Application of joint probability approach in derivation of rainfall temporal patterns: case study: Kan Watershed, Iran

摘要

Joint probability approach is a superior method of design flood estimation which considers the probabilistic nature of the inputs such as rainfall temporal pattern in the rainfall-runoff modelling. Design flood estimation is one of the major steps in the design and sizing of hydraulic structures and installations. Under the conditions of significant storage capacity or long return periods, use of mathematical models is a common choice for changing of design rainfall to design flood. One of characteristics of design rainfall that cause design flood is distribution of rainfall during the rainy period which is the so-called design rainfall temporal pattern. Design rainfall temporal pattern is a major source of uncertainty in rainfall-based design flood estimation methods. Despite high variability of temporal patterns from storm to storm, an average temporal pattern is used in the design event approach, the recommended rainfall-based design flood estimation method. This paper examines the variability of temporal patterns using joint probability approach. In this study, Monte Carlo simulation technique based on joint probability approach, that considers probability-distributed inputs, model parameters and their correlations, applied to find the probability-distributed rainfall temporal pattern in the study area.