摘要:

The methodology for assessing salinity damages is still in the development stage. This study develops an economic analysis of the effects of different levels of water quality on output and income for irrigated agriculture. First, a procedure for estimating physical crop losses due to salinity was summarized from the literature. Second, published enterprise and farm budgets were adjusted to show damages that might be expected for a specific irrigation project. A change in water quality, of the magnitude studied, did not indicate an adjusted cropping pattern in response to deteriorated water quality.

ISSN:0043-1397    

DOI:10.1029/WR005i001p00001

年代:1969

数据来源: WILEY

摘要:

This paper presents a mathematical model of regional water quality management using by‐pass piping. The model is developed within the framework of linear programming and a large‐scale problem is solved using semi‐realistic data from the Delaware Estuary. The technique of generation of elements is used in conjunction with the truncated tableau to provide efficient solutions. A possible method of taxation is indicated based on the values of the dual vari

ISSN:0043-1397    

DOI:10.1029/WR005i001p00013

年代:1969

数据来源: WILEY

摘要:

An estimated 2.5 to 3.0 million acre‐feet of runoff water accumulate annually in playas on the Southern High Plains. This large water resource should be developed for more intensive use; however, past lack of knowledge about its quality has impeded progress. Thirteen playas were sampled over an area extending about 100 miles from northeast to southwest and covering two major soil types. The water from playas contained less salts than ground water and was of excellent quality for irrigation. Nitrate contents were less than 1.0 mg/1 in nearly all playas. Nitrogen fertilizer applied to farmland added little, if any, nitrate to the surface runoff water. Suspended solids contained in playa waters were high and variable but were substantially reduced by settling in deep reservoirs protected from wind and wave actio

ISSN:0043-1397    

DOI:10.1029/WR005i001p00048

年代:1969

数据来源: WILEY

摘要:

An analytic solution of the one‐dimensional steady‐state diffusion equation for a conservative substance in an estuary of constant depthhin which the half‐widthYis related to the longitudinal distancexby the equationY= αxμmay be found if the turbulentdiffusion coefficientKxis given a general formKx=KYϕ. Because the form of the diffusion coefficient allows 2 degrees of freedom in fitting the solution of the diffusion equation to data from a real estuary, it is possible to determine the magnitude of the diffusion coefficient as well as the effect, on the distribution of the conservative substance, of assuming a constant coefficient. Data from the reach of the Delaware estuary from Torresdale, Pennsylvania, to Reedy Island, Delaware, were used to test the solution, because fresh‐water inflow data are available for the reach, and its channel geometry satisfies the above requirement. This reach also contains five U. S. Geological Survey water‐quality monitors that provide salinity data to test the solution. Analysis of these data indicates that, for low fresh‐water inflow into the estuary,Kxis of the order of 100 meters squared per second and that for most operational purposesKxmay be assumed to

ISSN:0043-1397    

DOI:10.1029/WR005i001p00059

年代:1969

数据来源: WILEY

摘要:

Hourly temperatures of small streams can be accurately predicted using an energy balance. Micrometeorological measurements are required to assess the environment of the small stream accurately. The temperature‐prediction technique was tested on three streams in Oregon. On unshaded stretches, net all‐wave radiation is the predominant energy source during the day; evaporation and convection account for less than 10% of the total energy exchange. Conduction of heat into the stream bottom is an important energy balance component on shallow streams having a bedrock bottom. Up to 25% of the energy absorbed by such a stream may be transferred into the bed. Hourly temperature changes of 0–16°F were predicted to within 1°F more than 90% of the time. This technique permits foresters to control water temperature through manipulation of stream‐side v

ISSN:0043-1397    

DOI:10.1029/WR005i001p00068

年代:1969

数据来源: WILEY

摘要:

The difficulties of predicting runoff rates and volumes owing to the inadequacy of existing functional forms of the prediction equation and a lack of analytic definitions for the pertinent parameters related to the runoff process are discussed. An analogy is established between the path of water on the watershed surface and the phenomenon of Brownian motion. Probabilistic approaches are used to model a watershed surface and to obtain a stochastic surface impressed force, which acts upon a fluid particle and is found to be a statistically homogeneous function of position. Analogously to Brownian motion theory, a Langevin‐type equation containing the stochastic surface impressed force is postulated as a model for fluid particle motion on an impermeable watershed surface. The influence of surface roughness on the amount of energy available to induce and perpetuate fluid motion on a surface is considered by examining the rate of available energy degradation for a particle collection undergoing random motion induced by surface‐impressed for

ISSN:0043-1397    

DOI:10.1029/WR005i001p00076

年代:1969

数据来源: WILEY

摘要:

A two‐soil‐moisture‐reservoir model is developed to improve the estimate accuracy of a runoff‐volume‐prediction model. Soil moisture accounting in the two reservoirs is an intermediate step to runoff prediction. A decay‐type function describes the moisture depletion between days of rainfall. The moisture depletion constant in the function varies by season with soil moisture, pan evaporation, and mean daily temperature. The runoff‐prediction equation relates runoff to rainfall and soil moisture at the beginning of the storm. Computed runoff volumes are compared with values observed on a 3‐acre native grass‐meadow watershed for an 11‐year period. Accumulated computed amounts for the period agree within 1% of the accumulat

ISSN:0043-1397    

DOI:10.1029/WR005i001p00084

年代:1969

数据来源: WILEY

摘要:

A set of differential equations has been obtained for the overland runoff from an arbitrary catchment when the rainfall excess over the catchment is known as a function of space and time. An analytical solution is given for a steady rain of finite duration. The differential equations obtained are also solved analytically for a moving top‐hat storm over a plane catchment, and the maximum depth is obtained explicitly as a function of the storm duration and catchment length. The results for all plane catchments with a given resistance formula are reduced to a single curve. It is found that the depth is increased if the storm moves downstream and decreased if the storm moves upstream, the slower the storm the greater being the change. If the storm period exceeds a critical value, with a storm moving downstream, then the depth is increased by a factorn1/n−1for a sufficiently long catchment. The parameternis the exponent of depth in the discharge depth relation. Finally, it is shown that all the results apply qualitatively to open channel flow where the kinematic wave approach is suitable. If the lateral inflow replaces the rainfall excess, it is found that the form of the curve describing the variation of depth with time is a function of the cross‐section geometry but is qualitatively similar to the overland flow curve described

ISSN:0043-1397    

DOI:10.1029/WR005i001p00095

年代:1969

数据来源: WILEY

摘要:

By using analytical methods, successive restrictions were imposed on a mathematical version of the U. S. Weather Bureau's graphical surface‐runoff model to develop an analytical model that expresses the API‐runoff relations with two equations and five coefficients. The analytical model is similar in concept to the graphical model in that both relate rainfall, week number, and the API measure to surface runoff. The concise relations of the analytical model, however, can be rapidly derived from a historical storm list by computer. When tested, runoff relations, derived with the analytical model over selected watersheds, predicted surface runoff from those watersheds somewhat better than the regional, graphical relations developed for the Val

ISSN:0043-1397    

DOI:10.1029/WR005i001p00103

年代:1969

数据来源: WILEY

摘要:

A mathematical model for channel networks represented by directed graphs on a rectangular grid is used to generate synthetic hydrographs. This makes possible simulation of the effects of changes in geometric factors specified by shape and connectivity, while keeping fixed a prescribed temporal and spatial precipitation pattern. Alternatively, this model may be used with fixed networks of interest to study effects of different types and motions of storms. The model provides for a discrete approximation of a distributed network, a transformation relating the runoff hydrograph and input precipitation. No combinations of generating parameters had to be determined, since only a single parameter associated with the collection and release of water to the channel was used. Although this parameter, which was the collection area storage constant, and the speed of travel for precipitation could be given different values at each point on the network, and might be varied as a function of time, both were assumed to be fixed in time and spatially uniform. The formation of hydrographs is determined by interlocking relationships between the network's geometry, its storage functions, and temporal and spatial variations of precipitation reaching and traversing a graphically specified network.

ISSN:0043-1397    

DOI:10.1029/WR005i001p00112

年代:1969

数据来源: WILEY