Background The rational use of soil and water resources is not only related to the sustainability of the ecological environment, but also directly affects the overall regional economic growth, and in turn the regional economic development will, to a certain extent, destroy the soil and water resources. As an important economic zone in Henan province, Sanmenxia city is also one of the regions with serious soil and water erosion, and it is necessary to study the relationship between water-soil resources and regional economic development in Sanmenxia city. It is necessary to understand the coordination mechanism and interaction between water and soil resources and economic development to provide theoretical support for realizing the target tasks of ecological protection and high-quality development.

Methods This study took Sanmenxia city as the research object and constructed the regional water-soil-economy composite system index system. This study determined the index weights by entropy weighting method and calculating the system comprehensive development indexes. Utilizing the system coupling theory, the coupling coordination model is constructed. This study investigated the change of the coupling coordination degree between the two and the three water-soil-economic systems in Sanmenxia city from 2000 to 2020. After that, this study adopted the path analysis to explore the role of water and soil resources on regional economic development.

Results The results of the comprehensive development indexes of the system showed that the level of economic development in Sanmenxia city from 2000 to 2020 shows a trend of increasing year by year. Water resources began to show a fluctuating upward trend after 2014. Land resources showed a gradual upward trend after 2004. The results of the coupling coordination degree model showed that the coupling coordination degree of land resources and economic development grows gradually after 2004, and began to reach a high degree of coordination in 2016. The degree of coupling coordination between water resources and economic development was on the verge of dislocation during the period of 2000-2012, and started to growed rapidly from 2012, reaching a highly coordinated degree in 2015. The degree of coupling coordination between water resources and soil resources reached a high degree of coordination after 2015. The coupling coordination degree of water-soil-economy showed a fluctuating upward trend from 2000 to 2014. And before 2015, the sacrifice of water and soil resources for economic development was highlighted, and the coupling coordination degree of water resources, soil resources and economic development was in a coordinated development in 2015. The results of the path analysis showed that land resources had a stronger driving effect on economic development than water resources.

Conclusions The coupling coordination between water, soil resources, and economic development in Sanmenxia city is currently high, with land resources playing a key role in driving sustainable economic growth. Effective land use planning and scientific water management are essential for maintaining ecological and economic balance. Further optimization of resource use is crucial to enhance long-term economic sustainability.