灌溉基础设施与卫星测度的土地耕作影响: 来自塞内加尔河流域的证据

Journal of Development Economics · 2025 · [{"name": "Abdoulaye Cissé", "affiliation": ["World Bank"]}, {"name": "Alain de Janvry", "affiliation": ["University of California, Berkeley"]}, {"name": "Joel Ferguson", "affiliation": ["University of Wisconsin–Madison"]}, {"name": "Marco Gonzalez-Navarro", "affiliation": ["University of California, Berkeley"]}, {"name": "Samba Mbaye", "affiliation": ["Université Gaston Berger"]}, {"name": "Élisabeth Sadoulet", "affiliation": ["University of California, Berkeley"]}, {"name": "Mame Mor Anta Syll", "affiliation": ["Université Gaston Berger"]}]

中文摘要

在撒哈拉以南非洲扩大灌溉被广泛视为弥合产量差距、增强气候变化韧性的一项有前景的策略。基于30年间逾3000幅卫星图像，我们考察了塞内加尔河谷灌溉基础设施发展的影响。研究发现，灌溉项目完工后耕种率大幅提高：在最初20年里，耕种率稳定维持在比灌溉前水平高出约25个百分点的水平，并在第20至25年间进一步呈上升趋势。此外，我们发现灌溉土地上种植的作物对正向和负向温度冲击的敏感性均显著降低，凸显了灌溉在气候适应中的作用。尽管存在这些总体收益，我们也记录到项目结果存在相当大的异质性，间歇性土地利用现象依然普遍。为阐明这些模式，我们以农户调查数据补充卫星分析，结果显示，持续存在的用水可及性约束是阻碍连续耕种的关键障碍——这些约束无法仅靠农户个体行动加以解决。 • 我们使用3000多幅卫星图像研究灌溉基础设施发展。 • 灌溉项目完成后，耕种率持续提高。 • 间歇性土地利用在灌溉项目中普遍存在。 • 农户调查数据表明，用水可及性约束是耕种的障碍。

Abstract

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.