ENTROPY-BASED ANALYSIS ' OF SEDIMENT DISCHARGE PREDICTORS

Abstract

Numerical modelling of alluvial rivers for planning,design and monitoring of river management problems have. gained appreciable momentum in recent years. This can be primarily asceribed to rapid strides achieved in the relm of digital computers as well as numerical methods. A major lacunae encountered by model developers and users can be turned as inadequate availability of sediment discharge data with respect: to space and time in a river. It is well stablished that quality of results of a numerical river model, especially, for an alluvial river mainly depends on sediment discharge data. To circumvent the problem of inadequate sediment discharge data, many research workers developed. different sediment discharge predictors over the years. The development of numerous sediment discharge predictors have made it incumbent to undertake comparative studies of different sediment predictors on an objective basis. Nakato has reported a comparative study of different models adopting measured data of the Sacramento river. However, Nakato based his comparative study through straight comparison by plotting the measured and simulated values. For a more objective assessment of the models, the criterion of 'trarnsinformat'ion' which has originated from the concept of entropy, has' been adopted for analysing the accuracy of twelve sediment discharge predictors. The present study reiterates the findings of. Amorocho and Espildora (1973), and Chapman (1986) regarding the efficacy of entropy criteria for objective assessment of hydrologic and hydraulic models. Using the data of the Sacramento river, the ranking obtained through application of entropy criteria is found to be in close agreement with the findings of Nakato. However further application of the above criteria needs to be extended to different rivers for a conclusive judgement on the accuracy of different sediment discharge predictors...