High Resolution Multispectral and SAR Remote Sensing Analysis of Agricultural Management Practices and Agricultural Intensity along the Senegal River Valley

Abstract

In the context of global change, the sustainable management of agricultural resources has become imperative, particularly for enhancing crop development in regions facing multifaceted challenges. West Arica, characterized by a rapidly growing population, persistently low agricultural yields, and climatic, social, economic and ecological stressors, exemplifies the need for innovative solutions. Addressing these pressures requires strategies for sustainable agricultural intensification – boosting yields without expanding cropland or exacerbating climate change impacts – and the implementation of robust mitigation and adaption measures tailored to local socio-economic contexts. Remote Sensing (RS) is a powerful tool for monitoring agricultural development across space and time, enabling actionable insights for these challenges. A detailed literature review on the potential of RS for mapping small-scale agricultural and cropping systems in West Africa highlights the importance of high-resolution multispectral sensors in agricultural monitoring, driven by advances in sensor technology and computing. This study synthesizes existing knowledge, identifying remote sensing potential and key research gaps to address challenges in West African smallholder agriculture. In this context, the Senegal River Valley, a critical agricultural production area with focus on rice, offers large potential for sustainable intensification. Its regulated river system enables various cropping intensities with up to three cropping cycles a year through irrigation patterns, yet the region faces climate-related risks such as flooding, shifts in rainy season onset, and socio-economic constraints. A currently ongoing study within the framework of the COINS (Co-developing innovations for sustainable land management in West Africa smallholder farming systems) project leverages high-resolution multispectral Sentinel-2 and Planet and Synthetic Aperture Radar (SAR) Sentinel-1 RS data to analyze agricultural management practices and cropping intensity across the Senegal River Valley, while also integrating data based on stakeholder collaboration. By deriving key parameters such field specific agricultural management practices, we aim to assess the spatial and temporal dynamics of agricultural activities. In a first step, our approach focuses on detecting management practices including irrigation and cropping schedules. Those parameters exhibit large variability in agricultural practices and farm sizes along the Senegal River. This contribution presents initial findings from these analyses. In the lower valley and delta regions towards the west, farming systems are more intensive. In contrast, as one moves eastward into the middle and upper valley, the agricultural landscape shifts towards smaller, subsistence-based systems. These smaller Senegalese farms face greater constraints in accessing resources such as sufficient irrigation, inputs, and labor, reflecting a gradient of decreasing agricultural intensity and commercialization along the river. These insights provide a foundation for optimizing land use, enhancing resilience to climate impacts, and supporting access to financing and insurance for smallholder farmers. This demonstrates that advanced RS methodologies can greatly contribute to sustainable farming practices and food security, fostering adaptation in smallholder systems with in the Senegal River Valley, amidst the broader challenges of climate change and population growth.