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101.
Scott W. Bailey James W. Hornbeck C. Wayne Martin Donald C. Buso 《Environmental management》1987,11(1):53-60
The streams tributary to acidic Cone Pond, pH 4.5–4.8, and circumneutral Black Pond, pH 5.3–6.4, in the White Mountains of New Hampshire, USA, were monitored for a year. The watersheds of these two ponds were characterized in terms of geology and stream hydrology. Chemical gradients and patterns in rock weathering and groundwater discharge explain many of the differences in mineral content and acidity of the streams. The rocks of Black watershed produced an average of ten times the equivalent of basic cations as rocks from Cone watershed. This is on the same order as the difference in acidity of the two streams. Down-stream changes in stream chemistry follow differing patterns, but reflect the same principle of residence time and water path length controlling chemical evolution of streamwater. Watershed and aquatic managers may use these parameters in an inexpensive and simple assessment of the susceptibility of individual streams and ponds to acidification. A method is recommended to determine quickly the potential influence of bedrock type to aquatic chemistry. 相似文献
102.
Donald C. Rundquist Merlin P. Lawson Lloyd P. Queen Randall S. Cerveny 《Journal of the American Water Resources Association》1987,23(3):493-508
ABSTRACT: Research is presented that statistically analyzes the relationship between lake area and precipitation. These hydrologic variables are assessed in part using LANDSAT MSS satellite data and digital-image processing techniques. Results show dramatic regional hydrologic differences in lake area fluctuations and in lake area response to short term climatic variation. 相似文献
103.
L. Wojtiw 《Journal of the American Water Resources Association》1987,23(5):849-855
ABSTRACT: Rainstorms which exceed the design capacity of conveyance systems and cause extensive damage to structures and property, occur frequently in Alberta. After such a severe storm, an early and quick assessment of the storm's location and magnitude and the corresponding frequency for various duration (storm intensity-duration curve) is often required to estimate the damage. The storm intensity-duration curve is produced with information obtained from a sparse network of recording raingages, thus, creating a high degree of uncertainty in the result. Short-duration precipitation is usually quite variable in Alberta; hencea very dense network of recording precipitation stations would be required to provide precise measurements of the storm intensity-duration curve at all locations. Such a dense network does not exist in Alberta; it would be very expensive to install, maintain, and thus difficult to justify financially. One solution for obtaining a large amount of closely spaced in-intensity-duration values is to use weather radar. Using weather radar data, intensity-duration curves could be produced routinely for any set of prespecified locations. The radar data thus have the potential for facilitating the identification of the return period of rainfall events quickly, cheaply, and precisely when the long-term intensity-duration curves are available. As a pilot project to demonstrate the feasibility of the method and the potential of the radar data, computer software was developed to derive from archived radar data, intensity-duration values for up to a 2,500 2 area for a given storm. 相似文献
104.
105.
Development of Stream Water Chemistry during Spring Melt in a Northern Hardwood Forest 总被引:1,自引:0,他引:1
Semkin R. G. Hazlett P. W. Beall F. D. Jeffries D. S. 《Water, Air, & Soil Pollution: Focus》2002,2(1):37-61
The role of snowmelt and subsurface hydrology in determiningthe chemistry of a small headwater stream in the TurkeyLakes Watershed (TLW) was evaluated for the spring meltperiods 1992 to 1996. Spring runoff is the dominanthydrological event at the TLW each year. Processesoccurring within the snowpack during snowmelt wereprincipally responsible for the above-ground changes inchemical fluxes relative to bulk deposition (the effect ofwinter throughfall was minimal). Large changes in chemicalfluxes occurred below ground. Organic matter decomposition,weathering, nitrification, and element cycling are some ofthe more important below-ground processes that operateduring the snow accumulation and ablation season and controlthe composition of the water ultimately appearing in thestream. Maximum stream discharge was accompanied byelevated concentrations of H+, NO3
-, K+,NH4
+, DOC, Al and Mn, but reduced levels ofCa2+, Mg2+, SO4
2- and SiO2. Theconcentration-discharge relationships were consistent withwater movement through and above the forest floor duringpeak discharge, a flowpath facilitated by rapid infiltrationof meltwater and the existence of a relatively impermeablelayer in the mineral soil creating a perched water table. Averaged over the five periods of snow accumulation andablation, it was estimated that pre-melt stream flow, andwater routed through the forest floor and through the uppermineral soil contributed 9, 28 and 63%, respectively, ofthe discharge measured at the outlet of the catchment. Theforest floor contribution would be greater at peak dischargeand at higher elevations. An end-member mixing modelestimated concentrations of SO4
2-, NO3
-,Cl-, Ca2+, Mg2+, Na+ and Al that werecomparable to average values measured in the stream. Othervariables (NH4
+, H+, K+ and DOC) wereover-estimated implying retention mechanisms operatingoutside the model assumptions. 相似文献
106.
Mary H. Nichols Kenneth G. Renard Herbert B. Osborn 《Journal of the American Water Resources Association》2002,38(1):161-172
ABSTRACT: The climate of Southern Arizona is dominated by summer precipitation, which accounts for over 60 percent of the annual total. Summer and non‐summer precipitation data from the USDA‐ARS Walnut Gulch Experimental Watershed are analyzed to identify trends in precipitation characteristics from 1956 to 1996. During this period, annual precipitation increased. The annual precipitation increase can be attributed to an increase in precipitation during non‐summer months, and is paralleled by an increase in the proportion of annual precipitation contributed during non‐summer months. This finding is consistent with previously reported increases in non‐summer precipitation in the southwestern United States. Detailed event data were analyzed to provide insight into the characteristics of precipitation events during this time period. Precipitation event data were characterized based on the number of events, event precipitation amount, 30‐minute event intensity, and event duration. The trend in non‐summer precipitation appears to be a result of increased event frequency since the number of events increased during nonsummer months, although the average amount per event, average event intensity, and average event duration did not. During the summer “monsoon” season, the frequency of recorded precipitation events increased but the average precipitation amount per event decreased. Knowledge of precipitation trends and the characteristics of events that make up a precipitation time series is a critical first step in understanding and managing water resources in semiarid ecosystems. 相似文献
107.
The objective of this research was to analyze the retention of acid precipitation as a viable policy issue on the Congressional
agenda during the 1980s. Issue maintenance (a term borrowed from Barbara Nelson's discussion of the four stages associated
with agenda decision making) was examined in relation to a set of issue characteristics originally developed by Roger Cobb
and Charles Elder, i.e., concreteness, social significance, temporal relevance, complexity, and categorical precedence. Each
issue attribute was found to be somewhat useful in explaining the longevity of acid rain as an agenda item although the direction
of influence for two factors, complexity and temporal relevance, was contrary to expectations. It was suggested that a conceptual
merger of this sort could contribute to the comparative analysis of agenda policy decisions by providing a clearer and more
restricted set of decision points to be explained. 相似文献
108.
John T. Riedel 《Journal of the American Water Resources Association》1970,6(3):439-451
To aid in planning and design of additional flood protection on the Lower Rio Grande, the Hydroraeteorological Branch prepared a probable maximum precipitation study for the International Boundary and Water Commission (United States and Mexico) and the Republic of Mexico. Five drainages from 2,000 to over 17,000 square miles in area between Falcon and Anzalduas Dams including Rio San Juan and Rio Alamo in Mexico are the areas of concern. The great rains of hurricane Beulah, September 19–24, 1967 verified that additional protection is needed. Procedures for estimating probable maximum precipitation (PMP) are described. A particular problem was to estimate rainfall potential for the Sierra Madre Oriental in Rio San Juan and Alamo drainages. These mountains form a north-south windward-facing slope and barrier of over 7000 feet in elevation. A detailed study was made of rains from hurricane Beulah. The storm produced the greatest known rain depths in North America for 50,000 square miles or greater, and durations longer than 48 hours. 相似文献
109.
Donald R. Haragan Kenneth H. Jehn 《Journal of the American Water Resources Association》1970,6(6):893-906
A study of the relationship among cloudiness, precipitable water vapor, stability and precipitation is presented for the Texas High Plains. A study of clouds during periods of above-normal rainfall indicates that precipitation during late fall and winter is associated with stratiform clouds which develop in conjunction with cyclonic activity. Spring and summer precipitation is most highly correlated with cumuliform clouds characteristic of convective activity. Investigation of other macroscale atmospheric features indicates that wet periods are further characterized by atmospheric instability and above-normal amounts of precipitable water vapor and water-vapor flux. Dry periods are associated with atmospheric circulation patterns which either serve to cut off the supply of low-level moisture, produce subsidence and consequent atmospheric stability, or both. 相似文献
110.