In confluence areas, where river flow slowdowns can be substantial, the selection of design flows for the purpose of designing a flood control system directly depends on flood waves at the mainstem and its tributaries. The aim of this paper is twofold: to elaborate a procedure that will define the flood exceedance probability in the analyzed area within a multidimensional probability space and to develop a methodology for defining flood coincidence in the mainstem reach with its main tributaries and thus determine design flows in order to design the flood control system in the confluence area. Mathematical models are based on (1) two-dimensional probability distribution (PROIL model) and (2) the copula function (Archimedean class of copulas), and fitted to a practical application in a two-dimensional probability distribution space. In case of random variables, simultaneous quantitative characteristics of flood wave (water flow) hydrographs for the mainstem and a tributary are considered. The paper discusses the specific reach of the Danube, from the Hungarian-Serbian border to the city of Smederevo, which encompasses three significant tributaries—the Drava, the Tisa, and the Sava.

在汇流地区，河水流量可能会大大降低，为设计防洪系统而选择的设计流量直接取决于主干河及其支流处的洪水波。本文的目的是双重的：拟定一个程序，该程序将在多维概率空间内的被分析区域中定义洪水超标概率，并开发一种方法来定义主干河段及其主要支流的洪水重合，从而确定设计流程。为了设计汇合区的防洪系统。数学模型基于（1）二维概率分布（PROIL模型）和（2）copula函数（Archimedean copulas类），并且适合于在二维概率分布空间中的实际应用。如果是随机变量，则要考虑主干和支流的洪水波（水流）水位图的同时定量特征。本文讨论了多瑙河的特定范围，从匈牙利-塞尔维亚边境到Smederevo市，其中包括三个重要支流-德拉瓦河，蒂萨河和萨瓦河。