Baseflow representation module on MODCEL

Módulo de representação de escoamento de base no MODCEL

ABSTRACT

The land use characteristics of rural watersheds allow infiltration and consequent generation of groundwater flow, which constitutes a significant contribution to the hydrograph. Prior to this study, the MODCEL-COPPE/UFRJ model simulated only runoff, disregarding the losses occurred in rainfall-runoff process. Therefore, its application was more appropriate to urban watersheds, simulating flood events where surface flows prevail. This study aimed at representing the infiltration process and at incorporating the groundwater flow in the MODCEL’s structure, making feasible the rural watersheds simulation thus expanding its applicability as a hydrological model. A case study was performed in a 417 km² subcatchment of Piabanha River, located at Petrópolis/RJ. It’s a predominantly rural watershed, with 80% of its area covered by forests. The model represented satisfactorily the seasonality and the magnitude of simulated recharges. In the parameter calibration procedure gave a coefficient of determination R² = 0.75, comparing the calculated flows to the observed flows. During validation period, we obtained a coefficient of determination R² = 0.76. The fit obtained was superior to that obtained in previous modeling of the same watershed by SMAP and MODCEL (previous version) and it was similar to TOPMODEL. In the hydrograph recession, new MODCEL presented R² = 0.75, against 0.52 obtained in its previous version.

Keywords:
Infiltration; Groundwater flow; Hydrograph