Entropy-based Model for Gully Erosion - A combination of probabilistic and deterministic components.

Gullies are a major threat to ecosystems, potentially leading to land degradation, groundwater depletion, crop loss, debris flow, and desertification. Gullies are also characterized by having a fast development and turning into primary sediment sources. Despite their impact, we have but scarce understanding of how gully erosion evolves and how to model it. In this paper, we propose a new gully erosion model that is based on the classical premise of net shear stress, i.e., hydraulic shear stress minus critical (resistant) shear stress, to calculate detachment rates. In order to calculate hydraulic shear stress, we developed a new equation derived from the principle of minimum cross-entropy; it was validated with laboratory measures from the literature with a Nash-Sutcliffe Efficiency of 0.95. Soil samples were analysed in the laboratory to assess critical shear stress and other soil properties. The novel gully erosion model was implemented in three gully impacted locations with catchment areas ranging from 10-2 to 10+1 ha. To assess channel geometry and eroded volumes, we used Unmanned Aerial Vehicle and Structure-from-Motion technique. The model successfully estimated long-term erosion rates, its efficiency was 0.77, and it is recommended for catchments up to 8 ha. Therefore, the new model provides planners and stakeholders with a tool to assess gully erosion, sediment yield and geometry in most areas.

Análise faunística e flutuação populacional de moscas-das-frutas (Diptera: Tephritidae) em pomares comerciais de goiaba na região do Cariri cearense / Faunistic and populational analysis of fruit flies (Diptera: Tephritidae) in commercial guava orchards in the Cariri region (State of Ceará), Brazil

Devido à importância das moscas-das-frutas como pragas da fruticultura, este trabalho teve como objetivos caracterizar as populações das moscas-das-frutas em pomares comerciais de goiaba na região do Cariri, Estado do Ceará, por meio de índices faunísticos e estudar a flutuação populacional dessas moscas ao longo do ano. Para isso, foram instaladas armadilhas McPhail nos Municípios de Barbalha, Crato e Juazeiro do Norte. As armadilhas foram examinadas semanalmente e as moscas capturadas foram triadas, conservadas em álcool a 70% e identificadas. Constatou-se que Anastrepha zenildae (Wiedemann), A. sororcula Zucchi, A. fraterculus (Wiedemann), A. obliqua (Macquart) e Ceratitis capitata (Wiedemann) foram as moscas-das-frutas associadas à goiaba. Dessas, A. zenildae. A. sororcula e A. obliqua foram dominantes e constantes na região estudada, enquanto que A. fraterculus e C. capitata foram não-dominantes, mas também constantes. A. zenildae ocorreu em quase todos os meses do ano, exceto em outubro e dezembro de 2008, nos três pomares de goiaba do Cariri e com picos populacionais nos meses mais chuvosos e com temperaturas amenas.

Due to the importance of fruit-flies as pests in fruit growing, the present study was aimed to characterize the populations of fruit-flies in commercial guava orchards in the Cariri region (state of Ceará), Brazil, by means of faunistic indexes and to study their population fluctuation during the year. For this purpose, McPhail traps were installed in the counties Barbalha, Crato and Juazeiro do Norte. The traps were examined weekly and the captured flies were separated, preserved in 70% alcohol and identified. Anastrepha zenildae (Wiedemann), A. sororcula Zucchi, A. fraterculus (Wiedemann), A. obliqua (Macquart) and Ceratitis capitata (Wiedemann) were associated with guava fruits. Of them, A. zenildae. A. sororcula and A. obliqua were dominant and constant in the studied region, while A. fraterculus and C. capitata were non-dominant but constant. A. zenildae occurred in almost all months of the year, except October and December of 2008, with population peaks in the rainy season with its milder temperatures.