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The focus of this work is the development of models to estimate evapotranspiration (ET), investigating the partitioning between soil evaporation and plant transpiration at field and regional scales, and calculating ET over heterogeneous vegetated surfaces. Different algorithms with varying complexities as well as spatial and temporal resolutions are developed to estimate evapotranspiration from different data inputs. The author proposes a novel approach to estimate ET from remote sensing by exploiting the linkage between water and carbon cycles. At the field scale, a hybrid dual source model (H-D model) is proposed. It is verified with field observations over four different ecosystems and coupled with a soil water and heat transfer model, to simulate water and heat transfer in the soil-plant-atmosphere continuum. At the regional scale, a hybrid dual source scheme and trapezoid framework based ET model (HTEM), using remote sensing images is developed. This model is verified with data from the USA and China and the impact of agricultural water-saving on ET of different land use types is analyzed, in these chapters. The author discusses the potential of using a remote sensing ET model in the real management of water resources in a large irrigation district. This work would be of particular interest to any hydrologist or micro-meteorologist who works on ET estimation and it will also appeal to the ecologist who works on the coupled water and carbon cycles. Land evapotranspiration is an important research topic in hydrology, meteorology, ecology and agricultural sciences.
Dr. Yuting Yang works at the CSIRO Land and Water, Canberra, Australia.

Inhaltsverzeichnis

Frontmatter

Chapter 1. Introduction

Abstract
Water servers as a fundamental component for almost all living creatures and plays a critical role in building a sustainable natural and social environment. However, with the increase of world population and degradation in water quality, there has been a significant decline in the availability of safe water resource across the globe. Studies have shown that nearly 1/3 of the world population lives in the area with per capital water resource lower than the minimum standard and there are more than 240 million people living in places with high water scarcity.
Yuting Yang

Chapter 2. Comparison of Dual-Source Evapotranspiration Models in Estimating Potential Evaporation and Transpiration

Abstract
Potential evapotranspiration (PET) is defined as the amount of ET that could occur if a sufficient water source were available, the value of which is a function of atmospheric conditions and surface vegetation distribution characteristics. However, traditional empirical PET models, such as the Hargreaves model and Priestley-Taylor model, only account for the effect of atmospheric demand on PET, whereas the impact of vegetation on PET is simply ignored. On the other hand, physical-based PET models, such as the Penman-Monteith model (refer to as the P-M model hereafter), take vegetation effect on PET into consideration. Nevertheless, the P-M model treats the land surface as a uniform layer, where the vegetation covers the land surface fully and uniformly as a “big leaf”. This simplification of vegetation treatment makes the P-M model unable to distinguish evaporation from soil (E) and transpiration from canopy (T), and therefore may not be appropriate for use in partially vegetated areas.
Yuting Yang

Chapter 3. A Hybrid Dual-Source Model of Estimating Evapotranspiration over Different Ecosystems

Abstract
In Chapter 2, we compared three dual source models in estimating potential ET and its partitioning under different vegetation cover conditions. The results show that the hybrid model (i.e., the TVET model) may be more suitable than the layer and patch model for a broad range of vegetated surfaces.
Yuting Yang

Chapter 4. A Hybrid Dual-Source Scheme Based Soil-Plant-Atmosphere Continuum Model (HDS-SPAC) for Water and Heat Dynamics

Abstract
Soil-plant-atmosphere continuum (SPAC) models are effective tools to describe the basic processes of coupled mass and energy transfer, which are important for climatic, hydrologic, ecological and agricultural studies.
Yuting Yang

Chapter 5. A Hybrid Dual-Source Scheme and Trapezoid Framework Based Evapotranspiration Model (HTEM) Using Satellite Images

Abstract
Remote estimation of land surface evapotranspiration from satellite imagery is probably the only effective way to obtain detailed spatial and temporal ET patterns for large scales.
Yuting Yang

Chapter 6. Remote Sensing Temporal and Spatial Patterns of Evapotranspiration and the Responses to Water Management in a Large Irrigation District of North China

Abstract
In arid and semiarid areas, agriculture relies heavily on irrigation of water diverted from rivers. However, with intensified changes of climate and land use, runoff of many rivers in arid area showed a declined trend during the past 50 years (Zhang et al. J Hydrol 410:204–216, 2011). Meanwhile, increasing water needs for industrial, domestic and environmental uses, has led to water resources scarcity globally (Vörömarty et al. Science 289:284–288, 2000). Consequently, traditional irrigation agriculture in these areas is now facing a big challenge, which appeals people to develop water-saving irrigation for sustainable water use.
Yuting Yang

Chapter 7. A Novel Method for Estimating Terrestrial Evapotranspiration by Exploiting the Linkage Between Water and Carbon Cycles

Abstract
As stated in Chap. 5, among many methods of ET quantification, satellite remote sensing has been shown to be one of the most promising ways of mapping ET over larger areas (e.g., Bastiaanssen et al. 1998; Norman et al. 1995). Numerous models with varying structure and complexities have been developed to derive ET from remotely sensed variables (e.g., land surface temperature, LST, and vegetation index, VI) in combination with concurrent meteorological measurements (e.g., near surface air temperature and vapor pressure) (e.g., Bastiaanssen et al. 1998; Long and Singh 2012; Lu and Zhuang 2010; Norman et al. 1995; Su 2002; Yang and Shang 2013).
Yuting Yang

Chapter 8. Conclusions, Limitations and Recommendation for Future Research

Abstract
Land surface evapotranspiration (ET) is one of the most active factors with the terrestrial hydrological cycle, which also provides an important lower boundary condition for understanding the climate system.
Yuting Yang
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