414 Development of Evapotranspiration Climatology for Indiana

Tuesday, 8 January 2019
Hall 4 (Phoenix Convention Center - West and North Buildings)
Sajad Jamshidi, Purdue Univ., West Lafayette, IN; and D. Niyogi

A compilation of daily, monthly and seasonal averages of measured reference evapotranspiration across Indiana weather stations during 2007 to 2017 were analyzed and compared with commonly used methods using REF-ET software. The ASCE Penman Monteith approach compared well the with observations giving the lowest RSME of 0.37 mm and the best fit. Using this method a broader climatology of ET was developed for a 30 year period across Indiana. Simple and usable spatial contour maps and plots were generated considering monthly average values keeping in view the agricultural community and growers as the end-users.
Results indicate that, January has the lowest ET rates range from 22 to 26 mm/month and June to July show the highest rate of ET range from 116 to 145 mm/month. In addition, based on the analyzsis maps, different zones in Indiana were identified. Average precipitation (P) maps were also created, and the amount of P-ET values were calculated for each zones in Indiana. P-ET maps were used to evaluate of the trend of positive or negative water balance for each zone across the state.
The spatial maps of ET created with point measurements stations were also compared to different remote-sensing based ET algorithms. The strength and weaknesses of each algorithm are considered to identify the best ET estimation over Indiana available from remotely-sensed based data. Among all remotely sensed sources we investigate, the operational Simplified Surface Energy Balance (SSEBop) model presented higher accuracy with 0.51 of R2. The result also help an ongoing study to compare two drought indicator SPEI and SPI over Indiana. Our findings should make a practical tool that farmers and water managers, crop advisors can use to estimate the crop water use and provide advice for managing water resources, irrigation and planting practices.
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