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81.
Huw Thomas 《Journal of Environmental Planning and Management》1985,28(2):55-59
This article examines the potential contribution of analytical philosophy to planning theory. In contrast to some recent discussions it takes as its starting point town planning as actually practised, and recognises the ideological framework within which, for the most part, twentieth century analytical philosophy has been conducted. It concludes that knowledge of philosophy may be of some limited use to the planning theorist. 相似文献
82.
The concern of this paper is with the spatial consequences of development in a given rural setting and the way in which physical planning fits into the revival of a dying rural area, particularly in Third World Countries. It is based on experience derived from Dekinal in Benue State, Nigeria and endeavours to define a rural area by briefly discussing its characteristics and highlighting its problems. It proposes a comprehensive development planning process to induce development based on available resources. 相似文献
83.
William Heasom Robert G. Traver Andrea Welker 《Journal of the American Water Resources Association》2006,42(5):1329-1347
ABSTRACT: The goal of this research was to develop a methodology for modeling a bioinfiltration best management practice (BMP) built in a dormitory area on the campus of Villanova University in Pennsylvania. The objectives were to quantify the behavior of the BMP through the different seasons and rainfall events; better understand the physical processes governing the system's behavior; and develop design criteria. The BMP was constructed in 2001 by excavating within an existing traffic island, backfilling with a sand/soil mixture, and planting with salt tolerant grasses and shrubs native to the Atlantic shore. It receives runoff from the asphalt (0.26 hectare) and turf (0.27 hectare) surfaces of the watershed. Monitoring supported by the hydrologic model shows that the facility infiltrates a significant fraction of the annual precipitation, substantially reducing the delivery of nonpoint source pollution and erosive surges downstream. A hydrologic model was developed using HEC‐HMS to represent the site and the BMP using Green‐Ampt and kinematic wave methods. Instruments allow comparison of the modeled and measured water budget parameters. The model, incorporating seasonally variable parameters, predicts the volumes infiltrated and bypassed by the BMP, confirming the applicability of the selected methods for the analysis of bioinfiltration BMPs. 相似文献
84.
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
85.
Frank J. Triska John H. Duff Richard W. Sheibley Alan P. Jackman Ronald J. Avanzino 《Journal of the American Water Resources Association》2007,43(1):60-71
Abstract: Dissolved inorganic nitrogen (DIN) retention‐transport through a headwater catchment was synthesized from studies encompassing four distinct hydrologic zones of the Shingobee River Headwaters near the origin of the Mississippi River. The hydrologic zones included: (1) hillslope ground water (ridge to bankside riparian); (2) alluvial riparian ground water; (3) ground water discharged through subchannel sediments (hyporheic zone); and (4) channel surface water. During subsurface hillslope transport through Zone 1, DIN, primarily nitrate, decreased from ~3 mg‐N/l to <0.1 mg‐N/l. Ambient seasonal nitrate:chloride ratios in hillslope flow paths indicated both dilution and biotic processing caused nitrate loss. Biologically available organic carbon controlled biotic nitrate retention during hillslope transport. In the alluvial riparian zone (Zone 2) biologically available organic carbon controlled nitrate depletion although processing of both ambient and amended nitrate was faster during the summer than winter. In the hyporheic zone (Zone 3) and stream surface water (Zone 4) DIN retention was primarily controlled by temperature. Perfusion core studies using hyporheic sediment indicated sufficient organic carbon in bed sediments to retain ground water DIN via coupled nitrification‐denitrification. Numerical simulations of seasonal hyporheic sediment nitrification‐denitrification rates from perfusion cores adequately predicted surface water ammonium but not nitrate when compared to 5 years of monthly field data (1989‐93). Mass balance studies in stream surface water indicated proportionally higher summer than winter N retention. Watershed DIN retention was effective during summer under the current land use of intermittently grazed pasture. However, more intensive land use such as row crop agriculture would decrease nitrate retention efficiency and increase loads to surface water. Understanding DIN retention capacity throughout the system, including special channel features such as sloughs, wetlands and floodplains that provide surface water‐ground water connectivity, will be required to develop effective nitrate management strategies. 相似文献
86.
Xiaoying Yang Benedykt Dziegielewski 《Journal of the American Water Resources Association》2007,43(1):160-169
Abstract: Thermoelectric power generation is responsible for the largest annual volume of water withdrawals in the United States although it is only a distant third after irrigation and industrial sectors in consumptive use. The substantial water withdrawals by thermoelectric power plants can have significant impacts on local surface and ground water sources, especially in arid regions. However, there are few studies of the determinants of water use in thermoelectric generation. Analysis of thermoelectric water use data in existing steam thermoelectric power plants shows that there is wide variability in unitary thermoelectric water use (in cubic decimeters per 1 kWh) within and among different types of cooling systems. Multiple‐regression models of unit thermoelectric water use were developed to identify significant determinants of unit thermoelectric water use. The high variability of unit usage rates indicates that there is a significant potential for water conservation in existing thermoelectric power plants. 相似文献
87.
Warren A. Gebert Mandy J. Radloff Ellen J. Considine James L. Kennedy 《Journal of the American Water Resources Association》2007,43(1):220-236
Abstract: The average annual base flow/recharge was determined for streamflow‐gaging stations throughout Wisconsin by base‐flow separation. A map of the State was prepared that shows the average annual base flow for the period 1970‐99 for watersheds at 118 gaging stations. Trend analysis was performed on 22 of the 118 streamflow‐gaging stations that had long‐term records, unregulated flow, and provided aerial coverage of the State. The analysis found that a statistically significant increasing trend was occurring for watersheds where the primary land use was agriculture. Most gaging stations where the land cover was forest had no significant trend. A method to estimate the average annual base flow at ungaged sites was developed by multiple‐regression analysis using basin characteristics. The equation with the lowest standard error of estimate, 9.5%, has drainage area, soil infiltration and base flow factor as independent variables. To determine the average annual base flow for smaller watersheds, estimates were made at low‐flow partial‐record stations in 3 of the 12 major river basins in Wisconsin. Regression equations were developed for each of the three major river basins using basin characteristics. Drainage area, soil infiltration, basin storage and base‐flow factor were the independent variables in the regression equations with the lowest standard error of estimate. The standard error of estimate ranged from 17% to 52% for the three river basins. 相似文献
88.
D. G. Wallen 《Journal of the American Water Resources Association》1977,13(2):299-308
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
89.
M. Almar L. Otero C. Santos J. Gonzalez Gallego 《Journal of environmental science and health. Part. B》2013,48(6):769-783
Abstract Glutathione content and glutahione‐dependent enzymes were measured in the liver of two fish species, gudgeon (Gobio gobio) and roach (Rutilus arcasii), from the river Bernesga (Spain) caught downstream and upstream of the waste site of several chemical industries. Animals from contaminated sites display a reduced glutathione concentration and a tendency to the decrease of glutathione S‐transferase activity. Glutathione peroxidase activity was significantly elevated only in the liver of Gobio gobio and glutathione reductase activity in that of Rutilus arcasii. Our data indicate that the glutathione system constitutes a sensitive biochemical indicator of chemical pollution. Relative changes of glutathione and glutathione‐dependent enzymes in both fish species suggest a different susceptibility to toxins. 相似文献
90.
Abstract: Habitat fragmentation is a severe threat to tropical biotas, but its long‐term effects are poorly understood. We evaluated longer‐term changes in the abundance of larger (>1 kg) mammals in fragmented and intact rainforest and in riparian “corridors” in tropical Queensland, with data from 190 spotlighting surveys conducted in 1986–1987 and 2006–2007. In 1986–1987 when most fragments were already 20–50 years old, mammal assemblages differed markedly between fragmented and intact forest. Most vulnerable were lemuroid ringtail possums (Hemibelideus lemuroides), followed by Lumholtz's tree‐kangaroos (Dendrolagus lumholtzi) and Herbert River ringtail possums (Pseudocheirus herbertensis). Further changes were evident 20 years later. Mammal species richness fell significantly in fragments, and the abundances of 4 species, coppery brushtail possums (Trichosurus vulpecula johnstoni), green ringtail possums (Pseudochirops archeri), red‐legged pademelons (Thylogale stigmatica), and tree‐kangaroos, declined significantly. The most surprising finding was that the lemuroid ringtail, a strict rainforest specialist, apparently recolonized one fragment, despite a 99.98% decrease in abundance in fragments and corridors. A combination of factors, including long‐term fragmentation effects, shifts in the surrounding matrix vegetation, and recurring cyclone disturbances, appear to underlie these dynamic changes in mammal assemblages. 相似文献