Assessment of county level urbanization with the consideration of coupling coordination among population–economy–space–society–green in the Lower Yellow River basin of China

This study examines the lower Yellow River basin in China, constructing an evaluation system for county-level urbanization from the perspectives of population, economy, space, society, and green development. Between 2000 and 2020, the urbanization within counties accelerated steadily in the lower Yellow River basin. The urbanization index, which stood at 0.291 in the year 2000, climbed to 0.329 by 2010 and subsequently reached 0.536 by the year 2020. The kernel density of county-level urbanization has consistently remained unimodal. The multimodal characteristics on the curve’s right tail gradually weaken, suggesting a trend toward balanced urbanization development across counties. The degree of coupling coordination among county-level urbanization processes has steadily improved, with the centroid, originally located in Puyang, Henan Province, gradually shifting northeastward, suggesting a future transition from Henan Province to Shandong Province. The distribution pattern of county-level urbanization follows a “northeast-southwest” axis, with Jinan and Zhengzhou, serving as the primary axis. This pattern is becoming more prominent, though some changes are still observed along the “northwest-southeast” direction.