HillslopeHydrologic Connectivity Controls Riparian Groundwater Tturnover: Implications of Catchment Structure for Riparian Buffering and Stream Water Sources

TitleHillslopeHydrologic Connectivity Controls Riparian Groundwater Tturnover: Implications of Catchment Structure for Riparian Buffering and Stream Water Sources
Publication TypeJournal Article
Year of Publication2010
AuthorsJencso K.G, McGlynn BL, Gooseff M.N, Bencala K.E, Wondzell S.M
JournalWater Resources Research
Volume46
Date PublishedOct 15
ISBN Number0043-1397
Accession NumberWOS:000283100600002
Keywordsbasin, chemistry, dynamics, electrical-conductivity, headwater catchment, hydrograph separation, storm runoff, temperate forest, topographic controls, zones
Abstract

Hydrologic connectivity between catchment upland and near stream areas is essential for the transmission of water, solutes, and nutrients to streams. However, our current understanding of the role of riparian zones in mediating landscape hydrologic connectivity and the catchment scale export of water and solutes is limited. We tested the relationship between the duration of hillslope-riparian-stream (HRS) hydrologic connectivity and the rate and degree of riparian shallow groundwater turnover along four HRS well transects within a set of nested mountain catchments (Tenderfoot Creek Experimental Forest, MT). Transect HRS water table connectivity ranged from 9 to 123 days during the annual snowmelt hydrograph. Hillslope water was always characterized by low specific conductance (similar to 27 mu S cm(-1)). In transects with transient hillslope water tables, riparian groundwater specific conductance was elevated during base flow conditions (similar to 127 mu S cm(-1)) but shifted toward hillslope signatures once a HRS groundwater connection was established. The degree of riparian groundwater turnover was proportional to the duration of HRS connectivity and inversely related to the riparian: hillslope area ratios (buffer ratio; r(2) = 0.95). We applied this relationship to the stream network in seven subcatchments within the Tenderfoot Creek Experimental Forest and compared their turnover distributions to source water contributions measured at each catchment outlet. The amount of riparian groundwater exiting each of the seven catchments was linearly related (r(2) = 0.92) to their median riparian turnover time. Our observations suggest that the size and spatial arrangement of hillslope and riparian zones along a stream network and the timing and duration of groundwater connectivity between them is a first-order control on the magnitude and timing of water and solutes observed at the catchment outlet.

Short TitleWater Resour Res
Alternate JournalWater Resour Res