Lin Lou

The Yellow River Delta region is not only a concentrated area of human activities in coastal zones, but also a zone strongly influenced by regional environmental changes, where land cover changes are significantly affected by natural factors. Current historical LUCC datasets overlook the importance of partitioning to obtain accurate information on the potential maximum distribution range, which may lead to uncertainties in climate and environmental predictions. This study aims to reconstruct historical cropland changes in the Yellow River Delta via a region-adapted allocation model, supporting improved LUCC data accuracy and related research. Based on historical river course, settlement, and cropland survey data, this study identifies natural factors using historical settlement density through correlation analysis. Subsequently, a reclamation suitability model conforming to regional characteristics was constructed, and it obtains the cropland changes in the Yellow River Delta Basin at a spatial resolution of 0.5′ × 0.5′ over five time periods since 1855. The research indicates the following: (1) Through the method of analyzing the correlation between historical settlement density and natural factors, it is found that elevation (−), soil pH (+), soil organic carbon density (−), and NDVI (+) are the primary natural factors influencing the distribution of farmland in the Yellow River Delta. (2) The amount of farmland in the Yellow River Delta increased initially and then decreased after 1885; the average reclamation rate increased from 5.65%, peaked at 23.46% in the early 20th century, and then fell back to 7.68%. Spatially, the reclamation area expanded from scattered local areas along the Yellow River towards the sea, with a distinct coastal distribution. (3) Evaluation through absolute difference analysis shows that, compared with the HYDE 3.2 data, our reconstruction reflects the impacts of coastal changes, river distribution, and regional policy history on the allocation results. Based on the findings of this study, relevant issues can be improved from two aspects: first, by correlating settlement density with natural factors to identify key regional natural factors, which can then be applied to the update of LUCC data in small spatial units and similar regions to enhance data accuracy; second, by referring to the historical laws of cropland reclamation and suitability conditions, to optimize the current land planning of the Yellow River Delta and balance cropland utilization with ecological protection.

In historical regional cropland reconstruction in floodplains and delta areas, changes in the river system and the historical distribution of settlements are important to the spatial–temporal dynamic process of historical land reclamation. This paper takes the Yellow River Delta as the research area, combines historical data with field investigation, and analyzes the influence of river system change and delta formation on settlement establishment and land reclamation. The results revealed the following. (1) The development timing of the Yellow River determines the order of deposited land by old river courses and the settlement or resettlement process of the village. Since 1855, approximately 90% of new villages have been located within the 1–5 km buffer of the Yellow River channels. Two peak tides for village establishment along the Yellow River corresponded to the fluvial periods and the 20 ± 10 yr after the river silted out. It took over 100 years for the cultivation range to advance 5 km from the coastline of 1820 to the sea for the lengthy desalination and subsequent freshwater-driven dilution of the newly deposited land. (2) It is necessary to introduce the locations of the settlements, distance from the river courses, and coastline change to the cropland distribution model by setting parameters for different buffer zone distances. This paper provides data and theoretical parameters for cropland construction in the Yellow River Delta suitable for the floodplains and delta areas. The relevant findings can provide valuable references for land use policy formulation, agricultural development planning, and management practices in delta regions.