Friday April 29 CSL Meeting

Evaluation of six drought indices for agricultural drought monitoring in South Central United States
Presenter: Liyan Tian
Time: Friday 29 April 2:00-3:00 p.m.
Location 311 CSA

Abstract: Drought is a recurrent natural hazard that has impacts on agriculture, hydrology, ecosystem, and economy. Drought indices are widely used tools for drought monitoring. At present, there are more than 100 drought indices. In this study, performances of six commonly used drought indices were compared for agricultural drought monitoring application in south central United States. The drought indices include the Palmer's Drought Severity Index (PDSI), Palmer's Z-index, Precipitation Percent normal, Precipitation Percentiles, Standardized Precipitation Index (SPI), and Standardized Precipitation Evapotranspiration Index (SPEI). Monthly precipitation data from the Parameter-Elevation Regressions on Independent Slopes Model (PRISM) dataset and monthly potential evapotranspiration data from the North American Land Data Assimilation System (NLDAS) were used for the drought indices calculation. Soil moisture data from North American Soil Moisture Database (NASMD) and crops yield data, including winter wheat yield, corn yield, cotton yield and hay yield, from United States Department of Agriculture (USDA) were used for the assessment of the performance of drought indices. Correlations between the time series of abnormal yielding and soil moisture years and drought indices were calculated. The correlation shows variability in abnormal yield and soil moisture explained by the drought conditions. The near normal condition years were excluded because the yield and soil moisture over time depend on several factors besides climate. The result indicated precipitation percent normal and percentiles are most representative of soil moisture and crop yield conditions in South Central United States.

Top: box plots (the black and orange solid lines within the boxes correspond to the median and mean values, respectively) showing the correlations (Pearson coefficient) between the continuous series of the soil moisture in 145 sites across the study region and the six drought indices compared in this study; bottom: correlations between crop yields and drought indices.