Estimation of Vine and Inter-row Transpiration/Evaporation for Improved Water Management Using Remote Sensing

In California, there is concerted effort to improve water management of irrigated croplands, which requires the development of tools and technologies for monitoring water use and improving irrigation efficiency at both the field and regional scale. California grows many different crops, and devotes significant acreage to the cultivation of orchard crops, particularly vineyards. The demand for wine has led to expansion of vineyards to many types of climates ranging from temperate to arid/desert, but California remains one of the largest wine producers world-wide. Unique to orchard crops, and particular vineyards, is the unique vine canopy architecture and row spacing. The architecture of wine-grape vineyards is characterized by tall plants (°1.5 m) and widely spaced rows (°3 m). This wide row spacing, facilitating sunlight interception, air flow, and field operations, results in two distinct management zones: the vines and the inter-row. Any water management tool/technique for vineyards must consider how these two systems interact and affect water and energy exchange. Additionally, geographical, geological, and climatological characteristics of a region all interact with the vine plant's genetics to impart the taste and other characteristics of the wine. Hence any water management tool will need to consider these aspects/impacts in developing a more efficient irrigation strategy that does not compromise grape productivity and wine quality. To develop a multi-scale operational system for monitoring vineyard water use and vine plant and inter-row stress and moisture conditions necessitates the use of remote sensing and a land surface model that captures the micro and macro-scale exchanges between the vine plant, inter-row and atmospheric boundary layer exchange of momentum, water and energy fluxes. Such a remote-sensing-based modeling system has been developed called the Atmospheric Land EXchange Inverse (ALEXI) model together with a Disaggregation module (DisALEXI) for using high resolution thermal remote sensing data. The ALEXI/DisALEXI modeling system has been applied and tested over a wide variety of landscapes and found to be robust. An experiment conducted at vineyard sites in California will be described where ground validation data of water and energy fluxes, soil moisture and biophysical properties were collected during different vine phenological stages along with high resolution aircraft imagery for discriminating inter-row and vine cover and thermal temperatures. A description of the experiment and initial results applying the thermal-based model with satellite and airborne data will be presented. In particular, the capability of the land surface scheme to quantify vine plant and inter-row water and energy fluxes for the unque vineyard architecture will be discussed.