Characterization of homogeneous regions for regional frequency analysis of heavy daily precipitation in central Tunisia
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ORIGINAL PAPER
Characterization of homogeneous regions for regional frequency analysis of heavy daily precipitation in central Tunisia Amira Merzougui 1 & Adel Zghibi 2 Received: 12 February 2020 / Accepted: 19 October 2020 # Saudi Society for Geosciences 2020
Abstract The Sebkhet El Kalbia and Sidi El Hani catchment is the second largest watershed in Tunisia, which represents a typical semi-arid area localized in the central region. Characterized by a high risk related to the high spatio-temporal rainfall variability, this region represents one of the most vulnerable zones where hydrologists try to assess and predict the behavior of such a climatic component. The regional frequency analysis of annual maximum daily rainfall can help enormously in the estimation of the expected rainfall at high return periods. Eventually, the principal objective of this research is to determine the regional statistical distribution for homogeneous regions in the Sebkhet El Kalbia and Sidi El Hani catchment. The Sebkhet El Kalbia and Sidi El Hani catchment was selected to represent semi-arid regions in Tunisia as it covers a large area in addition to the availability of rainfall data. The data was analyzed using multiple frequency analysis methods and was subjected to various statistical tests including Akaike information criterion (AIC), Bayesian information criterion (BIC), and the khi-square test (khi2) in order to determine the best regional statistical distribution and define the homogeneous regions using regional analysis. The study concluded that the GEV distributions were the best model to describe the distribution of the annual maximum daily rainfall in the central region of Tunisia. The Sebkhet El Kalbia and Sidi El Hani catchment was sub-divided into three homogeneous regions. The contour maps for the 10, 20, 50, and 100 years rainfall associated to other components (the slope and the sea effects) were produced to predict the behavior and dynamic of heavy rainfall events in the study area. Keywords Frequency analysis . Annual maximum daily rainfall . Semi-arid region . Central Tunisia
Introduction In Tunisia, rainfall time variability in semi-arid regions is more distinguishable than that in humid regions. This is valid for the annual scale. Moreover, long period of time with very little amount of precipitation is common in the study area, with large amounts of rainfall in one or two days followed by no significant rainfall for years. Also, the rain gauge density is very heterogeneous within the study area. This leads to large sampling errors resulting from sparsely gauged data being unrepresentative of Responsible Editor: Broder J. Merkel * Adel Zghibi [email protected]; [email protected] 1
National Institute of Agronomy, University of Carthage, 1082 Tunis, Tunisia
2
LR01ES06 Laboratory of Mineral Resources and Environment, Department of Geology, Faculty of Sciences of Tunis, University of Tunis El Manar, Tunis– El Manar 2092, Tunisia
average rainfall over a watershed, as well as the potential error of not c
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