Sunday, September 4, 2016

Forecast Water Demand Shifting

John Fleck at  http://www.inkstain.net/fleck/ alerted me to this: A-Community-Guide-for-Evaluating-Future-Urban-Water-Demand-1.pdf/. A good guide for water providers and those that are in a position to assess the infrastructure needs and costs in delivery of water.

The first figure in the report is history of water demand projections for the City of Seattle.

 
The graph shows how the water demand forecast has changed over time from assumed steady increase to nearly no increase projected in the latest forecast. The graph also shows that consumption of water by the City of Seattle has declined significantly since 1990. The big drop after 1990 was related to a drought year. But post 1992 drought demand never returned to the pre 1990 levels and has continued downward. The pattern shown by Seattle has been consistent in most U.S. cities. Changing attitudes and social norms, conservation efforts, regulations and pricing has pushed total demand downward despite increased population and economic activity. 

3 comments:

Rabbits' Guy said...

Quite awhile ago it was forecast that usmail would grow so much we all would have to be mail carriers!

It was the same thing with computer programming - there were once projections where the entire population would have to be maintaining computer programs at the rate they were being written and the labor per line of code to maintain!.

Dave said...

One day we will have a very similar graph that depicts global average temperature and the various forecasts thereof.

Dan McShane said...

Dave: We already do have that. There have been all sorts of forecasts including multiple scenarios by the ICP which have been adjusted after updates. Those adjustments have been towards more warming. Anyone that has put out a prediction can be plotted against the actual results.
Perhaps the most interesting would be the longest term predictions such as that of Broeker (1975): http://blogs.ei.columbia.edu/files/2009/10/broeckerglobalwarming75.pdf
He did pretty well both on the CO2 levels and the temperature.