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Interannual and Interdecadal Climate Variations of Floods in the Western United States

美国西部洪水的年际和年代际气候变化

基本信息

批准号：
9973125
负责人：
Upmanu Lall
金额：
$ 26.22万
依托单位：
Utah State University
依托单位国家：
美国
项目类别：
Continuing Grant
财政年份：
1999
资助国家：
美国
起止时间：
1999-12-01 至 2001-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=9973125&HistoricalAwards=false
关键词：
Interannual Interdecadal Climate Variations Floods

项目摘要

9973125LallThe proposed research seeks to empirically connect low frequency climate variability to nonstationarity in the frequency of flood occurrence. The primary focus is on regions in the Western United States where the extreme flood regime is dominated by winter/early spring snowmelt and rainfall. Zonal atmospheric flow mechanisms coupled to the planetary jet stream, rather than convective thunderstorms determine such events. Nonstationarity of floods in this region has been recognized. The American River has experienced 7 floods since 1945 larger than the 100 year flood estimated on the basis of the previous 40 years. Sacramento, California may thus have significantly less than 100 year flood protection. The floods have come earlier in the year, and there are indications of corresponding changes in the seasonality of temperature, precipitation and the snow line. A hierarchical, Bayesian framework for relating at site and regional flood processes to structured low frequency climate variability will be developed. Hypotheses that relate flood potential to basin precipitation and temperature seasonality, to atmospheric circulation patterns, and in turn to modes of the ocean-atmosphere system and to anthropogenic climate change will be developed and tested using historical hydroclimatic data and ensemble simulations from a coupled ocean-atmosphere General Circulation Model.

9973125 Lall拟议的研究旨在经验连接低频率的气候变率的洪水发生频率的非平稳性。主要关注的是美国西部地区，那里的极端洪水状况主要是冬季/早春融雪和降雨。纬向大气流动机制耦合到行星急流，而不是对流雷暴决定这样的事件。该地区洪水的非平稳性已得到公认。自1945年以来，美国河经历了7次洪水，超过了根据前40年估计的100年洪水。因此，加州的萨克拉门托可能具有明显小于100年一遇的洪水保护。今年的洪水来得更早，有迹象表明，温度、降水和雪线的季节性也发生了相应的变化。一个层次，贝叶斯框架有关的网站和区域洪水过程的结构性低频气候变率将被开发。将利用历史水文气候数据和海洋-大气环流耦合模式的集合模拟，发展和检验洪水可能性与流域降水和温度季节性、大气环流模式以及海洋-大气系统模式和人为气候变化相关的假设。