Uso da fitossociologia na avaliação da efetividade da restauração florestal em uma várzea degradada do rio Mogi Cuaçu, SP

This study objective was to evaluate the effective revegetation in a Mogi Guaçu River degraded floodplain area, located at Luiz Antonio municipality (21° 31' S e 47° 55' W), São Paulo State, Brazil. Two native riparian forest remnants (RIP1 and RIP2) and three 10-year-old reforested areas, planted of native species (R1, R2 and R3), were analyzed by using phytosociological describers of the arboreal stratum (trees with DBH ≥ 5 cm) as indicators. The arboreal stratum inventory was accomplished by 180 plots (10 × 10 m each), 60 representing every native forest and 20 for every reforested area. A total of 60 arboreal species was recorded, only six species (Cecropia hololeuca, Crotón urucurana, Genipa americana, Inga striata, Nectandra megapotamica e Peltophorum dubium) occurring in all the five studied areas. Seventeen species were common to both native forests, and nine species were recorded in all the reforested areas. Sebastlania commersonlana and Guarea macrophyllawere recorded in the native forests (RlP1 and RIP2), and Cecropia hololeuca, Croton urucurana and Inga striata occurring in all the reforested areas, were the species that best characterize the physiognomy of local diversity and were the most important among the studied species. The results showed that the rehabilitation of the areas made by the reforestation created conditions to implant forests with similar structures of the adjacent natural remainders. The reforestation with native species performed in the degraded floodplain of Mogi Guaçu River, initially with the predomination of invasive grasses, has been effective at the first stage of the ecological restoration process. The reforestation is making possible the natural regeneration of species from the adjacent remnants, what indicates that the similarity between planted forests and the native ones are rising through the time. The phytosociology, accomplished ten years after the planting date, is adequate to evaluate the effectiveness of the reforestation during the restoration process of degradated areas in the Mogi Guaçu floodplain.

Geotechnology applied to land use and sealing in urban areas

Through the geotechnology's use, the aim of this study was to characterize the urban occupation interference and occurrence of floods in the upstream area of watershed from the stream Wenzel (Rio Claro-SP/Brazil). Urbanized watersheds are composed of a variety of features and the development of cartographic material allowed the analysis of the evolution of land used for 1958 and 2006 scenarios. The thematic maps were generated using software Spring 4.3.3, wherein it got the separation of matters from vegetation cover and other intra urban features. Procedures of digital processes and classification of surface cover allowed quantifying the occupied area by each coverage type: woody vegetation, grass, grass with bare soil, bare soil, building, asphaltic sheets and exposed soil. Quantification of the different covers' occupied areas allowed relating the parameter Curve Number (Soil Conservation Service) as efficient methodology for runoff values estimative. The results indicate vegetation cover's reduction, intensive surface's sealing and suppression of water bodies. These factors imply changes of hydrological dynamics of the source, increasing flow and transfer of larger volumes of water and flood peaks to downstream sectors. The use of geotechnology allowed analyzing the evolution of urbanization and it permits also to infer about trends for future or inadequate occupancy to hydrological and environmental point of view. © 2013 IEEE.

Aplicação de modelos hidrológicos para avaliação de reservatórios de retenção e detenção combinados à obra de recuperação do canal de macrodrenagem no controle de cheias em uma bacia hidrográfica urbanizada

The aim of this paper was to evaluate the effect of retention and detention reservoirs along with the regulation in channel flow upgrade on flood for an urban watershed located at Rio Claro, SP. For this purpose, modeling and simulation techniques were applied for runoff determination and its propagation in channel. The Soil Conservation Service – SCS hydrologic model as well as Pulz and non-linear Muskingum-Cunge model were used. The software IPHS1 was applied on simulations. The results pointed out that the combination of retention increasing and detention reservoir implementation (120,000 m3, corresponding to 1.5% of the watershed area) with the streamflow upgrade (n decreasing from 0,04 to 0,02) can minimize the flood on the investigated Servidão watershed. Further, after the proposed intervention, the flood was eliminated for the investigated times of recurrence: 5, 20, 50 and 100 years. The prognostic indicated that the available area occupation had a minor effect on flow increasing due to the observed high urbanization.