Monitoring Agricultural Water Use Using High-Resolution Remote Sensing Technologies

Abstract

Over the coming decades, both food consumption and agricultural water use are expected to increase in response to growing populations. In light of these concerns, there has been a growing awareness and appreciation of the objectives of agricultural sustainability, which has the broad aim of securing food and water resources, without adversely affecting the environment or disenfranchising future generations. To ensure that irrigated fields optimize their water use towards a more sustainable application while remaining compliant with any imposed restrictions on access to water supplies (i.e. through water licensing), it is necessary to understand and quantify the water consumption of crops at appropriate spatial and temporal scales. Evaporation (E), also commonly referred to as evapotranspiration (ET), is the physical process of water vapor transport from the surface into the atmosphere. Evaporation can be estimated via interpretive modeling approaches that combine meteorological, radiative, vegetation, and other related properties to estimate land surface fluxes at any given time. The research presented herein aims to investigate the evaporative response of agricultural croplands across a range of spatial and temporal scales, with a focus on high-resolution and field-scale estimation. In particular, we explore the utility of novel CubeSat imagery to produce the highest spatial resolution (3 m) crop water use estimates ever retrieved from space. These high-resolution results are expanded through time by retrieving a daily evaporation product, offering an enhanced capacity to provide new insights into precision agriculture. The effects and implications of higher spatiotemporal resolutions are explored and contrasted against governmental satellite missions that operate at lower resolutions. An exploratory study on the use of unmanned aerial vehicles (UAVs) is also performed, specifically in the context of their capacity to mount miniaturized thermal sensors: with the accuracy and limitations of these sensors for deriving evaporation-type products examined. The overarching goal of this research is to advance the utility of space-based estimates of evaporation for precision agricultural applications, and to provide new high-spatial and temporal agricultural insights that can be directed towards improving water management and address food security concerns in a more sustainable manner.