Study on the spatial distribution characteristics of traditional villages and their response to the water network system in the lower yangtze river basin

Abstract

Traditional villages hold significant historical and cultural value as the precious heritage of China’s agricultural civilization. Currently, against the backdrop of increasing urbanization and rapid expansion of urban construction land, the spatial patterns of traditional villages across various regions in China are being encroached upon and damaged, with protection pressures growing daily. As one of the important cradles of Chinese civilization, the Lower Yangtze River Basin (LYRB) has traditional villages closely linked with its water systems, forming a unique human-land relationship and spatial distribution pattern. However, influenced by the rapid urbanization process, the spatial patterns of traditional villages in this region also face a crisis, and the contradiction between protection and development is becoming increasingly prominent. How to balance this contradiction and ensure the reasonable protection and sustainable development of traditional villages has become an urgent issue to address. Therefore, this study focuses on the LYRB. Using ArcGIS tools and combined with mathematical analysis methods, the spatial distribution characteristics and essential influencing factors of traditional villages in this area were screened and analyzed. The objective was to examine the spatial structural relationship between traditional villages, four water system types, and nine sub-basin units, intending to reveal the unique interdependence between the water system and traditional villages in this area. This would provide scientific support for the formulation of scientific conservation strategies. The research results show that: (1) Traditional villages in The LYRB form two core clusters spatially and exhibit substantial spatial accumulation; (2) Water system characteristics are the main factors affecting the distribution of traditional villages; (3) In the LYRB, the spatial distribution of the nine sub-basins is closely related to the spatial distribution of traditional villages, resulting in typical regional spatial differentiation of traditional villages in this area. This study is based on a watershed perspective, and the results highlight the importance of the water system network in the development of traditional villages, revealing a unique spatial dependency relationship between traditional villages and the water network in the LYRB. In order to ensure the comprehensive protection of the traditional village system in this region, it is essential to adhere to the fundamental principles that govern its spatial configuration. A tripartite collaborative protection system based on the watershed should be formulated from the perspective of the overall distribution relationship between the water network and the traditional villages. This system would serve to protect the overall landscape, the water network pattern, and the traditional villages. Establishing an overall pattern view of integrating the water system network and the traditional villages is essential.

Introduction

Traditional villages, as the greatest legacy of China’s agricultural civilization, contain rich historical information and serve as vital carriers of cultural landscapes. These villages have witnessed humanity’s continuous development from ancient times to the present and hold incredibly high conservation value¹. However, with the rapid advancement of urbanization, the environment of traditional villages is being damaged, and the fragility of the human-land system is increasingly exacerbated². This intensifies the contradictions between humans and land and leaves traditional villages facing the dual crisis of declining local characteristics and fragmented overall structures³, with some villages even facing direct extinction¹. Therefore, the protection of traditional villages is an urgent matter.

The interaction between natural resources, geographical environments, and human activities is closely linked, with river basins serving as the basic units of the human-land system and also as the birthplaces of many early civilizations globally. The origins and evolution of civilizations are profoundly connected to rivers⁴. River regions have deep historical roots, and the relationship between humans and land, especially the relationship between humans and water, has significantly influenced the development of villages within these basins⁵. Within river basins, traditional villages have formed unique spatial distribution patterns due to their special human-land relationships⁶. Rivers play a crucial role in the selection and development of settlements⁷and have had a profound impact on human economies, societies, politics, and religions⁸. Previous research on traditional villages at the watershed scale has focused on major river basins around the world^{9,10,11,12,13,14,15,16,17}, and a series of representative results have been obtained from this perspective. However, existing research often adopts a holistic river basin perspective, focusing on various influencing factors. Further exploration into specific natural geographical spaces at the sub-basin scale, concentrating on core influencing factors, remains to be undertaken.

Chinese civilization originated in the Yellow and Yangtze River Basin, and the LYRB, as the downstream plain of the Yangtze River Basin, is also one of the important cradles of civilization, possessing abundant natural resources and a long history and culture. From a natural geographical perspective, the LYRB is located on the vast plain at the mouth of the Yangtze River, adjacent to the East China Sea, between 30°N-33°N latitude, within a temperate monsoon climate zone, rich in natural resources, with a superior geographical environment and abundant ecological assets⁴. The core of the basin is the river water system¹⁸, and this region has a dense network of waterways, being one of the areas with a highly developed density of water networks worldwide¹⁹. From a historical and cultural perspective, the region boasts a rich cultural heritage and numerous traditional village clusters²⁰, which are significant for studying the spatial distribution patterns of traditional villages. Furthermore, unlike other inland regions of China, the spatial distribution of traditional villages in the LYRB is profoundly influenced by the hydrological environment, forming a distribution pattern with unique regional characteristics with the water system as the core, making it an ideal place for studying the village-water relationship. In summary, traditional villages in the LYRB and the water system together have formed a spatial distribution pattern with distinctive regional characteristics. However, the features of this pattern and its interactive mechanisms with the water system have not been thoroughly analyzed. Therefore, this study proposes the following three core issues: (1) What are the particularities of the distribution pattern of traditional villages in the LYRB? (2) What factors influence the distribution of villages in this region, and does the water system play a central role? (3) How does the water system shape the spatial distribution pattern of traditional villages?

In light of the aforementioned considerations, this paper concentrates on the LYRB, employing the pertinent theories of settlement geography to extend the research scope from the overall basin to the secondary basin. A quantitative analysis of the spatial distribution of traditional villages in the region and their correlation with various water systems²¹ reveals a distinctive village-water relationship in the region and highlights the geographical environmental dependence of traditional villages and water systems in the LYRB. This conclusion not only enriches the theoretical connotation of settlement geography but also provides a new perspective for understanding the development and evolution of traditional villages in the regional environment. Furthermore, by examining the spatial distribution patterns of traditional villages and their interconnections with the water system network, our research can gain a deeper comprehension of the underlying principles governing the relationship between the water system and the rural distribution characteristics of the study area. This understanding, derived from an examination of the broader water network, will facilitate the preservation and protection of the macro-hydrological landscape base of traditional villages as a whole. In light of the accelerated pace of urbanization and modernization, these scientific insights are of immediate practical importance and long-term strategic value for the protection and preservation of the region’s rich cultural heritage and the maintenance of ecological balance.

Literature review

Since the call for the protection of traditional villages was made, scholars have embarked on an in-depth analysis of the spatial patterns of traditional villages from various spatial scales and perspectives, employing diverse analytical methods. These research findings have provided a multifaceted view and a rich theoretical foundation for the preservation efforts of traditional villages.

Progress in the study of traditional villages spatial pattern

The existing research on the spatial patterns of traditional villages is relatively abundant, mainly focusing on the spatial distribution and mechanisms^18,22,23, functions, and spatial evolutio^24,25of traditional villages. Methods such as mathematical statistics²⁶, G.I.S. spatial analysis²⁷, and geographical detectors²⁸have been employed to study different scales, including national/regional/provincial^{18,23,24,29,30}, natural geographical units^11,19,31,32, and village areas. Among these, Katapidi noted that many listed traditional settlements in Greece are highly concentrated in the Aegean Islands, Peloponnese Peninsula, and Magnesia, with significant differences in spatial structure³³. Sprague et al. conducted a multi-buffer zone analysis of Japanese traditional villages based on historical maps, indicating that traditional villages have a unique spatial structure and are correlated with specific factors within a limited area³⁴. Zheng et al. used the nearest neighbor index, kernel density estimation, and the minimum cumulative resistance model to analyze the distribution pattern of traditional villages in Southwest China, pointing towards a high degree of clustering and significant internal regional differences³⁵. Xu et al. utilized the nearest neighbor index, Lorenz curve, geographical centralization index, Gini coefficient, and kernel density analysis to reveal the distribution characteristics of 323 traditional villages in Shanxi Province, China³⁶. The results showed a significant imbalance in the distribution of traditional villages, differing from the expected average distribution, and the overall spatial distribution of traditional villages also exhibited significant regional disparities.

Progress in the study of factors affecting the spatial patterns of traditional villages

Traditional villages are products of the combined effects of socioeconomic development, cultural and historical heritage, and natural ecological evolution, closely related to human settlement and lifestyles in specific regions³⁷. In the field of traditional village influencing factors research, the contributions of numerous scholars have built a multidimensional system of results, revealing the complexity and diversity of traditional village distributions and their impact mechanisms. The results show that the factors affecting the spatial patterns of traditional villages mainly fall into two categories: socioeconomic elements and natural geographical elements³⁸. In terms of socioeconomic factors, Ghaderi pointed out that the extent of economic activities such as agriculture, animal husbandry, and handicrafts affects the size and spatial pattern of traditional villages³⁹. Geertz believed that social organizational forms such as family, tribe, and religion also influence the spatial distribution of villages⁴⁰. Xiao suggested that the spatial distribution of early traditional villages was more influenced by cultural activities such as royal life, capital construction, ancient military defense, transportation, and trade⁴¹.

Moreover, many scholars consider natural geographical factors to be an essential category affecting village distribution and layout. For example, Xu believes that differences between plains, mountains, and valleys directly affect human settlement and activity patterns⁴². Jing proposed that during the development period of traditional villages, the climate had a direct impact on agricultural production and living environment, with significant differences in lifestyles under different climatic conditions⁴³. The abundance of water resources is also an essential factor affecting village settlement. Fang and Li pointed out that during the development of traditional villages, humans chose to live near rivers due to the needs of family and agricultural water supply and navigation, suggesting that a developed river system can support human activities in traditional villages^44,45.

Progress in the study of factors affecting the spatial patterns of traditional villages from a watershed perspective

In recent years, some domestic and international scholars have conducted global perspective studies on the spatial patterns and influencing factors of traditional villages in large river basins. Unlike the fragmented administrative space of elements, a watershed is a complete and continuous geographical space concept, with relatively stable elements within the watershed³¹and with clear natural geographical boundaries. It has relative closure¹¹, providing a prerequisite for forming a stable human-land system. Under the effect of stable human-land relationships, traditional villages gradually developed and flourished⁴⁶.

The research indicates that first, there are regional differences in the spatial distribution patterns of traditional villages within the basin. In the Nile River basin, Bietak pointed out that since the Ptolemaic Dynasty, most parts of the Nile Delta have been widely settled¹². However, due to the high variability of the river in history, residential locations frequently changed, and its pattern gradually evolved from being concentrated along the riverbanks to a more homogeneous distribution. In the Yellow River basin, Xu and Yang identified several clusters of traditional villages, suggesting that traditional villages formed a point-like aggregated distribution pattern around the Yellow River³³. Secondly, among the factors affecting the spatial distribution pattern of traditional villages within the basin, the water system is a key influencing factor. Gao and Wu et al³². used spatial analysis methods to indicate that within the Yellow River basin, the spatial differentiation of traditional villages in the eight provinces traversed by the Yellow River is significant, affected by both natural factors and socioeconomic factors, with natural factors having a more significant impact. Neogi’s analysis shows that in the Indus River plain, there is a strong correlation between the location of traditional villages and specific landscape positions related to former river channels⁴⁷. Heyvaert and Bateman believe that the existence of traditional human settlements in the Tigris-Euphrates River Basin is directly affected by changes in river activities in the floodplain¹⁴. Garcia-Molsosa pointed out that in the Indus River basin, south of Punjab state in Pakistan, dynamic changes in watercourses led to the redistribution of related sediments and the cutting and evolution of landscapes, which is the crucial reason ultimately affecting the spatial pattern of traditional villages⁴⁸. Xu and Yang et al. explored, calculated, and evaluated the spatial distribution and site selection adaptation mechanisms of traditional villages in the Yellow River basin, concluding that the site selection of traditional villages in the Yellow River basin is influenced by factors such as river area density, distance from the river, river width, and river bank morphology³³.

In conclusion, the extant research on traditional villages from the perspective of river basins is concentrated mainly on large river basins, and the research perspective is predominantly holistic. This type of research has highlighted the intricate nature of traditional village development, particularly the pronounced regional nuances in the spatial distribution patterns. Secondly, the interaction between traditional villages and the various factors that influence them is a vital focus of the research. It is evident that the spatial distribution of traditional villages is the consequence of the cumulative impact of a multitude of influencing factors, which exhibit considerable variation across different regions. Lin’s research in the Minjiang River Basin indicates that the spatial distribution pattern of traditional villages in this area is characterized by a prevalence of mountainous terrain and a scarcity of plains and that topographical conditions play a significant role in the selection of village sites⁴⁹. Zeng investigated the geographical positioning of traditional settlements in the Yuanshui River Basin in Hunan Province, proposing that transportation infrastructure is a significant determinant of settlement distribution⁵⁰. In contrast to the aforementioned overall basin, the LYRB represents a discrete natural geographical space with a more circumscribed spatial scale. The most salient feature of this region is the dense network of water systems, which may be more closely connected to traditional villages than previously assumed. Although previous studies have found and confirmed the hydrophilic nature of traditional villages, the water system should not only affect the spatial distribution of traditional villages in a single form; differences in the characteristics of the water system itself may also lead to different spatial distribution patterns of traditional villages. Therefore, this study deems it necessary to conduct an in-depth discussion on specific characteristics of the water system, such as water system types, sub-basin differences, water system distances, and water network densities.

Based on the above considerations, this article takes The LYRB as the research area, focusing on the spatial relationship between traditional villages and the water system network. The following three steps are taken to conduct progressive research: (1) Using ArcGIS 10.8 spatial analysis tools to summarize the overall distribution characteristics of traditional villages in The LYRB; (2) Screening the main factors affecting the spatial distribution of traditional villages in the region and using geographical detector tools to determine further whether the water system is a core influencing factor; (3) Employing mathematical analysis methods to analyze water system factors, discuss the structural dependency relationship between traditional villages in The LYRB and the water system, and then propose targeted collaborative protection recommendations.

Materials and methods

Research objects and data sources

Research object

The subject of this study is the traditional villages within The LYRB, as outlined in Fig. 1. In China, the traditional name of the lower stretch of the Yangtze River from Nanjing to its estuary is known as the ‘Yangzi Jiang’, and in this research, the LYRB refers to the catchment area formed by this river section. This geographical scope covers Jiangsu Province and Shanghai City, with a total basin area of about 19,200 square kilometers. The region’s geographical environment is primarily characterized by the alluvial plain formed at the estuary of the Yangtze River, with hydrological features such as comprehensive and deep river channels, short tributaries, and a dense network of waterways⁵¹, as well as numerous lakes. The area has a long history and rich heritage resources, making it a typical cluster of traditional Chinese villages²⁰. It possesses profound historical significance and rich cultural connotations, displaying distinctive regional characteristics and cultural values. The protection and inheritance of these traditional villages are not only important historical materials and practical guidance for studying local folk culture but also hold profound value for the research on the protection of traditional villages in China.

Fig. 1

Location of the Lower Yangtze River Basin and Traditional Villages in China. Maps were drawn by authors, using ArcGIS 10.8 (Environmental Systems Research Institute, USA. https://www.esri.com/), created based on China’s 2022 prefecture and city administrative boundaries (http://www.resdc.cn/), Gaode map data.

Data sources

The data on traditional villages collected for this study originate from the Ministry of Housing and Urban-Rural Development of China, the State Administration of Cultural Heritage, the Jiangsu Provincial Department of Housing and Urban-Rural Development, and the General Office of the Jiangsu Provincial Government. All these villages conform to the characteristics above and are officially certified by the government. The dataset includes four categories of villages:

• (1) 31 national-level traditional villages identified across six batches by the Ministry of Housing and Urban-Rural Development;

• (2) 41 national-level famous historical and cultural towns and villages recognized across six batches by the Ministry of Housing and Urban-Rural Development and the State Administration of Cultural Heritage;

• (3) 352 provincial-level traditional villages announced across six batches by the Jiangsu Provincial Department of Housing and Urban-Rural Development;

• (4) 44 provincial-level famous historical and cultural towns and villages issued across eight batches by the General Office of the Jiangsu Provincial Government.

Considering that there might be instances where the same village has been granted multiple official certifications, the above data was filtered, and duplicates were removed, ultimately resulting in a total of 404 unique traditional village data entries. The geographic coordinates of the data points were obtained through an open map platform and converted to WGS1984 coordinates. Additionally, this study utilized other necessary data, including road density, railway density, Gross Regional Product, population size, river network density, average elevation, average slope aspect, and average slope gradient, with specific data sources referenced in Table 1.

Table 1 Data sources.

Research methods

This study follows the guiding ideas of innovation and practicality, and its methodology ensures high standards of comprehensiveness and accuracy. Initially, we started with the overall geographical environment of the LYRB by employing the ArcGIS kernel density and nearest neighbor index tools for regional spatial characteristic analysis. Subsequently, adopting the locations of traditional villages as the dependent variable, we selected socioeconomic and natural geographical factors. We utilized a geographical detector model to analyze each influencing factor, compare the interactive relationships between each factor and the spatial distribution of traditional villages, and consequently screened the core influencing factors. Finally, the water system is classified, and the perspective is focused on the sub-watershed scale. By detailing the various water system characteristics within the nine sub-basin, the spatial distribution characteristics of traditional villages in the area can be accurately identified and thoroughly discussed in relation to these specific characteristics. The specific technical route is provided in Fig. 2.

Fig. 2

Technology roadmap.

Analysis method for the spatial distribution characteristics of traditional villages

Kernel density analysis

The kernel density denotes the number density of nuclei within a specific volume and can be utilized to investigate the spatial distribution density of traditional villages⁵². The higher the kernel density value, the more densely the traditional village locations are distributed. This paper uses the kernel density estimation method in ArcGIS 10.8, with the bandwidth n set to 60 (km), to calculate the kernel density value of traditional villages. The results reflect their aggregation degree and facilitate the analysis of their spatial distribution features. The kernel density can be calculated as follows:

$$\:{f}_{n}\left(x\right)=\frac{1}{nh}\sum\:_{i=1}^{n}k\left(\frac{x-{X}_{i}}{h}\right)$$

(1)

where n denotes the total count of sample points, K is the kernel function, and h is the bandwidth. The larger the $\:{f}_{n}\left(x\right)$ value is, the more distinct the point-like features and the denser the distribution.

Nearest neighbor index analysis

The nearest neighbor index denotes the mean distance between each point and its nearest neighbor within a point set. It can be employed to analyze the spatial distribution type of traditional villages⁵³. If the nearest neighbor index is less than 1, the spatial distribution type is clustered; if the nearest neighbor index equals 1, the spatial distribution type is random; and if the nearest neighbor index exceeds 1, the spatial distribution type is uniform. In this paper, the nearest neighbor index analysis method in ArcGIS 10.8 is applied to determine the nearest neighbor index R, and the distribution morphology of traditional village locations is determined based on the value interval. The nearest neighbor index can be obtained as follows:

$$\:R=\frac{{\overline{r}}_{1}}{{r}_{E}}=2\sqrt{D{r}_{1}}$$

(2)

where $\:{\overline{r}}_{1}$ denotes the average distance $\:{r}_{1}$ from the nearest points, $\:{r}_{E}$ is the average distance from the nearest points in a random distribution model, and D is the density of the points.

Voronoi plot and analysis of the coefficient of variation

The coefficient of variation, also known as the dispersion coefficient, represents the dispersion level of a probability distribution on a normalized scale and is frequently used to compare the dispersion levels of two groups of data⁵⁴. In this paper, Voronoi diagrams and the coefficient of variation are employed to evaluate the concentration of traditional village locations, thereby revealing the spatial distribution shape of traditional villages, which can be expressed as follows:

$$\:CV=\frac{\text{S}}{\text{V}}\times\:100\text{\%}$$

(3)

This result reflects the relative degree of spatial variation among points. If the coefficient of variation (CV) varies between 33% and 64%, the point elements exhibit a random distribution; if the CV is less than 33%, the point elements exhibit a uniform distribution; and if the CV is greater than 64%, the point elements exhibit a clustered distribution.

Analysis method for the factors influencing the spatial distribution of traditional villages

Geodetector

The geodetector model is a statistical methodology designed to reveal spatial differences, shedding light on spatial heterogeneity and its determinants⁵⁵. The concurrent interplay of socioeconomic factors and natural geographic elements shapes the spatial arrangement of traditional villages. To answer these questions, we selected four categories of socioeconomic assessment factors⁴⁵(road density, railway density, regional gross domestic product, and population count) and four categories of natural geographic assessment factors³⁷ (mean elevation, mean aspect, mean slope, and river network density) to collectively establish an independent variable framework, as outlined in Table 2.

Table 2 Selection of impact factors.

The utilization of the geodetector model in this study aimed to determine the interaction between the different factors (x) and the spatial allocation of traditional village points. The computational results could be used to identify the primary influencing factors. The geodetector model can be expressed as follows:

$$\:q=1-\frac{\sum\:_{h=1}^{L}{N}_{h}{\sigma\:}_{{h}^{2}}}{{N}_{{\sigma\:}^{2}}}$$

(4)

where L denotes the dependent variable, $\:{N}_{h}$ and $\:{\sigma\:}_{{h}^{2}}$ are the number of units and the variance in $\:\text{h}$, respectively, and $\:q$ is the explanatory power, which varies between 0 and 1. The closer the value of $\:q$ is to 1, the higher the explanatory power of the influencing factors for the dependent variable.

Imbalance index

The imbalance index measures the extent to which certain portions of a system outweigh others⁵⁶. The S value varies between 0 and 1, with a higher S value indicating a higher level of imbalance. If it is assumed that traditional villages are uniformly distributed within each sub-basin, S equals 0. Conversely, if all traditional villages are assumed to be concentrated in one sub-basin, S equals 1. The imbalance index S can be calculated as follows:

$$\:S=\frac{\sum\:_{i=1}^{n}{Y}_{i}-50(\text{n}+1)}{100\text{n}-50(\text{n}+1)}$$

(5)

where n denotes the number of sub-basin units, and Yi is the ratio of traditional villages to the total number of villages in each sub-basin, arranged in descending order. This paper uses the imbalance index to illustrate the imbalance conditions of traditional villages within the various sub-basins.

Results

Analysis of the spatial distribution characteristics of the traditional villages in the lower Yangtze River Basin

Initially, data categorization and statistical data tabulation were performed according to the municipal administrative divisions to investigate the quantity and spatial distribution of 404 traditional villages in the study area, as outlined in Table 3; Fig. 3. Encompassing nine municipal administrative regions, the study area contains 93 traditional villages within the bounds of Suzhou, constituting 23.02% of the total number. In contrast, the territory of Shanghai includes only 15 traditional villages, accounting for 3.71% of the total number. The variance in the number of traditional villages between these two cities is nearly sixfold.

Fig. 3

Spatial distribution pattern of the traditional villages in the lower Yangtze River Basin Maps were drawn by authors, using ArcGIS 10.8 (Environmental Systems Research Institute, USA. https://www.esri.com/), based on China’s 2022 prefecture-city administrative division boundaries (http://www.resdc.cn/), traditional village point data (https://www.gov.cn/ & http://www.jiangsu.gov.cn).

Table 3 Statistics of the locations of the six types of officially recognized traditional villages in the lower Yangtze River Basin.

Furthermore, the ArcGIS 10.8 kernel density analysis tool was used, setting a 60-km bandwidth (search radius) to estimate the kernel density of traditional villages⁵⁷. This analysis aimed to provide insight into the broader distribution of traditional villages in the LYRB, and the findings are shown in Fig. 4.

Fig. 4

Kernel density of the traditional villages in the lower Yangtze River Basin. Maps were drawn by authors, using ArcGIS 10.8 (Environmental Systems Research Institute, USA. https://www.esri.com/).

The findings demonstrate that the spatial arrangement of traditional villages in the LYRB exhibits two predominant core gathering regions. The primary concentration area occurs in the Taihu Lake region (specifically, the central zones of Suzhou and southern districts of Wuxi), while the secondary concentration zone is observed along the northern stretch of the Beijing-Hangzhou Grand Canal and the banks of the Luting River (mainly covering the junction area between Yangzhou and Taizhou). By analyzing the outcomes from administrative demarcation and geographical spatial perspectives, it is clear that the overall distribution of traditional villages in the LYRB exhibits an imbalance characterized by an uneven spatial layout.

Building upon this analysis, ArcGIS 10.8 was used to calculate the average nearest neighbor index of traditional villages in the LYRB to delineate the spatial distribution types (refer to Table 4). Additionally, using ArcGIS 10.8, the Thiessen polygon tool was used to create a Voronoi diagram, obtaining the variation coefficient of the traditional village distribution (Fig. 5).

Fig. 5

Spatial distribution analysis of the traditional villages in the lower Yangtze River Basin. Maps were drawn by authors, using ArcGIS 10.8 (Environmental Systems Research Institute, USA. https://www.esri.com/).

Table 4 Nearest neighbor index of the traditional villages in the lower Yangtze River Basin.

The results of the calculation demonstrate that the actual average neighborhood distance of traditional villages in the study area ($\:{\overline{r}}_{1}$ =5580.9 m) is considerably smaller than the theoretical average neighborhood distance ($\:{r}_{E}$=8093.7 m). The neighborhood index R = 0.69 is less than 1, indicating that the actual distribution distance of traditional villages in the LYRB is smaller than the theoretical value, demonstrating a certain degree of aggregation. The mean value of the standard Voronoi polygon is 385.287 square kilometers, with a standard deviation of 1073.103 square kilometers and a coefficient of variation of 278.52%. This result suggests that the spatial distribution of traditional villages in the LYRB is predominantly clustered. The critical value of the nearest neighbor calculation is Z=-11.9379, with P = 0.00. A comparison of the observed value with the expected value of a random distribution reveals a significant discrepancy between the traditional villages in this area and a random distribution.

These results collectively corroborate the previous research conclusions, indicating that the traditional villages in the LYRB exhibit notable spatial clustering distribution characteristics.

Analysis of the influencing factors of the traditional village

With the utilization of the fishnet tool in ArcGIS 10.8, a 10 km × 10 km grid was created in the research area. The number of traditional villages in each grid was determined, as well as the road density, railway density, regional G.D.P., P.O.P., average elevation, slope, slope direction, and river network density, thereby establishing a database for impact factor analysis(refer to Table 2 above).

Table 5 Calculation results of the geodetector model for the effect of the traditional village impact factors in the lower Yangtze River Basin.

With the use of the factor detection method of the geographical detector, the eight chosen influencing factors were comparatively analyzed, and the calculation results are listed in Table 5. The findings indicated that the influence of the factors in descending order of magnitude was as follows: river > D.E.M.> train > direction > slope > G.D.P.> P.O.P.> road. Among these eight factors, river, D.E.M., train, and road passed the 0.05 significance test, indicating that the river network density, average elevation, railway density, and road density, respectively, significantly impact the spatial distribution of traditional villages. In particular, the influence of the river network density is the greatest, followed by the average elevation. In contrast, the influences of the railway and road densities, slope and slope direction averages, regional G.D.P., and population size are relatively minor. The calculation results reveal that the river network is the main influencing factor in the spatial distribution of traditional villages in the LYRB.

Type of water system - distribution quantity and distribution status of the traditional villages

The previous analysis revealed the general features of the spatial distribution of traditional villages in the LYRB and the predominant influence of the river network. Considering the differential roles of different types of river systems and integrating the functions of the river system, the LYRB can be categorized into four types of river systems, namely, the Yangtze River main stream, lakes, canals, and tributary river networks, as shown in Fig. 6. This allows for further research on the spatial association between the four types of river systems and traditional villages.

Fig. 6

Four types of water systems in the lower Yangtze River Basin. Maps were drawn by authors, using ArcGIS 10.8 (Environmental Systems Research Institute, USA. https://www.esri.com/), based on China’s 2022 prefecture-city administrative division boundaries (http://www.resdc.cn/) and water system data (https://www.resdc.cn/).

With the use of the buffer tool in ArcGIS 10.8, buffers are established at three levels: 1 km, 3 km, and 5 km. The number of traditional villages within each buffer zone is determined, and data tables and buffer maps are created to analyze the distance interaction relationships between the four types of river systems and traditional villages. The results are shown in Fig. 7. The buffer distance settings primarily consider that 1 km corresponds to an activity range of 10 min, residents have highly convenient access to and use of water resources, reflecting the high reliance and demand of traditional villages for water resources in daily life; 1–3 km corresponds to an activity range of 30 min, it is convenient to utilize water resources for agricultural, breeding, and other production activities, significantly impacting the production and living functions of traditional villages; 3–5 km corresponds to an activity range of 60 min, the use of water resources by traditional villages may be more focused on the needs of economic and social activities such as the agricultural product processing industry, which also influences the distribution of traditional villages.

Fig. 7

Statistical map of the number of traditional villages in the 0–1 km, 1–3 km, and 3–5 km buffer zones of the four types of water systems in the lower Yangtze River Basin. Maps were drawn by authors, using ArcGIS 10.8 (Environmental Systems Research Institute, USA. https://www.esri.com/).

The computation results revealed the following (Fig. 7): When arranged in the order of the Yangtze River mainstream, lakes, canals, and tributary river networks, the number of traditional villages in the 0–1 km buffer zone of the four types of river systems is 1, 7, 4, and 174, respectively; the number of traditional villages in the 1–3 km buffer zone is 5, 29, 13, and 153, respectively; and the number of traditional villages in the 3–5 km buffer zone is 4, 14, 11, and 49, respectively. The first significant feature that can be obtained from the above statistical results is that the number of traditional villages around the tributary river network is the largest among the three buffer zones with different scales relative to the other three types of river systems. The second significant feature is that as the distance from the tributary river network is increased, the number of traditional villages shows a rapidly decreasing trend, especially from 1 to 3 km to 3–5 km; the number of traditional villages in the tributary river network buffer zone sharply decreases from 153 to 49, revealing a clear inverse relationship.

The above two results indicate that the traditional villages in the LYRB are located closer to the waterfront area of the tributary river network, showing that the traditional villages in this area exhibit significant hydrophilic characteristics. This inverse distance relationship reveals that the establishment of ancient traditional villages more notably depended on tributary waterways. Compared with mainstream waterways or lakes, these waterways are easier to manage and use effectively, direct available resources can be obtained, and the connection between the villages and mainstream waterways or lakes can be ensured. These findings provide significant insight when analyzing site selection among traditional villages.

Sub-basin - spatial relationship and structural characteristics of the traditional villages

Within the large river basin, sub-basins divide the geographical space into distinct units, forming relatively independent ecological and environmental systems. This independence is reflected in different aspects, such as the aquatic environment and navigation channels with different freight-carrying capacities⁵⁸. These different aspects may also influence the distribution of traditional villages within the region. These diverse facets may also impact the distribution of traditional villages in the region. In order to obtain the structural correlation between sub-basin units and traditional villages, this paper further studies the spatial relationship between sub-basin units and traditional villages, thus revealing the unique spatial distribution of traditional villages in the LYRB. The number of traditional villages in each sub-basin area of the LYRB was counted, and the results are summarized in Table 6. The imbalance index analysis method was used to calculate the distribution balance of traditional villages in each sub-basin unit. The specific results are shown in Fig. 8.

Table 6 Number and percentage of the traditional villages in each sub-basin.

Fig. 8

Trend plot of the Lorenz curve of the traditional village sub-basin distribution in the lower Yangtze River Basin. Maps were drawn by authors, using ArcGIS 10.8 (Environmental Systems Research Institute, USA. https://www.esri.com/), based on traditional village point data (https://www.gov.cn/ & http://www.jiangsu.gov.cn) and Sub-basin boundary data (https://www.resdc.cn/).

According to the trend of the Lorenz curve, among the nine sub-basin units, 109 traditional villages are distributed in the area west of the Taihu Lake Basin, accounting for as much as 26.3% of the total area. In contrast, only six traditional villages occur in the Kauten Basin, accounting for only 1.5% of the total area. The difference is significant, highlighting the uneven distribution of traditional villages in the various sub-basins. Similarly, in addition to those in the western Taihu Lake Basin, the number of traditional villages in the three other sub-basins is larger than the average value; they are also the main traditional village gathering areas (the three sub-basins are the Lixiahe Basin, Wuyang Basin, Qingyi Basin, and Shuiyang Basin). Subsequently, the imbalance index S of the nine sub-basin units was calculated, and the result was 0.507444169, which is greater than the median value of 0.5. This indicates that the spatial distribution of the traditional villages is unbalanced, further verifying the above conclusion.

Based on the above results, combined with the two significant characteristics obtained from the comparative analysis of the four types of water systems in the previous section, the observation distances between the traditional villages and branch water networks in the nine sub-basin units were calculated and the results were arranged in descending order. The relationships between traditional villages and branch water networks were examined, and the specific data are listed in Table 7.

Table 7 Observed distances of the traditional villages from the water system in the nine sub-basins (in order of the number of villages).

The calculation results show that within these nine sub-basin units, the average observed distance between the traditional villages and branch water networks was 2.35 km. Five of these sub-basin units exhibited an average observation distance ranging from 0 to 2 km, which is smaller than the average distance, exhibiting distinct hydrophilic characteristics. Conversely, three sub-basins had an average observation distance ranging from 2.5 to 2.6 km, which is slightly above the average, demonstrating a certain degree of hydrophilic characteristics. By comparing the nine sub-basin units in the Huangpu River Basin, the average distance between the traditional villages and branch water networks is 0.09 km, which is significantly smaller than the average observed value. This suggests that, compared to those in the other eight sub-basins, the hydrophilic characteristics of the traditional villages in this region are more pronounced. In contrast, in the Kauten Basin, the average observed distance between the traditional villages and branch water networks reaches up to 9.40 km. This not only exceeds the average observed distance by a factor of three but also, compared to the Huangpu River Basin, the calculated result differs nearly 100 times. This indicates a substantial disparity in the distance relationship between the traditional villages and branch water networks in each sub-basin unit.

The results above may be influenced by the relatively unique natural geographical properties of each sub-basin unit. To investigate the interactive relationship between the water system environmental conditions of each sub-basin and the distribution status, we selected three data indicators that can reflect the basic features of the basin water system: basin area, river length, and water network density. These data were subsequently used to analyze the nine sub-basin units. The specific data are provided in Table 8.

Table 8 Statistics on the area of the nine sub-basins, length of the rivers and density of the water network, and number of traditional villages in their respective boundaries.

According to the ‘a’ chart in Fig. 9, among the nine sub-basin units, the western Taihu Lake Basin exhibits the largest area and the most traditional villages; the Kauten Basin exhibits the smallest area and fewest traditional villages. The calculation results for the other seven sub-basin units are mainly consistent with this pattern, indicating a positive correlation between the number of traditional villages and the area of the sub-basin unit in the LYRB. However, charts ‘b’ and ‘c’ in Fig. 9 show that the positive correlation between river length, water network density, and the spatial distribution of traditional villages is not significant. For example, although the Huangpu River Basin exhibits the highest river network density, this area contains fewer villages. In addition to being influenced by the smaller basin area, this result may be related to the later land formation time in the Huangpu River Basin, the shorter development history of traditional villages, and the higher urbanization level in this area. Therefore, subsequent research must comprehensively consider regional, historical, and geographical factors.

Fig. 9

Statistical map of the area of the nine sub-basins, the length of the rivers, the density of the water network, and the number of traditional villages within their respective boundaries.

Discussion

Exploration of the spatial pattern of traditional villages and influencing factors

Existing literature indicates that the spatial distribution of traditional Chinese villages varies significantly across different geographical environments, with each region’s traditional villages exhibiting distinct characteristics influenced by local attributes. Overall, there is a pattern of higher concentration in the south and lower in the north⁵⁹. Specifically, in the southwestern region, taking the traditional villages of Yunnan and Guizhou as examples, these villages typically conform to the mountainous terrain and river systems, forming terraced or scattered distribution patterns between mountains and valleys⁶⁰. In the northwestern region, such as Gansu and Ningxia, the scarcity of water resources leads traditional villages to be distributed around water sources and oases, creating spatial structures centered on irrigation systems within the areas⁶¹. However, in The LYRB, the spatial layout of traditional villages presents a unique clustered distribution. Within The LYRB, traditional villages form two core clusters overall, with both the primary and secondary core areas showing strong spatial agglomeration characteristics, which are also extremely evident at the local level. Additionally, combining the results of administrative divisions and regional spatial analyses, it is observed that the traditional villages in The LYRB generally show an imbalanced quantity distribution and an uneven spatial distribution.

The geographical environment of The LYRB is complex and diverse, including various landforms such as mountains, plains, lakes, and rivers⁴². This environmental diversity determines the spatial distribution characteristics of villages. For example, in mountainous areas, due to steep terrain and inconvenient transportation, people tend to live concentrated at the foot of mountains or in river valleys, forming clustered village distributions. The LYRB encompasses extensive plains with fertile land, numerous lakes, and dense river networks⁴. Water systems and rivers, serving as natural transportation networks, provided advantages for the early development of traditional villages⁴⁴. Therefore, traditional village sites tend to be close to water system rivers⁴⁵, gathering downstream and forming clusters centered around water systems. Relatively speaking, the influence of the density of railways and roads, the average values of slope degree and aspect, Gross Regional Product, and population size are minor. The LYRB has a long history and profound cultural heritage. The historical economic prosperity also promoted the formation of many village clusters. At the same time, differences in economic development levels may further lead to population movement towards cluster areas, resulting in sizeable traditional village clusters in some economically developed areas¹². However, uncontrollable factors such as historical population migration and wars could lead to the rise and fall of villages⁴¹, which might be the main reason why it is difficult for this region to form traditional village clustering patterns centered on economic and demographic factors. In summary, the water system is a crucial factor in the spatial distribution of traditional villages in the LYRB. Therefore, the water system will be discussed in detail below.

Exploration of the correlation between the water system type and the spatial distribution of traditional villages

According to related research, the development of traditional villages in China is influenced by multiple factors, such as the cultural economy and natural geography^37,62. This study further revealed that the LYRB exhibits the unique attribute of a close association between traditional villages and the river network, revealing the following main spatial distribution characteristics: (1) with water as the vein, the region is far from the mainstream and close to the tributary river network; (2) the traditional villages in the southern Yangtze River region are evenly distributed, while those in the northern Yangtze River region are linearly distributed; and (3) in the area around Taihu Lake, the traditional villages are distributed in layers.

By studying the distances between the traditional villages and the four types of river systems in the LYRB, it was found that the distances between the Yangtze River mainstream and traditional villages are larger than those between lakes, canals, and tributary river networks and villages. This phenomenon may be related to the drastic changes in the banks of the lower Yangtze River and frequent floods throughout history. For example, the LYRB exhibits historical evolutionary characteristics, such as a southward shift in the mainstream of the Yangtze River, sandbars merging with the bank, reduction in the river width, and extension of the river mouth⁵¹. The relatively drastic geographical environment evolution has kept the man-land relationship in this area in tension for a long time, making it difficult for the lower Yangtze River mainstream to become an ideal site for traditional villages. Second, according to historical records, the Yangtze River mainstream has been prone to floods since ancient times, making it difficult to form a stable ecological environment, which is also not conducive to the reproduction and development of agricultural civilizations and traditional villages. These two factors could explain why traditional villages were rarely established near the Yangtze River mainstream. Second, the spatial distance relationship between the tributary river network and traditional villages in the LYRB is closer than that between the villages and the mainstream lakes and canals. Historically, the Yangtze River Basin, especially the lower Yangtze River region, has long been a significant economic and cultural center in China. As an essential east-west transportation method and connecting and communicating north-south economy and trade in China⁶³, the dense and developed tributary river network in the LYRB connects and extends the canal transportation system in the lower Yangtze River region, promoting trade, material circulation, and cultural exchange⁶⁴, highlighting the typical characteristics of traditional villages in this region relying on the river network to connect and develop together. The high-density natural and artificial tributary river network is the core foundation for the reproduction and development of the water town–village spatial system⁶⁵ in this region.

In this study, significant differences in the distributions of traditional villages on both sides of the Yangtze River were revealed. Specifically, the distribution of traditional villages south of the Yangtze River is relatively homogeneous, while that north of the Yangtze River indicates a more notable linear distribution trend. The southern region of the Yangtze River contains a developed network of natural and artificial waterways interwoven into a relatively uniform network structure. Traditional villages are attached to the water network and exhibit a relatively uniform distribution. In the northern region of the Yangtze River, natural and artificial water systems, such as the Beijing-Hangzhou Canal and the Lu Ting River, are primarily linear along the north-south direction. Owing to the implementation and development of Jianghuai Canal transportation throughout history⁶⁶, this river section has become an essential corridor for connecting northern and southern economies and politics in China, while traditional villages are also affected by this section and form a typical linear distribution pattern along the north-south direction.

In addition to the above characteristics, traditional villages exhibit a unique circular distribution in the area around Taihu Lake. The area around Taihu Lake has long been one of the wealthiest areas in China. Since at least the beginning of the Han Dynasty, this area has become the economic center of the southern Yangtze River region⁶⁷. The area exhibits the characteristics of plains and hills, distinct seasons, and abundant rainfall. The natural environmental conditions are very favorable. Long-term water control projects and agricultural development activities around Taihu Lake have promoted the mutual adaptation of traditional villages and the natural environment in the lake area. In this process, villages and water systems were highly integrated⁶⁸, and they formed a stable traditional settlement mode and water resource utilization mode around Taihu Lake, reflecting the close historical production and lifestyles of residents and the Taihu Lake system.

Exploring the correlation between the sub-basin units and the spatial distribution of traditional villages

Major river basins represent expansive geographical entities that cross administrative boundaries and can be segmented into numerous sub-basin units based on the classification of river systems⁶⁹. These sub-basin units jointly form a comprehensive and stable ecological system that sustains its own cycle and can adapt to the evolving changes of the entire basin⁷⁰. In this study, we revealed that the sub-basin units in the LYRB exhibit a differential spatial distribution relationship with traditional villages, which is particularly evident in two aspects.

(1) A potential positive correlation existed between the sub-basin size and the number of traditional villages. Generally, larger sub-basin units contain more abundant natural resources such as water, land, and vegetation, which offer more robust foundational conditions for the existence and development of traditional villages⁷. Simultaneously, larger sub-basins generally possess a more complete network of water systems. The integrity of the water system is critical to maintaining the health and stability of the ecosystem and directly affects the quality and quantity of water resources. A complete water system can effectively regulate water flows, reduce the risk of floods and droughts, and also help protect biodiversity⁷¹. Conversely, fragmentation of the water system can lead to instability of water resources and degradation of the ecological environment, which in turn affects village production activities and the daily lives of the inhabitants⁷². Studies have shown that traditional villages in the LYRB are highly dependent on natural resources, especially water resources. For traditional villages that rely on natural water sources, the integrity of the water system means the stability of the overall pattern of the traditional village. In larger sub-basin units with more plentiful water resources, the quantity, density, and clustering of traditional villages are typically greater than those in other sub-basins. This is one of the characteristic features of the spatial distribution of traditional villages in the LYRB.

(2) Based on the data of our study, the river system length and the river network density did not demonstrate a positive correlation with the spatial distribution of traditional villages relative to the sub-basin area. However, the length and density of the river system could significantly influence the accessibility of traditional villages and economic and cultural exchanges. In ancient times, the length and density of river systems, especially navigable river networks, were often critical determinants of regional economic and cultural exchanges. Therefore, the specific inherent correlations between the length and density of river systems and traditional villages should be explored in future research.

Reflection on the protection of traditional villages in watersheds

Currently, a prevalent issue in the conservation of traditional villages in China is that most traditional villages remain in a state of individual conservation⁷³. A regional holistic structural system of traditional villages and their coordinated conservation with the natural geographical environment have not been adequately addressed⁷⁴. Moreover, there is a lack of foundational research offering references for understanding the spatial interaction mechanism between traditional villages and the natural geographical environment, causing challenges in providing empirical support for creating specialized conservation strategies. In this study, it was demonstrated that the LYRB exhibits a unique spatial relationship with traditional villages. This relationship holds reference value and practical significance for understanding and comprehensively conserving traditional villages in this region. Only by establishing a coordinated conservation system considering water system types, sub-basin units, and traditional villages, based on the cognitive foundation of river network–traditional village spatial relationship and the formulation of targeted policy measures, can essential safeguards be provided for the construction of a traditional village conservation system with distinct regional characteristics in the LYRB.

The river network is a core component of the geographical environment of the basin. It significantly impacts the regional distribution status of traditional villages in numerous ways, warranting particular attention and importance. Although the LYRB constitutes a complete geographical spatial unit, an inherent relationship has formed in the region that determines the relationship between humans and land due to the internal characteristics, such as water system type and sub-basin scale. A thorough exploration of the varying impacts of this inherent mechanism on the structural organization relationship of traditional villages can assist in forming a new holistic cognitive concept, thereby facilitating the proposal of more regionally characteristic targeted schemes for conserving traditional villages in this region.

The protection of traditional villages has become a global challenge against the backdrop of globalization and rapid urbanization. The individual protection problems facing China’s traditional village protection are not isolated phenomena but have similarities with the problems faced by other regions and countries around the world. The case of the LYRB provides a unique perspective, emphasizing the importance of the spatial relationship between the water system network and traditional villages for protection work. This perspective can provide important lessons for other regions around the world. For example, Venice and its surroundings in Italy, where the water system has a profound impact on the structure and culture of the city and the countryside; Giethoorn in the Dutch province of Overijssel, which retains a large amount of open water and green landscapes; the interaction between traditional villages and water systems in this region cannot be ignored. Therefore, the holistic conservation strategy proposed for the characteristics of the LYRB can also further enrich the theoretical basis for the protection of such traditional villages. In addition, the research on the LYRB highlights the importance of conservation strategies based on geographical and environmental characteristics, which is in line with the global recognition of the value of ecosystem services and natural capital. Globally, more and more regions are beginning to recognize the interdependence between natural resources and cultural heritage conservation and the importance of such conservation in maintaining local identity and economic sustainability.

In summary, the case of the LYRB provides valuable insights into the protection of traditional villages around the world, especially in terms of how to integrate the protection of physical and cultural heritage. Comparative research across regions and countries can further promote the understanding of traditional village protection strategies and provide tailored solutions for regions facing similar challenges.

Conclusion

The LYRB, with its unique natural geographical environment, has given rise to a traditional village system with a regional cultural presence that is unique in China and even the world. It is a concentrated display of the unique characteristics of the region’s traditional villages and their high degree of integration with the natural environment. The research results show that the number of traditional villages within a 0–1 km buffer zone of the tributary water network is as high as 174, accounting for 41% of the total, showing a strong attraction. This shows that the 10-minute living area of traditional villages is closely related to the tributary water network, indicating that the water system is not only the axis of village life activities but also an important link for cultural inheritance and social interaction. Among the nine sub-basin units in the LYRB, the West of the Taihu Lake Basin has the largest number of traditional villages with 109, accounting for 26.3%, while the Kauten sub-basin has the fewest traditional villages with only 6, accounting for 1.5%. This imbalance in distribution is particularly evident in the Lorenz curve trend plot, which highlights the regionally differentiated characteristics of traditional villages. These data results highlight the complexity and diversity of traditional village distribution, emphasize the importance of respecting the basic laws of spatial patterning, and reveal the important role of different water system types and specific sub-basin units in the formation of traditional village clusters.

Therefore, to protect the traditional village system entirely in this area, the fundamental laws of its spatial pattern should be respected. Particular attention should be paid to the traditional village agglomerations formed by different water system types and specific sub-basin units. A tripartite collaborative protection system should be established for the overall landscape protection, water network pattern protection, and traditional village protection based on the watershed, thereby establishing an overall pattern view that integrates the water system network with traditional villages. This study has gained a new perspective on the spatial relationship between the water system network and traditional villages. The results of this study can help to understand the unique spatial distribution characteristics of traditional villages in specific river basins from the perspective of water. On this basis, scientific recommendations can be provided for the formulation of traditional village protection strategies based on the water system network.

However, research in the LYRB also reveals a more general problem, namely the lack of systematic research on the interdependence between traditional villages and their natural and geographical environment. This is not only a problem for the protection of China’s traditional villages but also a challenge for the protection of cultural heritage in many regions of the world. In order to formulate effective protection strategies, more basic research is needed to understand the complexity and dynamics of human-land relationships. Future research can further focus on the historical development process of The LYRB to reveal the co-evolutionary relationship between the water system network and traditional villages. Additionally, the interaction mechanisms between functions carried by the water system network in the region, such as production and navigation, and traditional villages are also worthy of further study and discussion.