HR: 0800h
AN: H51B-1122    [Abstracts]
TI: Water and solute exports across catchment scales with varying proportions of hillslope and valley-bottom saturated areas
AU: * Inamdar, S
EM: inamdasp@buffalostate.edu
AF: SUNY College at Buffalo, 1300 Elmwood Avenue Great Lakes Center, Buffalo, NY 14222 United States
AU: Tuk, J
EM: jmtuk27@yahoo.com
AF: SUNY College at Buffalo, 1300 Elmwood Avenue Great Lakes Center, Buffalo, NY 14222 United States
AU: Graham, J
EM: jmgraham888@yahoo.com
AF: SUNY College at Buffalo, 1300 Elmwood Avenue Great Lakes Center, Buffalo, NY 14222 United States
AU: Mitchell, M
EM: mitchell@mailbox.syr.edu
AF: SUNY-ESF, 1 Forestry Drive, Syracuse, NY 14210 United States
AB: Recently there has been considerable interest in investigating how water and solute fluxes vary across catchment scales and if the relative proportions of hillslope and riparian landscape units can explain this response. We studied the export of water and solutes across four partly nested forested catchments located in Western New York, USA. The size of the catchments were - 696 (s1), 3.4 (s2), 1.6 (s3) and 1.9 (s5) ha. S1 was the main watershed oulet; s2 was nested in s1 with a 0.02 ha valley-bottom riparian area; s3 was nested in s2 and represents a headwater hollow catchment; and s5 was located outside s1 with a 0.07 ha valley-bottom wetland. The topographic index (ln[a/tanB]) was computed using a 2 m DEM and the mean values of ln[a/tanb] for s1, s2, s3, and s5 were 5.16, 5.38, 5.28, and 5.66, respectively. The spatial extent of hillslope and riparian units were mapped in the field and surface-saturation was observed in valley-bottom riparian areas, on hillslope benches, and near groundwater seeps. Streamflow and storm-event stream chemistry were monitored at the outlet of the watersheds. Water samples were analyzed for all base cations and anions, DOC and DON. Streamflow yields for s1, s2, s3 and s5 were 0.37, 0.15, 0.42, and 0.17, respectively. The headwater hollow catchment generated the highest discharge yield, with surface runoff being reduced as it traversed the valley-bottom deeper riparian stores. Average storm-event nitrate (ueq/L) and DOC (umol/L) (within []) concentrations for the four watersheds in order were: 22.7 [361.1], 41.8 [233.9], 43.5 [148.8], and 36.7 [316.9]. Corresponding nitrate and DOC flux (mol/ha) were: 0.42 [8.3], 0.54 [4.0], 1.28 [5.18], 0.50 [4.73]. DOC export increased with increase in saturated area whereas nitrate followed an opposite trend. This study shows that consistently-saturated areas located below groundwater seeps or on hillslope benches are as important source of DOC as the valley-bottom riparian areas. Although high values of ln[a/tanB] matched the valley-bottom saturated areas the topographic index map was not able to correctly identify all the hillslope saturated areas. This study suggests that we need to be cautious while partitioning the catchment into broad landscape units to explain catchment-scale water and solute patterns. Consideration needs to be given to saturated landscape parcels that form at hillslope benches and channel heads and which may be important sources for solute exports.
UR: http://www.buffalostate.edu/orgs/glc/gowanda/overview.htm
DE: 1860 Runoff and streamflow
DE: 1871 Surface water quality
SC: Hydrology [H]
MN: 2004 AGU Fall Meeting