260-GP Model for Predicting Evaporation and Seepage Losses from Reservoir.

Abstract

Evaporation is one of the least satisfactorily explained components of the hydrologic cycle because, unlike say stream flow, it cannot be directly measured but must be estimated based on mass transfer, or energy or water budget methods. As a consequence, a variety of techniques have been derived for determining or estimating vPpour transport from water surfaces. Numerous researchers have attempted to estimate the evaporation values from climatic variables, and most of these methods require data that are not easily available. Simple methods that are reported try to fit a linear relationship between the variables. However, the process of evaporation is highly non-linear in nature, as is evidenced by many of the estimation procedures. Many researchers have emphasized the need for accurate estimates of evaporation in hydrologic modeling studies. These requirements could be addressed through better models that will address the inherent non-linearities in the process. Further, there is a requirement for methods that consider only a few variables, since estimates are often needed where limited meteorological data only are available. In this study, a Genetic Programming based mathematical model is developed for Pilavakkal reservoir system in Tamilnadu where both evaporation loss and seepage losses are reported, which further complicates the whole modeling process. The proposed model gave very high Correlation coefficient of 0.94 and 0.85 for the two reservoirs under Pilavakkal scheme, namely Kovilar and Periyar reservoirs respectively. Genetic Programn iThg is found to be a potential technique for modeling inherent non-linearities in the model.