Dealing with Drought: Decoupling Climatic and Management-Related Drivers of Water Conservation Behavior

Abstract:

As global populations grow, cities in drought prone regions of the world such as California and South East Australia are faced with escalating water scarcity and water security challenges. The management approaches geared towards addressing these challenges are diverse. Given the myriad of possible approaches and the tendency to apply them in combination, successful management actions can be difficult to identify. Background climactic variability further complicates the story, making transfer of management lessons from one drought stressed region to another difficult. Here we use Melbourne, a city of 4.3 million people in South East Australia that recently faced and overcame a > 10 year “Millennium” drought, as a test case for evaluating the relative importance of various management-related and climactic factors in driving reductions in municipal water consumption (~60% in 12 years). Our analysis suggests that Melbourne's declining municipal consumption cannot be explained by potable substitution alone, as reductions in municipal consumption were not matched by increased use of alternative sources (e.g., urban rain or recycled water). Thus, water conservation behavior (not source switching) may be responsible for the majority of demand reduction in Melbourne. Interestingly, while voluntary or mandatory water restrictions appear to have substantially altered the rate of change of consumption near the end of Melbourne's Millennium drought (e.g., forcing a period of intense conservation), overall conservation behavior precedes these restrictions. This suggests that other rapidly implemented (and hither too unquantified) management approaches such as advertising or newspapers may have driven water conservation behavior early in the drought. Climatic factors, particularly precipitation may also have influenced conservation behavior; changes in precipitation were significantly positively correlated with changes in water consumption at a lag of 18 months. Similar correlations with reduced lags were observed between reservoir inflow and consumption (lag = 15 months), and reservoir storage and consumption (lag = 9 months), suggesting that the effects of precipitation on consumption may be indirect, and linked to its effects on reservoir storage and public perception of water security.