Banca de DEFESA: RAUL GOMES DA SILVA
Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.STUDENT : RAUL GOMES DA SILVA
DATE: 27/02/2026
TIME: 08:00
LOCAL: Sala Geologia (Hbrido_
TITLE:
Identification of sources and production of sediments in a watershed undergoing
desertification
KEY WORDS:
Fingerprinting approach. Land use changes. Environmental degradation.
PAGES: 89
BIG AREA: Ciências Agrárias
AREA: Agronomia
SUBÁREA: Ciência do Solo
SUMMARY:
The Cachoeirinha watershed is located in the Cabrobó Desertification Center (NDC), a
region in the state of Pernambuco characterized by desertification. For this purpose, the
sediment fingerprinting method is an approach for identifying sediment sources by assimilating
sediment characteristics based on their properties, making it possible to determine the origin
and pathways of sediments to the drainage network. Therefore, the objective of this research
was to identify sediment sources and land use change processes that lead to soil degradation.
The study identified sediments originating from native caatinga, deforested caatinga, channel
banks, and unpaved roads. River course regions were also considered as sediment sources and
were divided into upper, middle, and lower reaches in order to assess the levels of degradation
in the basin’s drainage macroregions. The study used X-ray fluorescence (FRX) to generate
geochemical signatures. Linear discriminant analysis was applied to select the best set of tracers
for the fingerprinting model. The post-transition metals Tl and Pb were the most effective
tracers for distinguishing sediment sources and were fundamental to the modeling process. The
Cachoeirinha basin showed deforested caatinga as the main sediment source (~29%), followed
by channel banks (~27%), native caatinga (~23%), and unpaved roads (~18%). We identified
carbon loss and greater mobilization of chemical elements in the deforested caatinga. We also
observed a higher silt concentration in the deforested caatinga and evidence of particle loss in
the A horizon. Among the river course regions, the upper reach had the highest sediment
contribution (~43%), while the lower and middle reaches showed similar contributions (~28%
each). The high number of dams in the lower and middle reaches reduces hydrosedimentological
connectivity and retains much of the eroded sediment, thereby decreasing the
contribution from these regions. These findings provide scientific support for targeted land
management and restoration strategies in semiarid regions, contributing to more effective
actions to mitigate soil degradation.
COMMITTEE MEMBERS:
Presidente - YURI JACQUES AGRA BEZERRA DA SILVA
Externa à Instituição - LIDIANE BULIGON - UFSM
Externo à Instituição - RENNAN CABRAL NASCIMENTO - INSA