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1.
ABSTRACT: The empirical fit of an annual harmonic function to stream temperature measurements in central New England can be improved by considering a harmonic period of less than 365 days instead of 365 or 366 days. Generalized equations, developed using periodic temperature data from 27 streamflow stations, allow predictions of stream temperature at any site given (1) the mean basin altitude (E), in meters above mean sea level, and (2) station latitude (LAT), in degrees. Stream temperature t, in degrees Celsius, on day number d, in days starting with January 1, is estimated as: in which, M = 31.48 – 0.0025 (E) ? 0.4635 (LAT) with standard error of estimate of 0.62°C, and τ= 1228.88 – 21.01 (LAT) with standard error of estimate of 14.1 days.  相似文献   

2.
ABSTRACT: The Salmon Creek Watershed drains 325 km2 of forested terrain in the Cascade Mountains of western Oregon. Over a 30–year period (from 1955 to 1984) average daily maximum and minimum stream temperatures, calculated from the 10 warmest days of each year, have risen 6°C and 2°C, respectively. In contrast, a small decrease in maximum air temperatures was found over the same period. Regression analysis indicated a highly significant (p < 0.01) relationship between a cumulative index of forest harvesting and maximum stream temperatures. Maximum temperatures also tended to increase for several years following major peak flow events. The interaction between harvest activity (logging and road construction), changing forest and riparian management practices and the occurrence of natural hydrologic events (peak flows and associated mass soil movements) tend to obscure specific cause-and-effect relationships regarding long-term changes in maximum stream temperature.  相似文献   

3.
ABSTRACT: The infiltration of atrazine, deethylatrazine, and deisopropylatrazine from Walnut Creek, a tributary stream, to the alluvial valley aquifer along the South Skunk River in central Iowa occurred where the stream transects the river's flood plain. A preliminary estimate indicated that the infiltration was significant and warrants further investigation. Infiltration was estimated by measuring the loss of stream discharge in Walnut Creek and the concentrations of atrazine and its metabolites deethylatrazine and deisopropylatrazine, in ground water 1 m beneath the streambed. Infiltration was estimated before application of agrichemicals to the fields during a dry period on April 7, 1994, and after application of agrichemicals during a period of small runoff on June 8, 1994. On April 7, the flux of atrazine, deethylatrazine, and deisopropylatrazine from Walnut Creek into the alluvial valley aquifer ranged from less than 10 to 60 (μg/d)/m2, whereas on June 8 an increased flux ranged from 270 to 3060 (μg/d)/m2. By way of comparison, the calculated fluxes of atrazine beneath Walnut Creek, for these two dates, were two to five orders of magnitude greater than an estimated flux of atrazine to ground water caused by leaching from a field on a per-unit-area basis. Furthermore, the unit-area flux rates of water from Walnut Creek to the alluvial valley aquifer were about three orders of magnitude greater than estimated recharge to the alluvial aquifer from precipitation. The large flux of chemicals from Walnut Creek to the alluvial valley aquifer was due in part to the conductive streambed and rather fast ground water velocities; average vertical hydraulic conductivity through the streambed was calculated as 35 and 90 m/d for the two sampling dates, and estimated ground water velocities ranged from 1 to 5 m/d.  相似文献   

4.
ABSTRACT: A study was conducted in the Piedmont province of Maryland to determine if a relationship exists between stream quality and the extent of watershed urbanization. During the first phase of the study 27 small watersheds, having similar characteristics but varied according to land use, were investigated. Using these controlled conditions, eliminating as many interferences as possible, this first phase was intended to determine if a definite relationship did exist between the two factors. Finding that the first phase was successful the second was initiated which consisted of a comparison of biological sampling data, from other studies, with degree of watershed urbanization. The purpose of this second phase was to ascertain if the relationship between degrees of urbanization and decline in stream quality was linear as watershed area increased and in streams spread throughout the Maryland Piedmont. The principal finding of this study was that stream quality impairment is first evidenced when watershed imperviousness reaches 12%, but does not become severe until imperviousness reaches 30%.  相似文献   

5.
A paired watershed study was conducted in western hemlock/western redcedar/Douglas fir forests of southwestern British Columbia to assess the effects of clearcutting and clearcutting plus slash-burning treatments on stream water characteristics. In the case of stream temperatures, both treatments increased summer temperatures as well as summer daily temperature fluctuations. These effects lasted for seven years in the case of the clearcut stream but longer in the case of the clearcut and slashburned stream. Clearcutting increased winter stream temperatures whereas slashburning caused a decrease. These changes lasted less than four years. Clearcutting and slashburning had a greater impact on stream temperatures than did clearcutting alone.  相似文献   

6.
ABSTRACT. This study investigates economies associated with size of New England water utilities. Regression analysis techniques were applied to annual water cost and production data reported in the American Directory of Water Utilities (1968-1969). Modest economies of size in the production of water were found. Because in large communities more water is used per person, total cost increases at a slightly faster rate than population increases, but per unit costs of producing water decline. Substantial economies occurred when the number of customers was held constant and volume of water per customer increased. This study indicates possible economies when two or more of the many very small utilities combine activities to form a larger unit and by encouraging present customers to use more water.  相似文献   

7.
ABSTRACT. A promising technique for recognition of early stages of cultural eutrophication relies on determining production and respiration in streams. The most successful and most widely used method of estimating production of a segment of a stream is the upstream-downstream, diurnal curve method introduced by Odum [1956]. This technique is equivalent to obtaining an approximate solution to the oxygen balance equation. We report here an exact solution of the balance equation as a method for calculating primary production. Data presented by Owens [1966] are analyzed; effects of depth and oxygen saturation are studied. A major advantage of the method described here is that continuous temporal variation of net production may be rigorously handled. The method is shown to be well suited to our ultimate goal of studying energy budgets of streams, and thereby the eutrophication process.  相似文献   

8.
ABSTRACT: Benthic invertebrate faunas were compared to two fifth-order streams, the Atigun River flowing northward and the Dietrich River flowing southward. Sixty-eight taxa were collected, forty-nine from each stream. Aquatic insects comprised 88% of the taxa and 97% of the individuals from the Dietrich River and 73% of the taxa and 97% of the individuals from the Atigun River. Diptera, especially Chironomidae, were most abundant. Plecoptera, Ephemeroptera, Oligochaeta, Acarina, and Collembola were significant. In both streams the headwaters were dominated by the subfamily Diamesinae which was replaced by Orthocladiinae downstream. Diversity seemed to increase with stream order. Cluster analysis showed a high degree of resemblance between the benthic faunas of the rivers. Faunal resemblance decreased with increasing distance between stations, both within and between the streams. Although some taxa may occur in only one stream, the evidence for faunal resemblance is stronger than for faunal differences. Other studies have shown that differences in total radiation associated with valley aspect affect local climate, hydrology, and distribution of terrestrial plants and animals. However, the benthic faunas of Atigun and Dietrich Rivers were remarkably similar. Factors which operate independently of aspect, possibly freezing solid in winter, may control the occurrence of species in these streams.  相似文献   

9.
ABSTRACT: Regression models to predict baseflow alkalinity from basin hydrogeology were developed and verified for headwater streams on the Laurel Hill anticline in southwestern Pennsylvania. Predicted baseflow alkalinities were then used to estimate sensitivity to acidification and presence of trout (Salvelinus fontinalis) populations for 61 headwater streams. Sensitivity classifications were verified by surveying trout populations. Geologic variables relating to the carbonate rock burial depth, extent of carbonate rock recharge areas, and length of stream channel flowing through effluent carbonate rock outcrops were much more useful in predicting baseflow alkalinity than areal extent of carbonate rocks. Baseflow alkalinity was not well related to status of trout populations on these anticlinal basins, especially on noneffluent basins where bedrock dip exceeded surface slope.  相似文献   

10.
ABSTRACT: A study was conducted to 1) chemically characterize three AMD streams entering Chestnut Creek in southwestern Virginia below the town of Galax, Virginia, and 2) to assess the biological and chemical alterations in the creek. Over a six mile reach, the benthic macroinvertebrate population was reduced to zero, the naturally low alkalinity (~25mg/1) of the stream was reduced to less than 5 mg/1, and the pH was reduced from 7.2 to 6.3. Increased concentration of iron from less than 0.01 mg/I to more than 4.0 mg/1 were accompanied by the deposition of a coating of iron hydroxide up to 0.25 in. thick in the stream bed, a phenomenon most likely responsible for the absence of benethic macroinvertebrates. In situ bioassays with bluegill sunfish and one snail species showed that the creek water, after confluence with all the AMD streams, was not toxic in 192 hours to fish, and snails survived 96 hours before they began to die. The undiluted AMD itself was highly toxic.  相似文献   

11.
ABSTRACT: Geographic Information Systems (GIS) were used to assess the relationships between land use patterns and the physical habitat and macroinvertebrate fauna of streams within similar sized watersheds. Eleven second or third order watersheds ranging from highly urbanized to heavily forested were selected along Lake Superior's North Shore. Land use patterns within the watersheds were quantified using readily available digital land use/land cover information, with a minimum mapping resolution of 16 ha. Physical habitat features, describing substrate characteristics and stream morphology, were characterized at sample points within each stream. Principle component and correlation analyses were used to identify relationships between macroinvertebrates and stream physical habitat, and between habitat and land use patterns. Substrate characteristics and presence of coarse woody debris were found to have the strongest correlations with macreinvertebrate assemblage richness and composition. Agricultural and urban land use was correlated with substrate characteristics. Algal abundance, associated with macroinvertebrate compositional differences, was correlated with housing density and non-forest land covers. The use of readily available spatial data, even at this relatively coarse scale, provides a means to detect the primary relationships between land use and stream habitat quality; finer-resolution GIS databases are needed to assess more subtle influences, such as those due to riparian conditions.  相似文献   

12.
Results are reported from an application of the state space formulation and the Kalman filter to real-time forecasting of daily river flows. It is shown that the application of filtering techniques improves the overall forecasting performance of the model. As is true for most hydrologic systems, the model is not completely known. Therefore, the procedures pertaining to on-line parameter and noise statistics estimation, as presented in the first paper, are implemented. The example in this paper shows that these techniques also perform satisfactorily when applied to a real-world situation.  相似文献   

13.
ABSTRACT: A computer program written in BASIC calculates net changes in stream channel cross-sections. Calculations are based on dividing the channel cross-section into discrete regions of scour and fill. Internal boundaries of these regions (along the x-axis of the cross-section) are determined by the location of vertical depth measurements taken at two distinct times. The right and left boundaries of the cross-section can be specified so that scour or fill can be calculated for any portion of the profile desired.  相似文献   

14.
ABSTRACT: Information on biologically important physical and chemical variables is presented for Lake Oconee, a newly impounded pumped storage reservoir in Georgia. During its first summer, when no pumping occurred, temperature, oxygen, pH, inorganic nitrogen, and phosphorus were vertically stratified with severe hypolimnetic oxygen depletion. During the second summer, when pumped storage was in operation, more homogenous vertical profiles, generally higher oxygen, and lower dissolved nutrient concentrations were observed. These pumped storage effects were observed at all stations, rather than being confined to the immediate vicinity of the dam.  相似文献   

15.
ABSTRACT .A summary is presented of remarks made at a conference held at Louisiana Tech University on the possibility of diverting some of the Mississippi River water to Texas and New Mexico. The Texas Water Plan which has initiated the diversion possibility is discussed and particular reference is made to the activities of the federal and state agencies directly responsible for determining various aspects of the diversion study. These agencies include the Texas Water Development Board, Texas Water Quality Board, Louisiana Department of Public Works, State Engineer's Office of New Mexico, Mississippi River Commission, and the Bureau of Reclamation.  相似文献   

16.
ABSTRACT: Human induced long-term changes in precipitation and stream chemistry have been observed in eastern North America and Europe, but few long-term studies have been conducted in coastal western North America. The objectives of this research were to determine: (1) time trends in precipitation and stream chemistry in a pristine old-growth forest watershed, and (2) seasonal patterns in precipitation and stream chemistry. It was conducted in 58 ha West Twin Creek Watershed, Hoh River Valley, Olympic National Park, Washington from 1984 to 1993. Vegetation consists of old-growth forest, with western hemlock, Douglas-fir, western redcedar, Pacific silver fir, and Sitka spruce being the dominant tree species. Annual precipitation varied from 2336 to 4518 mm during the study period with the majority of the rain falling between October and May. Chemistry of precipitation was strongly dominated by oceanic influences with Na and Cl being the dominant ions. The chemistry of the stream was influenced by bedrock weathering and was dominated by Ca, HCO3, and SO4 and was not strongly related to precipitation chemistry. The pH of precipitation averaged 5.3 over time and ranged from 4.3 to 7.1, while the stream pH averaged 7.5 and ranged from 5.5 to 9.0. There were few long-term trends in the chemical constituents of bulk precipitation or stream water with the exception of a slight decrease in NO3 in precipitation and an increase of SO4 in stream water. A trend of decreasing concentrations of Ca, Mg and Na in precipitation also occurred. There were no significant seasonal patterns in precipitation although the highest SO4 concentrations usually occurred in late spring and summer perhaps due marine algal activity. Strong seasonal trends occurred in concentrations of HCO3, SO4, Ca, Mg, and Na in stream water resulting from weathering and stream flow patterns, with highest ion concentrations occurring just before the onset of the rainy season. Pulses of NO3 in the stream were observed during fall and early winter resulting from the release of NO3 which had accumulated in soils or sediments.  相似文献   

17.
ABSTRACT: Data from three ice-covered stations in Lake St. Clair were collected to evaluate the effect of ice and related variables on phytoplankton production. Primary production, phytoplankton standing crop, irradiation and temperature were measured from January to April, 1973. Mean production values ranged from 0.74 mgC/m3/h at station 1 near Mitchell Bay to 3.4 mgC/m3/h in waters at stations 2 and 3 below the Thames River mouth. A similar pattern was observed in chlorophyll a concentration, the mean values ranged from 0.63 μg/1 at station 1 to 2.1 and 1.3 μg/1 at stations 2 and 3. Temperature stratification occurred at the three stations. However, the temperatures at station 1 were consistently more than a degree warmer than at the other two stations. Irradiation was low, having a mean value at the sampling depth of .075 ly/min. The data is interpreted to indicate that the ice-bound phytoplankton were adapted to the low irradiation. It is suggested that the variation observed between stations is related to the formation of a plume by the Thames River and differences in nutrient loads carried by the St. Clair and Thames Rivers.  相似文献   

18.
ABSTRACT: The spatial changes in abiotic and biotic variables from riverine to lacustrine areas characterized by the river-lake concept of reservoir function was applied to the Tomhannock Reservoir, Rensselaer County, New York. To identify these longitudinal gradients, a two-year investigation (May 1991 to October 1992) was conducted to measure primary productivity, nutrient concentrations, chlorophyll α and phytoplankton biomass at three locations in the 705-ha water supply reservoir. Emphasis was placed on the measurement of primary production using the carbon-14 artificial incubator (photosynthetron) technique. The average annual production in 1992 was 247.3 gm?2 245 d?1, ranging from 52 to 2677 mg C m?2. Mean alphaB (assimilation efficiency), PBm (assimilation number), and Ik (saturation irradiance) were 4.40 mg C mgChl?1 E?1 m?2, 3.82 mg C mgChl?1 h?1, and 236.5 μE m?2 s?1, respectively. Neither seasonal nor spatial variability of these photosynethetic parameters were observed. Except for Secchi depth, distinct longitudinal zones from river inflow to darn were not statistically demonstrated in the Tomhannock Reservoir. Mean extinction coefficient, chlorophyll α and total phosphorus concentrations decreased; Secchi transparency and phytoplankton biomass increased; while primary productivity and dissolved inorganic nitrogen concentration remained the same from headwater to darn. These baseline data will be used to assess the future effectiveness of best management practices (BMPs) recently instituted on selected watershed farmland in an attempt to reduce the detrimental impact of agricultural activities on drinking water quality.  相似文献   

19.
ABSTRACT: A geographic information system (GIS) was used to determine the relation between the stream-water quality and underlying geology in Roberts Creek watershed, Clayton County, Iowa, for base-flow conditions during the spring and summer of 1988–90. Geologic, stream, basin and subbasin boundaries, and water-quality sampling-site coverages were created by digitizing available maps. A contour coverage was created from digital line-graph data. The areal extent of geologic units subcropping in each subbasin was quantified with GIS, and the results then were output and joined with the discharge and water-quality data for statistical analyses. Illustrations showing the geology of the study area and the results of the study were prepared using GIS. By using GIS and a statistical software package, a weak but statistically significant relation was found between the water temperature, pH, and nitrogen concentrations in Roberts Creek and the underlying geology during base-flow conditions.  相似文献   

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