22-Status of measurement accuracy in lake water balance studies

Abstract

Water balance studies of lakes without error estimation can be very misleading and can give a false sense of security. The accuracy required for the computation and measurement of water balance components is more stringent for shorter time intervals. Case studies of error estimates for different components of water balance of lakes in India are rare, but experiences from elsewhere could be the guiding ones for adopting suitable techniques in future. Errors mostly emanate from a lack of understanding of the physical principles. Measurement of different components using imperfect instruments, inadequate sampling designs and poor data collection procedures, and regionalization of point data in a time space continuum are the major sources of errors. Also, there could be serious problems in accuracy if some terms in water balance are ignored e.g., evapotranspiration from the marshy zone associated with shallow lakes.