A contribution to improved flood magnitude estimation in base of palaeoflood record and climatic implications – Guadiana River (Iberian Peninsula)

Abstract

Abstract.The Guadiana River has a significant record of historical floods, but the systematic data record is only 59 years. From layers left by ancient floods we know about we can add new data to the record, and we can estimate maximum discharges of other floods only known by the moment of occurrence and by the damages caused. A hydraulic model has been performed in the area of Pulo de Lobo and calibrated by means of the rating curve of Pulo do Lobo Station. The palaeofloods have been dated by means of 14 C y 137 Cs. As non-systematic information has been used in order to calculate distribution functions, the quantiles have changed with respect to the same function when using systematic information. The results show a variation in the curves that can be blamed on the human transformations responsible for changing the hydrologic conditions as well as on the latest climate changes. High magnitude floods are related to cold periods, especially at transitional moments of change from cold to warm periods. This tendency has changed from the last medium-high magnitude flood, which took place in a systematic period. Both reasons seem to justify a change in the frequency curves indicating a recent decrease in the return period of big floods over 8000 m 3 s −1 . The palaeofloods indicate a bigger return period for the same water level discharge thus showing the river basin reference values in its natural condition previous to the transformation of the basin caused by anthropic action.

Influence of solar forcing, climate variability and modes of low-frequency atmospheric variability on summer floods in Switzerland

“…Several authors (Pfister, 1999;Knox, 2000;Magny et al, 2003;Benito et al, 2003;Schulte et al, 2012;Ortega and Garzón, 2009) contend that the most significant variations in the frequency of flooding have occurred during cold climate phases, particularly during transitional stages of climatic pulses. This pattern has also been observed in Switzerland during the last 500 years (Schmocker-Fackel and Naef, 2010b; Glur et al, 2013;Wirth et al, 2013a, b), although after the 1970s the climate and flood pattern changed.…”

Historical flash floods retromodelling in the Ondara River in Tàrrega (NE Iberian Peninsula)

“…Besides, historical floods in the Iberian Peninsula have usually been used to find climatic temporal trends (Barriendos and Martín-Vide, 1998;Llasat et al 2005;Benito et al, 2008) and, except for floods occurred in large basins (Benito et al, 2003;Thorndycraft et al, 2006;Ortega and Garzón, 2009), rarely have they been hydraulically reconstructed.…”

Failure of infrastructure embankments induced by flooding and seepage: a neglected source of hazard

“…Values of peak water head and impoundment duration should be determined on the basis of the historical research and/or flood maps based on geomorphological, hydrological or hydraulic flood studies, if existing. At this stage, the quantitative extension of historical analysis is pursued by using stream flow routing (the stream flow hydrograph in a stream section or along a whole stream), which denotes mathematical or numerical 1-D to 3-D formulations and techniques for flow simulation in natural rivers and channels (Cunge et al, 1980;Herget and Meurs, 2010;Ortega and Garzón, 2009;Polemio, 2010). The basic purpose of this analysis is to quantify the peak water head, the discharge yield and/or the submerged area by using one or two of these types of data as input to assess the more reliable missing information as output.…”