Drainage density (Dd), defined as the total length of channels per unit area, is a fundamental property of natural terrain that reflects local climate, relief, geology, and other factors. Accurate measurement of Dd is important for numerous geomorphic and hydrologic applications, yet it is a surprisingly difficult quantity to measure, particularly over large areas. Here, we develop a consistent and efficient method for generating maps of Dd using digital terrain data. The method relies on (i) measuring hillslope flow path distance at every unchanneled site within a basin, and (ii) analyzing this field as a random space function. As a consequence, we measure not only its mean (which is half the inverse of the traditional definition of drainage density) but also its variance, higher moments, and spatial correlation structure. This yields a theoretically sound tool for estimating spatial variability of drainage density. Averaging length-to-channel over an appropriate spatial scale also makes it possible to derive continuous maps of Dd and its spatial variations. We show that the autocorrelation length scale provides a natural and objective choice for spatial averaging. This mapping technique is applied to a region of highly variable Dd in the northern Apennines, Italy. We show that the method is capable of revealing large-scale patterns of variation in Dd that are correlated with lithology and relief. The method provides a new and more general way to quantitatively define and measure Dd, to test geomorphic models, and to incorporate Dd variations into regional-scale hydrologic models.
Statistical analysis of drainage density from digital terrain data / Tucker G.E.; Catani F.; Rinaldo A.; Bras R.L.. - In: GEOMORPHOLOGY. - ISSN 0169-555X. - STAMPA. - 36(3-4):(2001), pp. 187-202. [10.1016/S0169-555X(00)00056-8]
Statistical analysis of drainage density from digital terrain data
CATANI, FILIPPO;BRAS, RAFAEL L.
2001
Abstract
Drainage density (Dd), defined as the total length of channels per unit area, is a fundamental property of natural terrain that reflects local climate, relief, geology, and other factors. Accurate measurement of Dd is important for numerous geomorphic and hydrologic applications, yet it is a surprisingly difficult quantity to measure, particularly over large areas. Here, we develop a consistent and efficient method for generating maps of Dd using digital terrain data. The method relies on (i) measuring hillslope flow path distance at every unchanneled site within a basin, and (ii) analyzing this field as a random space function. As a consequence, we measure not only its mean (which is half the inverse of the traditional definition of drainage density) but also its variance, higher moments, and spatial correlation structure. This yields a theoretically sound tool for estimating spatial variability of drainage density. Averaging length-to-channel over an appropriate spatial scale also makes it possible to derive continuous maps of Dd and its spatial variations. We show that the autocorrelation length scale provides a natural and objective choice for spatial averaging. This mapping technique is applied to a region of highly variable Dd in the northern Apennines, Italy. We show that the method is capable of revealing large-scale patterns of variation in Dd that are correlated with lithology and relief. The method provides a new and more general way to quantitatively define and measure Dd, to test geomorphic models, and to incorporate Dd variations into regional-scale hydrologic models.File | Dimensione | Formato | |
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