{"id":516,"date":"2010-11-29T14:12:12","date_gmt":"2010-11-29T19:12:12","guid":{"rendered":"http:\/\/hydrogeo.wordpress.com\/?p=516"},"modified":"2010-11-29T14:12:12","modified_gmt":"2010-11-29T19:12:12","slug":"agu-abstract-spatial-heterogeneity-in-isotopic-signatures-of-baseflow-in-small-watersheds-implications-for-understanding-watershed-hydrology","status":"publish","type":"post","link":"https:\/\/all-geo.org\/jefferson\/agu-abstract-spatial-heterogeneity-in-isotopic-signatures-of-baseflow-in-small-watersheds-implications-for-understanding-watershed-hydrology\/","title":{"rendered":"AGU Abstract: Spatial heterogeneity in isotopic signatures of baseflow in small watersheds: implications for understanding watershed hydrology"},"content":{"rendered":"<p><em>In a few weeks, I&#8217;ll be giving the following talk at the American Geophysical Union Fall Meeting in a session on Groundwater\/Surface Water Interactions: Dynamics and Patterns Across Spatial and Temporal Scales. My talk will be in Moscone West 3014 at 11:05 am on Wednesday, December 15th, 2010.<\/em><\/p>\n<p><strong>Spatial heterogeneity in isotopic signatures of baseflow in small watersheds: implications for understanding watershed hydrology<\/strong><br \/>\n<em>A. J. Jefferson<\/em><\/p>\n<p>Time  series of stable isotopes of oxygen and hydrogen in stream water are  widely used to characterize watershed transit times and flowpaths, but  synoptic sampling of multiple locations within a watershed can also  provide useful information about heterogeneity of stream water sources  and groundwater-surface water interactions that may affect  interpretations of watershed hydrology. Here I present results of  same-day baseflow sampling campaigns in low-relief, 0.1 to 100 km<sup>2<\/sup> watersheds. More than half of less than 5 km<sup>2<\/sup> forested and urban watersheds sampled in this study had variability in ?<sup>2<\/sup>H exceeding 2\u2030 and ?<sup>18<\/sup>O  variability exceeding 1\u2030, substantially larger than the analytical  uncertainty. In some cases, the heterogeneity was extreme, with ?<sup>2<\/sup>H  varying by &gt;10\u2030 over 150 m in one stream. Some isotopic  perturbations occur in conjunction with stream conductivity and  temperature changes, and such zones likely reflect localized  contributions from fractured crystalline bedrock.  In the urban 100 km<sup>2<\/sup> watershed, mainstem baseflow isotopes were relatively homogeneous, but ?<sup>2<\/sup>H  varied by more than 10\u2030 across tributaries, suggesting that  subwatersheds are fed by water with different sources or transit times.  Some urban streams were isotopically similar to the municipal water  supply, suggesting that water main leakage and wastewater discharge may  be locally significant contributors to baseflow. The isotopic  heterogeneity of small streams and watersheds suggests that an  understanding of groundwater-stream interactions is needed to correctly  interpret isotope-based inferences about watershed transit times and  flowpaths.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In a few weeks, I&#8217;ll be giving the following talk at the American Geophysical Union Fall Meeting in a session on Groundwater\/Surface Water Interactions: Dynamics and Patterns Across Spatial and Temporal Scales. My talk will be in Moscone West 3014 at 11:05 am on Wednesday, December 15th, 2010. Spatial heterogeneity &#8230;<\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"ub_ctt_via":"","footnotes":""},"categories":[3,12,45,33],"tags":[345,350,349,358,31,357],"class_list":["post-516","post","type-post","status-publish","format-standard","hentry","category-abstracts","category-groundwater","category-headwater-streams","category-isotopes","tag-abstracts","tag-charlotte","tag-groundwater","tag-isotopes","tag-urban","tag-watershed-hydrology"],"featured_image_src":null,"author_info":{"display_name":"ajefferson","author_link":"https:\/\/all-geo.org\/jefferson\/author\/ajefferson\/"},"_links":{"self":[{"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/posts\/516","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/users\/2"}],"replies":[{"embeddable":true,"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/comments?post=516"}],"version-history":[{"count":0,"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/posts\/516\/revisions"}],"wp:attachment":[{"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/media?parent=516"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/categories?post=516"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/all-geo.org\/jefferson\/wp-json\/wp\/v2\/tags?post=516"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}