An investigation into the mechanisms of stormflow generation on a glaciated hillslope in coastal British Columbia has been undertaken. The investigation included a controlled irrigation-runoff experiment on a 30 x 30 m hillslope plot in the U.B.C. Research Forest near Haney, B.C. Instrumentation included 12 rain gauges, 45 piezometers, and 2 outflow-tipping buckets. Piezometer slug tests to measure hydraulic conductivities and a geologic study to establish the representativeness of the experimental results were conducted to complement the irrigation experiment. The hydrogeologic units of the research plot consist of: A) 0.1 to 0.3 m of forest floor material consisting of organic material in various states of decay B) 0.3 to 0.8 m of heterogenous, red-brown B horizon containing many organic rich channels made up of live and decayed roots C) 0.5 to 2 m grey to grey-green Vashon till D) fractured to unfractured granodiorite bedrock The hydraulic conductivity of the till was approximately 10⁻⁷ m/s. A slightly higher value of 10⁻⁶ m/s was found for the lower B horizon matrix. A bulk conductivity for the lower B horizon was estimated at 10⁻⁴ m/s. The 2 to 3 order-of-magnitude difference is probably attributable to numerous, high conductivity root channels present throughout the lower B horizon. Stormflow was generated when the water table rose into the high conductivity B horizon. Outflow at the stream bank exited from the B horizon with most water flowing from high conductivity root channels. The rate of outflow was controlled by the position of the water table. Since the water table remained parallel to the overall hillslope, the hydraulic gradient remained approximately constant. Only the cross-sectional area available for flow varied. Once outflow had commenced, the rate of outflow was sensitive to variation in the rainfall rate. Input-outflow lag-times were as little as one hour. The time lag to initiation of outflow was 19 hours. Most of this lag was attributable to the filling of storage requirements after a two month period of no rain. The distribution of the hydrogeologic units in the research plot was found to be representative of the research area. Lag times were found to be in the range found in another similar B.C. mountain basin. It is concluded that the mechanism of stormflow generation operating in the research plot can be generalized to other similar basins. / Land and Food Systems, Faculty of / Graduate

This study examined the influence of landscape features on stream nutrient concentrations within the Ichawaynochaway Creek watershed in southwestern Georgia. Baseflow concentrations of both dissolved (SRP, NO3, NH4) and total (TN, TP) nutrients were measured at 17 sampling sites monthly for a period of six months (July 2012 to January 2013). A long-term dataset (January 2008 to March 2012) was also analyzed for baseflow/stormflow comparisons of dissolved nutrient concentrations. Relationships among land-use, geology, soils, physiographic features and nutrients were analyzed at both the sub-watershed and riparian corridor scales. SRP concentrations were lower and NO3 concentrations higher than reported in previous studies of the region. Due to dry conditions during the sampling period, nutrient input was likely limited to groundwater contributions and land-use effects were minimal. Trends among water quality variables varied between the upper and lower portions of the watershed, suggesting differences in nutrient transport pathways due to spatial variation.

This study characterizes the mass transport of ions in two streams in the Great Smoky Mountains National Park, comparing transport between stormflow and baseflow periods. By comparing ion mass transport between these two hydrological conditions, the importance of soil and the governing biogeochemical processes will be underscored. Two water quality monitoring study sites were located on the Middle Prong of the Little Pigeon River and Ramsey Prong within the same basin. These remote sites were equipped with YSI 6920 multi-parameter sonde to record continuous 15-min data of pH, depth, conductivity, turbidity, and temperature. Additionally, ISCO 6712 composite samplers were used to collect stream samples during storm events. Baseflow was collected by grab samples prior to storm events, and stormflow collected by ISCO samplers. Throughfall samples were collected after storm events. All samples were analyzed for pH, ANC, and conductivity using an autotitrator. Inductively coupled plasma spectrometry and ion chromatography were used to determine major cations, trace metals, and anions (Ca2+, Na+, K+, Mg2+, Aln+, Cu, Fe, Mn, Si, Zn, SO42-, NO3-, Cl-, NH4+). Stage-discharge relationships were developed at each site utilizing a combination of field measurements and modeling. Velocity and area field measurements were taken to calculate discharges for mid- to low-flow stages while mid- to upper-flow stages were modeled using RIVER2D and verified with field measurements. Stage-discharge curves and sample ion concentrations were used to compute ion mass transport for a two year period in 2006 through 2008. Differences in mass transport of ions between baseflow and stormflow periods found that greater mass transport of ions, except protons, occurred during baseflow periods. These results indicate that on an annual basis ions are stored from input throughfall sources and released gradually through groundwater flow over time more than rapid interflow transport during storm events. This information illustrates the importance of soils and groundwater storage in the regulation of ion transport and streamwater quality in the Great Smoky Mountains National Park.

No description available.