10.4122/1.1000001227 Dongo, K. Diamand\303\251, M. Ciss\303\251, G. Tanner, M. Bi\303\251mi, J. Optimizing Montana\342\200\231s model to permit urban drainage in humid tropical environment: the case of Abidjan (C\303\264te d\342\200\231Ivoire) DTU Library, Technical University of Denmark (DTU) 2005 Abidjan climatic variability humid tropical environment Montana's model urban drainage Centre Suisse de Recherches Scientifiques en C\303\264te d\342\200\231Ivoire (CSRS) Universit\303\251 de Cocody-Abidjan, UFR \342\200\223STRM, Laboratoire des Sciences et Techniques de l\342\200\231Eau et de l\342\200\231Environnement (LSTE) University of Basel, Swiss Tropical Institute (STI) en Conference presentation 10.4122/1.1000001228 text/xml 1 ABSTRACT In sub-Saharan Africa, the "hygienic" model used in urban drainage is faced with constraints in humid tropical environment, subjected to a high level of climatic variability. In C\303\264te d\342\200\231Ivoire adapting Montana's rain model is not satisfactory for certain time slots (Peuch and Gonni, 1984) whereas this model includes the Caquot's rate-of-flow model used in urban drainage. This work aims at optimizing and designing models which best simulate tropical downpours and help in calculations relating to urban drainage in Abidjan and elsewhere. The methodology based on a probabilistic and stochastic approach used rainfall data covering the period from 1958 to 2000, from the Abidjan Airport Weather Station. The various statistical processing, sustained by Kolmogorov and Cramer fit tests showed that the rainfall distribution in Abidjan area is in line with Gumbel\342\200\231s law (10-30mn rainfall) and that of Galton (45-240mn rainfall). Including the data in mathematical conversion formulas made it possible to optimize the Montana's parameters and to design a new model which best simulates downpours in Abidjan. In addition, analysis of the Nicholson index reveals a drop in rainfall in Abidjan with a cyclical evolution (17-year period), alternating dry, normal and wet periods. Waiting for its application to judge its value, this new model is relevant since it overlaps two very satisfactory models.