Abstract
Assessment of actual evapotranspiration (ET) is essential as it controls the exchange of water and heat energy between the atmosphere and land surface. ET also influences the available water resources and assists in the crop water assessment in agricultural areas. This study involves the assessment of spatial distribution of seasonal and annual ET using Surface Energy Balance Algorithm for Land (SEBAL) and provides an estimation of future changes in ET due to land use and climate change for a portion of the Narmada river basin in Central India. Climate change effects on future ET are assessed using the ACCESS1-0 model of CMIP5. A Markov Chain model estimated future land use based on the probability of changes in the past. The ET analysis is carried out for the years 2009–2011. The results indicate variation in the seasonal ET with the changed land use. High ET is observed over forest areas and crop lands, but ET decreases over crop lands after harvest. The overall annual ET is high over water bodies and forest areas. ET is high in the premonsoon season over the water bodies and decreases in the winter. Future ET in the 2020s, 2030s, 2040s, and 2050s is shown with respect to land use and climate changes that project a gradual decrease due to the constant removal of the forest areas. The lowest ET is projected in 2050. Individual impact of land use change projects decreases in ET from 1990 to 2050, while climate change effect projects increases in ET in the future due to rises in temperature. However, the combined impacts of land use and climate changes indicate a decrease in ET in the future.
Highlights
The estimation of actual evapotranspiration (ET) and its spatial distribution over a large area are considered an extremely important variable in the efficient management of water resources and agriculture
The seasonal land surface temperature (LST) and normalized difference vegetation index (NDVI) of three years are presented in Figures 3 and 4
Low LST is observed over the agricultural and forest areas in the central part of the study area, and high LST is observed over plain lands and less vegetated areas
Summary
The estimation of actual evapotranspiration (ET) and its spatial distribution over a large area are considered an extremely important variable in the efficient management of water resources and agriculture. ET is considered one of the major components of the hydrological cycle, apart from the rainfall and runoff It is affected at the interface of vegetation, soil, and atmosphere by atmospheric, soil, and biophysical processes [1]. According to Gowda et al [3], reliable estimation of ET is required to improve the water use efficiency. ET plays an important role in the atmospheric processes since it controls the water supply from the ocean and earth’s surface to the atmosphere. It influences the spatial distribution and magnitude of global temperature and pressure [5], and the incidence of heat waves [6]. ET determines climate drought in arid and semi-arid areas, and changes in meteorological variables due to climate affect crop water requirements [11,12]
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