Evapotranspiration estimation in the Brazil using NDVI data

Abstract

The purpose of this study is to analyze the monthly mean spatial and temporal distribution of evapotranspiration (ET) during the 1981-2000 period in Brazil using remotely sensed data. The methodology involves the use of a relationship between ET and Normalized Difference Vegetation Index (NDVI). ET was estimated for the main Brazilian biomes through the Penman-Monteith method using climatological data from 194 Brazilian meteorological stations during the 1961-1990 period. NDVI data for the July 1981 to July 2000 period was obtained from Advanced Very High Resolution Radiometer (AVHRR) sensor on board the NOAA satellite. A relatively high correlation coefficient between ET and NDVI (r=0.81) was found, showing a near linear relationship involving these variables. Also, the monthly mean ET over Brazil was estimated using NDVI data. The results showed that the ET rate in the Amazon region is not well defined because the maximum values occur after the rainy season, while for the Northeast Brazil, the highest ET values occur in according to period of rainy season. The annual cycle of ET is most defined in the Central region, with maximum values occurring in January to May period and minimum in September. In the South and Southeast regions, the annual cycle ET does not change very much. Finally, this study suggests that NDVI is an important variable for indirectly monitoring ET over large areas, thus with great potential for agronomical and climatic applications.

High Spatial Resolution WorldView-2 Imagery for Mapping NDVI and Its Relationship to Temporal Urban Landscape Evapotranspiration Factors

“…The strong significant positive correlation between ET WV2 and ET WUCOLS (r 2 = 0.96, p > 0.05) demonstrates well the feasibility and practicality of a remotely-sensed ET estimation approach in Veale Gardens. This finding is in line with several studies that have found a strong and reliable relationship between aerial-satellite-based Landscape NDVI measurements and ground-based ET measurements [17,[53][54][55][56][57][58][59]. A significant decrease in rainfall in January 2013 imposed stress conditions to the vegetation in Veale Gardens.…”

“…Statistical analysis and ground measurement has confirmed that a near linear relationship can be found between VIs and photosynthesis by vegetation canopy [16]. Long-term RS data analysis by Rossato et al [17] showed that ET and NDVI have a near-linear relationship. A linear relationship between NDVI and basal crop coefficient for irrigated agricultural fields was also reported by Duchemin et al [18].…”

Estimation of Crop Evapotranspiration Using Satellite Remote Sensing-Based Vegetation Index

“…These two seasons were characterized because in the initial stage crop needs smaller water requirements, whereas in the mid-season crop needs higher water requirements, as we can see in the next section. The ET c maps created in this study are in agreement with other researchers; for example, in [2,4,58,59], they generated ET c maps using c derived from remote sensing-based vegetation indices. Other researchers reported that c derived from canopy reflectance based vegetation index had the potential to estimate crop evapotranspiration at regional and field scales, for example, in [17,18,29,55,60,61].…”

Variations of NDVI and Its Association with Rainfall and Evapotranspiration over Bangladesh

“…NDVI has good correlation with evapotranspiration as NDVI is proportional to the vaporized water into the atmosphere [4,10]. This section deals with the relationship of NDVI with total evapotranspiration over Bangladesh through the use of interannual time series variation, spatial correlation, scatter plot and interannual correlation.…”