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Journal of Environmental Hydrology
ISSN 1058-3912 |
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Electronic Journal of the International Association for
Environmental Hydrology
JEH Volume 18 (2010), Paper 22 Posted November 30, 2010 THE EFFECT OF USING DIFFERENT TIME STEPS IN A SOIL WATER BALANCE MODEL TO ESTIMATE GROUNDWATER RECHARGE IN THE DRY ZONE OF SRI LANKA
R.P. de Silva ABSTRACT The importance of groundwater as a natural, renewable resource is well documented. The rate of replenishment of the water table (or rate of groundwater recharge) is a key issue central to sustainable development of this valuable resource. Although many workers have used soil water balance to estimate groundwater recharge, not many workers have investigated the effect of using different time steps (i.e. a day or a week) in the water balance calculation on estimates of recharge. This study looks at the effect of using weekly, 10 day and monthly time steps to estimate recharge in the dry zone of Sri Lanka. The findings suggest that the larger the time step, the lower the recharge estimate. Combining the results of documented studies and the current study, it is shown that wherever possible, a daily time step needs to be used in a soil water balance model. If daily evapotranspiration data is not available, the available data may be evenly distributed (for example weekly data divided by 7) and used as daily data. Together with actual daily rainfall data, which are likely to be available in most parts of the world, the daily time step approach gives good estimates of groundwater recharge. Reference: de Silva, R.P. 2010. The effect of using different time steps in a soil water balance model to estimate groundwater recharge in the dry zone of Sri Lanka. Journal of Environmental Hydrology, Vol. 18, Paper 22. CONTACT: R.P. de Silva School of Architecture Design & Built Environment Nottingham Trent University Nottingham NG1 4BU United Kingdom E-mail: roshan.desilva@ntu.ac.uk |
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