ACHIEVING WATER BALANCE: “To understand the OUT = IN equation in an engineering context, we need to think in terms of a safety margin or factor and what that actually means in practice” added Ron Smith, Ministry of Sustainable Resource Management, when he elaborated on the science-based understanding behind the Water Balance Equation (April 2005)
The OUT = IN equation is variable on both sides. In mathematics, one cannot solve for two variables with a single equation. “In a nutshell, when the service population is small and the safety factor is large, climate variability may be inconsequential. As population and water demand grow, however, the safety factor shrinks. Eventually we reach a condition of vulnerability where a small shift in the water balance can trigger a supply crisis. This has been the prevailing pattern for almost 20 years. We have effectively used up the safety factor because we have not understood climate variability,” stated Ron Smith.