Answer Happy

1) Numerous lines of evidence (e.g., dendrochronology, sediment core stratigraphy, archaeology, etc.) provide clues about the variability in abundance and distribution of water in North America(see figures below from Ingram and Malamud-Roam 2013). Drawing upon such information what trends/patterns emerge for water in western North America over the last two millennium (e.g., evidence of wet/dry periods and magnitude thereof)? What might the forecast for the next 100 years for water in this region look like for (be sure to justify your answer)? What do you feel is the best solution to meet water needs into the future? In order to reduce the file size of your submitted exam, please delete the figures prior to submitting. 60 0.16 Charcoal Tree-rings 40 Fire Frequency Charcoal (in²) 20 0 -1000 20 15 Fire 10 Frequency 5 0 Age (cal yr B.P.) Stratigraphy 01 250 500 750 1000 1250 1500 1750 2000 2250 2500 2750 ****** Diatoms Chenopodiaceae SC(% PDB) 0 0.5 0 40 AMS ¹C Date clay 80 -25 -15 peaty clay with vertical roots ostracods-gastropods peaty clay FIGURE 13. Stratigraphy of the sediment core from Rush Ranch, Suisun Marsh, in the northern San Francisco Bay. From left to right are the calibrated radiocarbon ages, the sediment types in the core, the diatom index, the percentage of Chenopodiaceae pollen, and carbon isotope values. The diatom index refers to the percentage of diatoms that live in higher salinity waters versus fresher waters. Values ranging between 0.00 and 0.30 are dominated by marine taxa, 0.31 to 0.70 are dominated by a mixture of taxa, and 0.71 to 1.00 are dominated by fresh- water taxa. The Chenopodiaceae pollen (from marsh plants that grow in higher salinity waters, such as Salicornia and Atriplex) represents the percentage of that pollen relative to the total marsh pollen. The disc value 8" (plotted on the right) of fresher marsh plants is closer to -25 per mil, with those growing in higher salinity waters being closer to -15 per mil. The data show a higher salinity interval from 1750 to 750 years ago. encompassing the Medieval Climate Anomaly. (Graph modified using data from Byrne et al. 2001.) A -500 500 1000 AD -2 Dry ↑ -1 Summer PDSI 0 ↓ -Fire Frequency 1 Wet 0 400 2000 800 1200 1600 Year (AD) FIGURE 27. (A) Fire frequency in the Sierra Nevada based on charcoal abundances from sediment cores from five meadow or bog locations, compared with fire histories based on fire scars from Giant Sequoias. Note that fire frequency was lower prior to 2,300 years ago (300 BC) and particularly high during the Medieval period (AD 900-1600). Multidecadal- to centennial-scale fluctuations in fire frequency are also exhibited in the record. (B) Fire frequencies (solid line) and means of the Palmer Drought Severity Index (PDSI, dashed line) showing the close correlation between the two. Fire frequencies, mean summer temperatures, and PDSI all peaked at the end of the Medieval period and declined throughout the Little Ice Age. (Figure redrawn from Swetnam et al. 2009.) BC B 0 Year 1500 10.0 2000 POSI