SPFC: a tool to improve water management and hay production in the Crau region

Correspondance: [email protected] ; UMR SYSTEM équipe CONSYSTThis article deals with the development and application of SPFC, a model used to improve water and grassland production (HC) in this region of France. This model is composed of two sub-models: an irrigation model and a crop model. As the fields are border irrigated, these two sub-models are coupled. The crop model simulates dry matter, Leaf Area Index (LAI) and soil water reserve (SWR) variations. LAI and SWR are both used for border model updating: SWR for the deficit of saturation required by the infiltration equation and LAI for the roughness coefficient n. After calibration and validation, SPFC is then used to identify realistic management strategies for the irrigation and production system at the plot level. By scheduling irrigation when SWR is 50% depleted, would result in a low Dry Matter DM production loss (around 10%), reduced labour (8 irrigation events instead of 11) and in significant water saving compared with farmers' practices, on the basis of an average climatic scenario. Furthermore, this improvement of irrigation efficiency is not incompatible with groundwater recharge used for the potable water supply of the region

Le goutte à goutte enterré : une solution innovante pour irriguer sous conditions restrictives en eau

La mise en oeuvre de techniques d'irrigation innovantes telles que le goutte à goutte enterré est la solution adoptée par la plupart des pays confrontés aux problèmes de pénurie d'eau en raison de sa très bonne efficience. De plus en plus de régions françaises étant soumises à des restrictions d'eau, sa possible utilisation pour irriguer les grandes cultures est à l'ordre du jour

Effect of cropping strategies on irrigation water productivity of durum wheat

The interest of irrigation for durum wheat is often questionable because of possible spring rainfalls in the SE of France. In this study cropping strategies i.e. plant density (PD), sowing date and irrigation management were analysed for improving irrigation water productivity (IWP). An experiment was carried out for calibrating and validating PILOTE model. An adaptation of the potential harvest index to PD was implemented in PILOTE. The latter satisfactory simulates different model outputs with coefficients of efficiency greater than 0.97. The model was employed for simulating the impact of cropping strategies on IWP for a long climatic series. According to model simulations, the necessity of irrigation is questionable under our conditions. IWP was notably lower under high PD than under low PD for the same sowing date. Under low PD and without irrigation it would be possible to obtain a yield similar to that obtained under high PD with irrigation

Disentangling the complexity of groundwater dependent social-ecological systems

Groundwater resources are part of larger social-ecological systems. In this chapter, we review the various dimensions of these complex systems in order to uncover the diversity of elements at stake in the evolution of an aquifer and the loci for possible actions to control its dynamics. Two case studies illustrate how the state of an aquifer is embedded in a web of biophysical and sociopolitical processes. We propose here a holistic view through an IGM-scape that describes the various possible pathways of evolution for a groundwater related social-ecological system. Then we describe the elements of this IGM-scape starting with physical entities and processes, including relations with surface water and quality issues. Interactions with society bring an additional layer of considerations, including decisions on groundwater abstraction, land use changes and even energy related choices. Finally we point out the policy levers for groundwater management and their possible consequences for an aquifer, taking into account the complexity of pathways opened by these levers

Using a furrow system for surface drainage under unsteady rain

Water excess during winter limits crop development on heavy clay soil conditions of the Gharb valley (Morocco). The furrow system to eliminate these negative effects is the adopted solution. This article focuses on the development of a water transfer model through a furrow system during unsteady rainfall event to evaluate the runoff volume resulting from a reference rainy event. This model contains a production function associated to a transfer function. The production function is based on the Green-Ampt infiltration equation. The latter has been adapted to account for unsteady rain conditions and rainfall intermittence. The transfer function is based on the kinematic wave model, the explicit solution of which is coupled with the water excess generated by the production function. Simulated runoff in the furrows is collected by a drainage ditch evacuating the flow outside a plot of 1.3 ha. The similarity between parameters of a furrow irrigation model and those of the production function is advantageously used for model calibration. The proposed modelling approach shows capabilities to predict water amount and peak discharges evacuated from a plot of around I ha by a furrow system under unsteady rainfall events. As an application, it is used to evaluate the ability of the surface drainage system to evacuate the excessive volumes of water under typical rainfalls

Appui à la mise en place, au suivi et à l’analyse des résultats d’un dispositif d’irrigation au goutte à goutte enterré. Ferme de la Mirandette 2012

La Compagnie d'Aménagement des Coteaux de Gascogne a fait appel à l'équipe Envirri de l'UMR GEAU pour une aide technique et scientifique à la mise en place de parcelles irriguées en Goutte à Goutte. Un suivi des deux parcelles équipées de Goutte à Goutte enterré en comparaison d'un parcelle en aspersion à été réalisé et à donné lieu à un rapport de synthèse présentant la campagne de maïs 2012