Modelagem De Canais Incisivos - Revisão

Abstract

1 O presente trabalho foi realizado como o apoio do Conselho Nacional de Desenvolvimento Científico e Tecnológico -CNPq -Brasil. 2 ruth-maria.quadros@mma.gov.br, Secretaria de Recursos Hídricos/MMA, SGAN 601, lote 1, Brasília-DF. 3 cewisni@agrarias.ufpr.br, professora, DSEA -UFPR, R. dos Funcionários, 1540 -80035-050, Curitiba-PR 4 everton@ufpr.br, UFPR RESUMOO objetivo deste artigo é documentar as mais importantes pesquisas e aspectos histórico-cronológicos sobre a modelagem da incisão de canais. São apresentados os aspectos qualitativos e quantitativos envolvidos, desde a dedução das equações de Saint-Venant e de Exner, até as mais recentes pesquisas sobre o alargamento e o deslizamento das margens dos canais, considerando a coesão das mesmas. Do ponto de vista quantitativo, ainda há muitos processos importantes a serem solucionados, com destaque para os mecanismos envolvidos na desagregação e transporte de partículas de solo coesivas. Pesquisas recentes mostram que a estimativa da desagregação pelos métodos tradicionais de determinação da resistência do solo pode não ser a mais recomendada para avaliar a resistência na interface solo-água. Isto aponta para a importância dos processos físico-químicos envolvidas na estabilidade das partículas do solo e, conseqüentemente, na sua suscetibilidade à erosão, assim como a importância da sua representação matemática e inclusão na modelagem do processo de incisão de canais. Palavras-chave:Sulco, voçoroca, desagregação, estabilidade de agregados, erosão. ABSTRACTThis paper aims at documenting some of the more important research and historical-chronological aspects concerning incised channels modelling. Qualitative and quantitative aspects are presented, beginning with the deduction of the Saint-Venant and Exner equations and going through the more recent equations explaining the enlargement and stability of cohesive riverbanks. From a quantitative point of view, there are still many important processes to be solved, specially those regarding detachment mechanisms and transport of cohesive soil aggregates. Recent research has shown that soil evaluation aggregates detachment by conventional methods (soil strength determination) cannot measure the properties at the soil-water interface with the necessary resolution. These results allow visualizing the importance of the physicochemical mechanisms involved on aggregate stability at the soil-water interface; and, consequently, its degradation suscetibility. These mechanisms should be mathematically described and included in incised channel modeling.

Effect of Terrestrial LiDAR Point Sampling Density in Ephemeral Gully Characterization

“…Ephemeral gullies are defined as small channels located in agricultural fields eroded primarily from concentrated overland flow that can be easily filled by normal tillage, only to reform again in the same location by additional runoff events [5]. Due to their small dimensions, producers often reshape the channel's topography, by refilling the channel through tillage, to maintain regular farming operations [6]. Because the field topography is often unchanged between seasons, ephemeral gullies have a tendency to re-form at the same or nearby location [7].…”

AGNPS GIS-Based Tool for Watershed-Scale Identification and Mapping of Cropland Potential Ephemeral Gullies

“…Ephemeral gullies are defined as small eroded channels, generally in agricultural fields, formed mainly as a result of concentrated overland flow from a rainfall event. These channel features are considered seasonal/periodical in nature due to their small size (0.5 to 50 cm in depth) and the agricultural producer's capability to remove these channels by refilling them with soil during farming operations (Quadros et al, 2004). Ephemeral gullies often form in the same or nearby locations due to field topographic characteristics that remain relatively unchanged (Foster 1982;Thorne, 1984;Casalí et al, 2000).…”