396 research outputs found
New 2012 Precipitation Frequency Estimation Analysis for Alaska: Musings on Data Used and the Final Product
INE/AUTC 13.1
Hydrology of the Central Arctic River Basins of Alaska
The work upon which this report is based was supported in part by funds (Project A-031-ALAS) provided by the United States Department
of Interior, Office of Water Resources Research, as authorized under
the Water Resources Act of 1964, as amended
Heat and Mass Transfer in Cold Regions Soils
The work upon which this report is based was made possible by a cooperative
aid agreement between the U.S. Forest Service, Institute of Northern
Forestry, Fairbanks, Alaska, and the Institute of Water Resources, University
of Alaska. Contributions to this study were also made by the University of
California at Davis and Ohio State University. The collection of winter
data on pore pressures was made possible by a separate grant by the Office
of Water Research and Technology (project A-053 ALAS)
Effects of seasonability and variability of streamflow on nearshore coastal areas: final report
General nature and scope of the study:
This study examines the variability of streamflow in all
gaged Alaskan rivers and streams which terminate in the ocean.
Forty-one such streams have been gaged for varying periods of
time by the U. S. Geological Survey, Water Resources Division.
Attempts have been made to characterize streamflow statistically
using standard hydrological methods. The analysis scheme
which was employed is shown in the flow chart which follows.
In addition to the statistical characterization, the following
will be described for each stream when possible:
1. average period of break-up initiation (10-day period)
2. average period of freeze-up (10-day period)
3. miscellaneous break-up and freeze-up data.
4. relative hypsometric curve for each basin
5. observations on past ice-jam flooding
6. verbal description of annual flow variation
7. original indices developed in this study to relate streamflow
variability to basin characteristics and regional
climate.This study was supported under contract 03-5-022-56, Task Order
#4, Research Unit #111, between the University of Alaska and NOAA,
Department of Commerce to which funds were provided by the Bureau of
Land Management through an interagency agreement
Hydrologic Properties of Subarctic Organic Soils
Completion Report
for
U. S. Forest Service
Institute of Northern Forestry
Cooperative Agreement No. 16 USC 581; 581a-581iThe need for understanding the natural system and how it responds
to various stresses is important; this is especially so in an environment
where the climate not only sustains permafrost, but develops
massive seasonal frost as well. Consequently, the role of the shallow
surface organic layer is also quite important. Since a slight change in
the soil thermal regime may bring about a phase change in the water or
ice, therefore, the system response to surface alterations such as
burning can be quite severe. The need for a better understanding of the
behavior and properties of the organic layer is, therefore, accentuated.
The central theme of this study was the examination of the hydrologic
and hydraulic properties of subarctic organic soils. Summarized
in this paper are the results of three aspects of subarctic organic soil
examinations conducted during the duration of the project. First, a
field site was set up in Washington Creek with the major emphasis on
measuring numerous variables of that soil system during the summer. The
greatest variations in moisture content occur in the thick organic soils
that exist at this site. Our major emphasis was to study the soil
moisture levels in these soils. This topic is covered in the first
major section, including associated laboratory studies. Those laboratory
studies include investigations of several hydraulic and hydrologic
properties of taiga organic and mineral soils. Second, some field data
on organic moisture levels was collected at the site of prescribed burns
in Washington Creek to ascertain the sustainability of fires as a function
of moisture levels. This portion of the study is described under the
second major heading. The last element of this study was a continued
application of the two-dimensional flow model that was developed in an
earlier study funded by the U. S. Forest Service, Institute of Northern
Forestry, and reported by Kane, Luthin, and Taylor (1975a).
Many of the results and concepts gathered in the field work were
integrated into the modeling effort, which is aimed at producing better
estimates of the hydrologic effects of surface disturbances in the black
spruce taiga subarctic ecosystem. This knowledge should also contribute
to better fire management decisions of the same system.The work upon which this report is based was made possible by a
cooperative aid agreement funded by the U. S. Forest Service, Institute
of Northern Forestry, Fairbanks, Alaska. Contribution to this study was
also made by Ohio State University
Compatibility analysis of precipitation and runoff trends over the large Siberian watersheds
The consistency of long-term yearly precipitation and runoff trends over the largest Arctic watersheds (Ob, Yenisei and Lena Rivers) is examined. Three gridded precipitation datasets (Climatic Research Unit, University of Delaware, NCEP) are used for comparative analyses with runoff data collected at basin outlets. The results generally demonstrate inconsistency in long-term changes of basin precipitation and runoff. The Yenisei River runoff increases significantly, while precipitation data show mostly negative trends. The Ob River does not show any significant trend either in precipitation or runoff. Positive trend in the Lena River runoff is accompanied by a weak precipitation increase; however, the precipitation increase is not strong enough to support the observed runoff change. The inconsistency identified in basin precipitation and runoff trends suggests uncertainty in both the quality of basin precipitation and runoff datasets, as well as the perceived hydrologic factors impacting runoff change
Meteorological and hydrologic studies in the Alaskan Arctic in support of long-term ecological research
Long-term hydrologic studies in the Arctic simply do not exist. Although the Arctic has been identified as an area that is extremely sensitive to climate change, continuous scientific research has been limited to the past seven years. Earlier research was spotty, of short duration, and directed at only one or two hydrologic elements. Immediate future research needs to encompass all the major hydrologic elements, including winter processes, and needs to address the problem of scaling from small to larger areas in hydrologic models. Also, an international program of cooperation between northern countries is needed to build a greater scientific base for monitoring and identifying potential changes wrought by the climate
Juvenile Fish Passage Through Culverts in Alaska: A Field Study
In the past, culvert design where fish passage was considered generally has been based on the weakest-swimming adult fish in a river system. It has also been recognized for some time that juvenile fish are very active throughout the year, moving upstream and downstream in response to a number of environmental factors. In Alaska, many natal and nonnatal streams in southcentral and southeastern Alaska support both Chinook (Oncorhynchus tschawytscha (Walbaum)) and Coho (Oncorhynchus kisutch (Walbaum)) for one to three years, respectively, before they emigrate to sea. Are we restricting desirable habitat for these juvenile salmonids with hydraulic structures such as culverts? Unfortunately we have little information on either the behavior of juveniles in the vicinity of hydraulic structures or their swimming abilities. The objective of this study was to examine the behavior of juveniles when attempting to ascend a culvert. It was hypothesized that vertical obstacles or high velocity of opposing flow may prevent juvenile fish from moving upstream. It was also hypothesized that they would determine and take the path of least resistance to optimize their chances of successfully ascending a culvert.
Four culverts were selected for intensive study regarding juvenile fish passage: Beaver and Soldotna Creeks on Kenai Peninsula and No-name and Pass Creek Tributary on Prince of Wales Island. It was postulated that fish are motivated to move upstream to obtain food if they can establish its presence. We used salmon eggs as an attractive food source both to initially capture the juveniles and then to motivate them to ascend the culvert for possible recapture. Juvenile fish were captured in a baited minnow trap and stained with a dye. They were released downstream of the culvert while the food source was placed upstream in a minnow trap. We supplemented our visual observations with underwater video cameras. We made numerous hydrologic and hydraulic measurements at each site. Although we attempted to select culverts that would prove to be quite challenging to juvenile fish passage, in three of the culverts selected, juvenile fish, of the full range of the fork length initially captured, succeeded in ascending through the culvert. For the fourth culvert, some larger juvenile fish succeeded in ascending the culvert, but not the smaller of each fish type. It was clearly established that juvenile fish were motivated to move upstream to obtain food.
In the Beaver Creek culvert, fish used the large corrugations to their advantage when ascending the culverts. The Pass Creek Tributary culvert had corrugations too small for fish to utilize. No-name Creek appeared to present not problems for juvenile fish for the water levels at the time of the visit as they small along the bottom on the centerline of the culvert. In general, observations of fish attempting to move upstream through the culvert revealed that they swam very close to the culvert wall, and in the case of high velocities (Beaver Creek and Pass Creed Tributary) they swam near the surface along the sidewall where velocities are reduced. It is obvious that the juvenile fish are attempting to minimize power output and energy expenditure by taking the path of least resistance.
Although not quantitavely proven, it appears that as long as fish make some headway in their upstream movement they are content. The rationale for this conclusion is that fish do not know what they may encounter upstream so they attempt to conserve as much power and energy as possible while still moving forward. They generally do so by seeking out the lowest velocities in the cross-section. In areas of steep velocity gradients along the wall (where the areal extent of low velocities is limited), it is clear in our videotapes that fish have problems maintaining their position and preferred orientation. It is apparent from our observations that because of their small size, juvenile fish are hindered by turbulence and that this area needs more study.List of Figures - ii
List of Tables - iv
Disclaimer - v
Abstract - vi
Acknowledgment - ix
Introduction - 1
Objectives - 2
Procedure - 3
Study Sites - 8
Selection - 8
Beaver Creek - 8
No-name Creek - 9
Soldotna Creek - 12
Pass Creek Tributary - 12
Past Studies - 14
Fish Behavior - 14
Juvenile Movement - 15
Results - 16
Beaver Creek - 16
No-name Creek - 26
Soldatna Creek - 29
Pass Creek Tributary - 39
Summary - 47
Research Needs - 49
References - 5
An Approach to the Cosmological Constant Problem(s)
We propose an approach to explaining why naive large quantum fluctuations are
not the right estimate for the cosmological constant. We argue that the
universe is in a superposition of many vacua, in such a way that the resulting
fluctuations are suppressed by level repulsion to a very small value. The
approach combines several aspects of string theory and the early history of the
universe, and is only valid if several assumptions hold true. The approach may
also explain why the effective cosmological constant reamins small as the
universe evolves though several phase transitions. It provides a non-anthropic
mechansim leading to a small, non-zero cosmological constant.Comment: Talk given at Rencontres de Moriond, 2004 by G.L. Kan
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