Belém, the capital of the state of Pará, host of the 30th UN Climate Change Conference (COP30), which is located in the Brazilian Amazon, suffers from flooding caused by rainfall and tides. The objective was to estimate the daily flooding probability in Belém based on the two assumptions, i.e., the compound effect of rainfall and tides and rainfall only. In this case, rainfalls were analysed considering intensity and duration. Thus, it was possible to evaluate the flooding probability for each assumption and propose technological solutions to reduce this probability. Rainfall and tide height data for the 2003 to 2021 period were used. The minimum level causing flooding was defined analysing the compound effect (rainfall + tide height). The effects of rainfall and tides were also separately analysed with the aim of isolating the entry of tides into city canals. The daily flooding probability was estimated based on the study of the a priori probability derived from the ratio between the number of flooding events and the number of possible floods. The results showed that certain areas of Belém-PA could be flooded with a minimum value of rainfall plus tide height is 640.4 mm, if the rainfall intensity reaches at least 30 mm/h. Regarding the rainfall duration, the minimum value of rainfall plus tide height is 1398 mm for flooding to occur if rainfall lasts at least two hours. The flooding events were validated by examining local newspaper reports and photographic records describing and capturing flooding, respectively. The highest daily flooding probability occurred during the wettest period in the city, from January to May. The daily flooding probability was greatly reduced when only rainfall was considered. Thus, if city canals encompass floodgate systems, flood damage could be reduced. A floodgate systems project would be an important COP30 legacy for Belém. This system could help reduce the losses suffered by the poorest populations in Belém, who live in floodplain areas.

中文翻译：

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通过降雨和潮汐的复合效应估算亚马逊流域大都市的每日洪水概率


位于巴西亚马逊地区的第30届联合国气候变化大会（COP30）主办国帕拉州首府贝伦遭受降雨和潮汐引发的洪涝灾害。目的是根据降雨和潮汐的复合效应以及仅降雨的两种假设来估计贝伦每日洪水概率。在这种情况下，分析降雨量时考虑了强度和持续时间。因此，可以评估每个假设的洪水概率，并提出降低这种概率的技术解决方案。使用 2003 年至 2021 年期间的降雨量和潮汐高度数据。通过分析复合效应（降雨量 + 潮汐高度），定义了引起洪水的最低水平。还分别分析了降雨和潮汐的影响，以隔离潮汐进入城市运河。每日洪水概率是根据洪水事件次数与可能发生洪水次数之间的比率得出的先验概率的研究来估计的。结果表明，如果降雨强度达到至少 30 毫米/小时，贝伦-PA 的某些地区可能会被洪水淹没，降雨加潮高的最小值为 640.4 毫米。关于降雨持续时间，降雨量加上潮高的最小值为1398毫米，如果降雨持续至少两个小时，就会发生洪水。通过检查当地报纸报道和分别描述和捕捉洪水的照片记录来验证洪水事件。每日洪水概率最高发生在该市最潮湿的时期，即一月至五月。当仅考虑降雨时，每日洪水概率大大降低。 因此，如果城市运河包含水闸系统，则可以减少洪水损失。水闸系统项目将成为贝伦 COP30 的重要遗产。该系统可以帮助减少居住在洪泛区的贝伦最贫困人口所遭受的损失。