Progress 07/01/06 to 06/30/09
Outputs
OUTPUTS: The overall goal of the proposed research was to investigate the thermal condition in a river that was recently restored and address the effects of spring inundation on stream water temperature in dry summer months. Specifically, this study focused on water and heat exchange between stream and groundwater in a constructed floodplain, which is located in the middle Provo River, near Heber City, UT. Data collected from the field study were used in groundwater flow modeling and 1-D stream temperature modeling. Flow is regulated by the Jordanelle Dam in the study reach. Base flow is maintained at 125 cfs, and in the spring, the flow is increased to emulate spring runoff, usually > 2000 cfs. Stream discharge > 2000 cfs will begin inundating floodplains, enhancing lateral connectivity. The study was carried out in two consecutive years with different spring flow pattern. During 2007, fall-winter precipitation of 599 mm occurred which is considered to be drought conditions. In 2006, 914 mm was observed which is slightly higher than average. As a result, the emulated spring runoff differs considerably between 2006 and 2007. It should be noted that inundation occurred in 2006 but not in 2007. Field study was carried out in a constructed meander bend that was located in the downstream end of the restored 15-km reach. In summer 2006, a network of wells in two transects was installed in the study site. Each transect consists of 7 wells, running 200 m from the main channel, crossing two artificially constructed side channels. Temperature and water tables were monitored in those wells. Data collected in field study was used in groundwater flow modeling and 1-D stream temperature modeling. Field data collection started late summer in 2006 and continued in summer 2007. Temperature loggers were installed in each well, and in the upstream and downstream end of the main channel and two side channels. We were interested in water temperature during summer time, so temperature loggers were deployed in June and retrieved in September. Water table in the stream and wells were periodically measured to study groundwater flow direction. Saturated hydraulic conductivity of the constructed meander bend, which was used as an input variable in groundwater flow modeling (MODFLOW), was measured using slug tests at each well. Incoming solar radiation, wind speed, and humidity were measured for 48 hours in sunny days of early August 2007 and 2008. Discharge is continuously measured at the USGS gauging station located about 5km upstream from the study site. Groundwater flow and stream water temperature simulations were carried out in spring and summer 2008. We are still in process of calibrating the models.re currently working on a manuscript. PARTICIPANTS: Nothing significant to report during this reporting period. TARGET AUDIENCES: The findings of this study will be communicated with the Upper Colorado Region Bureau of Reclamation in addition to scientific communities. The Upper Colorado Region Bureau of Reclamation carried out the restoration project in the middle Provo River (http://www.mitigationcommission.gov/prrp/prrp.html) PROJECT MODIFICATIONS: Nothing significant to report during this reporting period.
Impacts
Steady state MODFLOW simulation was used to estimate difference in groundwater inflow between 2006 and 2007. The RMSE between the observed and simulated water tables were < 0.1 m. Groundwater inflow was higher in 2006 than 2007 by about 1.4 times in main channel and 1.8 times in the side channel. Stream Temperature Modeling: Based on research by Neilson (2006), a new version of a dynamic stream temperature model was developed to simulate surface heat fluxes, bed conduction, dead zone heat transfer, and tributary and groundwater inflows. The model requires boundary condition flows and temperatures, meteorological information, and tributary and groundwater flows and temperatures. The model was calibrated by estimating the cross sectional area and exchange coefficients associated with the dead zones. However, to best fit the observed data, groundwater inflow value was also increased by 5 times of the estimate from the MODFLOW simulation. This is within the range of variation observed in hydraulic conductivity. Effects of Spring Inundation and Water Table on Stream Water Temperature: The resulting increase in the groundwater table in 2006 due to inundation did not affect temperature fluctuations in the main channel. Groundwater inflow is < 0.1 % of stream discharge in the main channel, and the 1.4 times increase in groundwater inflow did not affect water temperatures in the 830m reach. There was an effect on the Side Channel: a 1.8 times higher groundwater inflow resulting from a prolonged inundation may lower maximum water temperatures of the side channel by about 0.5 degrees C, compared to a year with no inundation. The results from this study were presented in the Fall meeting of the American Geophysical Union in December 2006 and in the annual meeting of the North American Benthological Society in May 2008. We are currently working on a manuscript.
Publications
- No publications reported this period
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Progress 01/01/07 to 12/31/07
Outputs
OUTPUTS: The objective of this project is to study water and heat exchange between restored stream channel and an artificially constructed meander bends. The study site is located in the downstream end of the restored 13-km reach in the Provo River in the Heber Valley. In summer 2006, a network of wells in two transects was installed in the bend. Each transect consists of 7 wells, running 200 m from the main channel, crossing two artificially constructed side channels. Data collection continued in summer 2007. Temperature loggers were installed in each well, the main channel, and the two secondary channels to measure summer (June-August) water temperatures. Water table in the stream and wells were periodically measured to study flow direction. Saturated hydraulic conductivity of the constructed meander bend, which is necessary to estimate mass transfer, was measured using slug tests at each well. Incoming solar radiation, wind speed, humidity were measured for 48 hours in sunny days
of early August. Discharge is continuously measured at the USGS gauging station located about 5km upstream from the study site. Discharge of the main channel, side channels in the study reach were measured twice over the summer.
TARGET AUDIENCES: The findings of this study will be communicated with the Mitigation Commission in addition to the scientific communities.
Impacts
Stream water temperature was measured in summers 2006 and 2007. The flow pattern, which is regulated by the Jodanelle Dam, considerably differed between the two years. In spring 2006, flow was increased to > 2,000 cfs over two-week period to simulate spring runoff and inundate the floodplain. In spring 2007, because of the preceding dry winter, the dam operation was tightened, and the restored reach of the Provo River received only about 5 days of increased flow in spring just over 300 cfs, which was not enough flow to inundate the floodplain. This difference in flow pattern might have resulted in warmer water temperature in summer 2007. The daily maximum temperatures in the main channel at the study site exceeded 21 degrees C for about a week in summer 2006 and for over a month in summer 2007. Temperature of the water released from the Jodanelle Dam was slightly higher in 2007, where temperature fluctuated between 9.5 degrees C and 11 degrees C in 2006 and between 10
degrees C and 12 degrees C in 2007.
Publications
- No publications reported this period
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Progress 05/01/06 to 12/31/06
Outputs
This study is at a preliminary stage. Site selection and instrumentation were conducted in early summer, and the data collection began in mid summer. The study site, an artificially constructed meander bend, is located in the downstream end of the restored 13-km reach in the Provo River in the Heber Valley. A network of wells was installed in the bend, where one transect runs through the portion covered by riparian trees, and the other transect through the open area. Each transect consists of 7 wells and runs from the main channel for about 200m. Both transects cross two artificially constructed secondary channels. Temperature loggers were installed in each well, in the main channel, and in the two secondary channels. The study bend was surveyed in, and the water table in the stream and wells were periodically measured to study flow direction. The logger was retrieved at the end of September to assess summer warm temperatures. The daily maximum temperature in the main
channel in the study reach exceeded 21 ۫C over the summer. Water released from Jodanelle Dam has a constant temperature of 11 ۫C, thus water temperature increased 10 ۫C in the11 km restored reach. The study site is located in a gaining reach, where groundwater diagonally flows from the field to the main channel. The water passing through the upstream well-transect under the riparian cover should move toward the downstream well-transect in open area. The ground water temperature in the downstream transect is about 1.5 ۫C degree higher than the upstream transect, suggesting heat gain as water moved through the meander bend. Analysis of the data has just begun, and the questions such as whether the riparian cover influences on the temperature of groundwater inflow, and whether the groundwater inflow raises the daily minimum temperature in main stream, will be addressed in subsequent years. Measurement of water temperature and water table will be repeated next
summer, and climatic variables will also be measured.
Impacts
This type of restoration project has become an important activity in the US in recent years. Water temperature is a crucial variable to sustain a healthy stream ecosystem, yet the problem of high daily maximum temperature that the Provo River faces occurs rather commonly in restored rivers. The study of heat gain mechanisms in a restored river can provide useful information to improve restoration techniques that may prevent rapid temperature increases. Improvement in restoration techniques increases the efficiency of these projects, and consequently lowers their cost.
Publications
- No publications reported this period
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