Banca de DEFESA: JULIANA FARIAS SANTOS DE MORAES

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : JULIANA FARIAS SANTOS DE MORAES
DATE: 13/07/2023
TIME: 16:00
LOCAL: meet.google.com/fvu-rnda-vwk
TITLE:

LATERAL HYDROSEDIMENTOLOGICAL CONNECTIVITY AND APPROACH FOR DETERMINATION OF SOIL ERODIBILITY AT WATERSHED SCALE

KEY WORDS:

Sediment Connectivity; Hydrological Connectivity; Connectivity Index; Lateral Connectivity; Curve Number; Watershed Critical Shear Stress.

PAGES: 83
BIG AREA: Engenharias
AREA: Engenharia Sanitária
SUMMARY:

The relationships between the bedload sediment flux, which is associated with the shear stress of the main channel, and the suspended sediment flux in a watershed can be understood through soil resistance, known as erodibility. In this context, soil erodibility plays a crucial role in determining sediment transport within the watershed, directly affecting the movement of sediments from slopes to the drainage network. However, the link between bedload sediment and suspended sediment flux, which enters the main channel through lateral sediment flow, still needs further understanding. To address this issue, studies were conducted in two semiarid and one coastal watershed in the state of Pernambuco, Brazil, where data on bedload and suspended sediment transport, soil characteristics, and hydrological data. The concept of hydro-sedimentological connectivity was used to assess the lateral sediment transport from slopes, quantified through the Connectivity Index (IC), a geomorphometric index that considers topography and provides a pixel-based representation of the degree of connection between different parts of the watershed. To represent the resistance to flow and lateral discharge of suspended sediments, the Curve Number parameter was used, which reflected the soil resistance and its hydrological group, allowing for an estimation of soil erodibility in the evaluated watersheds. IC values were obtained by spatializing the data into thematic maps and indicated that regions with higher connectivity values are those closer to the watershed's headwaters in both studied watersheds. The Curve Number was identified as an appropriate parameter to represent hydro-sedimentological lateral connectivity in the evaluated watersheds in this study, as it showed a direct relationship with suspended sediment concentration. Thus, the suspended sediment load from slopes was added to the bedload sediment load, allowing the determination of soil erodibility values for the studied watersheds. The erodibility values were determined through linear regression analysis between the total sediment discharge and the flow shear stress, resulting in values of 0.0009 kg.N-1.s-1 for the Jacu Creek watershed, 0.0015 kg.N-1.s-1 for the Exu Creek watershed, and 7.93x10-8 kg.N-1.s-1 for the Beberibe River watershed, with corresponding critical shear stress values of 5.22 Pa, 13.27 Pa, and 91.55 Pa, respectively. The results indicate that the semiarid watersheds, which are naturally less evolved pedogenetically compared to the coastal watershed, are more susceptible to water erosion. The presented results, along with the Connectivity Index maps, provide support for decision-making regarding water resource management and sustainable development of the studied watersheds. This information allows for the implementation of specific strategic measures in localized areas to mitigate the effects of water erosion, directing effective actions to protect and preserve water resources, and promoting more appropriate and sustainable soil management and conservation practices.

COMMITTEE MEMBERS:
Externo à Instituição - JONAS OTAVIANO PRAÇA DE SOUZA
Presidente - JOSE RAMON BARROS CANTALICE
Interno - VICENTE DE PAULO SILVA