Last week on Rainwater and You: the unanswered questions and mysteries! Water and cows? Connection, coincidence, or conspiracy? Why do kids love cinnamon toast crunch? And the most fundamental of them all: where is rainwater harvesting when we need it the most and can it save us?
I apologize if this post is more dry and lacking in dorky humor than the last, the research is much more nitty-gritty.
This past week, I researched average precipitation for Flagstaff for the past decade and got more detes on the predicted shortages! First off, according to the report Colorado River Basin Water Supply and Demand Study - Executive Summary by the US Department of the Interior Bureau of Reclamation the amount of water available in the Colorado River Basin over the next 50 years are uncertain and are dependent on several factors. First, I don't mean to name drop but I did meet the former Secretary of the Interior, Ken Salazar (he told me to call him Ken), which was pretty dang sweet. Anyways, they continue to say that "the potential impacts of future climate change and variability" contribute to the uncertainties. Now what in the world does this mean? What these smart scientists are saying is that because we are not 100% certain about how climate change will affect the globe and that there are numerous possible scenarios, we are also uncertain as to how future water supplies will be affected. Speaking more about the different scenarios, they outline four broad-range outcomes regarding future supply. The first is the Observed Resampled (OR). In this scenario, future "hydrologic trends" and variabilities are similar to those of about the past 100 years. The second is the Paleo Resampled (PR). This predicts that the trends and variabilities represent those of a much long period--approximately 2,500 years. In the Paleo Conditioned (PC), the trends and variabilities will be similar to the wet-dry states of the PR period but with magnitudes of the OR period. The final scenario is the Downscaled GCM Projected. In this, the climate will continue to warm and the natural flow (amount of flow in the river if all the extracted water was returned) will drop by 9%.
Following this trend, there will also be an increase in frequency and duration of droughts and droughts lasting 5+ years will happen 50% of the time within the next 50 years. So in conclusion, the GCM scenario predicts that there will be continued warming across the Basin, a trend towards drying increased evapotranspiration, and decreased snow pack as a higher percentage of precipitation falls as rain. Though the Colorado River itself does not contribute to Flagstaff, these trends might be able to apply to overall climate and yearly precipitation.
With the average precipitation, according to the city's report on climate, Flagstaff has two periods: winter (November-April) and summer/monsoon (July-August). Furthermore, it reports the average precipitation is 21.77 inches/year, saying that the average period to measure climate is 30 years. NOAA has taken the same statistics from the same length of time (1971-2000) and discovered that, as an average, the highest amount of precipitation is February-March (most snowfall) and July-August (monsoon). Considering how bipolar weather can be here in Flagstaff (snowing in June? Seriously?!), I'm surprised there is a definite pattern! Here is the graph of average precip. and temperature:
Links: http://drought.unl.edu/archive/climographs/FlagstaffANC.htm and http://drought.unl.edu/archive/climographs/pdf/Flagstaff.pdf
Furthermore, they predicted that there will be a 0-10% reduction in average annual precipitation when compared to the 1971-2000 trend with less frequent but heavier precipitation events. Finally, coming back to the city's report, a characterization of the Colorado Plateau/ Flagstaff is high variability in precip. and temp., partly due to El Nino/La nina (which will also kills people and burns down trees), but no significant trend in precipitation within the last 50-100yrs (I told you, its all over the place, man). In the next post, I hope to get more numbers on specific averages for several decades!
Well, thank you all again for reading even if it was dry but informative!
Until next week,
-Lia
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