Infographic: Will Your City Run Dry? Report: 'America's Water Risk: Water Stress & Climate Variability'

I just received a PR email from Veolia Water's publicity folks touting the release of a new report (although it is dated February 2013 - guess I am on the 'D-List' with Kathy Griffin) from the Columbia Water Center and Veolia, America's Water Risk: Water Stress and Climate Variability'.

Download GB_CWC_whitepaper_climate-water-stress_final

I think some of the material from this report was presented here.

Read a news release from Growing Blue.

Here is an infographic:

From the infographic page at Growing Blue:

According to Upmanu Lall, the director of Columbia’s Water Center, many of the tools which are currently developed to help businesses assess water risk “actually understate the risk of climate variations.” Lall noted that in addition to water scarcity projections, certain areas should also consider their exposure to drought, since droughts will magnify any problems created by water scarcity.

In developing this study, Columbia researchers first developed a new water research metric that they call the Normalized Deficit Cumulated (NDC) index. The index pulls from more than 60 years of precipitation data and the current water use pattern for the United States in order to better depict the discrepancy between water use and availability.

The study clearly shows that decision-makers need to be thinking beyond the problems of water scarcity, to the way drought will affect regions that are already facing problems. Said Lall, “Droughts will create an additional impact that needs to be understood, because drought magnifies the effects of scarcity.”

Explanation of the Normalized Deficit Index (NDC)
Two risk metrics were developed to capture the influence of within year dry periods (Normalized Deficit Index – NDI) and of drought across years (Normalized Deficit Cumulated – NDC). The NDI is computed as one number for each year using historical daily rainfall data for the area and current daily water needs. It measures the maximum cumulated water shortage each year during the dry period that needs to be provided for from ground water or from surface water storage or transfers from other areas.

The NDC is computed as one number over the historical climate record. It represents the largest cumulative deficit between renewable supply and water use over the entire period. Consequently, it reflects the stress associated with multi-year and within-year drought impacts at a location. Given that 60 years of historical climate data were used, the maximum of the NDI (i.e. the worst single year), and the NDC (i.e., the effect of a string of bad years) may have an average recurrence interval of approximately 60 years. The NDI data provides insights into other recurrence intervals as well.

I'm curious - from the above discussion it would appear that stationarity is tacitly assumed since the historical record is used.

This should be a good one - CWC and Upmanu Lall are top-shelf.
 

Enjoy!
 

“The needed focus for the study of climate change and variability is on the regional and local scales. “ - James Hansen(?)  - source: Roger Pielke, Sr.

Comments

[geohydro2011]

I'm not sure I agree with the map. It is difficult for me to see that eastern Washington is at high risk whereas many locations in Arizona are at low risk. This seems especially troubling since the map indicates that only local sources are used to meet demand. If the methodology combines different types of demand (i.e., municipal plus agriculture) then I think the following is true (if methodology does not combine demand then I'm full of schist and my apologies). So here goes, from two distinct regions on the map: I would think that the Columbia Basin Project (CRB) would be well hydrated due to the influx of Columbia River water to the canals of the CRB. Sure the Odessa Aquifer is dropping like a led zeppelin (sic) and I would agree that center pivot demand likely exceeds or at least exacerbates problems with supply. But is the Columbia River in the CRB considered to be not local? Seriously, how you can make the Columbia River a non-local source of water either hypothetically or physically in the CRB? On the other hand, we are to believe that certain parts of Arizona are not in danger of being dry, so to speak? Sure there is reuse and conversation, both are important, but as I recall, land subsidence from groundwater mining left huge cracks in the land surface in many parts of Arizona. Hell from the recent USGS report on groundwater decline in the US talked about on this blog, we see decline in groundwater in nearly every regional aquifer. If the caveat is that we are only using local sources, then for some parts of Arizona, I doubt one could really make the case that Colorado River water is more local than Columbia River water. I don't want to be seen as picking on Arizona here--it just seems to be a nice visual counterpoint example to the case of eastern Washington. I could have just as easily pointed out that some local surface water irrigation districts in Nebraska received enough water in 2012 during the drought that their lands appeared "green" (i.e., NDVI green) on satellite imagery contrary to what one might conclude from the map given here. Water rights to far off sources of water, in many cases, are going to trump problems with demand due to limits on local sources of water.

[Kerry]

Interesting about the understatement of risk. Why do you think these tools aren't conveying the magnitude of the issue?