SOME GEOMORPHIC RELATIONSHIPS AND HYDROGRAPH ANALYSIS1

ABSTRACT: First order drainage channels originate when the tractive force exerted by flowing water is sufficient to move surface sediment. The amount of runoff available to move sediment is a function of geologic and climatic characteristics. An experimental analysis showed that soils derived from fine grained rocks had lower infiltration rates and higher runoff volume than soils derived from coarser grained rocks in a semi-arid climate. Root density and penetration increased in a more humid climate and increased infiltration rates. The number of first order channels was inversely proportional to the infiltration capacity of the soil. Each first order channel acts as a source area for surface runoff. The distribution of first order channel distances from the gage determines the timing of the delivery of water to the gage. A comparison of the frequency histogram of first order channel distances for drainage basins in Pennsylvania and their hydxographs of runoff from general storms showed marked similarity. This close correspondence indicated the shape of the surface runoff hydrograph and was largely controlled by the distribution of first order channel distances.     

Water quality management worldwide

This article analyzes water quality on a global scale. An overview of the global water supply and demand situation is presented first, including regional and country information, as well as data on selected water use patterns. The focus then shifts to a discussion of water pollution, its various causes, impact, and remedies, with emphasis on legal and administrative solutions. Water pollution control expenditures and the resultant achievements are dealt with in the final third of the article, with projections to 1995. A wide variety of published sources was dovetailed to obtain a composite picture and most likely scenario; this was supplemented with primary interviews by the author conducted in North America, Western and Eastern Europe, and Oceania at the start of the 1980s.     

Economic Analysis of Selected Offshore Petroleum Arrangements

As a result of the current decline of oil prices, exploration decisions are more carefully analysed than ever before. At the same time various governments have introduced incentives to reinvest in exploration and development in order to maintain or increase activity. As a result, most exploration decisions are now being analysed as "incremental investments". This has the effect of "trapping" investments in areas where profits are currently being made. This in turn creates serious problems for those developing countries which would like to attract exploration. The paper analyses issues related to sliding scale formulae based on the ROR, and the economic impact of the size of the area to which fiscal terms apply.     

SHORT-TERM FORECASTING OF SNOWMELT RUNOFF USING ARMAX MODELS1

ABSTRACT: Time series models of the ARMAX class were investigated for use in forecasting daily riverflow resulting from combined snowmelt/rainfall. The Snowmelt Runoff Model (Martinec-Rango Model) is shown to have a form similar to the ARMAX model. The advantage of the ARMAX approach is that analytical model identification and parameter estimation techniques are available. In addition, previous forecast errors can be included to improve forecasts and confidence limits can be estimated for the forecasts. Diagnostic checks are available to determine if the model is performing properly. Finally, Kalman filtering can be used to allow the model parameters to vary continuously to reflect changing basin runoff conditions. The above advantages result in improved flow forecasts with fewer model parameters.     

RELATIONSHIP BETWEEN ANNUAL RUNOFF AND WATERSHED AREA FOR THE EASTERN UNITED STATES1

ABSTRACT: As part of the U.S. Environmental Protection Agency's effort to determine the long-term effects of acidic deposition on surface water chemistry, annual runoff was estimated for about 1000 ungaged sites in the eastern U.S. using runoff contour maps. One concern in using contour maps was that a bias may be introduced in the runoff estimates due to the size of the 1000 ungaged sites relative to the size of the watersheds used in developing the maps. To determine if a bias was present the relationship between the annual runoff (expressed as depth) and the watershed area for the Northeast (NE) and Southern Blue Ridge Province (SBRP) was tested using five regional data bases. One short-term data base (1984 Water Year, n = 531) and two long-term data bases (1940–57, n = 134 and 1951–80, n = 342) were used in the NE. In the SBRP one short-term database (1984 Water Year, n = 531) and one long-term data base (1951–80, n = 60) were used. For the NE and the SBRP, runoff was not directly correlated with watershed area using the five regional databases. Also, runoff normalized by precipitation was not related to watershed area.     

A TAU-LIKE TEST FOR TREND IN THE PRESENCE OF MULTIPLE CENSORING POINTS1

ABSTRACT: A common problem arises in testing for trends in water quality when observations are reported as “less than detection limit.” If a single detection limit is used for the entire study, existing non-parametric statistical methods, modified for ties, are applicable. If, however, the detection limit varies during the course of the study, resulting in multiple detection limits, then the commonly used trend detection methods are not appropriate. A statistic similar to Kendall's tau, but based on expected ranks, is proposed. Monte Carlo simulations show that the normal approximation to the distribution of this statistic is quite good, even for small samples and a large proportion of censored observations. The statistic is also shown to have greater power than the ad-hoc method of treating all observations less than the target censored observation as tied.     

Structure-biodegradation relationships of polymeric materials. 1. Effect of degree of oxidation on biodegradability of carbohydrate polymers

The biodegradability of oxidized starch and inulin has been studied in relation to the degree of periodate oxidation to dialdehyde derivatives, by measuring oxygen consumption and mineralization to carbon dioxide. A higher degree of oxidation of dialdehyde starch and dialdchyde inulin results in a lower rate at which the polymers are biodegraded. It is demonstrated that the biodegradation rate of dialdehyde inulin derivatives decreases more than that of equivalent starch derivatives. The differences in biodegradation behavior between dialdehyde starch and dialdehyde inulin, resulting from comparable modifications, are discussed in terms of conformational structure.     

Nautical safety and efficiency: simulation and reality

The paper deals with training and research using maritime simulation techniques to provide cost-effective and safe solutions to maritime transportation problems. In order to reduce the probability of accidents, training and research is required in which the human factors are fully taken into account.     

The new regime for managing US—Mexican water resources

United States-Mexican transboundary water resources management is presently experiencing significant reform resulting from long-term demographic processes in the border region and greater economic integration. The recently concluded North American Free Trade Agreement and supplementary environmental accord modify existing agreements and provide old institution with new mandates. Particularly affected is the International Boundary and Water Commission (IBWC), long the lead agency in binational water management. This essay reviews the development of the new water management regime against the two preceding phases of management reform and considers its implications for improved water management in the border region.