TOPMODEL: Hydrological Modelling in Tropical Regions

Resumen

Hydrological distributed modelling is a key point for a comprehensive assessment of the feedback between the dynamics of the hydrological cycle, climate conditions, and the land use. Aforementioned modelling results are markedly relevant within the fields of water resources management. Here TOPMODEL (Topography based hydrological MODEL) is subjected for the hydrological modelling of the zone in the Middle Magdalena Valley (MMV), a tropical basin located in Colombia. This study is set in the intertropical convergence zone and is characterized by special meteorological conditions, with fast water fluxes over the year. It has been susceptible to significant land use changes and as well, a result of intense economic activities, i.e., agriculture, energy and oil & gas production. The model procures a record of 12 years of daily precipitation database from observed gauges, daily evapotranspiration database from temperature data and streamflow database as observed data from calibration. Calibration is implemented using data from 2000 to 2008, and the validation is accomplished with data from 2009 to 2012. The Nash-Sutcliffe coefficient is used to assess the robustness of our calibration process (values of this metric being 0.74 and 0.73, respectively for model calibration and validation). The results reveal high water storage capacity in the soil, and a marked subsurface runoff, consistent with the characteristics of the soil types in the regions. The calibrated model provides relevant indications about recharge in the region, which is essential to quantify the interaction between surface water and groundwater, chiefly during the dry season, which is more relevant in climatechange and climate-variability scenarios.