Water Resources Research Act Program

Details for Project ID 2020HI274B

Forecasting daily reference evapotranspiration for water resources conservations and sustainable agriculture in Hawaii

Institute: Hawaii
Year Established: 2020 Start Date: 2020-03-01 End Date: 2021-02-28
Total Federal Funds: $35,000 Total Non-Federal Funds: $70,942

Principal Investigators: Sayed Bateni

Abstract: Accurate forecasts of ETo play a key role in the optimal irrigation scheduling and efficient management of water resources. Recently, the University of California Extension developed CropManage for smart irrigation scheduling of farmlands in California. The PI and Co-PI are currently adapting the CropManage web application for use in Hawaii, which will be operational by mid-2020. CropManage provides daily irrigation recommendations for the next 7 days by utilizing the long-term ETo average as the ETo forecast. This often yields erroneous irrigation scheduling because ETo in the next 7 days can be very different from the long-term ETo average, leading to cases where CropManage generates a poor irrigation scheduling, which can damage crops, and reduce yields. It is evident that providing CropManage with an accurate ETo forecast with up to 7 lead days is of vital importance, and enhances its capability to provide more reliable irrigation recommendations with the ultimate goal of conserving water resources.The objectives of this project are to 1) forecast daily ETo for lead times of 7 days for 5 locations across different agricultural irrigation areas in Hawaii by using the hybrid wavelet-MLP (multilayer perceptron) and wavelet-NARX (nonlinear autoregressive network with exogenous inputs) approaches, 2) assess the accuracy of wavelet-MLP and wavelet-NARX approaches against daily ETo values from the FAO Penman-Monteith (FAOPM) equation, 3) incorporate the forecasted ETo values into CropManage to improve water use efficiency for farmlands in Hawaii, 4) validate CropManage in improving water use efficiency at the farm level with field trials, consisting of side-by-side strip trials comparing the use of long-term-average and forecasted ETo values in the CropManage system, and 5) increase growers’ awareness and adoption of irrigation management strategies that maintain profitable crop yield and quality.