Year Established: 2015 Start Date: 2015-03-01 End Date: 2016-02-28
Total Federal Funds: $20,000 Total Non-Federal Funds: $6,359
Principal Investigators: Anna Liljedahl, Tom Trainor
Abstract: Alaska’s rivers are strongly influenced by snow and glacier melt, which contribution to overall runoff is rarely quantified. This uncertainty ultimately impacts the ability of managers and communities to plan and adapt to short- and long-term variations in runoff. For example, the anticipated climate warming will likely increase the release of water that is stored in glaciers, which can play a major role in maintaining runoff during periods of low rainfall. Effective forecasts and projections depend not only upon realistic total runoff amounts, but also an understanding of the contributing sources. Increased glacial runoff may also increase suspended solids, primarily inorganic silts and clays associated with mechanical erosion. Changes in streamflow chemistry, including suspended solids, has implications for downstream water quality and can help us better understand the export of inorganic nutrients (e.g. iron) and organic matter from permafrost and glacier affected terrestrial systems. The proposed effort, which is a continuation of a 1st year NIWR project, will provide perhaps the first hydrograph partitioning and colloidal analysis of an Interior Alaskan glacial river. The field measurements, laboratory and modeling analyses will equip us to address three main objectives: a) Quantify the contribution of glacier melt, snow melt and rainfall to stream runoff; b) Assess the hydrologic pathways of glacier wastage within a watershed underlain by discontinuous permafrost; and c) Describe the variations in streamflow suspended load during the thawed season. The approach includes a combination of field measurements, laboratory analysis and modeling efforts. Samples collected in the field will include end-of-winter snow pack cores, snow, rain, surface water, melt water on top of the glacier, runoff at the glacier terminus, winter baseflow and groundwater from a variety of locations in the Jarvis Creek watershed (634 km2). The geochemical composition of the diurnal maximum runoff will be measured continuously during the thawed season (late-April through mid-October) and hourly during a few selected days in summer using an ISCO automatic sampler. The water samples will be processed and analyzed using ion chromatography for major/minor ions, stable isotope spectrometry (Picarro isotope analyzer) for δ18O and δD. Asymmetric Flow Field-Flow Fractionation, FFF, (Postnova Anlytics) will be used for colloid characterization. Water samples will be analyzed for major ions (Ca2+, Mg,2+ Na+, K+, NH4+, Cl-, F-, SO42-, PO42-, NO3-) and oxygen (δ18O) and deuterium (δD) stable isotope ratios. The colloidal fraction of suspended solids will be a new addition to the protocol. Finally, the measurements and laboratory analyses of stable isotope and dissolved ion concentrations will inform our end-member volumetric mixing models to allow us to gain fundamental knowledge about the regional hydrologic system. The proposed effort will strongly integrate with and complement a recently funded National Science Foundation project (ARCSS 1304905, 1304684; 2013-2016), which pays the summer salary of MSc student Tiffany Gatesman. The funds from this proposal will support Ms. Gatesman’s 2015 Fall semester salary, tuition and insurance, which are not covered by the existing NSF award. The proposed effort would allow Ms. Gatesman to fully focus upon her course work and thesis research during her second year and ultimately speed-up the delivery of a quality product to benefit communities and mangers in their water resources decisions.