The Ratio Distribution of Evapotranspiration to Precipitation well Related With Soil Thickness in Karst Watershed of Southwest China. Issue 4 (10th February 2023)

• Record Type: Journal Article
• Authors: Zhang, Rongfei; Xu, Xianli; Guo, Jingsong; Sheng, Zhuping
• Is Part Of: Journal of geophysical research. Volume 128:Issue 4(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-02-10
• Subjects: evapotranspiration -- eco‐hydrology -- landscape ecology -- ventilated chambers -- remote sensing models; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2022JD037951
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: Evapotranspiration ( ET ) is predominant variable for water management in various types of ecosystems, and it has been intensively studied through in situ measuring and modeling methods. However, it is challenging to measure actual ET and upscale it to regional level for karst landscapes, where aquifers typically show remarkable and rapid responses to precipitation events. There is an urgent need to quantify water fluxes to provide reliable evidence for the protection and sustainable management of karst water resources. Therefore, in this study, five plots were built to observe actual ET based on Thermal Dissipation Probes, redesigned ventilated chamber and in‐site microlysimeters in a karst watershed in southwest China. Then, three models (Penman‐Monteith‐Leurning, PML; Remote Sensing‐Priestley and Taylor; and Hargreaves) were constructed to upscale ET estimation to the regional level based on Landsat‐8 images and MODIS data. The results showed that: (a) The PML model performed better than other models ( p < 0.01) with higher R 2 values (0.72 for MODIS images and 0.87 for Landsat‐8 images); (b) Daily ET exhibited significant seasonal variability and different spatial distribution, and yearly ET exhibited well related with soil thickness ( R 2 = 0.58); (c) Daily ET had a slightly positive correlation with DEM, however, had a negative correlation with ground temperature. This study is helpful to improve accuracy of measured and estimated ET by combining remote sensing data, and it has important implications for upscaling it to regional level. It suggests that ET is strongly regulated by constant supply of water, vegetation coverage, and available energy in karst catchments. Plain Language Summary: Evapotranspiration ( ET ) process bonds water, energy cycle, and carbon cycles. Aiming to characterize ET processes and impact controls at regional level for karst landscapes, five plots were built to observe actual ET, and three models were selected to upscale ET estimation to the regional level using Landsant‐8 and MODIS data in this study. The results showed that the Penman‐Monteith‐Leurning model performed the best and additional validation data observed in experimental spots were identified and corresponded with satellite data. Vegetation coverage and the density of conducting tissue (e.g., LAI ) both contributed to ET seasonality and the spatial distribution differences. Soil thickness is a key prediction for the ratio distribution of yearly evapotranspiration to precipitation in karst watershed in southwest China. Key Points: Multiple models based on different data sources exhibited different accuracy on evapotranspiration simulation in karst basin Yearly evapotranspiration distribution is well related with soil thickness Ground temperature exhibited negative correlation with daily evapotranspiration