## 3 Results and Discussion
### Quantitative Evaluation of Agricultural Drought Hazard in NEC Based on CDI  
The static drought hazard for NEC was determined grid by grid for the years 1982 to 2020 using CDI and the static hazard evaluation model. To determine the agricultural drought hazard class thresholds (Table 3) in the growing season of NEC, the dynamic hazard of CDI at \(-0.2\), \(-0.4\), \(-0.6\), and \(-0.8\) was calculated for each grid point based on the CDI thresholds for drought levels (Table 2), and the 20%, 40%, 60%, and 80% quartiles of these hazards for all grid points in farmland and grassland areas were also counted. Figure 10 shows the spatial pattern of various agricultural drought hazard levels during the growing season in NEC and the statistical results. The high and above hazard areas were mainly concentrated in the grassland and farmland areas in the west-central and northeastern parts of the study area, whereas the extra-low hazard areas were primarily distributed in the wet zone and woodland areas in the eastern part of the study area. The woodland area was dominated by very low and low hazards, the grassland area was dominated by moderate and above hazards, and the farmland area was in between. For crop layout adjustments, irrigation project building, and the design of policies for disaster  
Figure 9: Temporal changes in drought impact scope based on the CDI during the growing season in NEC from 1982 to 2020.  
prevention and mitigation in NEC, the outcomes of the static drought hazard evaluation serve as significant reference values.  
The dynamics of agricultural drought hazard in farmland and grassland areas (Figure 11) revealed that the drought hazard increased non-significantly (\(p<0.05\)) over the course of different months from 1982 to 2020, with the largest increasing trend in May at 0.021/10 years. According to the results of the MK test, the drought hazard trend changed significantly around 2000; the hazard trend from 1982 to 1999 did not reach a significant (\(p<0.05\)) level, and all months from 2000 to 2020 showed a significant (\(p<0.01\)) decreasing trend, with the largest trend of \(-0.153/10\) years in June. With a warming climate and frequent drought events, the hazard of drought increased significantly after 2000. During the growing season, the hazard generally decreased as the months increased but was noticeably higher in May and June than in other months. The years of high drought hazard were concentrated in 2000-2009, when there was also a period of high incidence of drought events in NEC (Figure 9). During the crop-growing season (May-September) in NEC, precipitation is lowest in May, and droughts induced by a combination of low precipitation and high temperatures frequently occur in spring and autumn [9; 51]. May is the sowing and seedling stage of crops in NEC. During this period, drought delays sowing, inhibiting the growth rate of crop seedlings and reducing biomass, leaf area index (LAI), and chlorophyll content; prolonged drought can even lead to seedling death, forcing farmers to replant [58]. Therefore, the drought hazard index was highest in May.  
Figure 10: Spatial pattern of various levels of static agricultural drought hazard (**a**) and statistics (**b**) during the growing season in NEC.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline
**Hazard Levels** & **May** & **Jun** & **Jul** & **Aug** & **Sep** \\ \hline Extra-low & [0, 0.206) & [0, 0.192) & [0, 0.151) & [0, 0.104) & [0, 0.136) \\ Low & [0.206, 0.335) & [0.192, 0.335) & [0.151, 0.247) & [0.104, 0.173) & [0.136, 0.218) \\ Moderate & [0.335, 0.475) & [0.335, 0.465) & [0.247, 0.348) & [0.173, 0.260) & [0.218, 0.301) \\ High & [0.475, 0.651) & [0.465, 0.629) & [0.348, 0.494) & [0.260, 0.397) & [0.301, 0.429) \\ Extra-high & [0.651, 1] & [0.629, 1] & [0.494, 1] & [0.397, 1] & [0.429, 1] \\ \hline \hline \end{tabular}
\end{table}
Table 3: Agricultural drought hazard level thresholds for the growing season of crops in NEC.