Variation and Transformation of Evapotranspiration at Different Scales in a Desert Steppe
Water resources are severely scarce in desert steppes, and precipitation rarely collects in rivers or is transformed into groundwater. Evapotranspiration (ET) is the primary “export” of precipitation conversion and is the main mechanism for water vapor exchange between the underlying surface and atm...
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| Format: | Article |
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MDPI AG
2024-01-01
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| Series: | Water |
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| Online Access: | https://www.mdpi.com/2073-4441/16/2/288 |
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| author | Pengcheng Tang Jianying Guo Xiaoyu Gao Ying Zheng Bo Wang Lei Hao Jiashuang Wang |
| author_facet | Pengcheng Tang Jianying Guo Xiaoyu Gao Ying Zheng Bo Wang Lei Hao Jiashuang Wang |
| author_sort | Pengcheng Tang |
| collection | DOAJ |
| description | Water resources are severely scarce in desert steppes, and precipitation rarely collects in rivers or is transformed into groundwater. Evapotranspiration (ET) is the primary “export” of precipitation conversion and is the main mechanism for water vapor exchange between the underlying surface and atmosphere. ET changes have certain scale effects. This study focused on the natural grasslands in the Xilamuren Desert Steppe and analyzed and estimated the ET patterns at different scales, including micro-, point-, and surface scales, using observational data from instruments such as a photosynthetic meter, Eddy-covariance system (EC), and large-aperture scintillometer (LAS) from the Ecological Hydrology National Field Science Observation Station in the northern foothills of the Yin Mountains, Inner Mongolia. The spatial scale was extended based on this analysis. The results showed that at the microscale, the diurnal variation in the photosynthetic and transpiration rates of <i>Leymus chinensis</i> followed a bimodal curve. In July and August (high-temperature months), photosynthetic and transpiration rates were almost synchronous. In May and October, when the temperature was moderate, the transpiration rate was delayed compared to the photosynthetic rate at the first peak, and the second peak was significantly smaller than the first peak. At the point-scale, the daily average ET during the growing season was 1.37 mm·d<sup>−1</sup> and the total cumulative ET was 251 mm. Transpiration levels exhibited significant seasonal variation in the following order: July > August > June > September > May > October. At the surface-scale, the daily average ET during the growing season was 1.60 mm·d<sup>−1</sup> and the total cumulative ET was 294 mm, which was 17% higher than that of the point-scale. The surface-scale ET was estimated using the observed values of the EC and the scale relationship formula and was optimized using different spatial scales of crop coefficients. This well reflected the ET patterns at the surface-scale. Therefore, this study proposes a spatial scale expansion method for a homogeneous underlying surface, verifies its value, and provides methodological support for estimating ET in cases of data scarcity. |
| first_indexed | 2024-03-08T10:32:54Z |
| format | Article |
| id | doaj.art-dab9d3ea600d45b89ee84fda19b9d499 |
| institution | Directory Open Access Journal |
| issn | 2073-4441 |
| language | English |
| last_indexed | 2024-03-08T10:32:54Z |
| publishDate | 2024-01-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Water |
| spelling | doaj.art-dab9d3ea600d45b89ee84fda19b9d4992024-01-26T18:51:38ZengMDPI AGWater2073-44412024-01-0116228810.3390/w16020288Variation and Transformation of Evapotranspiration at Different Scales in a Desert SteppePengcheng Tang0Jianying Guo1Xiaoyu Gao2Ying Zheng3Bo Wang4Lei Hao5Jiashuang Wang6Yinshanbeilu Grassland Eco-Hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing 100038, ChinaYinshanbeilu Grassland Eco-Hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing 100038, ChinaWater Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, ChinaYinshanbeilu Grassland Eco-Hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing 100038, ChinaYinshanbeilu Grassland Eco-Hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing 100038, ChinaYinshanbeilu Grassland Eco-Hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research, Beijing 100038, ChinaWater Conservancy and Civil Engineering College, Inner Mongolia Agricultural University, Hohhot 010018, ChinaWater resources are severely scarce in desert steppes, and precipitation rarely collects in rivers or is transformed into groundwater. Evapotranspiration (ET) is the primary “export” of precipitation conversion and is the main mechanism for water vapor exchange between the underlying surface and atmosphere. ET changes have certain scale effects. This study focused on the natural grasslands in the Xilamuren Desert Steppe and analyzed and estimated the ET patterns at different scales, including micro-, point-, and surface scales, using observational data from instruments such as a photosynthetic meter, Eddy-covariance system (EC), and large-aperture scintillometer (LAS) from the Ecological Hydrology National Field Science Observation Station in the northern foothills of the Yin Mountains, Inner Mongolia. The spatial scale was extended based on this analysis. The results showed that at the microscale, the diurnal variation in the photosynthetic and transpiration rates of <i>Leymus chinensis</i> followed a bimodal curve. In July and August (high-temperature months), photosynthetic and transpiration rates were almost synchronous. In May and October, when the temperature was moderate, the transpiration rate was delayed compared to the photosynthetic rate at the first peak, and the second peak was significantly smaller than the first peak. At the point-scale, the daily average ET during the growing season was 1.37 mm·d<sup>−1</sup> and the total cumulative ET was 251 mm. Transpiration levels exhibited significant seasonal variation in the following order: July > August > June > September > May > October. At the surface-scale, the daily average ET during the growing season was 1.60 mm·d<sup>−1</sup> and the total cumulative ET was 294 mm, which was 17% higher than that of the point-scale. The surface-scale ET was estimated using the observed values of the EC and the scale relationship formula and was optimized using different spatial scales of crop coefficients. This well reflected the ET patterns at the surface-scale. Therefore, this study proposes a spatial scale expansion method for a homogeneous underlying surface, verifies its value, and provides methodological support for estimating ET in cases of data scarcity.https://www.mdpi.com/2073-4441/16/2/288desert steppesspatial scaleevapotranspiration patternscale extension |
| spellingShingle | Pengcheng Tang Jianying Guo Xiaoyu Gao Ying Zheng Bo Wang Lei Hao Jiashuang Wang Variation and Transformation of Evapotranspiration at Different Scales in a Desert Steppe Water desert steppes spatial scale evapotranspiration pattern scale extension |
| title | Variation and Transformation of Evapotranspiration at Different Scales in a Desert Steppe |
| title_full | Variation and Transformation of Evapotranspiration at Different Scales in a Desert Steppe |
| title_fullStr | Variation and Transformation of Evapotranspiration at Different Scales in a Desert Steppe |
| title_full_unstemmed | Variation and Transformation of Evapotranspiration at Different Scales in a Desert Steppe |
| title_short | Variation and Transformation of Evapotranspiration at Different Scales in a Desert Steppe |
| title_sort | variation and transformation of evapotranspiration at different scales in a desert steppe |
| topic | desert steppes spatial scale evapotranspiration pattern scale extension |
| url | https://www.mdpi.com/2073-4441/16/2/288 |
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