2.1.1. Objective Evaluation
The objective evaluation included three parts: The first was an evaluation of the comprehensive intensity of human activity; the second was an evaluation of natural ecosystem vulnerability; and the third was an evaluation of human–environment relationship in villages. The first and second parts were based on the raster data and analyzed from a geographical space, the third part was based on the results of the first two and analyzed from an administrative space (
Figure 2).
(1) Evaluation of Comprehensive Intensity of Human Activity
With the help of GIS spatial analysis, comprehensive intensity was analyzed, including settlement activity intensity and road construction intensity.
Human activity intensity varied significantly with the degree of population agglomeration, so settlement population density was taken as the basic value of human activity intensity of the settlement center grid I; i.e., source intensity. The source intensity was calculated as follows.
where
Mn is the source intensity of the settlement center grid in village
i,
Pi is the total population of village
i,
vij is the residential area of settlement j in village
i, and
Vi is the total residential area of village i,
Aij is the total area of settlement
j in village
i. After calculating the source intensity of the center grid in different settlements, the settlement intensity was calculated as follows:
where
ISm is the human activity intensity of grid point m whose distance from the settlement center grid n is
R,
Mn is the source intensity of the settlement center grid n, and
S is the slope correction factor (the greater the slope, the greater the resistance to human activity intensity spread, so we set 25° as a threshold; when the slope is more than 25°, the settlement activity is no longer spreading).
R is the distance from grid point
n to grid point
m.
Expert scoring methods and the analytic hierarchy process (AHP) were used to determine the source intensity of roads of different grades (IRm), which was taken as the intensity value of the grid of the road center point. Considering the road distance attenuation effect of radiation to the surrounding areas, as well as the impact of topography on radiation limits, and using the inverse distance weighting method (IDW), with the slope as a limiting factor for spatial interpolation, when the slope is greater than 25°, the strength value is 0.
After calculating the settlement activity intensity and road construction intensity, using overlay analysis in GIS, the comprehensive intensity of human activity was calculated.
where
Im is the comprehensive intensity of human activity of grid m,
Ws and
WR is the weight of settlement activity intensity and road construction intensity,
ISm is the settlement activity intensity of grid point m, and
IRm is the road construction activity intensity of grid point m.
Finally, based on the result, the layer of comprehensive intensity of human activity was divided into four levels, where ‘level 1′ meant human activity was low and ‘level 4′ meant human activity was high.
(2) Evaluation of Natural Ecosystem Vulnerability
Considering the erosion risk and disaster risk, the natural ecosystem vulnerability was calculated.
Firstly, considering rainfall erosion, relief degree of land surface, soil erodibility, and vegetation coverage, as well as the soil erosion situation, the erosion risk were obtained. The result was divided into three levels, including low, general, and high, through the natural fracture method in GIS. Then, using overlay analysis in GIS, the erosion risk layer and disaster risk layer was overlaid and, according to the discriminant standard (
Table 1), the natural ecosystem vulnerability was calculated.
(3) Evaluation of Human–Environment Congruity of Villages
Based on the result of the evaluation of the comprehensive intensity of human activity and natural ecosystem vulnerability, the human–environment congruity of geographical space was obtained using the overlay method. Focus group discussions (FGD) were conducted in order to determine the discrimination model of human–environment congruity (
Table 2). The focus group consisted of sixteen experts from the Chinese Academy of Sciences, Yunnan University, Sichuan University and Sichuan Normal University. Experts debated the issue that human activities and environment conditions, which had a greater impact on the human–environment relationship. Through discussion, most of the experts thought human activities had a slightly larger impact on human–environment relationship, so the discrimination model first focuses on human activity intensity, and then integrated the environment conditions. Based on the conclusion, this study divided human–environment congruity into five categories, including excessive area, antagonism area, background area, balanced area, and harmonious area.
Excessive area means intense human activity within a fragile ecological environment; antagonism area means the human activity was generally high while the ecological environment was generally fragile. The areas with low human activity and fragile ecological environment were divided into the background area, while balanced area included the areas with low human activity and a healthy ecological environment; harmonious area means human activity was intense in the area but the ecological environment was not fragile.
As we focus on the human–environment congruity of villages, the value assignment of different categories is necessary in order to obtain the human–environment congruity of administrative space. Through the focus group discussions (FGD), the value assignment was determined (
Table 3) and the human–environment congruity of different villages is calculated. Using spatial analysis in GIS, including the natural fracture method, the village was divided into five categories: The higher the value, the more harmonious the human–environment congruity.
2.1.2. Subjective Evaluation
The data of subjective evaluation was acquired from the questionnaire. We hypothesized that cognition on a single environment (such as air condition, water condition, etc.) affected cognition on the overall environment; the findings of our investigation supported this hypothesis. Therefore, in addition to the demographic questions, the questionnaire included two components that refer to environment cognition. One was focused on a single environment and the other on the comprehensive perception. Most of the questions were closed questions. These questions were developed to measure attitudes to the environment on a three-point scale from ‘well’ to ‘bad’ (e.g., What do you think of the situation of vegetation and the change of vegetation? What do you think of the living environment in this village? What do you think of the effect of human activity on the environment, such as farming, industry, road construction, or tourism development?)
Meanwhile, a small number of questions were semi-closed questions to get more information from these questions (e.g., How is the environment changing, for better or worse? What causes this change? Do you think the environment was suitable for living and why?)
The subjective evaluation model was based on closed questions and, through the focus group discussions, the AHP method was used to determine the weight of two components, as well as different factors were determined. The model was as follows:
where HEC
S_E means the subjective evaluation of human–environment congruity;
W1 and
W2 were the weight of two components;
wi was the weight of
xi in component 1 and
xi was the factor about the cognition of a single environmental component, such as air condition, land quality, etc., in component 1;
wj was the weight of
xj in component 2 and
xj was the factor on comprehensive perception and attitude to the comprehensive environment in component 2. The higher the value of HEC
S_E was, the more harmonious the human–environment congruity. This study then divided the HEC
S-E into three categories including harmonious, general, and inferior. The percentages of different categories were calculated; the category with the highest proportion is the result of a subjective evaluation of the village.