Monitoramento e modelagem de processos hidrogeomorfológicos : mecanismos de geração de escoamento e conectividade hidrológica

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

This dissertation discusses the runoff generation mechanisms and hydrological connectivity, based on monitoring and modeling of hydrogeomorphologic processes in the Saci Experimental Watershed (10 ha) completely covered with forest and located within the municipality of Rio Negrinho, Santa Catarina State, Brazil. An intensive monitoring system was implemented with automatic 10 minutes-interval measurement of the gross rainfall, throughfall, stemflow, soil water tension, water table, runoff and suspended sediment. For monitoring automation, sensors for water-table, tensiometers, and tipping-bucket devices for measuring stemflow and throughfall were developed. The soils were characterized in terms of a hydrologically-active depth, grain size, infiltration rate and saturated hydraulic conductivity. Twenty hydrograph-events which occurred during the period from July to November 2008 were analyzed with all the monitored data and by application of TOPMODEL. This model is semi-distributed and based on topographic and soil characteristics of the watershed. The results show that the runoff generation mechanisms are driven by the magnitude of rainfall events with threshold between 30 and 40 mm, and by the initial soil-moisture conditions in the watershed. Simple events, with small rainfall and initially-dry soil conditions, generate overland saturated flow just from a small area corresponding to the riparian zone. Complex events, with large rainfall and initially-wet soil conditions, generate saturation in larger areas which are, however, not connected by the overland flow. In this case, predominantly the subsurface flow occurs and activates preferential flow, which interconnect the saturated areas. This mechanism generates the second peak at the hydrograph. This phenomenon may be called subsurface connectivity. The TOPMODEL simulated very well the simple events, but did not adequately simulate the complex ones. The results of the present study are consistent with some recent similar studies in small forested watersheds, strengthen the importance of subsurface flow and hydrological connectivity to understand the runoff generation mechanism and the need of intensive monitoring adding this knowledge onto computational models.

ASSUNTO(S)

geografia bacias hidrograficas - rio negrinho (sc) - monitoramento escoamento hidrologia geografia

ACESSO AO ARTIGO

Documentos Relacionados