Assessment of drip irrigation sub-units using airborne thermal imagery acquired with an Unmanned Aerial Vehicle (UAV)

Abstract

The proper maintenance of irrigation sub-units is a key aspect for efficient irrigation and for ensuring that the theoretical high drip irrigation application efficiencies are achieved. The performance assessment methods are based on the discharge measurements of some emitters sampled within the irrigation unit. The emitter selection is a key aspect for guaranteeing that plot heterogeneity is well represented. In this work, thermal images obtained by means of an Unmanned Aerial Vehicle over an irrigation district were used to determine irrigation performance. Four irrigation sub-units were assessed with standard methods. Canopy temperature showed a good correlation with the total flow discharge when plant water status variability in the sub-unit was high. When standard irrigation performance assessment protocols are used, the sample of emitters is small and so the large existing variability might not be taken into account. Aerial thermal images can quantify plant water status in large areas enabling the detection of some failures in the irrigation delivery system that might not be always detected with the standard irrigation performance assessment protocols.