MODELED IMPACTS OF DEVELOPMENT TYPE ON RUNOFF VOLUME AND INFILTRATION PERFORMANCE1

ABSTRACT: Development type has emerged as an important focal point for addressing a wide range of social, cultural, and environmental concerns related to urban growth. Low impact development techniques that rely heavily on infiltration practices are increasingly being used to manage storm water. In this study, four development types (conventional curvilinear, urban cluster, coving, and new urbanism) were modeled both with and without infiltration practices to determine their relative effects on urban runoff. Modeling was performed with a modified version of the Natural Resources Conservation Service (NRCS) runoff method that enables evaluation of infiltration practices. Model results indicate that urban cluster developments produce the smallest volume of runoff due to the large portion of land kept in a natural condition. Infiltration practices are most effective for small storms and in developments with Hydrologic Group A soils. Significant reductions in runoff can be achieved in all four development types if infiltration practices treat many impervious surfaces. As more infiltration practices are implemented, the differences in runoff among development types diminish. With a strategic combination of site layout and infiltration design, any development type can reduce hydrologic impacts, allowing developers to consider other factors, such as convenience, marketability, community needs, and aesthetics.     

FORPLAN: A FORest Planning LANguage and Simulator

A Forest Planning Language and Simulator (FORPLAN) has been developed to facilitate the use of simulation for integrating fire into the land management planning process.FORPLAN incorporates unique characteristics of previous systems, links numerous models and data bases, allows selection of variable resolution levels, and permits discrete time simulation of disturbances on plants, fuels, and animals. No previous computer experience is required of the user, sinceFORPLAN recognizes simple English words and phrases.     

IMPACT OF NONCHLORINATED SECONDARY AND TERTIARY EFFLUENTS ON WARM WATER FISH COMMUNITIES1

ABSTRACT: The fish communities in three sewage receiving Illinois streams were monitored by electrofishing as treatment changed from secondary with chlorination to secondary without chlorination to tertiary without chlorination over a 40-month period. Degradation of the fish communities was severe during the secondary treatment/chlorination period. When treatment was changed to secondary without chlorination, strong improvements occurred in the fish communities of all streams, and degradation could no longer be demonstrated on the basis of species number. The onset of tertiary treatment resulted in few additional changes in the fish communities, with the possible exception of increased abundance of several species of minnows. Tertiary treatment consisted of nitrification, sand filtration, and, in two streams, phosphorus removal.     

INTERACTIONS BETWEEN LAND USE AND URBAN WATER RESOURCES PLANNING1

ABSTRACT The patterns of land use and their relationship to urban water resources are examined from the point of view of population growth, consumer behavior, and preferences of price, income, and land use controls. The changes that need to be made in present social attitudes or water resources laws to satisfy the desired new developments are examined. Several implementation methods that are feasible and effective for changing urban development patterns are considered as well as models for assessing alternate development plans. The needs for research are outlined.     

The fish fauna of a seasonally closed Australian estuary. Is the prevalence of estuarine-spawning species high?

The fish at sites located throughout the large, seasonally closed Wilson Inlet, on the southern coast of Western Australia, were sampled bimonthly between September 1987 and April 1989. Seine nets were used to sample nearshore shallow waters, while gill nets were employed in slightly more offshore and deeper waters. Twenty species were recorded in the shallows, of which the three species of atherinid and the three species of goby comprised >97% of the total catch. In terms of number of individuals, the 27 species recorded in gill nets in the deeper waters were dominated by Cnidoglanis macrocephalus and Platycephalus speculator, and to a lesser extent Engraulis australis, Aldrichetta forsteri, Sillaginodes punctata and Arripis georgianus. Fifty-five percent of the species recorded in the nearshore shallow waters and 18% of those in offshore deeper waters spawn within Wilson Inlet; these species contributed 98.5 and 63.0%, respectively, to the total catches in those waters. Classification and ordination showed that the composition of the fauna in the shallows was similar at all sites throughout the large basin and did not change conspicuously with season. However, the composition of catches taken in offshore waters differed between the lower part of the basin and the middle and upper regions of the basin, which in turn differed from those in the saline reaches of a tributary river. The four diagnostic species of the lower estuary were all marine species, while the three diagnostic species in the river included a marine species (Mugil cephalus) that often penetrates far upstream in other systems, and a species which was confined to the rivers (Acanthopagrus butcheri). The composition of the fish fauna in the offshore waters of the lower estuary between the middle of spring and middle of autumn was different in 1987/1988 (when the estuary mouth was open for only the first two months of that period) from that in 1988/1989 (when the mouth was open for the whole of that period). This difference is related to the greater number of marine species that were retained in the first of these years, when the estuary was open to the ocean for only a short period. The greater retention of marine species in 1987/1988 than in 1988/1989 probably reflects a far lower level of freshwater flusing and/or a less marked decline in salinity.     

Interactions between two species of marine diatoms: Effects on their individual copper tolerance

The purpose of this study was to examine the effect of the interaction of two species of marine diatoms,Skeletonema costatum (Cleve) Greville andNitzschia thermalis (Ehrenberg) Auerswald, on their individual copper tolerances. The two species, obtained from stock cultures in 1989, were grown together at three copper concentrations (1, 4 and 5 × 10^–7 M added total copper). In the unialgal cultures that were used as controls, the two species grew as predicted from their tolerance tests. However, in mixed cultures,N. thermalis was the only species that exhibited growth, regardless of the copper concentration in the medium. Growth retardation ofS. costatum in the presence ofN. thermalis was attributed to an inhibitory exudate. The effect of the exudate appeared to have been temporary, as demonstrated by the extended lag phase and subsequent satisfactory exponential growth rate ofS. costatum. It is suggested that the exudate degraded within a period of 5 d (=lag phase) because exponential growth rate was resumed. It thus appears that the interaction between the two diatom species is more important in determining the survival ofS. costatum than its individual copper tolerance. This is not the case forN. thermalis. Such interactions would be unaccounted for in single-species toxicity tests. On the other hand, if they are known, prediction of how a community that includes these two species would respond to copper additions becomes possible.