Applicability of the flood‐pulse concept in a temperate floodplain river ecosystem: thermal and temporal components

Annual growth increments were calculated for blue catfish (Ictalurus furcatus) and flathead catfish (Pylodictis olivaris) from the lower Mississippi River (LMR) to assess hypothesized relationships between fish growth and floodplain inundation as predicted by the Flood‐Pulse Concept. Variation in catfish growth increment was high for all age classes of both species, and growth increments were not consistently related to various measures of floodplain inundation. However, relationships became stronger, and usually direct, when water temperature was integrated with area and duration of floodplain inundation. Relationships were significant for four of six age classes for blue catfish, a species known to utilize floodplain habitats. Though similar in direction, relationships were weaker for flathead catfish, which is considered a more riverine species. Our results indicate the Flood‐Pulse Concept applies more strongly to temperate floodplain‐river ecosystems when thermal aspects of flood pulses are considered. We recommend that future management of the LMR should consider ways to ‘recouple’ the annual flood and thermal cycles. An adaptive management approach will allow further determination of important processes affecting fisheries production in the LMR. Copyright © 2006 John Wiley & Sons, Ltd.     

Nitrogen management in reservoir catchments through constructed wetland systems.

In this study, nitrogen removal was investigated in pilot-scale subsurface flow (SSF) and in free water surface flow (FWS) constructed wetlands installed in the campus of TUBITAK-Marmara Research Center, Gebze, near Istanbul, Turkey. The main purposes of this study are to apply constructed wetlands for the protection of water reservoirs and to reuse wastewater. Experiments were carried out at continuous flow reactors. The effects of the type of plants on the removal were investigated by using emergent (Canna, Cyperus, Typhia spp., Phragmites spp., Juncus, Poaceae, Paspalum and Iris.), submerged (Elodea, Egeria) and floating (Pistia, Salvina and Lemna) marsh plants at different conditions. During the study period HLRs were 30, 50, 70, 80 and 120 L m(2)d(-1) respectively. The average annual NH4-N, NO(3)-N, organic N and TN treatment efficiencies in SSF and FWS wetlands are 81% and 68%, 37% and 49%, 75% and 68%, 47% and 53%, respectively. Nitrification, denitrification and ammonification rate constant (k20) values in SSF and FNS systems have been found as 0.898 d(-1) and 0.541 d(-1), 0.488 d(-1) and 0.502 d(-1), 0.986 d(-1) and 0.908 respectively. Two types of the models (first-order plug flow and multiple regression) were tried to estimate the system performances.     

Design of the experimental air curtain for the dam of the Krivoporozhsk hydroelectric station

Translated from Gidrotekhnicheskoe Stroitel'stvo, No. 10, pp. 11–13, October, 1992.     

PRINCIPAL AND AGENCY TRADES BY STOCKBROKERS ARE COMPLEMENTARY: THE WELFARE EFFECTS OF DEREGULATING AGENCY TRADING AND BANNING PRINCIPAL TRADES

This paper models the demand for stockbrokers' services in Australia, consisting of two related services, agency trades and principal trades. The relationship between agency and principal trades is estimated. The results indicate that the two services are complements rather than substitutes. Using unique accounting information, a model of agency and principal trading activities is estimated to determine the welfare effects of (i) deregulating brokerage commissions and (ii) a ban on principal trading by brokers. The results show a sizeable welfare gain to investors (amounting to about 60% of the gross revenue of brokers) stemming from deregulation of the minimum charge for agency trades. The loss in profitability by brokers due to deregulation is also computed and shown to be negligible. The results also show that due to complementarity, a ban on principal trading, even with deregulation of agency trading, can impose an arbitrarily high cost on investors which could, in principle, offset the gains from agency deregulation.     

Endogenous Growth and Negative Externalities

Received March 5, 2001; revised version received August 5, 2002 Published online: April 30, 2003     

Expenditure patterns on food and non food items of Khayelitsha households,Western Cape,South Africa

Food insecurity or lack of access to adequate and nutritious food is a major determinant of under‐nutrition. Expenditure patterns accompanied by unemployment, low level of education, inflation and high food prices have a direct negative impact on food availability within households (Moller, 1997). Ghany and Schwenk (1993) found that as household income increases, the proportion of expenditures on food decreases, the proportion of expenditures on clothing, rent, fuel, and light stayed the same and that of sundries increased. The aim of this study was to investigate household expenditure patterns on food and non‐food items in Khayelitsha. A total of 20 households (10 from the formal and 10 from the informal settlements) were randomly selected from those willing to participate in the study. A questionnaire with open ended and closed questions was used to collect data. The questionnaire comprised four sections namely: biographical information, socio‐economic information which used wealth quintiles to assess households’ social economic status, total expenditure information and a food/hunger scale was used to assess households’ food availability. The findings revealed that households from informal settlements spent more money (62.2%) as a proportion of their income on food compared to households from the formal settlement (39%). There was higher unemployment rate (100%) at the informal settlement compared to the formal settlement (40%). Wealth quintiles scales did not reflect the social status of the households as equipment and assets owned by households were only used as fallback position during times of economic hardships. Households used different purchasing strategies; food and non‐food items were mainly purchased from outside the township (60%). Forty percent of the households bought their items from local shops and spazas because they allowed them to buy items whenever little money was available or to take items on credit. All the respondents preferred to buy bread and small items from spazas and local shops. Prices of items in the spazas and local shops were higher compared to prices of items in bigger shops outside the townships. The food/hunger scale and wealth quintiles showed that informal settlement households were more food insecure (as they were all unemployed and about 50% of the households ran out of food always) and had fewer assets compared to the formal settlement households. The implications of these findings underscore the need to improve socio‐economic conditions of low resource households through empowerment programs. These programs can be in the form of training in management/decision making, work related skills/literacy (to help them access formal employment), business management/income generation skills (to help them to be self‐employed), budgeting, and food gardening. This approach can help to increase the resource base and alleviate food insecurity in low resource households.     

Simulation of runoff and phosphorus transport in a Carpathian catchment,Slovakia

A comprehensive, GIS‐based modelling approach is developed to estimate runoff and phosphorus transport within a watershed at a daily time step. The approach relies on the use of GIS data for deriving major critical model parameters that exhibit distinct spatial variability over the catchment. Surface runoff is calculated by a modified rational method, which depends upon rainfall intensity, soil moisture status, slope, land‐use and soil characteristics. Phosphorus loading is estimated as a function of the runoff volume and the event mean concentration for different land use categories. A diffusive approximation method is used to trace runoff and phosphorus transport to the basin outlet. The modelling approach is tested in the Margecany catchment, Hornad River basin, Slovakia, to simulate runoff, phosphorus loading, and its transport on a daily time scale using data observed between 1995 and 2000. Satisfactory results of the hydrographs and phosphorus concentration at the basin outlet are obtained, though more efforts regarding the phosphorus cycling and its biochemical reactions need to be clarified by further research. Copyright © 2006 John Wiley & Sons, Ltd.     

A flight to Q? Firm investment and financing in Korea before and after the 1997 financial crisis

We examine investment behavior among exchange-listed Korean manufacturing firms before and after the 1997 financial crisis using firm-level panel data. Starting with the standard Q-theory of investment, we augment it by allowing for a sales accelerator and the possibility of cash constraints, categorizing firms based on their age, size and affiliation to an industrial conglomerate (i.e., chaebol). We find that Tobin’s Q is a robust determinant of investment in a pooled sample for 1992–2001, but that it became more important for small firms and less important for chaebol-affiliated firms after the crisis. Investment by chaebol firms also became more sensitive to the availability of internal cash balances after the crisis. We interpret this as reflecting a shift in the Korean economy to a stronger market orientation after the crisis and to a business climate in which the quality of potential projects became more important relative to capital market imperfections in determining the destination of investment funds.