Banca de DEFESA: PAULO ANDRÉ DA SILVA MARTINS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : PAULO ANDRÉ DA SILVA MARTINS
DATE: 01/12/2025
TIME: 14:00
LOCAL: Auditório Milton Santos, Bloco 1T do CEGEA
TITLE:

Estimates and Space-Time Distribution of Erosivity Resulting from Rainfall in the State of Rondonia

KEY WORDS:

El30, Spatialization, Precipitation, Northern Region.

PAGES: 119
BIG AREA: Ciências Exatas e da Terra
AREA: Geociências
SUBÁREA: Geografia Física
SPECIALTY: Climatologia Geográfica
SUMMARY:

The process of soil erosion is a dynamic phenomenon resulting from the interaction of multiple geomorphological agents, with precipitation standing out as the main triggering factor. The kinetic energy of rainfall plays a critical role in initiating erosive processes, determining key characteristics such as intensity, frequency, and magnitude of events. Surface runoff emerges as a central mechanism in this dynamic, promoting the detachment and transport of sediment particles. This movement causes significant transformations in the landscape and soil structure, highlighting the complex relationship between climatic elements and local geological features.This study aims to demonstrate the variation in the Erosivity Index associated with differences in precipitation and its kinetic energy across the state of Rondonia. It seeks to verify that the Erosivity Index variation is related to seasonal differences and seasonality. The study area covers the state of Rondonia, Brazil. The research was based on a robust dataset from 1980 to 2023 from 58 meteorological stations of the National Water Agency (ANA) in Rondonia and precipitation estimates from the Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) for the same period. CHIRPS data were validated against surface data, and the Erosivity Index was calculated. Validation was conducted using statistics based on monthly and annual averages.The relationship between measured and estimated values was analyzed through Pearson's correlation coefficient "r," which measures the degree of linear correlation between two quantitative variables. Accuracy analysis was performed using the Willmott index "d," which relates the distance of estimated values compared to observed ones, with values ranging from 0 (no match) to 1 (perfect match). The Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) were also analyzed, indicating the average absolute deviation between estimated and measured values.After data validation, Fourier's equation was used, which relates monthly, annual average precipitation, and total annual average erosivity values, thus calculating monthly values. Data classification followed the Erosivity classes based on the following values: R < 2452 (Low) to R > 9812 (Very High).The results showed that CHIRPS displayed a mixed pattern of overestimating (32 stations) or underestimating (25 stations) precipitation. Significant monthly and annual differences occurred in only four stations, including Escola Caramuru (C32 - Ariquemes), Porto Velho (C3), Principe da Beira (C53 - Costa Marques), and Sao Mateus (C4 - Ji-Parana) (Figure 3a). Station C4 showed the highest overestimation at 48.3%, while the station in Cerejeiras (C56) had the smallest discrepancy at 0.2%. Conversely, the highest underestimation of monthly precipitation from CHIRPS was at the Porto Velho station (C3) at 63.7%.Rainfall erosivity showed great variation according to seasonality, with high peaks during the rainy season and low ones during the dry season. Erosivity classification throughout the state was mostly "Very High" during much of the year.The use of CHIRPS reanalysis data allowed for the formulation of satisfactory responses regarding the use of these data in investigating rainfall erosivity in Rondonia. The analysis of the results validated the initial hypothesis, which suggested a direct correlation between the erosivity index and seasonal variations, as well as the influence of different seasons. This hypothesis was confirmed by observing that the highest erosivity indices occurred during the period of greatest precipitation, covering the transition between spring and summer, specifically between October and April, when the recorded values ranged from "high" to "very high."

COMMITTEE MEMBERS:
Presidente - 396929 - DORISVALDER DIAS NUNES
Externo à Instituição - HENRIQUE DOS SANTOS PEREIRA
Interno - 3102827 - JOAO PAULO ASSIS GOBO
Interno - 2313615 - MICHEL WATANABE
Externa à Instituição - TAMIRES CUNHA DE AGUIAR