Continuous Hydrological Time-Series Discretization

by Luis Valadares Tavares, Prof.; Systems Engrg. Div., Civ. Engrg. Dept., Instituto Superior Tecnico, Tech. Univ. of Lisbon, Lisbon, Portugal,

Serial Information: Journal of the Hydraulics Division, 1975, Vol. 101, Issue 1, Pg. 49-63

Document Type: Journal Paper


The available information about many continuous hydrological time series Xt is often given by continuous time records with given finite duration and in many cases (i.e. rainfall and runoff records) the autocovariance function of Xt can be approximated by a function of exponential type. Once the data have been deseasonalized, stationarity is usually assumed. A discretization technique is required to estimate the mean and the variance of Xt which implies setting a value for the lag of time, L, between any two successive observations taken from the continuous record. The greater the time lag, the smaller is the number of used Xt values, the weaker is the dependence between them and the shorter is the required computing time. The aim of this paper is to study the three effects to make possible the selection of an optimal value for L. Numerical results of general use are derived and presented. Obviously, these conclusions also can be applied to any nonhydrological time series providing the assumed statistical assumptions are acceptable.

Subject Headings: Hydrology | Time series analysis | Numerical analysis | Rainfall duration | Rainfall-runoff relationships | Runoff | Numerical methods

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