Return to HydroWeb HomepageISSN 1058-3912
Electronic journal of the International Association
for Environmental Hydrology
On the World Wide Web at http://www.hydroweb.com
JEH Volume 7 (1999), Paper 4, March 1999 Posted
March 23, 1999
ESTIMATING GROUNDWATER RECHARGE IN THE DRY ZONE OF SRI LANKA USING
WEEKLY, 10-DAILY OR MONTHLY EVAPOTRANSPIRATION DATA
R.P. de Silva
Department of Agriculture and Plantation Engineering, The Open University,
Nawala, Nugedoda, Sri Lanka
ABSTRACT
Howard and Lloyd (1979) have shown that daily values for rainfall and
potential evapotranspiration are required in estimating recharge with a
soil water balance model. However, available data may not be daily but
weekly or even monthly. This is true for potential evapotranspiration data
which are usually derived from pan evaporation data. This paper examines
the effect of using distributed weekly, 10-daily or monthly potential evapotranspiration
values rather than the actual daily values in estimating recharge with
a soil water balance model. The results clearly show that in the dry zone
of Sri Lanka, the evenly distributed weekly, 10-daily or even monthly potential
evapotranspiration data can be used in a soil water balance model to obtain
realistic groundwater recharge estimates, instead of actual daily potential
evapotranspiration data.
Reference: de Silva, R.P.; Estimating Groundwater Recharge
in the Dry Zone of Sri Lanka Using Weekly, 10-Daily or Monthly Evapotranspiration
Data, Journal of Environmental Hydrology, Vol. 7, Paper 4, March 1999.
Dr. R. P. de Silva
The Open University of Sri Lanka
Division of Agricultural & Plantation Engineering
Faculty of Engineering Technology
Nawala Nugegoda
Sri Lanka
E-mail: rpds@agri.ou.ac.lk