## 5 Results and Discussion
### Spatiotemporal Distribution of Drought Indices  
In this study, several maps were prepared to evaluate the spatial distribution of drought indices. Drought maps for the crop development periods in 2016, which was consistently represented as a drought year across all indices, are presented in Figure 7. In the first month of the development period, all indices indicate a wet month; however, according to the CDI, this is predominantly observed in the southeastern region, while SPEI and scPDSI show wetter  
Figure 6: Annual time series of drought indices and crop yield of the test districts.  
conditions in the northern regions. Additionally, it is observed that as the SPEI month index increases, there is an increase in wet areas. In November 2016, CDI indicates widespread drought, while SPEI_6 and SPEI_9 show increasing wetness in the north. December also shows high drought according to CDI, SPEI_1, SPEI_3, SPEI_6, and scPDSI. In January, CDI suggests near-normal to slightly wet conditions, but SPEI indices are inconsistent, with some showing drought and others indicating wet areas in the north. February sees CDI and scPDSI aligning, showing drought in the west. By March, CDI notes drought in the east, with mixed conditions across SPEI indices. April is dominated by drought across all indices. In May, CDI shows wet conditions near the borders and drought in the central area of the study region, while SPEI transitions from wet to drought. June ends with normal to mild drought, with scPDSI highlighting widespread drought for most of the period.  
Figure 7: CDI, SPEI, and scPDSI maps for all months of the winter wheat growing season during the 2016 dry year.  
The variability of the CDI over the study period is illustrated in Figure 8. The maps were generated using the average values for the nine months of the growing season, from October to June. The years 2001, 2005, 2008, 2014, 2016, and 2020 were mild to moderate drought years, while 2011 and 2015 were moderately to severely wet years. Drought years generally show variability along the north-south axis.  
In the maps produced with the same resolution as CDI (1 km), a resolution of 5 km was chosen for mapping SPEI and scPDSI values to avoid issues related to scaling. Additionally, in Figure 9, which analyzes changes over the years, SPEI_3 values were used because they generally align better with crop yield. Similar to CDI, SPEL_3 was classified as mild drought across most of the study area in 2001, 2005, 2008, and 2016. The years 2011 and 2015 were classified as slightly wet and moderately wet, respectively. Unlike CDI values, which were generally classified as near-normal and mild drought in 2004, 2007, and 2020, SPEL_3 remained in the near-normal class across the entire region during these years. However, in 2014 and 2019, CDI and SPEI_3 were observed to belong to similar drought classes in similar areas.  
When examining Figure 10, which illustrates the distribution of scPDSI values across the study area, 2001 is mildly to moderately drought-affected, similar to CDI and SPEI_3. However, when analyzing the spatial distribution, drought is more pronounced in the western and southern regions according to scPDSI and predominantly observed in the northern regions in CDI and SPEI_3. In 2002, a drought occurred in the northeastern region, which was not captured by CDI and SPEI_3. One noteworthy feature of the scPDSI values is the variation of drought along the northeast-southwest axis during consecutive years, particularly in 2007, 2008, and 2009. While 2012 could be classified as wet according to CDI  
Figure 8: The CDI drought map for winter wheat growing seasons in the study region.  
and SPEI_3, scPDSI placed it in the very wet category. In contrast to CDI and SPEI_3, 2017 is generally depicted as drier in scPDSI.  
Figure 10: The same as Figure 9 but for scPDSI.  
Figure 9: SPEI drought map for the winter wheat growing season across the study area.