摘要:

In water resources field problems, unknown physical parameters are present in the governing partial differential equations that must be determined before relevant numerical results can be obtained. The identification of these parameters is formulated in this paper as a minimization problem in which the function to be minimized is a least squares comparison between the model equation and the systems responses, the field data. The minimization technique utilized is the Fletcher‐Powell method. Three typical water resources field problems are used as examples to demonstrate the techniqu

ISSN:0043-1397    

DOI:10.1029/WR010i001p00073

年代:1974

数据来源: WILEY

摘要:

A sample ofNobservations is taken from ap+ 1 variate normal distribution. The firstNobservations include values on allp+ 1 variates, whereas the remainingN‐nobservations include values forpof the variates only. This paper reviews the properties of the estimators that use theNcomplete observations on thepvariates to improve estimation of the mean and variance of the variate with onlynobservations. In particular, the relationship of suggested estimators to maximum likelihood estimators, corrected for bias, is given. The general advantages and limitations of such estimators are discusse

ISSN:0043-1397    

DOI:10.1029/WR010i001p00081

年代:1974

数据来源: WILEY

摘要:

A first‐order Gaussian Markov chain is used to produce a Markovian series of numbers uniformly distributed in the interval (0, 1), which in turn is used for generating a first‐order Markov chain with a gamma‐type marginal distrib

ISSN:0043-1397    

DOI:10.1029/WR010i001p00087

年代:1974

数据来源: WILEY

摘要:

Systems for forecasting downstream water temperatures for water passing through man‐made impoundments are discussed. Two forecasts that were made for deep, stratified reservoirs in the Northwest with low outlets are verified. The forecasts were made before the dams forming them had been constructed. Water temperature observations made below the dams after they were constructed are compared with the original forecasts. In both cases the forecasts agreed very well with the observations. A forecast for a high dam and a reservoir with near‐surface outlets is also compared with observed temperatures, but this agreement is not as good as that for the reservoirs with low outl

ISSN:0043-1397    

DOI:10.1029/WR010i001p00093

年代:1974

数据来源: WILEY

摘要:

River discharge frequency distributions, based on long‐term records of daily streamflow, are often found to have an inverse power law dependence on discharge. This is shown to reflect the recession of individual river floods, which are found to have an inverse power law dependence on time with an exponent of 1/(s+ 1) wheresis the slope of the power law dependence on discharge of the river discharge frequency distribution. This relationship will allow forecasting of river discharges with about ±5% uncertainty for as much as 30 days after flood pea

ISSN:0043-1397    

DOI:10.1029/WR010i001p00098

年代:1974

数据来源: WILEY

摘要:

The intent of this investigation was to verify whether the previously observed attraction of the goldfish to a sublethal concentration of copper ions presented in a shallow gradient also occurs when the fish are confronted with a steep gradient of the same concentration. The locomotion of goldfish exposed to laboratory water and a steep gradient of ‘copper‐polluted’ water in a free choice situation was monitored to establish the orientation of the fish in relation to the copper‐containing mass of water. Separate tests were made for 0.005, 0.01, 0.025, and 10.0 ppm Cu++at 21°C ± 1° in continuously flowing water. In all concentrations the number of entries into the copper‐affected zone and the time spent there per entry decreased significantly. Absolute avoidance of the copper‐containing water mass did not occur even at 10.0 ppm. It is apparent that the locomotor response of the fish is dependent on the slope of the gradient of the copper ion, all other conditions being similar. A steep gradient may elicit avoidance escape; a shallow gradient may produc

ISSN:0043-1397    

DOI:10.1029/WR010i001p00103

年代:1974

数据来源: WILEY

摘要:

Tropical storm Agnes generated flooding with a recurrence interval much greater than 100 years in a Piedmont watershed: 633 cfs/mi2from 60 mi2. Deposits on floodplains were scarce and could be mapped as sand and gravel and as sand. Deposition occurred where tributaries joined the main channel, across meander bends, and below valley constrictions such as roads and bridges. Despite the magnitude of the rainfall and flooding there were no slope failures in the basin. The only modifications to the watershed were observed in the lowlands along the main channels. Channel widening was the most spectacular modification. Within 1 year of the flood, channel cross sections were well along recovery toward pre‐Agnes dimensions. Meandering reaches of the channel recover faster than straight reaches. The Agnes flood is nearly the largest ever reported from a Piedmont watershed of this size. Large floods in the Piedmont apparently play a minor role in shaping the landscape, whereas large floods in the Blue Ridge/Valley and Ridge and Appalachian Plateau provinces, and consequent slope failure, are very active landscaping agent

ISSN:0043-1397    

DOI:10.1029/WR010i001p00106

年代:1974

数据来源: WILEY

摘要:

Soluble phosphate data from the stream draining a 7.7‐km2Pennsylvania agricultural watershed are reported. Yearly watershed soluble phosphate output and monthly and within‐month phosphate concentration variations are interpreted. The stream approaches constant and low phosphate concentrations of 10‐ppb or less PO4‐P during continuing base flow recession. Concentrations vary seasonally, 10‐ to 15‐ppb PO4‐P commonly occurring in the winter and 20‐ to 30‐ppb occurring in the summer. Implications of the between‐sample variation of phosphate concentrations as related to the partial area hydrologic concept

ISSN:0043-1397    

DOI:10.1029/WR010i001p00113

年代:1974

数据来源: WILEY

摘要:

A two‐layer model is constructed in order to describe water flow over an impermeable boundary. The model consists of vertical flow through an unsaturated layer and flow along a boundary in a saturated layer. The governing equations are solved for the nonsteady case, where the gradient of the thickness of the saturated layer is small compared with the slope of the impermeable boundary. It is shown that in most cases the discharge from shallow snowpacks will preserve the diurnal cycles of input at the surface, although for deep snowpacks (such as temperate glacier firn) the diurnal cycle is smoothed and only long‐term responses are expected. The flow of a diurnal meltwater wave through a small (2.10 m deep by 100 m long) snowpack is calculated as an example. The case of steady flow is also descri

ISSN:0043-1397    

DOI:10.1029/WR010i001p00119

年代:1974

数据来源: WILEY

摘要:

By combining equations for salt concentration by water removal from porous bodies with those for freezing point depression in normal solutions, equations are developed for calculating freezing point depression shifts due to the gradual removal of water upon freezing in porous bodies. The same equations can be used for the calculation of shifts in the osmotic potential of the water in drying porous bodies by using a simple conversion factor. Graphs relating the remaining water content to the freezing point shift for various initial soluble salt contents are given. Good agreement is found between the measured freezing point depression shifts for a silty clay soil treated with three concentrations of sodium chloride and with dimethyl sulfoxide at various contents of unfrozen water and the calculated values. The order of magnitude of the shifts expected in various natural conditions is discussed.

ISSN:0043-1397    

DOI:10.1029/WR010i001p00124

年代:1974

数据来源: WILEY