Generation of Hydrographs of the Chosica Sub-basin Using the GR4J Model of the RS Minerve Modeling Platform

There are plenty of models in hydrology but they do mean a solid work until the calibration and validation phases are finished. This paper shows the process of the GR4J (Génie Rural à 4 paramètres Journalier) modeling using 11 sub-basins of the Rimac basin, located in Lima, Peru. The meteorological information was analyzed through the use of the mass curve and box diagrams, as well as, there were some missing data that were completed by the Wavelet transform method, the proportions method and simple average. Afterwards, a selection of 11 stations of the 18 completed was made due to the distance with the study area. With the meteorological information of the 11 stations selected and the geographical information, the sub-basin was modeled using the GR4J model and following two different methodologies, one sectorizing the sub-basin at the micro-basin level and the second dividing the first sectorization at the level of altitudinal bands. For the calibration of the parameters and their validation, the Nash coefficient, the Nash-Ln coefficient, the Root Mean Square Error (RRMSE) and the Bias Relative Volume (RVB) were used as statistical indicators. Then, a comparison was made of the simulated discharges obtained by the two modeling methodologies with the reference discharge used, with which similar results were obtained. Finally, another comparison was made of the discharges obtained within the sub-basin by the two methodologies. At the end, the methodology of altitudinal bands shows a better approximation of the reference discharges in all the time scales, making GR4J a good model that uses a few parameters and, as a result, less use of computational processor resources.