The expansion of irrigated croplands throughout the 20th century boosted global agricultural productivity, yet limited improvement occurred in sub-Saharan Africa where many irrigation schemes and policies under-delivered. We mapped the distribution of croplands under active irrigation between 1986 and 2020 for one of Africa’s largest and most important transboundary river basins – the Senegal River Valley (SRV); using Landsat imagery with a Random Forest classifier and Hidden Markov Model. We document two distinct epochs of irrigation development. Initially, a period of stagnation where less than 900 ha per year was added, lasting until 2008. Followed by a boom phase of rapidly expanding intensively irrigated production with ∼ 9,000 ha per year added for the last 12 years. These epochs overlap with national agricultural policy frameworks: the 1980s laissez-faire policies limited state involvement in agriculture and promoted Asian imports; followed by a more interventionist period focused on promoting domestic production following the food price crisis of 2008.

<p>Crop-water simulation models are powerful tools to support efficient and sustainable agricultural water use and management globally. However, uptake of these tools beyond the research community in policy and industry has traditionally been constrained by the complexity and closed-source nature of model codes, which limit ability for models to be adapted and applied to address complex real-world agricultural water management challenges. In this talk, we present AquaPlan, an interactive web-based tool crop management tool that enables farmers, businesses, and governments to make more informed decisions about water management, irrigation investments, and climate risks. AquaPlan combines a state-of-the-art open-source crop-water model, AquaCrop-OSPy, with global weather and soil datasets to enable users to conduct rapid on-the-fly assessments of field and regional-scale crop yield and water demands anywhere in the world. The tools also integrates future climate projections from CMIP6 models, providing insights to support efforts to enhance long-term resilience of agriculture and food supply chains to climate change. In this talk, we will present a range of use cases of AquaPlan, highlight how these kinds of interactive tools can strengthen uptake of models developed by researchers in water management policy, practice, and business.</p>

<p>Smallholders make up the vast majority of farms globally in terms of numbers (over 400 million), cultivate around 20% of global cropland, and produce 30% of global food. Although 70-80% of smallholders are located in areas already facing water scarcity which may be further exacerbated by climate change and population and economic growth, little is known about the relationship between smallholder farming and water scarcity. This study aims to shed light on this relationship, both regarding how water scarcity affects smallholders’ production and vice versa, how smallholders’ production and water productivity contribute to local water scarcity.</p> <p>Hereto, we first estimated smallholders’ green and blue water consumption using ACEA 2.0 (AquaCrop-Earth@lternatives 2.0) in 56 countries around 2010, for main crops, and three farming systems. ACEA 2.0  is an updated version of the ACEA global gridded crop model based on AquaCrop-OSPy with a soil fertility module. It leverages a recently developed gridded global crop map that is both farm-size-specific and crop-specific. This inclusion allows us to incorporate the effects of soil fertility stress at an unprecedented level of granularity based on GAEZv4, which is highly relevant for evaluating the low-input rainfed, high-input rainfed, and (high-input) irrigated farming systems separately. The water productivity of smallholders was assessed in terms of a unit of water footprints and nutritional water productivity. Water scarcity was evaluated at the subnational basin level using global hydrological models PCR-GLOBWB, H08, and WaterGAP2-2C through ISIMIP 2a. The individual and combined effects of water and soil fertility stress on smallholders’ production were assessed and compared.</p> <p> </p>