Banca de DEFESA: KLEYMERSON PEREIRA LINS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : KLEYMERSON PEREIRA LINS
DATE: 27/02/2023
TIME: 19:00
LOCAL: videoconferência
TITLE:

Estimation of Real Evapotranspiration in a Semiarid Region, using the SAFER algorithm

KEY WORDS:

Remote Sensing, Landsat, Semiarid, QGIS.

PAGES: 55
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Meteorologia
SUMMARY:

The effects of global climate change are diverse, such as increased pollution, deforestation, to
water and food shortages. In this sense, it is essential to use techniques to estimate the amount
of water needed for the development of agricultural crops. Therefore, the main objective of this
work is using remote sensing techniques and the SAFER algorithm (Simple Algorithm for
Evapotranspiration Retrieving) to estimate evapotranspiration for the central-north region of
the state of Pernambuco and southwest of Paraíba. It is a semi-arid area, except for the city of
Triunfo (PE), characterized as an altitude swamp. For estimation, was used surface data from
the meteorological station of Serra Talhada (PE), belonging to the National Institute of
Meteorology (INMET), as well as images from the Landsat8 satellite. From the observed data,
the reference evapotranspiration was calculated using the Penman-Monteith (PM) method,
necessary for the calculation of the Real SAFER evapotranspiration. Using the QGIS Software,
mosaics were made with the images of the quadrants 216/065 and 216/066 and the clipping of
the region of interest, with a radius of 50 km, starting from the meteorological station. After
processing and analyzing the images, four dates were selected for the study, which are
referenced in the text by the season of the year, to better understand their differences:
01/02/2014 (summer), 05/26/2014 (autumn), 07/18/2016 (winter) and 11/05/2015 (spring). The
variables estimated by SAFER were analyzed: albedo, surface temperature and Normalized
Difference Vegetation Index - NDVI. The results obtained for the albedo showed higher values
for spring, the hottest and driest season analyzed, and lower values for autumn, the wettest
period. These results are in agreement with those of NDVI, which are inversely related to
albedo. Higher NDVI values were estimated in the rainy season, while lower indices were found
for the driest season, for which the vegetation is less robust. They also corroborate the results
for surface temperature (Tௌ

), which suggest higher temperatures during spring when compared

to autumn. Comparing the estimates of the average Tௌ

of the study area with the data observed
at the Serra Talhada station, it was verified that there was an overestimation of the variable,
with a greater difference in spring, while for autumn the Tௌ

was underestimated. As for the
estimation of real evapotranspiration by SAFER, it was verified that the average value was
higher in autumn, period with higher precipitation index, and lower in spring, hot period and
with lower water availability. Subsequently, an analysis was carried out for a smaller area,
measuring 750 meters by 750 meters, with the meteorological station in the center, and the
variables were analyzed to verify whether a more homogeneous area would present adverse
results compared to the previous ones. The results showed slightly different estimates, however,
within the standard deviation. Comparing the SAFER evapotranspiration estimates with the
data collected at the station, the ETோ ௌ஺ிாோ and KCௌ஺ிாோ (SAFER evapotranspiration fraction)
quotient was calculated for the original study area; quotient of ETோ ௌ஺ிாோ and KCௌ஺ிாோ for the
smaller area; and ETோ ௌ஺ிாோ from the clipping and KCௌ஺ிாோ from the total area, verifying that
the values of ETோ ௌ஺ிாோ are close to ET଴ ௉ெ, due to dependence from ET଴ ௉ெ to estimate by
SAFER. Greater differences occur when using the ETோ ௌ஺ிாோ value of the clipped area and the
KCௌ஺ிாோ of the total area, with greater variations in autumn and spring, due to the dependence
of surface temperature on the evapotranspiration estimate. It was concluded that SAFER, even
though it was developed to estimate ET for crops, is efficient for estimating in heterogeneous
areas, and can be used as a tool to aid irrigation management in different areas.

BANKING MEMBERS:
Interno(a) - 1537309 - FABRICIO DANIEL DOS SANTOS SILVA
Presidente - 4421297 - HELIOFABIO BARROS GOMES
Externo(a) à Instituição - JANNAYLTON EVERTON OLIVEIRA SANTOS
Interno(a) - 1653612 - MARIA LUCIENE DIAS DE MELO