Choice of a rainfall-runoff model for complex hydrological conditions

The main purpose of this study is to compare the application possibilities of different rainfall-runoff models and how to choose that which best corresponds to certain hydrological conditions. The system chosen for analysis lies in the Bolivian highlands. The region is drained by the River Desaguadero, which flows out of Lake Titicaca (altitude 3810 m), and into Lake Poopo (altitude 3686 m). Following an analysis of hydrological models in general, the conclusions are applied to the particular characteristics of the Bolivian highlands. A simulation procedure, based on the decomposition of the basin into elements, was used. Detailed provisions to represent the losses along one of the channel reaches led to significant improvements in the simulation. It is concluded that channel losses are due to the characteristic geographic position and the specific characteristics of the system. The results of the study suggest that modelling of the surface water runoff may be applied with success in the Bolivian highlands but that the present, commonly used, methods are inadequate and adjustments are necessary.