Ecohydrology

The objective of this paper is to present ongoing results and future directions regarding hydrologic interactions in a 20-year paired watershed study in Juniper woodlands of Eastern Oregon. Beginning in 1993, this study led by Oregon State University and with the support of Crook County SWCD, the Hatfield High Desert Ranch and the Prineville District BLM has provided valuable information concerning how different components of the water budget have responded to overstory vegetation removal. Data for precipitation, spring flow, shallow groundwater level, and ephemeral stream runoff have been collected. Comparison of pre-treatment data (12 years) versus post-treatment data (8 years) shows a positive trend in spring flow. As previously reported by Deboodt et al. (2008), an increase in late spring flow of more than 200% has been observed in the treated watershed. Also, higher soil moisture in the deeper profile and greater shallow groundwater levels observed suggest that Juniper removal may have a positive effect in soil moisture recharge and subsurface flow processes.  The interactions between surface water and shallow groundwater are being studied in more detail. Additional monitoring wells are being added to the study to better understand the magnitude and directionality of groundwater flow. Also, the hydrologic connectivity between the upland-stream-valley-groundwater continuum within the watershed is being explored using a systems approach. Ongoing and future data collection and analysis will provide critical data for the better understanding of hydrologic processes and the quantification of different water budget components in Juniper woodlands.