摘要:

ABSTRACT:In a cooperative demonstration project, NASA and the U.S. Army Corps of Engineers (Corps) compared conventional and Landsat‐derived land‐use data for use in hydrologic models, and the resulting discharge frequency curves were analyzed. When a grid‐based data‐management system was used on a cell‐by‐cell basis (size about 1.1 acres or 0.45 hectare), Landsat classification accuracy was only 64 percent, but, when the grid cells were aggregated into watersheds, the classification accuracy increased to about 95 percent. When both conventional and Landsat land‐use data were input to the HEC‐1 model for generating discharge frequency curves, the differences in calculated discharge were judged insignificant for subbasins as small as 1.0mi2(2.59 km2). For basins larger than 10mi2(25.9km2), use of the Landsat approach is more cost‐effective than use of conventional methods. Digital Landsat data can also be used effectively by local and regional agencies for hydrologic analysis by incorporating the data into grid‐based data‐management systems. The transfer of this new technology is well under way through inclusion in some Corps training courses and through use by both county government personnel an

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05310.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:Cores were obtained from several tree species located both on a river floodplain and a nearby terrace. A ratio of annual tree growth on floodplains to terrace growth was developed and shown to be related to the annual river discharge. Growth ratios from the time prior to written records can therefore be used to reconstruct river discharge and infer past unrecorded flood frequency. Oak and basswood ratios yielded the best models for discharge reconstruction, whereas those of elm and birch were less useful. This method permits reconstruction of river discharge from an assemblage of growth cores obtained within a relatively small area.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05311.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:The salinity of the lower South Platte River in Colorado is characterized by plotting the average annual flow, total dissolved solids, and salt mass flow against distance along the stream. The plots show that salts are being leached from the irrigated lands above Greeley and are being deposited on the irrigated lands below Greeley. The salt deposition on the lower lands will result in their salination. The plots show also that fall and winter stream flows carry most of the salt loads. These fall and winter flows are stored in off stream reservoirs for use during the irrigation season. Therefore these salts are transferred to the lower irrigated lands where they accumulate. The salt balance for these lands can be improved by permitting the fall and winter flows to leave the basin, or by providing adequate land drainage coupled with supplemental irrigation water.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05312.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:Spatial variation of five water quality variables were analyzed using composite water samples collected periodically from eight small watersheds (11.4–71.6 km2) in forested East Texas during 1977 through 1980. Based on 31 observations during the four‐year period the average yield of nitrate‐nitrite nitrogen (NNN), total kjeldahl nitrogen (TKN), total phosphorus (PO4), chloride (CHL), and total suspended sediment (TSS) were 1.43, 21.96, 3.09, 50.11, and 90.39 ka/ha/yr, respectively. Compared to the water quality standards of the U.S. Environmental Protection Agency (1976) and the Texas Department of Water Resources (1976) for CHL, TSS, and NNN, none of the observations exceeded the limits for public water supplies.The study showed that forested watersheds normally yielded stream flow with better quality than that from agricultural watersheds. Watersheds of greater percent of pasture area, mean slope, stream segment frequency, and drainage density produced greater concentrations for these five chemical parameters in water samples. Meaningful equations were developed for estimating mean average yields for each chemical parameter for each watershed with R2ranging from 0.77 to 0.96 and standard error of estimates from 17 to 33 percent of the observed

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05313.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:Four 10‐ha plots in dense watermilfoil beds of Lake Seminole, Georgia, were each treated with either 2,4‐D DMA or 2,4‐D BEE at rates of 22.5 and 45 kg a.e./ha. Both formulations were shown to be rapidly converted to the 2,4‐D acid form, with no detection of 2,4‐D DMA or 2,4‐D BEE in the water within less than 24 hours after treatment. The maximum detected 2,4‐D concentrations in the high rate 2,4‐D DMA and 2,4‐D BEE plots were 3.6 and 0.68 mg/, respectively. However, all but seven samples at a 2,4‐D BEE plot showed nondetectable herbicide levels by day 7, with all water samples showing nondetectable levels by day 13. Dimethylnitrosamine and 2,4‐dichlorophenol, potentially toxic transformation products of the herbicide formulations, were at nondetectable levels in all water samples. Sediment samples showed no significant net accumulation of 2,4‐D, 2,4‐D BEE, or 2,4‐dichlorophenol during the summer monitoring; dimethylnitrosamine remained at nondetectable levels. There was no accumulation of 2,4‐D in fish collected from the two plots treated with 2,4‐D DMA. Four of 24 game fish from the 2,4‐D BEE treatment plots contained low levels of 2,4‐D in muscle tissue, with a maximum value of 0.29 μg/g. In contrast, 18 of 20 gizzard shad collected from these plots through day 13 contained detectable 2,4‐D in the muscle, with a maximum concentration of 6.9 μg/g. All fish collected after day 13 contained nondetectable levels of 2,4‐D. Small decreases in dissolved oxygen and pH, associated with the complete watermilfoil control in all plots, had r

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05314.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:Tradeoffs between regional economic development and resource use is a question often confronting local decisionmakers. A resource‐interindustry model can be used to depict the interrelationships between regional economic sectors as to household income and/or employment and resource use. A resource‐interindustry model was developed for Humboldt and Lander Counties in Nevada which shows the tradeoffs between regional household income (wages, salaries, profits, and rents) and/or employment and water usage. Water income and water employment multipliers can be ranked, enabling decisionmakers to realize sectors which require greatest regional water usage to regional household income and/or employm

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05315.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:Bluegills were exposed for one hour to 0.2 or 2.3 mg/liter water soluble fraction (WSF) of JP‐4 in a testing chamber designed to contain individual fish. A strain gage paddle was used to monitor activity. Whole body movement of individual fish did not change appreciably during exposure to either 0.2 or 2.3 mg/liter WSF‐JP‐4. Strength of pectoral fin movement, accounting for the majority of the fish behavior, increased in six of ten individuals exposed to 2.3 mg/liter WSF‐JP‐4. Pectoral fanning may be a useful parameter to indirectly assess wate

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05316.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:Dieback of the ohia forest over a large part of the Hilo watershed and adjacent areas has resulted in a severe loss of the overstory crown component of the vegetation. The decline could cause serious damage to the watershed. To evaluate possible changes in conditions in the Hilo area since the decline began, stream flow, water quality, and precipitation data from 1929 to 1980 were collected and analyzed. The limited data available do not indicate that the ohia decline has resulted in a significant change in either annual stream flow or peak stream flow of a stream discharging from the ohia forest in the Hilo area. Suspended sediment production of two streams remains well within accepted levels as does the chemical makeup of components dissolved in the streams.

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05317.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:This paper reports an analysis of the water budgets of 10 small (5–6 ha) diked areas (cells) within the Delta Marsh in southcentral Manitoba, Canada. The important terms in the water budget equation in this study were precipitation (P), water pumped in (SWI), evapotranspiration (ET), seepage in (GWI) and out (GWO), and change in storage (ΔS). P, SWI, and S were measured directly, and the sum of ET and GWO determined by difference. Estimating ET as 0.7 pan evaporation gave a seepage loss of 2.9 mm/day from the most intensively studied cell. Other methods of estimating ET produced estimates of GWO ranging from 2.4 to 3.8 mm/day. Water budgets for less intensively studied cells indicated seepage loss increased as perimeter available for seepage increased, but not proportionately. Efforts to measure seepage directly or estimate it from measured hydraulic gradients and hydraulic conductivity produced estimates much lower than the estimates from the water budget equation. Hydraulic conductivities were very heterogeneous, reflecting the sorting of water deposited sediments. Comparison of the hydraulic conductivities with seepage estimates from the water budget strongly suggests water movement downward as well as laterally from these diked are

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05318.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY

摘要:

ABSTRACT:Soil surface roughness and the topographic orientation of microrelief influence runoff and water storage. Distances measured following the surface of the microrelief and horizontally across the area with the microrelief can be used with the number of microridges or microhills to estimate the average cross‐sectional areas of the depression, the microslope angles, and crest heights. Microridge sideslope angles which effect the rate of runoff were estimated reasonably well in field plots by the metho

ISSN:1093-474X    

DOI:10.1111/j.1752-1688.1983.tb05319.x

出版商:Blackwell Publishing Ltd    

年代:1983

数据来源: WILEY