ADAPTATION OF FLOOD PEAKS AND DESIGN HYDROGRAPHS FROM GAGED TO NEARBY UNGAGED WATERSHEDS1

ABSTRACT: Equations were developed to transform peak flows and to adapt design hydrographs and unit hydrographs from gaged watersheds to ungaged watersheds with similar hydrologic characteristics. Dimensional analysis was used to develop adjustment equations for peak flow and time base, and these equations were reinforced with results from regional flood frequency research. The authors believe that the use of these transformation equations should yield more reliable flood peak values and hydrogrphs than the common use of empirical flood estimating curves or equations.     

FRICTION SLOPE MODELS FOR M2 PROFILES1

ABSTRACT: Results of studies which have considered the relative merit of various friction slope averaging equations previously used in water surface profile computations are described. Limitations of the most accurate equation known for the M2 profile have indicated that a new equation which gives more emphasis to the upstream energy gradient is desirable. Based upon friction slope curves developed for M2 water surface profiles two new equations, one a parabolic and the other an elliptical approximation, are presented. The behavior of the new equations and of the previously most recommended equation is described by test calculations. The elliptical equation performed more satisfactorily than the harmonic method commonly recommended for M2 profile computations. Insertion of an additional cross-section about 50 feet upstream from a critical depth section was found to reduce computational errors for any energy gradient averaging method.     

A BIO ASSAY LABORATORY BOAT WITH COMPARISONS OF CENTRAL VS. BOAT LABORATORY BIOASSAY EVALUATIONS1

ABSTRACT: A laboratory boat designed to investigate toxic effects on site and its use as a bioassay tool in the study of a refinery effluent discharged into the Schuylkill River, a tributary of the Delaware River, is described. Three-hundred thirty-six-hour continuous-flow bioassay s exposing the bluegill sunfish, the channel catfish, the tadpole snail, the grass shrimp, and the sheephead minnow to concentrations of refinery effluent in Schuylkill, Delaware River, and Delaware Bay water, with and without the addition of sediment were performed. Results indicated that the toxicity (lethality) of fresh samples tested aboard the boat (refinery effluent, dilution water, sediment) were considerably higher (i.e., refinery effluent at full strength was 2.2X as lethal to the bluegill, 1.4X as lethal to the channel catfish, 1.5X as lethal to the sheep-head minnow and 100X as lethal to the grass shrimp) than the same test material collected from the refinery outfall and brought to a central laboratory for testing. Chemical analysis and bioassay data is presented showing the effects of aging and irradiation upon the refinery effluent.     

CALIBRATION OF SNYDER COEFFICIENTS FOR PENNSYLVANIA1

ABSTRACT Unit hydrograph theory is one of the most widely used techniques to predict surface runoff. The present study is concerned with the Snyder unit hydrograph and the calibration of the Snyder coefficients for Pennsylvania. Twenty-seven study basins were selected, located randomly across the state. With the rainfall and runoff recorded for several events for each basin (more than 500 events were analyzed) unit hydrographs were calculated and the Snyder coefficients determined. A map of the coefficients was drawn to illustrate the variability in the coefficients and two equations using multiple regression theory were developed. The unexplained variability of the coefficients suggests that upper and lower bounds on the peak flow might be placed on storm hydrographs developed for ungaged watersheds.     

Tourism and town planning in Catalonia

The coastal tourist areas of Spain have seen open conflict between planners and the public over the flood of tourist developments. The Costa Brava in the region of Catalonia is chosen for the purpose of this study which looks at the effects of the Land Use law of 1976 requiring all municipalities to prepare General Plans. The failure of plans which attempted to severely restrict tourist growth, and this paper's conclusions, that the expansion of tourist pressure into new areas may create new conditions, suggest a regional approach to policy.     

EVALUATION OF PHILODINA ACUTICORNIS (ROTIFERA) AS A BIOASSAY ORGANISM FOR HEAVY METALS1

ABSTRACT: A technique for using the rotifer Philodina acuticornis as a bioassay organism is described. The rotifer was exposed to a range of concentrations for each of 14 toxicants. The effects of the heavy metals cadmium, chromium, cobalt, copper, lead, mercury, nickel, silver and zinc were studied. Based upon 96 hours exposure in soft water the sensitivity of the rotifer to the metals from the most toxic to least toxic was: cadmium, mercury and copper, zinc, silver, nickel (chloride), chromium, nickel (sulfate), lead and colbalt. In hard water with 96 hours exposure the most to least toxic respectively were: cadmium, copper, mercury, chromium and lead. The 48 hour EC₅₀ value suggests that zinc will follow mercury in relative toxicity when Philodina is tested in hard water. In a comparison of the toxicity of the chloride and sulfate salts of cadmium, nickel and zinc in soft water cadmium sulfate and zinc sulfate were more toxic after 96 hours; nickelous chloride was more toxic than nickelous sulfate. Increased water hardness decreased the toxicity of the heavy metals studied. The results suggest that this rotifer may be more sensitive than the bluegill sunfish to the salts of cadmium, copper, nickel, zinc and chromium and less sensitive to lead. Data for cobalt, silver and mercury were not available. Philodina was extremely tolerant of ammonium chloride and phenol. The feasibility and economics of using an inexpensive, readily cultured and available organism such as Philodina acuticornis as a bioassay organism were discussed.     

Implementing CITES regulations for timber.

Foresters are currently confronted with a new challenge. For the first time a commonly traded timber species has been listed on the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). At the 12th Conference of the Parties in November 2002, countries voted 68 to 30 to place the premier timber species of Latin America, big-leaf mahogany (Swietenia macrophylla King [Meliaceae]), on CITES Appendix II. Under Appendix II regulations, trade in mahogany requires that exporting countries verify that each shipment was legally obtained and that its harvest was non-detrimental to the survival of the species. Unfortunately, implementation has been weak, in part because countries have yet to develop a common, pragmatic, cost-effective system to make the legal and non-detriment findings. This paper recommends what such a system might include.