Towards Multi-Scale Tracking of Water Movement across the Soil-Plant-Atmosphere Continuum Using Heated Fiber Optics.

Understanding the processes that control water movement across the soil-plant-atmosphere continuum and over wide range of temporal and spatial scales is crucial for protecting and better management of our water resources. Both measurement and modeling at the end-scales (at <1m or >10 km) are well established. However, the distribution of soil water content and plant/crop water use in natural and managed landscapes at the intermediate-scale (1 m to 10 km) is a realm of persistent uncertainty and importance in modeling climate, hydrology, and in precision ag-water management. Recent advances in employing heated Fiber optics (FO) in association with Distributed Temperature Sensing (DTS) technology demonstrated great potential for quantifying and tracking key constituents of the water cycle at scales ranging from 0.1 m to 10,000 m. Advances in two particular applications using Heated FO will be presented in this work: 1) tracking soil water content along subsurface deployments of heated FO cables and 2) tracking air movement along an aerial deployment of heated FO. The latest application being a first step towards actively tracking Evapo-transpiration fluxes above vegetative landscapes. We will present the theoretical background, test cases results, as well as the challenges and the potentials of both applications.