Difference in Flooding Character and Magnitude between Frequent Floods and Extreme Events
Abstract
Is a river's geomorphic expression and sediment distribution shaped more by moderate and frequent floods or by extreme events? This study aims to understand and characterize the differences between these flooding events as well examine the controls on each in different climatic contexts. We created a modern global river discharge database of daily discharge for 575 river gauging stations from around the world using data from the Global Runoff Data Centre to better understand the controls on discharge. These rivers are compared using a variety of different discharge variability indexes to examine how discharge variability occurs in different rivers systems and how flooding varies on different time scales. These indexes examine discharge on different time scales and normalize the discharge, allowing for comparison of river systems against each other, regardless of size.
The analyses reveal climate to be a main control on the character and magnitude of flooding. Seven different hydroclimate zones (arid, cold Dfa, cold and polar, humid subtropics, monsoonal, rainforest, and temperate) were created based the Köppen-Geiger climate types and precipitation variability analyses. These seven hydroclimates have characteristically different flood magnitude and flood frequency relationships and can be divided into four different hydrological groups: persistent, single storm controlled, seasonal, and extreme and erratic. Commonly there is a difference in factors causing the regularly occurring floods versus floods that occur once per record length. It is through understanding and quantifying these differences that we can start to answer the question of whether rivers and landscapes reflect a frequent, moderate forcing or rare, extreme event. This research leads towards the ultimate objective of understanding flood behaviour.- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFMEP23G2403H
- Keywords:
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- 1815 Erosion;
- HYDROLOGYDE: 1817 Extreme events;
- HYDROLOGYDE: 1824 Geomorphology: general;
- HYDROLOGYDE: 1861 Sedimentation;
- HYDROLOGY