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Montana State Watershed Lab Montana State University - Bozeman Hydrologic connectivity from hillslope to landscape scales: Implications for runoff generation and water quality Brian McGlynn Montana State University (MSU) Kelsey Jencso, PhD student (MSU) Kristin Gardner, PhD student (MSU) Collaborators Mike Gooseff Penn State Ken Bencala USGS, NRP Menlo Park Steve Wondzell USFS, Olympia Ward McCaughey USFS RMS Jan Seibert Stockholm University, Sweden EAR-0337650 - McGlynn EAR-0337781 - Gooseff RM-4151: Ecology & Management of Northern Rocky Mountain Forests, Tenderfoot Creek Experimental Forest and the USDA, Forest Service, Rocky Mountain Research Station R832449

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Montana State Watershed Lab Montana State University - Bozeman Does spatial location of change influence watershed response to perturbation? Big Sky, Montana an outdoor laboratory Requires : 1)understanding of hydrologic connectivity across landscape 2)relationships between pattern of change and landscape structure Residences (septic systems) increasing by 100s per year

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Map area ~ 22 km 2 7 gauged watersheds OBJECTIVES Investigate hydrologic connectivity over space and time Develop conceptual model of runoff generationwatershed structure Test ideas in a developing watershed (Big Sky) applied example Tenderfoot Creek Experimental Forest

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Hydrologic instrumentation 24 transects of nested wells and piezometers (140 recording GW wells) 7 flumes with real time specific conductance (SC), temperature, and stage recorders ALSM 1m topography data 9 water content probe nests across riparian hillslope transitions >8 rain gauges 4 snowmelt lysimeters 2 SNOTEL sites 2 H 2 O/CO 2 eddy-covariance towers w/ full energy budget instrumentation. 600 m 2 plot w/ intense water content (64 TDR probes) soil and snow temperature (80) Frequent stream and GW sampling with a focus on solutes, 18 O, D, and DOC Little Belt Mountains, Montana ~850 mm precipitation with ~550 mm ET ~75% as snow 0 degrees C average temperature Soil depths 1-2 meters Elevation range ~500m from 2300m base Highly instrumented USFS nested catchments with a focus on water and carbon research from the plot to multiple watershed scales

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Montana State Watershed Lab Montana State University - Bozeman 0 ha Log 10 40 ha Terrain-based riparian mapping Topographically-driven redistribution of water

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Montana State Watershed Lab Montana State University - Bozeman Combining upland drainage and local riparian area along the stream network Hilllsope area accumulation Hillslope area accumulation Upland area accumulation pattern 0 ha Area accumulation 40 ha > area accumulation > water accumulation > increase in streamflow stream Low riparian buffer potential High riparian buffer potential Low to High riparian buffer potential Buffering potential f (riparian area : hillslope area)

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Montana State Watershed Lab Montana State University - Bozeman Lateral inflows vary along the channel network Riparian buffering potential varies along the channel network Riparian buffering potential frequency Buffering potential

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Hillslope-riparian-stream hydrologic connectivity South hillslope South riparian 10/64/0710/7 Kelsey Jencso NO CONNECTIVITY North hillslope North riparian Water table elevation m Connectivity

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Date R 2 =0.91 n=24

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Montana State Watershed Lab Montana State University - Bozeman Examining watersheds in 4 th dimension (temporal connectivity) Max bar height = 100% Of the year Each side of the stream separated

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Montana State Watershed Lab Montana State University - Bozeman How does upland connectivity relate to streamflow magnitude?

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Montana State Watershed Lab Montana State University - Bozeman Obj. 1: Investigate hydrologic connectivity over space and time Obj 2: Develop conceptual model of runoff generationwatershed structure Topographically driven lateral redistribution of water drives transient upland-stream connectivity and runoff generation Riparian buffering potential spatially variable Intermediate summary

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Principles to apply to analysis of landuse change in the Big Sky watershed Hydrologic connectivity Riparian buffering potential Suggests location of change in watershed could be significant

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Montana State Watershed Lab Montana State University - Bozeman Does spatial location of change influence watershed response to perturbation? Big Sky, Montana - an outdoor laboratory Resort Residences (septic systems) increasing by 100s per year Sampling locations

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Montana State Watershed Lab Montana State University - Bozeman Weekly nitrate time series from 4 of 9 watersheds Residences Area km 2 NF = 1 SF = 151 MF = 1690 WF = 1880 NF = 21 SF = 118 MF = 85 WF = 207

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Montana State Watershed Lab Montana State University - Bozeman Winter nitrate Maximum Value 2.17 mg/l Yellowstone Club no access - Runoff mm/hr Nitrate mg/l

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Montana State Watershed Lab Montana State University - Bozeman Late summer nitrate Maximum Value 1.31 mg/l Runoff mm/hr Nitrate mg/l

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Montana State Watershed Lab Montana State University - Bozeman Stream nitrogen sources 15 N of dissolved N Septic Atmospheric Deposition Geologic sources Natural range Septic impacted Human-derived nitrogen can be tracked with stable isotope analysis Stream samples across Big Sky watershed

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Flow connected Not flow connected Spatial structure of stream N Synoptic sampling variograms October SeptemberJune March February August SUGGESTS N immobilization in the growing season, leads to complex spatial patterns and a lack of spatial correlation Distinct Seasonality in Spatial Dependence No spatial correlation

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Montana State Watershed Lab Montana State University - Bozeman Spatial Linear Models Generalized Least Squares Estimation: Potential explanatory variables for stream nitrogen # septics in subwatershed # septics weighted by connectivity potential geology (% shales) stream order % forest riparian buffer potential (riparian area/hillslope area) elevation slope roads bare rock and talus aspect watershed area and more Methods: Cressie et al., 2006; Ver Hoef et al., 2006; Peterson et al., 2007.

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Montana State Watershed Lab Montana State University - Bozeman Seasonal Influences on Streamwater Nitrate Dormant Season # Septics Geology Growing Season Septic connectivity Riparian buffer pot. Geology N loading N processing potential R 2 = 0.9R 2 = 0.45 -0.53

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Montana State Watershed Lab Montana State University - Bozeman Spatial Data Analysis Conclusions Seasonality in variograms suggest N immobilization in uplands, riparian areas and stream network break down spatial patterns during growing season. Spatial linear models indicate seasonality in the influences on streamwater NO 3 - N loading variables significant during dormant season Hydrologic connectivity and riparian buffer potential are significant during growing season Summer Winter

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Montana State Watershed Lab Montana State University - Bozeman Take home message Transient connectivity drives runoff generation (source areas change through time) Watershed structure strong control on runoff generation and riparian buffering potential Spatial location of change matters and intersection of change pattern and watershed hydrology influences response to perturbation *Gardner, K.K. and B.L. McGlynn. In revision. Spatio-Temporal Controls of Stream Water Nitrogen Export in a Rapidly Developing Watershed in the Northern Rockies. Water Resources Research. *Jencso, K. J., B. L. McGlynn, M. N. Gooseff, S. M. Wondzell, and K. E. Bencala. In revision. Hydrologic Connectivity Between Landscapes and Streams: Transferring Reach and Plot Scale Understanding to the Catchment Scale, Water Resources Research. EAR-0337650 - McGlynn EAR-0337781 - Gooseff R832449

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Montana State Watershed Lab Montana State University - Bozeman Extra slides to follow in case there are specific questions

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Montana State Watershed Lab Montana State University - Bozeman Spatial Linear Models 1) Flow Connected vs Flow Unconnected Site B and C are flow-connected Site A and C are flow-connected Site A and B are not flow connected 2) Downstream Flow Distance (DFD) BC = 20 AC = 18 AB = 19 A C B 10 9 [Cressie et al., 2006; Ver Hoef et al., 2006; Peterson et al., 2007.

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Montana State Watershed Lab Montana State University - Bozeman Spatial Linear Models 3) Proportional Influence of upstream site on downstream site ABC A100 B010 C0.20.81 FROM SITE TO SITE A C B WatershedArea A10 B40 C50

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Montana State Watershed Lab Montana State University - Bozeman Spatial Linear Models Covariance matrix ( ) is a function of downstream distance (DFD),flow connectedness, and proportional influence. = parameter estimates X = known explanatory variables z = known dependant variable (NO 3 - ) Generalized Least Squares Estimation: