On the use of the simple scaling of heavy rainfall in a regional estimation of IDF curves in Slovakia

Abstract

The aim of this study was to test the applicability of a simple scaling methodology for a regional estimation of intensity-duration-frequency (IDF) curves in Slovakia. The analysis is based on the regionalization process of Gaál (2006), which focused on the delineation of homogeneous regions for a regional frequency analysis of precipitation maxima. In order to examine the regionally estimated IDF curves, a region covering the western parts of Slovakia was chosen. The selected region, which encompasses 19 raingauging stations, may be characterized by the dominant influence of Atlantic circulation patterns. Three of the 19 stations belonging to the target region were set aside and flagged as verification stations.The regional dimensionless growth curve of 1-day precipitation maxima in the warm season was derived for the region, and the local T-year quantiles were estimated by the index value method for the stations. At the same time, a regionally averaged scaling exponent was derived using all the stations except for the three verification ones. The local IDF curves at the verification stations were estimated by downscaling the Tyear quantiles of the 1-day precipitation maxima using the regionally averaged scaling exponent. Finally, the IDF curves for these stations were compared with those defined by Šamaj, Valovič (1973). This study is the first step in assessing the applicability of a simple scaling theory for the regional estimation of IDF curves in Slovakia. Cieľom tejto práce bolo otestovať možnosť použitia metódy jednoduchého škálovania zrážok pri regionálnom odhade návrhových hodnôt zrážkových intenzít na Slovensku. Pre analýzu bolo vybraných 19 zrážkomerných staníc vo vopred vyčlenenom regióne na území západného Slovenska, pričom tri stanice boli separované ako verifikačné stanice. Pre vybraný región sme odvodili bezrozmernú regionálnu čiaru prekročenia jednodenných maximálnych úhrnov zrážok v teplom polroku a následne sme pre verifikačné stanice metódou indexovej hodnoty odhadli lokálne návrhové hodnoty pre rôzne významné doby opakovania T (tzv. T-ročné kvantily). Vo vyčlenenom regióne sme určili priemerný regionálny škálovací koeficient. Návrhové zrážkové intenzity pre tri verifikačné stanice sa stanovili zoškálovaním T-ročných kvantilov jednodenných maximálnych zrážok pomocou regionálneho škálovacieho koeficientu. Určené návrhové hodnoty sme porovnali s výsledkami Šamaja, Valoviča (1973). Štúdia potvrdila možnosť využitia metódy jednoduchého škálovania na regionálny odhad návrhových hodnôt zrážkových intenzít na Slovensku.KĽÚČOVÉ SLOVÁ: regionalizácia, intenzita zrážok, jednoduché škálovanie, návrhové hodnoty, teplý polrok, jednodenné maximálne úhrny zrážok.

A single scaling parameter as a first approximation to describe the rainfall pattern of a place: application on Catalonia

“…For instance, Menabde et al (1999) compared two sets of rainfall data representing two examples of quite different climate types, and found a scaling exponent of À0:65 for Melbourne (Australia), a city with a mid-latitude temperate climate and rainfall throughout the year, and a value of À 0:76 for Warmbaths (South Africa), having a semiarid climate with summer convective rainfall, and concluded that the scaling exponent appears to be dependent on the rainfall/climate characteristics. In addition, Bara et al (2009) found scaling exponents around -0.75 for three locations representing the western (Kuchyňa-Nový Dvor), central (Liptovský Hrádok), and eastern (Humenné) areas of Slovakia, and Yu et al 2004found three types of rainfall scaling behavior over northern Taiwan, related to the change in topography and the influence of the northeast monsoon. Rodríguez-Solà et al (2017) found a general concordance between the spatial distribution of b over the Iberian Peninsula and the mean annual precipitation distribution, with high values between -0.55 and -0.66 in rainy areas and low between -0.84 and -0.92 for the dry ones, with some discrepancies related to the kind of precipitation contributing to high rainfall amounts and the proportion of convective rainfall in total.…”

“…Applying this scaling approach, Aronica and Freni (2005) found better results than those coming from the classical subhourly rainfall regression formulas (Bell 1969;Ferreri and Ferro 1990). Likewise, studying the scaling properties of selected rainfall quantiles and applying this methodology, Bara et al (2009) derived the IDF curves for durations shorter than a day, calculated from a historical data set covering the whole territory of Slovakia. In a recent paper, Rodríguez-Solà et al (2017) used this methodology also to reproduce the well-known empirical IDF curves of three Spanish locations: Barcelona (Casas et al 2004;Rodríguez et al 2014), the Ebre Observatory (Pérez-Zanón et al 2015), and Madrid (Casas-Castillo et al 2016), taking into consideration the scaling behavior of rainfall.…”

“…the statistical moments of the annual maximum rainfall series. There is also a methodology based on the property of scale invariance (Menabde et al 1999;Yu et al 2004;Desramaut 2008; Bara et al 2010) to obtain IDF curves in those places where daily rainfall data are the only available. For instance, Aronica and Freni (2005) analyzed extreme rainfall data from a rain gauge network within the metropolitan area of Palermo (Italy) with the aim of combining and taking advantage of high-resolution rain gauges with a short working period along with low-resolution rain gauges with longer data records to obtain plausible depth-duration-frequency (DDF) curves.…”

Climate Change Impacts in the Design of Drainage Systems: Case Study of Portugal

“…Several studies comparing methodologies have been conducted but generally all methods seem to be able to produce accurate IDF estimates (Mohymont et al 2004;Veneziano et al 2007;Dame et al 2008). The type I extreme value, (EVI or Gumbel) distribution has been used successfully in many recent rainfall intensity studies in Europe (Llasat 2001;Bara et al 2010;Olsson et al 2012), Asia (Ariff et al 2012;Ben-Zvi 2009; Ahammed and Hewa 2012), Africa (Kuo et al 2013;Mohymont et al 2004) and America (Lumbroso et al 2011;Pizarro et al 2012). EVI is currently the recommended distribution function for use in Canada and the best choice for the estimation of IDF curves under changing climate conditions (Das et al 2013).…”

A study of the scaling properties of rainfall in spain and its appropriateness to generate intensity‐duration‐frequency curves from daily records

“…Such in most locations rainfall data are usually available only from totaliser rain gauges registering 1‐day precipitation, a method to infer intensity‐frequency values for short durations from daily rainfall data can be very useful. There is a methodology based on the fractal properties of rainfall, or more specifically on the characteristic scale invariance of the fractal processes (Bendjoudi et al , ; De Michele et al , ; Yu et al , ), to obtain the disaggregation or downscaling of low resolution precipitation data (daily) to high resolution (sub‐daily) (Menabde et al , ; Desramaut, ; Bara et al , ). Many atmospheric processes produced by complex dynamic mechanisms acting in a wide temporal range, as rainfall generation, give rise to phenomena that look the same regardless the scale where they are contemplated (self‐similarity).…”