# Hydropower Functional Zoning with Crowdsourced Geospatial Data: A Case Study in Sichuan Province
## 2 Materials and Methods
### Research Methods
#### 2.3.2 Zoning System  
1. Zoning Principle  
By considering the impact of hydroelectric development on the ecological environment, eco-functional zoning was implemented in this work in accordance with the common ecological environmental problems in hydropower-engineering development areas in the river basin. Hence, the zoning principle emphasized the coupling relationship between the terrestrial and aquatic ecosystems. Based on the aquatic-ecological-zoning principle [2], the principles of aquatic-and-terrestrial-coupled ecosystem, integral catchment unit, and dominance of human-activity stress should be also observed. In fact, eco-functional zoning is regarded as a zoning system encompassing a large scale to a small scale. The indexes were selected according to the aquatic-and-terrestrial-coupled ecosystem and the impact of human activities (Table 1). 2. Calculation of Zoning Indexes  
The geomorphic features were classified according to the geomorphological-classification system of China and were divided based on surface slope, fluctuation height, and altitude of the surface [45]. One of the most crucial indicators for estimating water resources is runoff depth, which is defined as the ratio between the total runoff and the river-basin area [46]. Moreover, the relative-humidity index represents the balance condition between precipitation and evaporation in a certain period, and the index gained comes from the following formula: (precipitation - potential evaporation volume) / (potential evaporation volume). In addition, vegetation coverage refers to the percentage of the vertical projected area of vegetation on the ground in the total regional area, and it is estimated by the vegetation index NDVI based on the dimidiate-pixel model. The value range was \([0,1]\). 3. Zoning Unit (Sub-River Basins)  
According to the level 3 division standard of the river basin, the following rivers can be found in Sichuan Province: Jinsha River Basin, Ya-lung River Basin, Dadu River Basin, Qingyi River Basin, and Anning River Basin. A total of 92 sub-river basins were further divided by combining them with level 3 river basins. Among them, the largest sub-river-basin area was 19,000 km\({}^{2}\) and the smallest sub-river-basin area was 422 km\({}^{2}\) (Figure 3). \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Levels** & **Scales** & **Targets** & **Indexes** \\ \hline \multirow{3}{*}{Level 1} & \multirow{3}{*}{River basins} & \multirow{3}{*}{Natural geographical condition} & Landform, relative-humidity index \\  & & & (temperature and precipitation), runoff \\ \hline \multirow{3}{*}{Level 2} & \multirow{3}{*}{Regions} & Terrestrial ecosystem & Vegetation coverage \\ \cline{3-4}  & & Human-activity interference & Construction-land-area ratio, Cultivated-land-area ratio \\ \hline \multirow{3}{*}{Level 3} & \multirow{3}{*}{Sub-basins} & Intensity of hydropower-project development & Reservoir capacity, installed capacity, reservoir quantity \\ \cline{1-1} \cline{3-4}  & & & \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Zoning index system. 2. Zoning Process  
(1) Level 1 zoning. Based on the zoning unit, the results of watershed level 1 zoning are obtained and combined with level 1 indicators of physical and geographical factors. (2) Level 2 zoning. By overlaying on the level 1 zoning, the results of level 2 zoning are obtained with level 2 indicators of background ecological status and human-activity interference. (3) Construction of spatial-weight matrix. Considering the connectivity effects of the basins, the spatial-weight matrix of sub-basins can be built. (4) Aggregation evaluation. The global Moran Index is calculated with the data from hydropower stations (large, medium, and above medium size) and the spatial-weight matrix. The aggregation of hydroelectric development is evaluated with the global Moran Index in the zoning unit. (5) Impact assessment of hydroelectric development.