Stochastic hydrology in the context of climate change

• Published in: Climatic change 1997-09, Vol.37 (1), p.89-101
• Main Author: Matalas, Nicholas C
• Format: Article
• Language: English
• Subjects: Climate; Climate change; Drought; Economics; Freshwater; Global warming; Hydrology; Stochastic hydrology; Trends; Water; Water management
• ISSN: 0165-0009; 1573-1480
• DOI: 10.1023/A:1005374000318

Hydrologic trends, real (physical) or perceived (statistical), suggest that water management be predicated on the assumption of hydrologic nonstationarity. The assumption leaves open the question to what extent will the "trends" be sustained locally and regionally over the future 25, 50 or 100 years corresponding to the economic time horizons of water projects. Whether hydrologic trends are real or perceived, record events of hydrologic extremes, floods and droughts, will be broken with exceedingly high probabilities over the economic lives of water projects. Before the assumption of hydrologic nonstationarity is accepted, the ability to cope with the uncertain impacts of global warming on water management via the operational assumption of hydrologic stationarity should be carefully examined. In the absence of strong physical evidence, trends cannot be unequivocally distinguished from slow oscillations. Slow oscillations can be mimicked by persistence in stationary processes. It is time to examine the relative merits of the assumptions of stationarity and nonstationarity in the operational context of water management. The strategy of wait-and-see, i.e. delaying the making of important, expensive and essentially irreversible capital investments, could served water managers well in coping with the uncertainties regarding climate change.