Irrigation infrastructure and satellite-measured land cultivation impacts: Evidence from the Senegal river valley
利用30年间3000多张卫星图像，研究塞内加尔河谷灌溉项目对耕作率的影响，发现耕作率持续上升且作物对温度冲击的敏感性降低，但间歇性土地利用普遍，农民调查显示水获取限制是关键障碍。
Expanding irrigation in sub-Saharan Africa is widely viewed as a promising strategy for closing yield gaps and enhancing resilience to climate change. Drawing on more than 3,000 satellite images over a 30-year period, we examine the impact of irrigation infrastructure development in the Senegal River Valley. We find that cultivation rates increase substantially following irrigation project completion. Cultivation rates are remarkably stable at around 25 percentage points above pre-irrigation levels for the first 20 years, and trend even higher from years 20 to 25. Moreover, we show that crops cultivated on irrigated land are significantly less sensitive to both positive and negative temperature shocks, underscoring the role of irrigation in climate adaptation. Despite these aggregate gains, we document considerable heterogeneity in project outcomes, with intermittent land use remaining widespread. To shed light on these patterns, we complement the satellite analysis with farmer survey data, which point to persistent water access constraints as a key barrier to continuous cultivation—constraints that cannot be resolved solely through individual farmer action. • We use over 3000 satellite images to study irrigation infrastructure development. • Cultivation rates increase persistently following irrigation project completion. • Intermittent land use is widespread among irrigation projects. • Farmer survey data point to water access constraints as a barrier to cultivation.