HR: 0800h
AN: H11F-0846    [Abstracts]
TI: Palaeo-recharge in Arid Northwestern China: Geochemical Inferences and Application to Predicting Hydrologic Response to Climate Change
AU: * Gates, J B
EM: john.gates@ouce.ox.ac.uk
AF: Oxford Centre for Water Reserach, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford, OX1-3QY, United Kingdom
AU: Edmunds, W M
EM: wme@btopenworld.com
AF: Oxford Centre for Water Reserach, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford, OX1-3QY, United Kingdom
AB: Recharge investigations based on ionic and isotopic properties of groundwater and vadose zone moisture have revealed temporal heterogeneity in recharge to the hyper-arid Badain Jaran Desert in northwestern China, which is situated near the contemporary northernmost extent of the East Asian Summer Monsoon (EASM). Chloride- based records indicate that rates of potential recharge have varied by at least a factor of three over the last 700 years in approximately century-scale cycles. Correspondence with palaeoclimatic proxy evidence from more humid regions of western and central China suggests that variations in the strength of the EASM are responsible for the observed changes. On longer timescales, hydrologic impacts of late-Holocene aridification on the desert's shallow aquifer system and related oasis lakes are apparent from total dissolved solids and δ¹⁸O of radiocarbon dated groundwaters, as well as diminishing piezometric levels. These results may aid in prediction of desert hydrologic response to future climatic changes because 1) a link between monsoonal rainfall and groundwater recharge rate is demonstrated and 2) general circulation models predict marked changes in Asian monsoon behavior over the 21st Century.
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1875 Vadose zone
SC: Hydrology [H]
MN: 2007 Fall Meeting