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This paper examines long-term settlement expansion in western Hunan region of China and presents a case study of socio-cultural landscape transformation. We extract historical settlements from historical documents in the area's representative counties and outline their spatial distributions during the eighteenth century. Following these distributions, we then examine the influencing factors behind the expansion. We found that when compared with older settlements, new settlements were concentrated primarily on sloping, high-elevation fields rather than more level, lower-elevation fields. Multiple factors affected this settlement expansion. Topography strongly influenced settlement distribution, while policy shifts strongly influenced settlement expansion. Among these was a policy shift from prohibition to encouragement. Other contributing factors to settlement expansion included population growth, immigration, the introduction of new crops, improved farming techniques, and farmland water conservation facilities, which likely benefited from temperature rises. Furthermore, a portion of the indigenous people gradually transitioned into permanent agriculture from slash-and-burn farming, possibly resulting in increased settlement activities. Overall, this study makes important contributions to understanding human impacts on mountainous environments of the past, highlighting patterns of historical-geographical continuity and change over time. Future investigations on historical settlements in a typical region would improve knowledge of these human-nature interactions over the long term. • Maps settlement in western Hunan mountainous areas during the eighteenth century. • Showing a trend of new settlements expanding to higher elevations and steeper slopes. • Describing Anthropogenic land cover change associated with settlement expansions. • Revealing historical landscape changes in conjunction with settlement expansions. • Examining the influencing factors behind the settlement distribution in space. [ABSTRACT FROM AUTHOR]

Centralized vs. decentralized sewage treatment is one of the key issues in the planning of rural sewage treatment (RST) in China due to the country's diverse regional characteristics. There are very limited comprehensive evaluation models for selecting regionally suitable schemes and facilities, particularly for national or provisional scale planning. As a scenario-based multi-attribute decision-making (MADM) issue, this paper develops a novel RST suitability evaluation model by integrating the multi-attribute analytic hierarchy process (AHP) with the technique for order preference by similarity to an ideal solution (TOPSIS). The suitability evaluation model sets up 3 small-centralized and 4 decentralized RST facilities as candidates and includes 12 evaluation indicators that cover economic cost, life cycle environmental impacts, technical features and operations management. Eight generic scenarios are classified for Chinese rural areas based on differences in three major characteristic factors, i.e., population density (PD), the economic development level (EDL), and topographic slope (TS). The universal evaluation results show that a centralized sewage treatment scheme is more suitable for areas with a high PD/high EDL/low TS, while a decentralized scheme is more suitable for areas with a low PD/low EDL/high TS. Sensitivity analysis shows that in regions with a high PD/low EDL, the indicator weight of the construction investment cost in the model has a great influence on the facility suitability ranking. However, in regions with a high PD/high EDL, the ranking is the most sensitive to the indicator weights of the global warming potential and sewage treatment effect. Furthermore, as a spatial decision issue, an RST suitability map of Hunan Province in China is produced at the county level of resolution, and the map is generally consistent with our field knowledge of several counties in Hunan Province. The presented evaluation framework can be integrated into environmental decision support systems in the future to help local and central governments, water utilities, design institutes and other stakeholders scientifically plan RST projects. [Display omitted] • A new suitability evaluation framework of rural sewage treatment (RST) facilities. • Considering life-cycle environmental impacts and regional differences on a large scale. • Optimal RST facilities for each 8 types of regions in China were selected. • A suitability zoning map of optimal RST facility was produced for Hunan Province. • It can help to develop an environmental decision support system for RST planning. [ABSTRACT FROM AUTHOR]