No abstract

This study aimed to use the Hydrologic Landscapes as environmental classification method in the Piracicaba, Capivari and Jundiaí river basins, validate and use it as an indicator of water yield and storage areas. The method comprises in the same Information Plan (IP) factors that interact with the hydrological cycle in its terrestrial phase. The state of São Paulo, where most of the area is located, constantly suffer from water scarcity. Climate, soil permeability, aquifer permeability, and relief data were used as evaluation units with the aim of identifying favorable areas of water yield/storage. Each pixel received a value of HLR - Hydrologic Landscape Region, which summarizes hydro-geomorphologic characteristics of the site. To evaluate the method efficiency, the annual water yield (R/P) of each sub-basin was calculated using flow data from its main rivers. This data is necessary to identify the factor "m" (Fuh’s equation), a parameter associated with characteristics of the river basin, such as slope and water infiltration into the soil. The values of water yield and the "m" factor corroborate with previous studies, proving that parameters chosen as evaluation units are effective to identify favorable areas for water yield and storage. The classification in Hydrologic Landscapes has proved to be an effective tool in the identification of these areas, which is essential for the optimization of limited financial resources applied in water resources management projects. The results indicate that basins can be considered as water yield areas and, at the same time, have high storage capacity, since the coefficients R / P and factor "m" had a positive correlation.

The runoff coefficient (C) represents the relationship between the surface runoff volume and the precipitated volume. It is used in engineering projects for flood estimation methods. Although C values are tabulated and consecrated in hydrological engineering, as if they were constant, they may not correspond to the reality, because in the same catchment, they can vary according to the intensity, temporal and spatial distribution of precipitation events, humidity conditions, and ground cover. This study had the objective of analyzing extreme events of precipitation and the corresponding flows to obtain experimental runoff coefficients (C) and compare them with the tabulated values. The study was conducted in four experimental catchments in the State of São Paulo, Brazil, with different land uses and soils. The runoff coefficients (C) were obtained from the analysis of hydrograms and using a digital filter, which allowed the separation of the direct runoff, of the total flow. When analyzing flow and precipitation data in different seasons of the year, selecting events of the floods of catchments and separating the flows, we observed a variation of the flow coefficient values, different from those obtained from tables.

Runoff coefficient (C) values are tabulated and enshrined in hydrological engineering. Its values are considered to be constant although it may not correspond to reality. In the same catchment, they can vary according to the intensity, temporal and spatial distribution of precipitation events, humidity conditions, soils and land uses. This study had the objective of analyzing extreme events of precipitation and their corresponding flows to obtain experimental runoff coefficients (C) and compare them with the tabulated values. The study was conducted in five experimental catchments in the state of São Paulo, Brazil, with different land uses. The runoff coefficients (C) were obtained from the analysis of hydrograms and using a digital filter, which allowed the separation of the direct runoff, of the total flow. We observed a variation of the flow coefficient values between catchments different from those obtained from the tables. The runoff coefficients had a high correlation with land use. In the catchments with original vegetation cover, such as cerrado and forest, it varied little among the events analyzed, differently from the catchments where land use is diversified, with predominantly agricultural and urban occupation.