Study on Daily ET Based on SEBAL Model in a Typical Watershed of the Loess Plateau of China

Xuexia Zhang,Yuepeng Gao,Yu Fang,Dianjun Zhang,Xinxiao Yu

doi:10.4236/jwarp.2019.112011

Abstract

Under the double impact of global climate change and human intervention, surface evapotranspiration (ET), as an important part of hydrological cycle, is affecting watershed land-use planning and economic development. The Loess Plateau is mostly arid and semi-arid areas and its ecological environment is fragile. Drought and soil erosion not only reflects the regional climate change, but also human social activities and ecosystems. In particular, these processes are directly related to the thermal and water gradients exchange in the soil-vegetation-atmosphere system. Luoyugou watershed, a typical Loess Plateau watershed, is selected for this study. Estimating ET through SEBAL (Surface Energy Balance Algorithm for Land) model demonstrates that the SEBAL model in the watershed is more applicable. At the same time, ET seasonal variation is got, combined with the corresponding periods of the land-use changes for analysis. The results show that ET in the Northwest of the basin is higher than the East on the spatial distribution, especially in the high vegetation coverage area. Land use changes significantly in the watershed over the past 20 years, mainly transferring from sloping terraces to the terraces and woodland. ET significantly increased area accounts for 47.6% of the total area in the valley, however, conspicuously reduced area accounts for 13.2%. The daily ET of different land use types had significant differences with the ET of water land and wood land was the largest. It is important that this study on the ET distribution can aid policy and decision makers for land use planning and environmental construction in Luoyugou watershed.

Highlights

ET is an important element in the process of terrestrial water and energy cycle, and the exchanges between the moisture and its carrying latent heat in the terrestrial hydrological processes among the oceans and land regulate the global distribution of water and energy
Estimating ET through SEBAL (Surface Energy Balance Algorithm for Land) model demonstrates that the SEBAL model in the watershed is more applicable
The results indicate that the use of remote sensing data in combination with SEBAL model inversion regional ET has a broad applicable prospects for water resources management in the Loess Plateau and provides a basis and reference

Summary

Introduction

ET is an important element in the process of terrestrial water and energy cycle, and the exchanges between the moisture and its carrying latent heat in the terrestrial hydrological processes among the oceans and land regulate the global distribution of water and energy. One relatively mature application of the model is SEBAL model proposed by Bastiaanssen [4], whose basic principle is energy balance. It is a typical method through the inversion of ET by remote sensing technology that has been verified in a number of places at home and abroad. Compared with the traditional manual measurement method, the RS-based inversion method requires less data and is less affected by the underlying surface condition It can dynamically observe the temporal and spatial changes of the target area, so it is the main method to study regional evapotranspiration at present because of economy and applicability

Methods

Results

Conclusion