Um modelo para simulação hidrossedimentológica em pequena escala.

Abstract

Hydrologieal event models do not consider, in general, antecedent conditions of precipitation, Moreover, in many models, the lows of physics, which are appropriated for small scales, are generally used to represent large scales. These aspects motivated this study in order to design a model to simulate the runoff and soil erosion at small scales (MOFIPE), capable of taking into account the soil moisture content between events of natural rainfall and soil parameters of the basin. The model takes into account, the process of evapotranspiration, with decreases the soil moisture content between events of rainfall and is calculated according to a relationship between the soil tension, moisture content and evapotranspiration. During the precipitation, evapotranspiration is not considered. The rainfall intensity and soil moisture control the generation of the runoff, which also depend on the infiltration capacity of the soil surface, while the soil erosion is governed by the impact of the raindrops. The sediment provided can be transported by the flow either at the rate of detachment or at the flow transport capacity, which can be calculated by three different methodologies. The channel phase is not considered because the model is for apply at small scales. In this study, the structure of the model is presented and examined using data from the Experimental Basin of Sume (BES), situated in the semiarid region, in the state of Paraiba, Brazil. The model parameters were set based on field information. The simulation results of the application showed that the model was able to reproduce the runoff and soil erosion processes without calibration. Moreover, the results were also compared with simulations carried out with other calibrated models and showed reasonable agreement, although all simplification adopted.