نتایج جستجو برای: river long
تعداد نتایج: 852580 فیلتر نتایج به سال:
This paper describes the Time series analysis of river water quality with emphasis on variation in parameters as evidenced by statistical approach and mathematical models. The extensive study enabled to differentiate and realize the behaviour of river and catchment's changes induced by human activities. The Time series analysis evaluation indicated trivial variation and movement in the water qu...
The interaction between human activities and watershed geology is accelerating long-term changes in the carbon cycle of rivers. We evaluated changes in bicarbonate alkalinity, a product of chemical weathering, and tested for long-term trends at 97 sites in the eastern United States draining over 260,000 km(2). We observed statistically significant increasing trends in alkalinity at 62 of the 97...
Construction of four dams on the lower Snake River (in northwestern United States) between 1961 and 1975 altered salmon spawning habitat, elevated smolt and adult migration mortality, and contributed to severe declines of Snake River salmon populations. By applying a matrix model to long-term population data, we found that (i) dam passage improvements have dramatically mitigated direct mortalit...
A fully nonlinear modal analysis identifies a critical centerline wave number q(c) for river meandering that separates long-wavelength bends, which grow to cutoff, from short-wavelength bends, which decay. Exact, numerical, and approximate analytical results for q(c) rely on the Ikeda, Parker, and Sawai [J. Fluid Mech. 112, 363 (1981)] model, supplemented by dynamical equations that govern the ...
Previously published field investigations and modeling studies have demonstrated the potential for sample bias associated with vertical wellbore flow in conventional monitoring wells constructed with long-screened intervals. This article builds on the existing body of literature by (1) demonstrating the utility of continuous (i.e., hourly measurements for ∼1 month) ambient wellbore flow monitor...
Measuring population connectivity is a critical task in conservation biology. While genetic markers can provide reliable long-term historical estimates of population connectivity, scientists are still limited in their ability to determine contemporary patterns of gene flow, the most practical time frame for management. Here, we tackled this issue by developing a new approach that only requires ...
As over 70 percent of the earth’s surface is covered by water, it is desirable to deploy underwater sensor networks to support river monitoring research applications. Underwater Acoustic Sensor Networks use acoustic waves and are characterized by long and variable propagation delays, intermittent connectivity, limited bandwidth and low bit rates. Within this research we propose a framework with...
Long-term streamflow data are vital for analysis of hydrological droughts. Using an artificial neural network (ANN) model and nine tree-ring indices, this study reconstructed the annual streamflow of the Sacramento River for the period from 1560 to 1871. Using the reconstructed streamflow data, the copula method was used for bivariate drought analysis, deriving a hydrological drought return per...
The Voluntary Nutrient Reduction Program (VNRP) for the Clark Fork River has set a target of reducing non-point source nutrient inputs by 20%. In-stream target levels are 20 ppb for total phosphorus and 300 ppb for total nitrogen. In order to assess whether this was being worked towards and to identify areas of concern, long-term monitoring was of nutrient input to the Clark Fork River and trib...
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