Figure 11: Spatio-temporal distribution of PDSI drought conditions in Iowa.

Discussions

The spatio-temporal analysis of these indices demonstrates their complementary roles in assessing drought impacts on crop yields. SPI-3 captures immediate precipitation anomalies, SPEI-3 incorporates temperature-driven evaporative demand, and PDSI reflects cumulative moisture conditions. The indices collectively highlight the temporal and spatial variability of drought impacts, with 2012 emerging as a critical year for agricultural productivity loss. The year was marked by prolonged precipitation deficits, elevated temperatures, and heightened evapotranspiration, which collectively exacerbated soil moisture depletion and hindered crop growth during critical developmental phases. This underscores the need for region-specific agricultural planning that considers the dual risks of drought and flooding.
These findings emphasize the importance of integrating multiple drought indices to develop resilient farming strategies. Future work should explore how these indices perform under changing climate scenarios, particularly with increasing temperatures and variability in precipitation patterns.