19 research outputs found
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Present-day and future contributions of glacier runoff to summertime flows in a Pacific Northwest watershed: Implications for water resources
While the impacts of long-term climate change trends on glacier hydrology have received much attention, little has been done to quantify direct glacier runoff contributions to streamflow. This paper presents an approach for determining glacier runoff contributions to streamflow and estimating the effects of increased temperature and decreased glacier area on future runoff. We focus on late summer streamflow (when flow is lowest and nonglacier contributions to flow are minimal) of a small glacierized watershed on the flanks of Mount Hood, Oregon, United States. Field and lab measurements and satellite imagery were used in conjunction with a temperature-index model of glacier runoff to simulate potential effects of increased temperature and reduction in glacier area on late summer runoff in the watershed. Discharge and stable isotope data show that 41–73% of late summer streamflow is presently derived directly from glacier melt. Model simulations indicate that while increased temperature leads to rapid glacier melt and therefore increased streamflow, the consequences of glacier recession overcomes this effect, ultimately leading to substantial declines in streamflow. Model sensitivity analyses show that simulation results are most sensitive to degree day factor and less sensitive to uncertainties in debris-covered area and accumulation area ratio. This case study demonstrates that the effects of glacier recession on streamflow are a concern for water resource management at the local scale. This approach could also be extended to larger scales such as the upper Columbia River basin where glacier contributions to late summer flows are also thought to be substantial
Study Protocol For Clinical Trial of the Fit Families Multicomponent Obesity intervention For african american adolescents and their Caregivers: Next Step From the orbit initiative
INTRODUCTION: This study will test the effectiveness of FIT Families (FIT), a multicomponent family-based behavioural intervention, against a credible attention control condition, Home-Based Family Support (HBFS). This protocol paper describes the design of a randomised clinical trial testing the efficacy of the FIT intervention. The protocol will assess the efficacy of FIT to improve health status in African American adolescents with obesity (AAAO) and their primary caregivers on primary (percent body fat) and secondary (physical activity, metabolic control, weight loss) outcomes and its cost-effectiveness.
METHODS: 180 youth/caregiver dyads are randomised into FIT or HBFS, stratified by age, gender and baseline per cent overweight. The proposed study follows a two condition (FIT, HBFS) by four assessment time points. Tests will be conducted to identify potential relationship of baseline demographic and clinical variables to our dependent variables and see whether they are balanced between groups. It is hypothesised that youth/caregiver dyads randomised to FIT will show significantly greater reductions in percent body fat over a 12-month follow-up period compared with AAAO receiving HBFS. Preliminary findings are expected by November 2023.
ETHICS: This protocol received IRB approval from the Medical University of South Carolina (Pro00106021; see \u27MUSC IRB 106021 Main Approval.doxc\u27 in online supplemental materials).
DISSEMINATION: Dissemination activities will include summary documents designed for distribution to the broader medical community/family audience and submission of manuscripts, based on study results, to relevant peer-reviewed scientific high-impact journals.
TRIAL REGISTRATION NUMBER: NCT04974554
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Present-day and future contributions of glacier melt to the Upper Middle Fork Hood River : implications for water management
Glaciers are effective reservoirs because they moderate variations in runoff and
supply reliable flow during drought periods. Thus, there needs to be a clear
understanding of the influence of glacier runoff at both the basin and catchment scale.
The objectives of this study were to quantify the late summer contributions of glacier
melt to the Upper Middle Fork Hood River and to simulate potential impacts of climate
change on late summer streamflow. The Upper Middle Fork Hood River catchment
(50.6 km²) is located on the northeast flanks of Mount Hood Oregon. Discharge
measurements and isotope samples were used to calculate glacier meltwater
contributions to the entire catchment, which feeds into a major water diversion used for
farmland irrigation. Data were collected over the period August 10 - September 7,
2007. This late summer period was selected because there is typically little rain and
suspected high glacier melt contributions. Discharge measurements taken at glacier
termini, show that just two of the mountains glaciers, Eliot and Coe, contributed 41% of
the total surface water in the catchment. The Eliot Glacier contributed 87% of the total
flow in the Eliot Creek, while the Coe Glacier supplied 31% of the runoff in Coe Creek.
Isotopic analyses, which include the inputs of all other glacier surfaces in the
catchment, show a total glacier contribution of 88% from the Eliot Glacier to the Eliot
Creek, in excellent agreement with the streamflow measurements. Isotopes also showed
an 88% contribution from the Coe Glacier to the Coe Creek, higher than the amount
measured from streamflow. This latter discrepancy is likely due to undersampling of
streamflow from the Coe Glacier. During the isotope measurement period, overall
contributions of both Coe and Eliot Glaciers to the Upper Middle Fork Hood River were
62 - 74% of catchment discharge. A temperature index model was used to simulate
projected impacts of glacier recession and warmer temperatures on streamflow. The
Snowmelt Runoff Model (SRM) was chosen for this task because it has been shown to
effectively model runoff in glacierized catchments where there are limited
meteorological records. SRM was calibrated using the 2007 discharge records to
quantify August – September glacier runoff in the Upper Middle Fork catchment under
a variety of glacier and temperature scenarios. SRM simulations indicate that runoff
from the catchment glaciers are highly sensitive to changes in glacial area, glacier
debris-cover, and air temperature. Model simulations show that glacier recession has a
greater effect on runoff than do projected temperature increases. Thus, even without
warmer summer temperatures, glacier contributions to streamflow will decrease as long
as the glacier continues to lose mass. Applying both current glacier recession rates and a
2°C temperature forcing, the model predicts a decrease of 31% of late summer glacier
runoff by 2059, most of which is lost in August. This study suggests that glaciers
currently play a significant hydrological role in the headwater catchments of the Hood
River Basin at a time when water is needed most, and that these contributions are
projected to diminish over time
Study protocol for clinical trial of the FIT Families multicomponent obesity intervention for African American adolescents and their caregivers: Next step from the ORBIT initiative
Introduction This study will test the effectiveness of FIT Families (FIT), a multicomponent family-based behavioural intervention, against a credible attention control condition, Home-Based Family Support (HBFS). This protocol paper describes the design of a randomised clinical trial testing the efficacy of the FIT intervention. The protocol will assess the efficacy of FIT to improve health status in African American adolescents with obesity (AAAO) and their primary caregivers on primary (percent body fat) and secondary (physical activity, metabolic control, weight loss) outcomes and its cost-effectiveness.Methods 180 youth/caregiver dyads are randomised into FIT or HBFS, stratified by age, gender and baseline per cent overweight. The proposed study follows a two condition (FIT, HBFS) by four assessment time points. Tests will be conducted to identify potential relationship of baseline demographic and clinical variables to our dependent variables and see whether they are balanced between groups. It is hypothesised that youth/caregiver dyads randomised to FIT will show significantly greater reductions in percent body fat over a 12-month follow-up period compared with AAAO receiving HBFS. Preliminary findings are expected by November 2023.Ethics This protocol received IRB approval from the Medical University of South Carolina (Pro00106021; see ‘MUSC IRB 106021 Main Approval.doxc’ in online supplemental materials).Dissemination Dissemination activities will include summary documents designed for distribution to the broader medical community/family audience and submission of manuscripts, based on study results, to relevant peer-reviewed scientific high-impact journals.Trial registration number NCT04974554