Interannual Variations of Evapotranspiration and Water Use Efficiency over an Oasis Cropland in Arid Regions of North-Western China
Abstract
:1. Introduction
2. Materials and Methods
2.1. Site Description
2.2. Field Management Practices
2.3. Flux Measurements and Data Processing
2.4. Satellites Data and Processing
2.5. Ecosystem Water Use Efficiency (WUE), Canopy WUE and Water Availability Index
2.6. Evapotranspiration Partitioning Methods Using a Remote Sensing-Based Model
3. Results
3.1. Seasonal and Interannual Dynamics of Biophysical Factors
3.2. Seasonal and Interannual Dynamics of Carbon and Water Fluxes and Water Use Efficiency
3.3. Biophysical Regulations of the Temporal Variations of Gross Primary Production, Evapotranspiration and Water Use Efficiency
4. Discussion
4.1. Wate Use Efficiency Variations of Cropland Ecosystems and their Biophysical Influencing Factors
4.2. Effects of Irrigation Practice on soil Moisture Dynamics, Evapotranspiration Components, and Water Use Efficiency in Arid Agricultural Systems
4.3. Potential Implications for Agricultural Water Resource Managements in Arid Regions
5. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Variables | 2013 | 2014 | 2015 | 2016 | 2017 | 2018 | Average |
---|---|---|---|---|---|---|---|
Solar radiation (Rg, W m−2) | 183.52 | 178.57 | 179.53 | 174.32 | 172.06 | 169.32 | 176.22 ± 4.45 |
Air temperature (Ta, °C) | 7.05 | 6.45 | 7.08 | 7.14 | 7.21 | 6.44 | 6.90 ± 0.3 |
Precipitation (P, mm) | 136 | 145 | 161 | 102 | 187 | 112 | 140 ± 27 |
Vapor pressure deficit (VPD, hpa) | 7.26 | 6.66 | 6.80 | 6.92 | 6.82 | 6.55 | 6.84 ± 0.21 |
4 cm soil moisture (SM_4cm, %) | 17.88 | 18.49 | 20.27 | 20.50 | 15.16 | 13.19 | 17.58 ± 2.44 |
40 cm soil moisture (SM_40cm, %) | 26.26 | 25.87 | 27.76 | 25.43 | 19.17 | 18.60 | 23.85 ± 3.32 |
160 cm soil moisture (SM_160cm, %) | 29.04 | 28.42 | 29.40 | 26.62 | 14.70 | 18.11 | 24.38 ± 5.37 |
Enhanced vegetation index (EVI) | 0.24 | 0.27 | 0.26 | 0.23 | 0.26 | 0.27 | 0.26 ± 0.01 |
Variables | Flood Irrigation | Drip Irrigation | Change Values | Change Ratios (%) |
---|---|---|---|---|
GPP (g C m−2) | 1339.72 | 1337.62 (1286.71) | −2.09 (−53.01) | −0.16 (−3.96) |
ET (kg H2O m−2) | 733.15 | 640.48 (640.39) | −92.67 (−92.76) | −12.64 (−12.65) |
T (kg H2O m−2) | 572.01 | 511.45 (494.22) | −60.57 (−77.80) | −10.59 (−13.60) |
E (kg H2O m−2) | 161.14 | 129.03 (146.17) | −32.11 (−14.96) | −19.92 (−9.29) |
WUEe (g C kg−1 H2O) | 1.84 | 2.09 (2.01) | +0.25 (+0.17) | +13.59 (+9.28) |
WUEc (g C kg−1 H2O) | 2.36 | 2.62 (2.60) | +0.26 (+0.25) | +10.98 (+10.46) |
SM_4cm (%) | 19.28 | 13.19 (14.17) | −6.10 (−5.11) | −31.62 (−26.49) |
SM_40cm (%) | 26.33 | 18.60 (18.88) | −7.73 (−7.45) | −29.37 (−28.28) |
SM_160cm (%) | 28.37 | 18.11 (16.40) | −10.26 (−11.97) | −36.18 (−42.19) |
Dependent Variable | Multiple R2 | Ta | P | SM | WAI | EVI | Best Model |
---|---|---|---|---|---|---|---|
GPP | 0.96 | 0.86 ** | 0.48 ** | 0.29 | 0.14 | 0.86 ** | GPP = f (Ta, P, EVI) |
ET | 0.87 | 0.76 ** | 0.17 | 0.21 | 0.54 ** | 0.02 | ET = f (Ta, WAI) |
T | 0.89 | 0.80 ** | 0.15 | 0.23 | 0.33 | 0.29 | T= f (Ta) |
WUEe | 0.92 | 0.49 ** | 0.25 | −0.02 | 0.10 | 0.80 ** | WUEe = f (Ta, EVI) |
WUEc | 0.89 | 0.05 | 0.21 | −0.09 | 0.35 | 0.72 ** | WUEc = f (EVI) |
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Wang, H.; Li, X.; Tan, J. Interannual Variations of Evapotranspiration and Water Use Efficiency over an Oasis Cropland in Arid Regions of North-Western China. Water 2020, 12, 1239. https://doi.org/10.3390/w12051239
Wang H, Li X, Tan J. Interannual Variations of Evapotranspiration and Water Use Efficiency over an Oasis Cropland in Arid Regions of North-Western China. Water. 2020; 12(5):1239. https://doi.org/10.3390/w12051239
Chicago/Turabian StyleWang, Haibo, Xin Li, and Junlei Tan. 2020. "Interannual Variations of Evapotranspiration and Water Use Efficiency over an Oasis Cropland in Arid Regions of North-Western China" Water 12, no. 5: 1239. https://doi.org/10.3390/w12051239