Stochastic Modeling Of Hydrologic Intermittent Daily Processes

Author : G. Quesada Tabios Iii
Publisher :
ISBN 13 :
Total Pages : 316 pages
Book Rating : 4.:/5 (71 download)

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Download or read book Stochastic Hydrology of Daily Streamflows written by G. Quesada Tabios Iii and published by . This book was released on 1979 with total page 316 pages. Available in PDF, EPUB and Kindle. Book excerpt: Daily streamflow simulation offers hydrologic planners the opportunity to study proposed and existing designs and operation schemes of water resource systems based on long sequences of synthetic streamflows. Stochastic hydrology deals with the development of stochastic models which simulate observed hydrologic processes and generate synthetic realizations of the processes. The synthetic sequences, on the other hand, are such that they must preserve important statistical characteristics of the observed process that are of relevance to water resource systems design and oprations. The major objective of this study is to test the applicability of some daily stochastic hydrology models to a typical Central Luzon Stream - the Talavera River in Nueva Ecija, Philippines. The stochastic models are a family of Gaussian model called autoregressive (AR) and mixed autoregressive-moving-average (ARMA) models, and a grouup of shot noise models. As an initial requirement for building the Gaussian models, the historical data are standardized and normalized in order that the residual flow variates are amenable for stramflow synthesis. The successive use of logarithmic and Wilson-Hilferty transformations are found suitable in rendering the flow residuals approximately normally distributed. The use of the parametric method of cyclic standardization is appropriate in removing the periodicities in the means and variances. Results from the time series analysis performed to the flow residuals virtually prescribed the adoption of a seasonal lag-one autoregressive model for generation of synthetic data. In using the shot noise models, seasonality is introduced by taking the harmonic representations of the raw daily statistics means, standard deviations, skewness coefficients and lag-one serial correlation coefficients. At the model-parameter estimation stage, only the simple shot noise model and the shot noise model with an added baseflow possess estimates consistent with parameter constraints, in contrast to the other candidate shot noise models. The three models fitted to the historical data yielded satisfactory reproduction of the daily means, standard deviations and serial correlation coefficients. Failure to reproduce the high skewness in the historical data is one of the model limitations noted. In general, this parper has demonstrated the applicability of stochastic hydrology models to the selected river. The seasonal AR(1) model, the simple shot noise model, and the shot noise model with baseflow are alternative models for daily stramflow synthesis, with unique advantages in each. Faithfulness in reproducing daily and monthly statistics differ among models; however, on an overall basis, all models show promise as daily streamflow synthesis models.