DAILY RAINFALL RUNOFF .MODELING FOR DONG NAI RIVER BASIN IN VIETNAM

Abstract

There exists a multitude of rainfall-runoff models and these are generally categorized to fall in the category of empirical models, conceptual models, or physically based distributed models, in the increasing order of complexities involved in modeling various processes of the hydrologic cycle. The last two types of models are generally used for daily flow simulation. Despite their comprehensive structure, many of the state-of-the-art physically based models have not yet become standard tools in hydrologic practice in developing countries because (a) most basins in these countries are ungauged and there is little hydrologic data available and (b) these models contain too many parameters, which are difficult to estimate in practice and vary from basin to basin. Although some of these models have been applied to ungauged basins, the fact is that they are not easy for practical applications. Furthermore, when these models are compared on the same basin, they are found to be widely varying in their performance. Thus, what is needed in developing countries is 'simple models which can provide reasonable simulations and need little data.