a coerência física do modelo. A abordagem tem sido testada numa bacia aluvial extensa e intensamente sujeita a rega, localizada no norte da Itália.

Optimal Flow Allocation in the Zambezi River System

The optimal flow allocation in the Zambezi system, the largest multi-reservoir water resources system in southern Africa, is analysed. The problem is formulated in network terms and solved with a network flow algorithm. The present configuration of the system is taken as the reference to evaluate the benefits of the proposed modifications to the existing hydropower schemes. The introduction of additional operational constraints is also considered in order to analyse the costs of environmental protection of paludal ecosystems and to account for secondary objectives (e.g. irrigation, fishery, navigation). The results show that the upgrade of Kafue Gorge scheme through the addition of a new generator stage is the most advantageous from the hydropower production view point. In addition, the protection of paludal ecosystems through periodic controlled flooding and an increase of withdrawals for irrigation purposes may be achieved without dramatically changing the hydroelectric energy production.

An integrated, multisensor system for the continuous monitoring of water dynamics in rice fields under different irrigation regimes

The cultivation of rice, one of the most important staple crops worldwide, has very high water requirements. A variety of irrigation practices are applied, whose pros and cons, both in terms of water productivity and of their effects on the environment, are not completely understood yet. The continuous monitoring of irrigation and rainfall inputs, as well as of soil water dynamics, is a very important factor in the analysis of these practices. At the same time, however, it represents a challenging and costly task because of the complexity of the processes involved, of the difference in nature and magnitude of the driving variables and of the high variety of field conditions. In this paper, we present the prototype of an integrated, multisensor system for the continuous monitoring of water dynamics in rice fields under different irrigation regimes. The system consists of the following: (1) flow measurement devices for the monitoring of irrigation supply and tailwater drainage; (2) piezometers for groundwater level monitoring; (3) level gauges for monitoring the flooding depth; (4) multilevel tensiometers and moisture sensor clusters to monitor soil water status; (5) eddy covariance station for the estimation of evapotranspiration fluxes and (6) wireless transmission devices and software interface for data transfer, storage and control from remote computer. The system is modular and it is replicable in different field conditions. It was successfully applied over a 2-year period in three experimental plots in Northern Italy, each one with a different water management strategy. In the paper, we present information concerning the different instruments selected, their interconnections and their integration in a common remote control scheme. We also provide considerations and figures on the material and labour costs of the installation and management of the system.

Is soil water potential a reliable variable for irrigation scheduling in the case of Peach Orchards

Abstract Monitoring the crop water status of high-value crops such as fruit trees is generally performed through periodic measurements of physiological indicators on leaves or fruits using sophisticated instruments and complex procedures. These measurements are very often difficult to translate into irrigation advice. Soil water potential (SWP), however, is a basic soil water status variable that is correlated with plant water uptake, and it can easily be measured using sensors. Soil water potential can provide useful support for irrigation scheduling at the field scale, thus enhancing water savings in agricultural areas. In this work, we present the results of an experimental study conducted in the 2014 agricultural season on a peach orchard located in Lodi (Northern Italy). The purpose of this study was to evaluate the effects of an irrigation scheduling based on continuous SWP measurements collected at two soil depths (−15 and −35 cm) on the crop water status and the peach production relative to the farmer’s commonly adopted irrigation practice. To answer the question in the title, periodic measurements of physiological parameters such as leaf water potential, stomatal resistance (rs), transpiration (E), and crop water stress index were performed, along with monitoring of fruit size evolution and fruit sugar content at harvest. All of these variables were measured to assess the crop physiological state of the trees subjected to the two different irrigation treatments, with the final objective of determining whether the irrigation scheduling based on SWP measurements compromised the quality and quantity of produced peaches. Although obtained for only one agricultural season, the results showed that no considerably crop water stress occurred, even for the irrigation treatment based on SWP measurements. In particular, the most extreme values of leaf water potential, rs, E, and crop water stress index measured at midday were −2 MPa, 45 s m−1, 1.4 mm h−1 and 0.5, respectively, which are in good agreement with those observed in many studies for well-watered orchards in Mediterranean areas. In conclusion, we can stress that SWP monitoring can be considered to be a reliable alternative to the more costly and time-consuming physiological measurements for the irrigation scheduling of fruit crops such as peach orchards. This approach provides continuous information about the soil water status, thereby preventing plant water stress and reducing irrigation water consumption at the farm scale.

Integrated catchment modelling and decision support

This issue of Environmental Modelling and Software contains a selection of papers on the role of integrated modelling in supporting decision processes addressing regional catchment management issues. The papers have been selected from two sessions of the International Environmental Modelling Software Society (iEMSS) conference, held in Lugano, Switzerland, in June 2002 and all have a water allocation and management focus. Much of the emphasis of catchment management today, and thus the focus of catchment modelling, is on the prediction of the impact of proposed changes in water management, land management, or land use on the catchment character. In the past, much of this modelling has been to support decision makers within planning or resource management agencies. Increasingly, this decision-making is being taken into the public forum and integrated catchment models are being used to facilitate debates and consultation between the various stakeholders in regional planning exercises. Traditionally prediction of impacts has been confined to biophysical characteristics such as stream flow and water quality. While this has served the engineering community well, today’s more open and participatory approach to catchment management must also consider impacts on the human landscape. In fact, within the European region, the use of models and evaluation of environmental and social impacts is specifically included in the prospectus of the Water Framework Directive (2000/60/EC) of the European Union. Indeed, it is legislated that, by 2009, each European basin must have a plan that clearly specifies the interventions required to meet set water quality conditions, and the integrated approach to be followed. In this issue, we have assembled practical examples of integrated catchment modelling applications. These illustrate the wide-ranging nature of integrated catchment modelling and the contribution that it can make to the complex debate over resource development and resource conservation. The papers describe modelling work to support decision making at a range of scales, in both regulated and unregulated catchments, and for a range of users. The genesis of the modelling systems is interesting. Most have been commissioned by water management or regulatory bodies (eg water department or environmental protection agencies) to model likely impacts of alternate

Flow velocity measurement in Italy between Renaissance and Risorgimento

A review of the main instruments developed in Italy over more than two centuries to measure flow velocity of experience is presented, highlighting the relation with the development of hydraulics as a physical–mathematical science from the seventeenth century. The number and variety of Italian velocity meters partly reflect the vitality of a tradition, characterized by political polycentrism and rivalry among the individual cities and universities. In other aspects, the invention of ever-newer measuring instruments corresponds to the attitude of many of the early Italian hydraulicians, who interpreted hydraulics as a science of nature, based almost exclusively on observation and experience, which requires rather the gift of intuition than mathematical deduction. This work is part of a project of the BEIC Library and of the University of Milan, which will make available digital versions of hundreds of Italian historic texts of hydraulics on the portal www.beic.it.