1. Potential Evaporation and Irrigation in Manoa Valley Geography 405 Liat Portner, George Bugarin, Alexa Grinpas,Henry Pascher, Nicole Miller, Maeghan Castillo, Joshua Silva, Elise Kama, Keiichiro Yoshida

2. Purpose Main Objective: Main Objective: Evaluate the water balance of Manoa Valley Our Objective: Estimate the Potential Evaporation and Irrigation for Manoa Valley

3. PE Modeling Methods Net Radiation, (Air) Temperature, Wind speed and Relative Humidity measured at the 2 weather stations were used to calculate PE Net Radiation, (Air) Temperature, Wind speed and Relative Humidity measured at the 2 weather stations were used to calculate PE Interpolated to Grid cells using inverse distance weighting and the Normal Ratio Method Interpolated to Grid cells using inverse distance weighting and the Normal Ratio Method Distance from each grid to each weather station Distance from each grid to each weather station Mean PE at each grid and both weather stations Mean PE at each grid and both weather stations PE _i= [1/d _l*( PE_ l *(N_ i/ N_ l ))]+[1/d_ m *( PE_ m *(N_ i/ N_ m ))] 1/d_ l +1/d_ m

4. Irrigation Sampling Methods Based on four main residential streets, spanning entire length of Manoa Valley Based on four main residential streets, spanning entire length of Manoa Valley Rate, Frequency, Area, Grid Location Rate, Frequency, Area, Grid Location

5. Irrigation Modeling Interpolating to grid: Interpolating to grid: y = mean daily irrigation y = mean daily irrigation x = mean daily (PE-RF) x = mean daily (PE-RF) Assumptions: Days with no rainfall- days with irrigation (and the reverse) All irrigation occurring at 6:00 PM

6. PE Results (1) PE Results (1) PE peaks during midday Low PE during night Driven by Radiation Cloud Cover

7. PE Results (2)

8. Seasonal variation of PE

9. Irrigation Results (1) Peak mean PE correlates with IRR events Peak mean PE correlates with IRR events

10. Irrigation Results (2)

11. Discussion (1) Inverse relationship between PE and RF Grids 6,12 and 19 can be accounted for by orientation of valley

12. Discussion (2) IRRaIRR 7.5163090 00 00 00 9.1665479.2 60.9021761 92.2145392.3 129.6004129.6 198.5493198.5 203.6276203.6 Direct relationship between PE and IRR Note: Irrigation not actually occurring in every grid cell

13. Basin Totals IRR mmIRR m^3PE mmPE m^3 4084.67640263369787.2514110.47474218910311.2

14. Potential Evaporation Errors Weather stations Weather stations Interpolating from only two sources Interpolating from only two sources Topography Topography Crude assignment of mean values Crude assignment of mean values

15. Irrigation Errors Measuring Irrigation Measuring Irrigation Imprecise measuring tools Imprecise measuring tools Sample size and randomization Sample size and randomization Interpolation Assumption Interpolation Assumption Everyone irrigating when no rain Everyone irrigating when no rain Everyone irrigating at 6:00 PM Everyone irrigating at 6:00 PM Irrigation occurring in all grids Irrigation occurring in all grids

16. Conclusion PE and IRR lower at back of valley, higher at front PE and IRR lower at back of valley, higher at front Rainfall decreases as PE increases Rainfall decreases as PE increases Irrigation increases as PE increases Irrigation increases as PE increases Irrigation increases as rainfall decreases Irrigation increases as rainfall decreases Making up for increasing demands of water Making up for increasing demands of water Less water available because less water and land cover Less water available because less water and land cover

17. Questions?