Paved Areas Research Articles

Analyzing the land cover of an urban environment using high-resolution orthophotos

To estimate the impact of light-colored surfaces (roofs and pavements) and urban vegetation (trees, grass, shrubs) on meteorology and air quality of a city, it is essential to accurately characterize various urban surfaces. Of particular importance is the characterization of the area fraction of various surface-types as well as the vegetative fraction. In this paper, a method is discussed for developing data on surface-type distribution and city-fabric (land cover) makeup (percentage of various surface-types) using high-resolution orthophtos. We devised a semi-automatic Monte Carlo method to sample the data and visually identify the surface-type for each pixel. The color aerial photographs for Sacramento covered a total of about 65 km 2, at 0.3-m resolution. Five major land-use types were examined: (1) downtown and city center, (2) industrial, (3) offices, (4) commercial, and (5) residential. In downtown Sacramento, the top view (above-the-canopy) shows that vegetation covers 30% of the area, whereas roofs cover 23% and paved surfaces (roads, parking areas, and sidewalks) 41%. In the industrial areas, vegetation covers 8–14% of the area, whereas roofs cover 19–23%, and paved surfaces 29–44%. The surface-type percentages in the office area were 21% trees, 16% roofs, and 49% paved areas. In commercial areas, vegetation covers 5–20%, roofs 19–20%, paved surfaces 44–68%. Residential areas exhibit a wide range of percentages among their various surface-types. On average, vegetation covers about 36% of the area, roofs about 20%, and paved surfaces about 28%. Trees mostly shade streets, parking lots, grass, and sidewalks. In most non-residential areas, paved surfaces cover 50–70% of the under-the-canopy area. In residential areas, on average, paved surfaces cover about 35% of the area. Land-use/land cover (LULC) data from the United States Geological Survey (USGS) was used to extrapolate these results from neighborhood scales to metropolitan Sacramento. Of an area of roughly 800 km 2, defining most urban areas of the metropolitan Sacramento, about half is residential. The total roof area comprises about 150 km 2 and the total paved surfaces (roads, parking areas, sidewalks) are about 310 km 2. The total vegetated area covers about 230 km 2. The remaining 110 km 2 consist of barren land and miscellaneous surfaces.

The Prehistoric Archaeology of Norfolk Island, Southwest Pacific

VOLUME ABSTRACT. This Supplement documents the discovery, excavation and analysis of material of the Polynesian occupation of Norfolk Island about 600 years ago. The main excavation, in the dunes of Emily Bay, revealed a probable house, with some posts in place, and an adjacent paved area, which we interpret as a possible marae. Some obsidian, mostly sourced to Raoul Island, was associated with the paving. Stone artefacts, including adzes, were made of local basalt. Shell and bone tools were also found. Both stone and shell tools retained residues and usewear. The nature and morphology of the artefacts suggest New Zealand or the Kermadec Islands as the most likely source of the settlement. Faunal remains included a limited range of mammals and reptiles, along with fish, birds and shellfish. Some specialization in collection is evident in each of the three latter classes of remains. Rattus exulans is the only animal which was clearly introduced, and there is also pollen evidence for plant introductions. Detailed analysis of the radiocarbon data establishes that the settlement was occupied between early thirteenth and early fifteenth centuries A.D., although the duration of occupation many have been considerably shorter. Reasons for abandonment of the island are discussed; extreme isolation may have been important.

Sacramento’s parking lot shading ordinance: environmental and economic costs of compliance

A survey of 15 Sacramento parking lots and computer modeling were used to evaluate parking capacity and compliance with the 1983 ordinance requiring 50% shade of paved areas (PA) 15 years after development. There were 6% more parking spaces than required by ordinance, and 36% were vacant during peak use periods. Current shade was 14% with 44% of this amount provided by covered parking. Shade was projected to increase to 27% (95% CI 24–37%) when all lots in the sample were 15-year-old. Annual benefits associated with the corresponding level of tree shade were estimated to be US$ 1.8 million (CI US$ 1.5–2.6 million) annually citywide, or US$ 2.2 million less than benefits from 50% shade (CI US$ 1.4–2.5 million). The cost of replacing dying trees and addressing other health issues was US$ 1.1 million. Planting 116,000 trees needed to achieve 50% shade was estimated to cost approximately US$ 20 million. Strategies for revising parking ordinances to enhance their effectiveness are presented.

Assessing the Impact of Urban Growth on Flooding with an Integrated Curve Number-Flow Accumulation Approach

This paper presents a GIS-based analytical flooding model that integrates a widely used Curve Number method with the concepts of flow direction and flow accumulation. Simulated runoff depths and flood stage elevations for 1980 and 1992 in the Mill Creek watershed, an urban stream in Cincinnati, Ohio, USA were compared. Results show strong spatial connection between urban growth and increased runoff and flood stage elevation, which indicates that rapid urban growth, a process of expansion of urban area and conversion of farm land to paved areas, has contributed to higher risk of flooding. Therefore, strategies and policies that address flooding problems must take a watershed approach

Growth of Trees on the Virginia Tech Campus in Response to Various Factors

Soil stresses allegedly repress tree health, growth, and longevity. Such stresses commonly occur on college campuses where soil compaction can result from pedestrian and vehicular traffic. Trees on campuses, as their forest counterparts, also sustain damage from storms and biotic stress agents. We monitored an expression of stress on selected trees on sites judged to be stressful or nonstressful (control) on the Virginia Tech campus. We measured dbh (diameter at breast height) of 9 species and crown diameter of 8 species, from 1993 to 1995. Trunk growth rates differed significantly among species. Five major factors influenced growth of trees: ice damage, percentage of paved area beneath the crown, heart rot, chlorosis, and Dutch elm disease. Almost half (49%) of trees were injured physically or manifested disease or rot. We also compared growth rates of trees in 2 groups classified by percentage of paved area beneath the crown, viz. low stress versus presumed stressed sites. Annual rates of trunk growth of campus trees were higher than comparative growth rates of the same species in forests. This was the combined result of several factors, including the fact that open-grown trees, lacking competition in a forest, grow faster. Based on our results, we cannot state conclusively that site stress suppressed growth of trees on campus. Health and longevity variables were not monitored.

The Thermal Enrichment of Storm Runoff from Paved Areas - a Statistical Analysis

The thermal behaviour of storm runoff from paved surfaces was studied at two different urban catchments in order to determine the reliability of some statistic…

Evaluation of Water Quality Factors in Storm Runoff from Paved Areas

Continuous water quality measurements of storm runoff into a single road inlet have been carried out at two experimental catchments in Belgrade, Yugoslavia, and Lund, Sweden. Both sites were equipped with similar instrumentation for measurements of overland flow, turbidity, pH, conductivity, and temperature. The data were recorded at 10-s time intervals during rainfall events. To measure suspended solids concentration, turbidity meters were calibrated in conditions very similar to the real world. A detailed description of the field-measuring facilities used in the Belgrade catchment and the results of the measurements from both sites are presented. After detailed examination of possible errors in measurement, only the reliable data were used for statistical analysis. Event mean, extreme, and aggregated values were analyzed. The results indicate that the antecedent dry weather period length has only a minor upon road sediments wash-off, but it has an influence upon conductivity. The first-flush effect of suspended solids appears only in a limited number of events. Cross-correlation coefficients of rainfall, overland flow, and water quality were calculated for each event, taking into account the time lag between observed characteristics. These coefficients showed that suspended solids loading rate is influenced by rainfall intensity and overland flow rate. The results presented in this paper have been used in development of the physically based wash-off model published by Deletic and colleagues.

Contaminated Soil Management at Construction Sites

New Jersey Transit (NJT) is constructing a 34 km long dual-track Hudson-Bergen Light Rail Transit System (H-BLRTS through restoration of contaminated and abandoned sites and along the Hudson River water front in New Jersey to ease local traffic congestion and to improve the region's economy. The proposed development includes the construction of various passenger stations and park-and-ride facilities. Among many environmental issues that posed challenges during the planning and construction of the project were the appropriate remedial alternatives for the management of contaminated soil and ground water. A soil reuse plan (SRP) was proposed under which low-to-moderate level contaminated soil excavated during construction was reused on-site under paved areas and engineered structures where they would pose no risk to the public. The SRP has been successfully implemented at one of the proposed park-and-ride facilities, known as the Gateway Transit Hub, located within the H-BLRTS, in Jersey City, New Jersey.

The vital role of street design and management in reducing barriers to older peoples' mobility

Travel encompasses a much wider environment than a journey by a person in a vehicle, thus actual travel takes place within the ‘travel environment’. Travel is very complex but it can be subdivided into three broad components: the person; the vehicle; and the built environment. Travel can only be carried out if the three components are linked by means of a ‘travel chain’ and a journey cannot be made effectively if all the links are not efficiently joined. For many mobility-impaired people the ‘travel chain’ is negated by ‘built environment barriers’. Travel is interdisciplinary and only an interdisciplinary approach can reduce barriers and increase mobility. Thus this paper is interdisciplinary in its approach to a major transport problem — the ‘unfriendly street’. Accessible buses are starting to come into operation in the United Kingdom and expectations are high that the travel of older people will increase because of these buses. The authors use recent research to challenge this belief and argue that there will be little increase in travel by older people owing to present low patronage and built environment barriers. The authors then identify major barriers to travel which make streets very unfriendly and itemize 18 barriers to access which can be removed by good design. Design parameters are presented to overcome the major problem of unfriendly surfaces in paved areas and the paper concludes by reiterating that travel for older people can only be increased by an interdiscipline approach which links ‘friendly buses’ with ‘friendly streets’.

Drainage from Highways and Other Paved Areas: Methods of Collection, Disposal and Treatment

ABSTRACTDrainage of surface water from paved areas has been a fundamental part of urban planning and highway design for more than 100 years, and many aspects have changed little during this time. However, there have been recent developments in awareness of the need to treat potential pollution from paved surface runoff, as well as the need for flow attenuation and for water quality monitoring. A product of this increased awareness has been the conversion of vegetative treatment systems, traditionally designed to treat domestic and industrial wastewaters, to the treatment of paved surface runoff. The use of vegetative treatment systems for this purpose is as yet relatively untested. This paper therefore provides a brief review of the engineering methods for the collection, transport and treatment of paved surface runoff. It then goes on to describe the different types of vegetative treatment systems which are available, their value and role, and appropriate situations for their use. Finally, consideration is given to the need to monitor the efficiency of these systems in order to establish their effectiveness, and a description is given of monitoring methods which may be appropriate.

A Study of the Relationship Between Site Conditions and Urban Tree Growth

A study of 105 urban London plane (Platanus acerifolia) was undertaken between May 1990 and May 1992. One third of the 25 year old trees were in compacted gravel, one third in a paved area and one third in turf. Significant differences in tree condition were found between the three sites, as well as significant differences in soil dry bulk density, aeration (measured using steel rods), soil moisture tension and foliar essential element concentrations. Regression analysis was used to explore these relationships; spring soil aeration, summer soil moisture stress, and foliar nitrogen and potassium concentrations were found to have most influence on tree performance. Leaf colour and shoot extension were found to be the most sensitive measures of tree condition. Practical advice is given on the implications of the study on the assessment and monitoring of urban trees.

An analysis of microclimatic variation in a suburban environment

An observational and modeling study of the microclimate of a suburban area, as related to the physical and biological nature of the site, is presented. The measurements and calculations are made in comparison with a nearby open agricultural location or “control site”. The measurement program was conducted during the summer of 1981 in Davis, CA, and consisted of a series of paired observations in which simultaneous measurements were made at a control site, located in a nearby rural area, and one suburban site at a time. Results indicate that this methodology was generally successful. The various suburban sites were as often cooler than the rural site as they were warmer. In one case, a suburban site was found to be substantially cooler, averaging 7.38°C over a 5 day period, than the rural site. This special case was observed to be associated with unusually dry environmental air resulting in large evaporative cooling in the plant canopy. Comparison between the suburban temperature deficit and the physical nature of the various sites reveals that canopy height explained most of the variance of this data set. Two generally important mechanisms are hypothesized to be operating in this system: the effect of canopy size on turbulent mixing and on site shading, especially of paved areas. A simple energy balance model was applied to study the processes that control the daytime suburban temperature deficit. In particular, it is found that suburban sites can be as cool as observed when the following conditions are obtained: low-canopy humidity, large canopy size, low wind speed and high radiation load. The model simulated the overall average suburban temperature deficit of all sites for physically reasonable choices of model parameters. It is pointed out that the fact that suburban areas may be cooler than surrounding rural areas may have significance to the problem of assessing the role of the urban heat island in relation to possible global warming.

Design of geotextile reinforced paved roads and parking areas : Sellmeijer, J B Proc 4th International Conference on Geotextiles, Geomembranes and Related Products, The Hague, 28 May–1 June 1990V1, P177–182. Publ Rotterdam: A A Balkema, 1990

Design of geotextile reinforced paved roads and parking areas : Sellmeijer, J B Proc 4th International Conference on Geotextiles, Geomembranes and Related Products, The Hague, 28 May–1 June 1990V1, P177–182. Publ Rotterdam: A A Balkema, 1990

CONTRIBUTION OF PRECIPITATION TO QUALITY OF URBAN STORM RUNOFF1

SummaryPrecipitation and runoff samples were collected for 13 storms in a nonindustrial urban area in Central Pennsylvania between July 1980 and June 1981. Runoff was collected from tree surfaces, a residential roof and street, a shopping mall parking lot, a downtown business district alley, and a heavily traveled street. Analysis of the water samples showed 10 to 25 percent of the nitrogen, 25 percent of the sulfate, and less than 5 percent of the phosphorus, potassium, and calcium in water below a tree was deposited by the precipitation. The residential roof caused insignificant changes in water chemistry. The results for the four paved areas showed that all the nitrogen, and from 16 to 40 percent of the sulfate and 13, 4, and 2 percent of the phosphorus, potassium, and calcium, respectively, in runoff was deposited by the precipitation. Precipitation can also be an important source of sulfate and phosphorus in runoff. All of the surfaces raised the pH of the runoff, with the largest increases, from a pH of 4 to about 7, occurring in runoff from the paved areas. Precipitation and runoff chemistry was not related to antecedent conditions such as the length of the preceding dry period.

CW Microwave location of voids beneath paved areas : Koerner, R M; Lord, A E; Bowders, J J J Geotech Engng Div ASCE, V108, NGT1, Jan 1982, P133–144

CW Microwave location of voids beneath paved areas : Koerner, R M; Lord, A E; Bowders, J J J Geotech Engng Div ASCE, V108, NGT1, Jan 1982, P133–144

CW Microwave Location of Voids Beneath Paved Areas

The problem of locating voids beneath paved areas is a perplexing and costly one. Usually voids are investigated by test borings, which is a discontinuous hit-or-miss process. The use of a continuous nondestructive testing method is a very attractive alternative. One such method is based upon the use of continuous wave (CW) microwaves which can penetrate the upper paved material and, depending upon the nature of the underlying material (soil, air or water), will give different return reflections. Such a method is described and results based on large scale laboratory tests are presented. It is concluded that the method could be used to indicate differences between the underlying material (soil, air or water), but fell short of assessing the thickness of the air void when it was present.

A late sundial at Aphrodisias

During the excavations at Aphrodisias in Caria several ancient sundials have come to light Most are only fragmentary, but one, standing as a pedestal in a paved area of the city (the post-scaenam piazza) is substantially in one piece and of considerable interest.The dial (PLATE II) is in the form of a cylindrical pillar of marble, the upper surface of which is horizontal and stands approximately one metre above ground level. The top is slightly larger than the main body of the column because of a lip and was originally an oval of diameters 88·5 cm (east–west) and 78 cm (north–south) though the south side is broken away for perhaps one fifth of its original width. The base of the dial, 40–50 cm below pavement level, also has a similar lip, which betrays its earlier use, which was as an altar. The religious symbols have been erased—unless the crescent within a circle on its north side is one (but see below).

What Should a Playground Offer?

ethic, the concept of play as a legitimate pursuit has been difficult to accept. Many adults regard play as a frivolous waste of time, even though these same adults may go to extreme, even ludicrous, lengths to engage in leisure-time activities-the adult expression of play. As a result of the current misunderstanding of the value of children's play, the development of the playground in America has not paralleled developments in other areas of child study (1). According to Moore and Bond, Today's typical American elementary school playground is either a haphazardly planned grassy area covered with dangerously crowded unmovable structures or a small paved area bounded by permanent basketball goals (2: 21). The dangerously crowded unmovable structures to which

Vindblæs-fundet

Vindblæs-fundet

The Greek Theatre Cavea: Addenda and Corrigenda

The Olympia Stadium. A detailed publication of the German excavations at the Olympia stadium is given by E. Kunze and H. Schleif, III. Olympiabericht (in JdI 1941), 12 ff., pls. 2–5, 9–10. This shows that the Greek καθέδρα well preserved, consisted of a paved area, fenced round, on which wooden seats must have been placed at the time of the festival. This, and not the later extension, is the ‘schlichte Steinpodium’ referred to in BSA XLIII, 159, n.3.