Lithologic control on the multifractal spectrum of river networks Roberto Gaudio a, * , Samuele G. De Bartolo a,1 , Leonardo Primavera b,2 , Salvatore Gabriele c,3 , Massimo Veltri a,4 a Universita` della Calabria, Dipartimento di Difesa del Suolo ‘‘V. Marone’’, Ponte P. Bucci, Cubo 42b, 87036 Rende (CS), Italy b Universita` della Calabria, Dipartimento di Fisica, Ponte P. Bucci, Cubo 33b, 87036 Rende (CS), Italy c CNR-IRPI – Sezione di Cosenza, Via Cavour, 4-6, 87030 Rende (CS), Italy Received 22 December 2004; received in revised form 28 October 2005; accepted 17 November 2005 Summary Previous observations on some natural river networks showed the similar values of the support fractal dimension and the information entropy in basins having similar source rocks. In the present work, lithologic control on river network multifractality is investigated through the reconstruction of the spectra belonging to two classes of different lithology: the plutonic- metamorphic class and the coherent sedimentary one. Two computational methods of the generalised fractal dimensions and multifractal spectra are illustrated and applied to river networks of the Calabria region (Southern Italy). It is shown that an increment of both the frac- tal dimensions and the Lipschitz-Ho ¨lder exponents of singularity occurs when passing from a coherent sedimentary to a plutonic-metamorphic river network. The importance of this finding emerges from the direct link between flood hydrographs and multifractal spectra, as expressed in the Multifractal Instantaneous Unit Hydrograph (MIUH): the increment of the multifractal parameters produces an increment of the flood peaks. Ó 2005 Elsevier B.V. All rights reserved. KEYWORDS River networks; Lithologic control; Multifractals; Fixed-size algorithms (FSA); Hydrologic response Introduction Many studies can be found in the literature about the multi- fractal analysis of river basins and networks, devoted to the scale properties of many relevant hydrological and hydraulic variables, such as contributing drainage areas of given hier- archical order, slopes, dissipation energy, channel initiation functions, optimal channel networks, width functions, topo- graphic fields, landscape of river basins etc. (see e.g. Schertzer and Lovejoy, 1989; Ijjasz-Vasquez et al., 1992; 0022-1694/$ - see front matter Ó 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.jhydrol.2005.11.025 * Corresponding author. Tel.: +39 0984 49 6551; fax: +39 0984 49 4050. E-mail addresses: gaudio@unical.it (R. Gaudio), debartolo@dds. unical.it (S.G. De Bartolo), lprimavera@fis.unical.it (L. Primavera), gabriele@irpi.cnr.it (S. Gabriele), veltrim@dds.unical.it (M. Veltri). 1 Tel.: +39 0984 49 6568; fax: +39 0984 49 4050. 2 Tel.: +39 0984 49 6138; fax: +39 0984 49 4401. 3 Tel.: +39 0984 835 505; fax: +39 0984 835 319. 4 Tel.: +39 0984 49 6569; fax: +39 0984 49 4050. Journal of Hydrology (2006) 327, 365– 375 available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/jhydrol