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Annual Report for 2009-2010 (1 year of extension) for Current-topography driven exchange processes between water columns and heterogeneous permeable sediments (ACS PRF# 46655-G8, Principal Investigator- M. Bayani Cardenas, University of Texas at Austin)

1. Research Questions and Goals

This study is investigating the relative contributions of heterogeneity and anisotropy in sediment permeability, and current-topography and channel morphology driven flow towards mass and energy transport along and across the interface between a river and its bed and banks. We proposed to accomplish these goals mainly through numerical modeling using geostatistically-generated permeability fields. Analog experiments will further support our findings.

2. Accomplishments During the Second Year

            The delivery of the flume which was to be used for experimental work was delayed but it was finally delivered just this summer (June 2009). In its absence, we pursued alternative opportunities to use other flumes. My research group was fortunate to have had the opportunity to run experiments at the Outdoor Stream Laboratory (OSL) of the National Center for Earth-surface Dynamics at the St. Anthony Falls Laboratory of the University of Minnesota. The OSL is a full-scale but fully-controlled river and floodplain. We determined even larger scale effects of permeability patterns on topography-driven exchange between surface water and sediment. We discovered that the permeability of floodplain deposits changes due to transport of fine-grained particles. This work constituted an MS thesis and two papers are soon to be submitted.

            We also pursued mapping streambed temperatures in the field in year 2. In year 3 (the extension year), we developed methods to analyze these results. These results have now been published in Limnology and Oceanography.

            Since these related research directions grew, we opted to no longer run flume experiments. The initial modeling also proved sufficient to test our hypotheses.

3. Goals for additional years of grant funding

This project has now concluded. No further extensions are requested.

4. Impacts on the investigator and students

            This starter grant is the PI’s first external and competitive grant. It has provided much needed experience on managing research funding, making sure research goals are met, and supervision of research assistants.

The grant has opened up new avenues of research. I have proposed to further use the permeability fields we developed for testing hypothesis regarding biogeochemical reactive transport in stream sediment. I used results from this work as the basis of an NSF CAREER grant which got funded. This grant, partly owing to internal student matching support, has supported 1 undergrad student, 3 MS students, and 1 PhD student. The undergrad student has graduated and is in the process of applying to grad school. The 3 MS students all published papers arising from their theses and 2 have gone on to pursue their PhDs; 1 is employed by BP. The PhD student will be graduating at the end of this school year (2011).