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University of the Aegena (2017)

Trend assessment of low flows in four major Chilean rivers (EL)

Κοραλή, Άλκηστις-Αικατερίνη

Titre : Trend assessment of low flows in four major Chilean rivers (EL)

Εκτίμηση και ανάλυση των τάσεων των χαμηλών απορροών σε τέσσερις κύριους ποταμούς της Χιλής (EL)

Auteur : Κοραλή, Άλκηστις-Αικατερίνη

Etablissement de soutenance : University of the Aegena

Grade : Master 2017

Résumé
Understanding and analyzing low-flows is considered one of the most important tasks of effective water management. Low-flow periods appear in almost every river as a seasonal phenomenon. Due to the unfavorable distribution of rainfall throughout the year, drought and relative water scarcity have always been a major problem for Chilean semi-arid areas. In order to analyze accurately and efficiently the trends of low-flows, it is necessary to assess a variety of indices. This diploma thesis presents and calculates the main low-flow indices for 17 gauging stations of 4 Chilean rivers located in the semi-arid region. Among the indices are the ninety-percentile flow (Q90) and ninety-five percentile flow (Q95) which indicate severe low-flow conditions, the mean annual minima (MAM [x-day]), the maximum annual cumulative deficit below Q90 (MXDF90) & Q95 MXDF95), the maximum flow duration below Q90 (MXDU90) and Q95 (MXDU95), and finally the baseflow index. In order to calculate these indices, flow data were obtained from gauge stations located throughout the watersheds of the rivers assessed. The calculation of the indicators and their statistical analysis were carried out in a programming environment. There is both analytical and visual presentation of the results. For the estimation of the low-flows trends and their significance, non-parametric tests as Mann-Kendal, P-value and Sen’s slope were carried out. The results of these tests have been analyzed, compared and evaluated. Finally, conclusions are drawn for the presence of trends of low-flows which result from the use of all aforementioned methods.

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Page publiée le 29 décembre 2021