• Energy Research

Remote sensing estimation of evapotranspiration (ET) was done by combining remote sensing data and the ISBA soil‐vegetation‐atmosphere transfer model over the Alpilles test site. We tested the possible use of low resolution data (∼1km) to derive leaf area index (LAI) at the field scale using a disaggregation method. Disaggregated LAI were then used as inputs of ISBA for monitoring ET for 9 months. Estimation of LAI and ET were first performed at high resolution for being used as reference for evaluating the use of low resolution data. Estimations of LAI at high spatial resolution using an artificial neural network (ANN) algorithm were in very good agreement with ground measurements. At low resolution, we found that it was possible to estimate accurately LAI for the most frequent types of vegetation cover, wheat and sunflower, but not for the other types. However, the estimation of ET from disaggregated low resolution data was found to be quite accurate for any type of vegetation cover (the comparison to h...

Abstract. The Indian and French Space Agencies, ISRO and CNES, have conceptualized a space-borne Thermal Infrared Reflectance (TIR) mission, TRISHNA (Thermal infRared Imaging Satellite for High-resolution Natural Resource Assessment). The primary design drivers of TRISHNA are the monitoring of (i) terrestrial water stress and use, and of (ii) coastal and continental water. A suit of four TIR bands and six optical bands is planned. The TIR bands will be centred at 8.6 μm, 9.1 μm, 10.3 μm and 11.5 μm to provide noon-night global observations at 57m nadir resolution over land and coastal regions. The field of view (FOV) is ±34° and the orbit of 761 km altitude was designed to allow 3 sub-cycle acquisitions during the 8-day cycle. The optical bands correspond to blue, green, red, and NIR plus two SWIR bands at 1.38 μm and 1.61 μm. The green, red, NIR and the 1.61 μm SWIR bands will have better radiometry quality than those of AWiFS. ISRO and CNES will develop optical and TIR payloads, respectively. Assessing evapotranspiration and furthermore Gross and Net Primary Productivity (GPP and NPP) will in turn assist in quantifying water use in rainfed and irrigated agriculture, water stress and water use efficiency, with expected applications to agricultural drought and early warning, crop yield prediction, water allocation, implementation of water rights, crop insurance business and agro-advisories to farmers. The other scientific objectives of TRISHNA are also briefly described. TRISHNA instrument will fly aboard a ISRO spacecraft scheduled to be launched from 2024 for a minimum period of 5 years’ mission lifetime.

Hydrology and crop water management require daily values of evapotranspiration ET at different time-space scale. Sun synchronous optical remote sensing, which allows for the assessment of ET with high to moderate spatial resolution, provides instantaneous estimates during satellites overpass. Then, usual solutions consist of extrapolating instantaneous to daily values by assuming that evaporative fraction EF is constant throughout the day, providing that daily available energy AE is known. The current study aims at deriving daily ET values from ASTER derived instantaneous estimates, over an olive orchard in a semi-arid region of Moroccan. It has been shown that EF is almost constant under dry conditions, but it depicts a pronounced concave up shape under wet conditions. A new heuristic parameterization is then proposed, which is based on the combination of routine daily meteorological data for characterizing atmospheric dependence, and on optical remote sensing based estimates of instantaneous EF values to take into account the dependence on soil and vegetation conditions. Using the same type of approach, a similar parameterization is next developed for AE. The validation of both approaches shows good performances. The overall method is finally applied to ASTER data. Though performances are reasonably good, their moderate reduction is ascribed to errors on remotely sensed variables. Future works will focus on method portability since its empirical formulation does not account for the direct stomatal response to water availability, as well as on application over different surface and climate conditions.

Under the new oneCGIAR 2030 strategy, the CGIAR has been undertaking an integrated land-food-water systems research transformation, to deploy sustainable agricultural innovations at a faster rate for smallholder agriculture in the developing countries. France has been supporting this CGIAR reform, with a France-CGIAR action plan signed in February 2021, along three joint priority development themes: adapting and mitigating against climate change (theme coordinated by IRD), nutrition and agroecological transformation of farming and food systems in the South. Under the climate change theme, an inception 2 Degree workshop was co-organized by CGIAR and IRD in 2019. Six collaboration themes were discussed: One health; adapting to multiple stresses; climate security in the MENA region; resilient and adaptive water systems; securing Asian mega deltas; circular bioeconomy. For more, go to “BRIDGE_Origin_2019-France-CG-dialogue-integrated-climate-action”. Several France CGIAR collaborations emerged from this workshop including: A literature review « Agroecology and climate change: a case study of CCAFS research programme » published in 2020 (Andrieu N., Kebede Y., 2020). A BRIDGE concept note was submitted to the DEvelopment Smart Innovation through Research in Agriculture (DESIRA) on low-cost digital decision tools to improve water efficiency and cli-mate resilience of legume-based systems. While not successful due to tight deadline, its unique inter and transdisciplinary approach has attracted positive feedback for donors and research partners. DESIRA project “Strengthening the evidence base for a climate resilient and low-carbon small-holder agriculture through agroecology in Latin America” developed and launched in 2020, with the participation of IRD and CIRAD teams. One promising area of climate change research collaboration between France and CGIAR is the co-creation of holistic climate and water smart decision-support systems. Data revolution and more integrated model-based approaches could help water and agriculture stakeholders better evaluate the potential impact and trade-offs of various climate adaptation options to select locally adapted, robust solutions for a much needed sustainable and inclusive transformation of the agriculture and food sector. This trans- and interdisciplinary approach is called BRIDGE for co-Building Resilient climate and water smart farming systems with Interdisciplinary and Integrated models and multi-actor Decision and chanGE platforms. For more details about BRIDGE, read 1-CGIAR_BRIDGE_brief. A BRIDGE research consortium has been set up to pursue this trans and interdisciplinary research for development roadmap, composed of researchers from DIADE (Dr. Vincent Vadez, BRIDGE coordinator), UMR EspaceDev, LMI Naila, CIRAD, the International Center for Advanced Mediterranean Agronomic Studies (CIHEAM), University Mohamed VI Polytechnique (UM6P with its School of Agriculture and specialized institutes (remote sensing, water), the Institute of Environmental Geosciences (IGE) and their national research and development partners in water-scarce MENA and Sahel regions (Morocco, Tunisia, Senegal). The consortium was engaged in the CGIAR initiative on climate resilience called ClimBeR in 2021-2024, under the ClimBeR work package 3 “climate adaptation instruments / policy pathways”, led by Leeds University (PI: Dr. Andy Challinor) and ICARDA, with activities in Morocco / Tunisia and Senegal, to co-develop cross-scale water and climate resilience integrated assessment frameworks. Some teams explored multidisciplinary / integrated modelling approaches (crop, hydrological and socioeconomic in silico assessment). Others look at processes and methodologies used for the co-development of climate adaptation decision-support frameworks and tools. This dataset represents the legacy of BRIDGE work under ClimBeR, with the following information: Webinars and peer-review publications presenting the BRIDGE approach and its applications in target countries (Morocco, Tunisia, Senegal) Research and Policy recommendations from the BRIDGE collective on climate adaptation for the agriculture sector 2024-2023 activity reports and other knowledge products from the eight (8) BRIDGE teams in Morocco, Tunisia and Senegal A BRIDGE Background folder where you will find BRIDGE initial proposals per country team, background documents on the origin of BRIDGE consortium and 2022 BRIDGE knowledge products.

Rainfed agriculture supports a significant share of global food production, balancing water storage with competing demands through runoff management. Human interventions to manage runoff range from temporary practices (e.g., tillage adjustments, crop residue retention) to permanent structures such as terraces and ditches. While practices are adaptable, structures are less flexible but critical for climate resilience. Their life-cycle comprises design/construction, maintenance, abandonment/destruction, and rehabilitation. Despite extensive research on design, rehabilitation, and abandonment, the description, understanding, and impact of maintenance practices remain understudied. This paper addresses this gap through a configurative review (1954-2024), integrating scattered knowledge. We show that rainfall variability, driven by climate change, accelerates biophysical degradation (e.g., terrace deformation, ditch occlusion), requiring adaptation and knowledge sharing to ensure structural stability and hydrological connectivity. Results highlight how regional inconsistencies in structure names hinder cross-regional comparisons and research consolidation. Our contributions include a framework for standardizing: (1) a context-specific evaluation of maintenance practices and (2) an assessment of runoff management structure efficiency under climate change. By integrating biophysical durability, socioeconomic feasibility, and adaptive governance, this framework provides stakeholders and academic actors with a common basis for systematically evaluating and improving runoff management. In practice, we urge policymakers and practitioners to adopt proactive, climate-adaptive maintenance, and to incentivize local community involvement for hybridizing traditional knowledge and technical innovation. By integrating maintenance into farming system design and management, these structures may effectively mitigate the impacts of an increasingly unpredictable climate, ensuring long-term resilience and sustainability in rainfed agriculture.

Abstract Water scarcity is already set to be one of the main issues of the 21st century, because of competing needs between civil, industrial, and agricultural use. Agriculture is currently the largest user of water, but its share is bound to decrease as societies develop and clearly it needs to become more water efficient. Improving water use efficiency (WUE) at the plant level is important, but translating this at the farm/landscape level presents considerable challenges. As we move up from the scale of cells, organs, and plants to more integrated scales such as plots, fields, farm systems, and landscapes, other factors such as trade-offs need to be considered to try to improve WUE. These include choices of crop variety/species, farm management practices, landscape design, infrastructure development, and ecosystem functions, where human decisions matter. This review is a cross-disciplinary attempt to analyse approaches to addressing WUE at these different scales, including definitions of the metrics of analysis and consideration of trade-offs. The equations we present in this perspectives paper use similar metrics across scales to make them easier to connect and are developed to highlight which levers, at different scales, can improve WUE. We also refer to models operating at these different scales to assess WUE. While our entry point is plants and crops, we scale up the analysis of WUE to farm systems and landscapes.

The monitoring of the water cycle at the Earth surface which tightly interacts with the climate change processes as well as a number of practical applications (agriculture, soil and water quality assessment, irrigation and water resource management, etc…) requires surface temperature measurements at local scale. Such is the goal of the Indian-French high spatio-temporal TRISHNA mission (Thermal infraRed Imaging Satellite for High-resolution Natural resource Assessment). The scientific objectives of the mission and research work conducted to consolidate the mission specifications are presented. Progress in modelling of surface fluxes is then discussed. The main specifications of the mission such as the revisit, the spatial resolution, the overpass time, the spectral bands and the orbit are analyzed and justified. The resulting baseline of the mission is given.