Abstract
Estimation of ground-truth daily evapotranspiration (ETc) is very useful for developing sustainable water resource strategies, particularly in the North China Plain (NCP) with limited water supplies. Weighing lysimetry is a well-known approach for measuring actual ETc. Here, we introduced an alternative to lysimetry for ETc determination using Insentek sensors. A comparison experiment was conducted for maize plants at Xuchang Irrigation Experiment Station, in the NCP, in 2015 and 2016. Insentek ETc was evaluated using data on clear days and rainy days independently. We found that daily ETc increased gradually from VE (emergence) to VT (tasseling) stages, peaked at the R1 (silking) stage with the highest value of 7.8 mm·d−1, and then declined until maturity. On average, cumulative total of lysimetric ETc was 19% higher than that of Insentek ETc. The major depth of soil water extraction might be 60 cm for maize plants on lysimeters according to soil water depletion depth monitored by Insentek sensors. Daily ETc significantly related to soil water content (SWC) in topsoil (0–30 cm) in an exponential function (coefficients of determination (R2) = 0.32–0.53), and to precipitation (Pre) in a power function (R2 = 0.84–0.87). The combined SWC (0–30 cm)–Pre–ETc model may offer significant potential for accurate estimation of maize ETc in semi-humid environment of the NCP.
Highlights
The North China Plain (NCP) produces 58 and 33% of the domestic wheat and maize yields in China, ensuring China’s food security [1]
An alternative based on Insentek soil moisture data to estimate ETc was evaluated in comparison with lysimetry in the NCP
Since precipitation and soil water content (SWC) play an important role in water balance calculation for ETc, responses of ETc to them were analyzed on different weather days
Summary
The North China Plain (NCP) produces 58 and 33% of the domestic wheat and maize yields in China, ensuring China’s food security [1]. Alternatives this method usually needs a span of time to measure soil water content (SWC), and is difficult to should be developed to facilitate ETc monitoring. This method needs a span of time to watermodels content (SWC), is difficulthave to strong studies have shownusually that different algorithms of measure remote soil sensing for ETcand estimation estimate or sub-daily. Insentek sensor emerging technology that can automatically monitor soil moisture data hourly or sub–hourly (Figure allows the changes in soilmonitoring water storage (SWS), making calculation. It is an apparatus of fordaily real–time soil moisture powered by solar energy.the. C quantify the relationships among ETc, SWC and precipitation for maize plants in the NCP
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