Abstract:

To optimize the drainage engineering layout in the Lixia River water network area, it is essential to consider the interaction between the internal lowland and the incidence of heavy rainfall in adjacent waterlog-prone areas. Using the Copula function, we constructed a joint distribution of rainfall frequencies for these waterlogged areas to calculate the heavy rainfall probability. Pearson Type-III marginal distributions for the rainfall frequencies in the Fubu and Doubei areas, together with Frank Copula function for the fitting of their two-dimensional joint distribution, facilitates the calculation of the probabilities of heavy rainfall for specified durations and return periods. By integrating observed rainfall time series with frequency analysis, we found that the risk of both waterlog-prone areas (namely the Fubu and Doubei areas) experiencing heavy rainfall beyond design standards is minimal. Specifically, when heavy rainfall in the Fubu area exceeds design drainage criteria, the likelihood of heavy rainfall in the Doubei area surpassing design flood control thresholds remains low. These findings support the feasibility of the proposed drainage channel scheme in the Doubei area.

Key words: drainage risk, probability of encountering heavy rain, Copula function, plain water network, depression drainage, Lixiahe water network area, water resource planning