## 3 Results
### Spatial Autocorrelation Analysis  
According to the hydrological analysis based on the DEM data in ArcGIS, 6614 HRUs are obtained, as shown in Figure 7. The traditional HRU has a large number of small plaques at the boundary, and the small plaques of less than 75 hectares are eliminated by the elimination tool, and 83 HRUs are  
Figure 5: Ordinary kriging interpolation result in (**a**) 2005, (**b**) 2009, (**c**) 2013, (**d**) 2017. Figure 6: Cokriging interpolation result in (**a**) 2005, (**b**) 2009, (**c**) 2013, (**d**) 2017.  
obtained. The groundwater characteristics of HRU less than 75 hectares do not significantly differ in land type. The HRU is only based on the topographical division of the study area. The spatial division of the groundwater depth is also affected by the type of land use. Cultivated land, forest land, and construction land have different groundwater diversion and confluence and impacts. Different land types have characteristics such as soil types, vegetation coverage, soil water content, and water use; therefore, the hydrological response unit based on the topography is divided according to the land-use situation. After the division, the small shift is eliminated, and finally, 551 MHRUs are obtained. The MHRU represents different land-use types and groundwater confluence directions, which is of great significance for spatially presenting the recharge and convergence of groundwater depth. The response unit is divided according to the actual situation. The transmission of groundwater depth is not bounded by a fixed grid cell size, and the MHRU is a more realistic response unit constructed according to the actual situation. A single MHRU has consistent groundwater depth and spread with the same type of land use, approximate soil type, vegetation cover, terrain slope characteristics, and groundwater flow direction; therefore, the analysis of the spatial differentiation law of groundwater depth based on the MHRU is highly feasible, scientific, and implementable. The distribution of the MHRUs in the study area is shown in Figure 8. Different types of MHRUs have certain distribution characteristics. Among them, 50 min response units of forest land are distributed in the west and southwest of Wengniute Banner, and there are national highways as boundaries. The west of the national highway is mainly forest land, and the elevation is generally above 1000 m. The distribution of MHRUs in forestland is relatively concentrated in one large area. In the forest, the aggregation characteristics of the MHRU are prominent, and the groundwater depth recharge and convergence characteristics are consistent. The distribution of water bodies in the study area is also concentrated. The MHRU is divided into the main distribution of water in the Xilamulun River Basin in the north and the Hongshan Reservoir in the lower reaches of the Laoha River. The MHRUs of water are divided into 26 sections with small areas. The MHRUs of cultivated land are divided into 158 sections with small areas, scattered distribution, and unspecific characteristics. One MHRU for construction land was obtained and is located in the city center of Wengniute Banner. There are 230 MHRUs for grassland, which are the most common of the six land types, and have  
Figure 7: Hydrological response unit distribution map. the smallest distribution unit with the widest distribution. The only characteristic is the distribution around the bare ground area. There are 86 MHRUs in the bare ground, which are mainly distributed in the middle and east of the study area. Among them, five are larger and more concentrated. The law of groundwater diversion in such minimum response units should be most pronounced. The results of collaborative kriging interpolation are assigned to the MHRU, and then the local autocorrelation under the spatial autocorrelation in the spatial statistical tool is used to analyze the distribution and evolution of groundwater depth in four years.