Monitoring Advection-Enhanced Evapotranspiration in a Semiarid Region Irrigated Field Using Eddy Covariance and Optical/microwave Scintillometers
Abstract
Water is crucial for agriculture, especially in semiarid regions such as the Central valley of Chile (33.6°S - 70.6°W) where in recent years droughts have worsened the problem of water scarcity. During the 2008-2018 drought, for instance not only there was less precipitation but also more water was lost through evapotranspiration (ET). This pattern is expected to enhance in this region in the future as a result of climate change. Over irrigated agricultural fields ET rates are enhanced further by advection of dry air coming from the surroundings. These advection-enhanced ET episodes typically occur at sub-hourly temporal scales and at spatial scales that are typically much larger than those of traditional in-situ methods, such as evaporation pans, lysimeters, but much smaller than those based on remote sensing using satellites and weather numerical models. Hence, collecting ET data in these environments provides critical information for sustainable farming practices is challenging.
This work presents a field campaign that was performed in an irrigated vineyard during berry formation stage, in Pirque, Chile, with the aim of quantifying ET water loss during advection-enhanced ET episodes. To achieve this objective, an eddy covariance (EC) tower and an optical-microwave scintillometer (OMS) were deployed for direct observation of ET fluxes and the surface energy balance at different spatial scales. In parallel, we monitored the soil moisture with electrical resistivity tomography. These systems were installed for ~10 days to observe a complete irrigation cycle in the vineyard. The results of all measuring techniques are compared, highlighting the advantages and disadvantages of each technique for determining the magnitude of the advection-enhanced ET episodes, and a discussion is provided on how these results can improve sustainable farming practices.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2019
- Bibcode:
- 2019AGUFM.B42E..06S
- Keywords:
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- 0402 Agricultural systems;
- BIOGEOSCIENCES;
- 0452 Instruments and techniques;
- BIOGEOSCIENCES;
- 0466 Modeling;
- BIOGEOSCIENCES;
- 0480 Remote sensing;
- BIOGEOSCIENCES