Truck count data and calculations.

Sand, shaping both natural waterways and urban infrastructure, has recently seen a major surge in extraction, particularly in rapidly urbanizing regions like West Africa. To assess the organization, quantification, and socio-ecological implications of sand mining around Mali’s capital Bamako, we employed a mixed methods approach including structured and unstructured interviews, truck counts, turbidity analyses, and river depth measurements. Our study identified five artisanal systems for mining sand and gravel from the Niger River, using tied-up pirogues, single pirogues, carts, tractors, and trucks. Recent increases in extracted quantities, workforce size, and sand prices were observed, resulting in an estimated annual extraction of 4.86 million m3 in 2022, mainly sourced from upstream of Bamako. With extraction rates surpassing natural replenishment, the riverbed in the study communities of Gouni and Usine Toch has reportedly lowered by 1.4 m and 1.8 m during the last 50 years. Mining activities are highly informal, characterized by self-organization, low and irregular salaries, and unsafe working conditions, particularly for women. Economically, sand mining activities have created symbiotic relationships rather than conflicts with local farming, fishing and other livelihoods. Sand mining operations did not significantly affect the Niger River’s water turbidity, which varied primarily with seasonal rainfall fluctuations. Recent developments suggest that mining activities are accelerating, with mechanized practices likely to replace current artisanal methods and underlying social structures.砂石兼具塑造天然水道与支撑城市基础设施的作用，近年来其开采规模急剧扩张，在西非等快速城市化区域尤为突出。为评估马里首都巴马科周边砂石开采的组织模式、量化特征及社会生态影响，本研究采用混合研究方法，涵盖结构化与非结构化访谈、车辆计数、浊度分析以及河道水深测量。本研究识别出尼日尔河沿岸砂石与砾石开采的五种手工作业模式，分别依托系泊独木舟、单体独木舟、手推车、拖拉机与货运卡车开展作业。研究观测到开采量、从业规模与砂石售价均呈上升趋势，据此估算2022年巴马科周边砂石年开采量达486万立方米，主要取自巴马科上游河段。由于开采速率远超自然补给能力，研究涉及的古尼（Gouni）与乌西纳托奇（Usine Toch）河段河床在近50年间分别下降了1.4米与1.8米。砂石开采活动高度非正规化，呈现自发组织、薪酬偏低且不稳定、作业环境不安全的特征，女性从业者受影响尤为显著。从经济层面来看，砂石开采与当地农业、渔业及其他生计模式形成了共生关系，而非对立冲突。砂石开采作业并未对尼日尔河河水浊度造成显著影响，浊度变化主要随季节性降雨波动而改变。最新动态显示，砂石开采活动正不断加速，机械化作业模式或将取代现有手工作业模式及背后的社会结构。