The movement of sediment in a channel in relation to magnitude and frequency concepts- a New Zealand example

In areas where surface wash contributes most of the debris to a channel network, the effect of events of moderate magnitude and frequency appear to be more important than catastrophic events for land form development. In previous studies this idea has been emphasised, largely as a result of the fact that the contribution of bedload to sediment yield has rarely been considered. Examination of these ideas under certain New Zealand conditions would seem to present a somewhat different picture. Where rapid mass movement is the main contributor of sediment to the channel, both the development of hill-slope form and the movement of sediment in channels must be related to the frequency of occurrence of mass movements. The evidence seems to suggest that most major mass movements are triggered during high-intensity, low-frequency storms. The Orere River catchment in the Hunua greywacke block of South Auckland, New Zealand, is examined to test these ideas. Although historical data are limited, the character of the sediments in the lower catchment would suggest a succession of major periods of deposition. High-intensity storms of 1966 and 1967 resulted in the deposition of large amounts of material in the channels throughout the catchment, with a gradual removal of material mainly from the upper catchment since that time. From the limited evidence that is available, a simple model of sediment movement through the catchment is presented

Impact of broom, Cytisus scoparius (Fabaceae), in naturally treeless sub-alpine frost-hollow vegetation communities at the Barrington Tops, south-eastern Australia

The exotic shrub Cytisus scoparius (L.) Link (family Fabaceae), known as broom, is having a major impact on native vegetation in naturally treeless sub-alpine frost-hollow areas (c. 32o 01’ 37” S, 151o 26’ 12” E’, 1440 m elevation) at the Barrington Tops, New South Wales, in south-eastern Australia. This vegetation is of limited extent and has significant biogeographical and ecological importance. Nine paired 10 m line transects were compared, with one of the pair in areas of almost 100% Cytisus scoparius and the other in adjacent areas without Cytisus scoparius. Results were compared with species recorded from this area in the 1930s. There are obvious differences in native vegetation in areas with and without Cytisus scoparius. On average there were 5.1 (range 2–10) species per 10 m in areas of almost 100% Cytisus scoparius cover and 17.0 (12–25) species per 10 m in areas adjacent to infested areas but without Cytisus scoparius. Other than Cytisus scoparius, the area surveyed had little in the way of exotic species and these were only present at low densities. Native species present in 2008 are similar to those recorded in the 1930s; there were no records of Cytisus scoparius in the area in the 1930s. The study suggests that control of Cytisus scoparius in naturally treeless areas at the Barrington Tops should be a priority to prevent a decline in the distribution and abundance of many plant species, many of which only occur in treeless areas of the Barrington Tops

The Value of the Trout Fishery at Rhodes, North Eastern Cape, South Africa, A Travel Cost Analysis Using Count Data Models

The National Environmental Management: Biodiversity Act, no.10 of 2004) makes provision for the presence of alien trout in South African waters by means of a zoning system, partly in recognition of the significant income generating potential of trout fishing in South Africa. This paper reports the first formal recreational valuation of a trout fishery in South Africa, the one in and around Rhodes village, North Eastern Cape. The valuation is carried out by applying the individual travel cost method using several count data models. The zero truncated negative binomial model yielded the most appealing results. It accounts for the non-negative integer nature of the trip data, for truncation and over-dispersion. The paper finds that in 2007 consumer surplus per day visit to the Rhodes trout fishery was R2 668, consumer surplus per trip visit was R13 072, and the total consumer surplus generated was R18 026 288.

A stochastic maximum principle for a stochastic differential game of a mean-field type

We construct a stochastic maximum principle (SMP) which provides necessary conditions for the existence of Nash equilibria in a certain form of N-agent stochastic differential game (SDG) of a mean-field type. The information structure considered for the SDG is of a possible asymmetric and partial type. To prove our SMP we use a spike-variation approach with adjoint representation techniques, analogous to that of S. Peng in the optimal stochastic control context. In our proof we apply adjoint representation procedures at three points. The first-order adjoint processes are defined as solutions to certain mean-field backward stochastic differential equations, and second-order adjoint processes of a first type are defined as solutions to certain backward stochastic differential equations. Second-order adjoint processes of a second type are defined as solutions of backward stochastic equations of a type that we introduce in this paper, and which we term conditional mean-field backward stochastic differential equations. From the resulting representations, we show that the terms relating to these second-order adjoint processes of the second type are of an order such that they do not appear in our final SMP equations

An Economic Approach to Allocating River Water to Estuaries in South Africa

Estuaries are last in line as a recipient of river water and for this reason they are particularly vulnerable to negative environmental impacts due to water scarcity and pollution. They only receive the runoff that has not been abstracted or prevented from reaching rivers. When this runoff is substantially reduced their functionality is undermined and they often become less attractive for recreational use. This paper explores some aspects entailed in efficiently managing the allocation of water to estuaries problem and some associated problems. It is shown that efficient management requires the marginal social costs of the inflows to be brought into equivalence with the marginal social values of the inflows, and these values may be estimated, but that there are the challenges in this estimation and in linking these estimates to the welfare of the people in whom the managers of river systems are (presumed to be) interested

Respiratory diseases, as affecting the New Zealand Expeditionary Forces serving in France and United Kingdom: an analysis of the histories of 2433 men boarded as unfit for further service, June 1916 to December 1918

#1.The outstanding feature of the Respiratory Diseases affecting men of the N.Z.E.F, has been their low immunity to attack by the organisms of catarrh. #2.This was one of the main causes of invaliding. The frequency of catarrhal attacks with lesions similar to Tubercular disease of the lungs was pronounced. #3 The percentage of Positive Tubercle of the lung is found to be about that of the British Army pre- war, taking statistics for 1913. #4.It was necessary to evacuate invalided men to New Zealand. This meant a long sea voyage of over six weeks in a crowded Transport.Thus it became necessary to use great care in classification,and the cases diagnosed Clinical Tubercle of the Lung amounted to a large number. #5.The improvement under changed conditions was rapid,and to avoid the stigma of Tubercle, the class of Chronic Pulmonary Disease Indeterminate was instituted.Men with the lesser apical changes were included in this class. #6.Comparison of histories as provided in Board Papers (Table 7) shows the similarities and variations in the three types of case. #7.The matter of diagnosis is open to question,and will be viewed by critics according to the value placed on Clinical signs and symptoms apart from the finding of the Tubercle Bacillus. #8.Tubercular diseases in New Zealand are not common. The view that the Clinical and CPDI cases are due to lighting of old foci in the lungs is not substantiated, but deserves consideration. #9. Sputum examinations shewed the presence of respiratory catarrhal organisms without the presence of T.B and it is probable that even the typical apical lesions are set up by the former alone. #10. The fact that the men were evacuated if still unfit for service after a period of three months or more,probably prevented the developetent of T.B.in a greater ratio. By watching the future of the suspects ,fresh grounds for opinion will arise.In the meantime the men should not be lost sight of. #11. The class CPDI was composed of two groups as in Clinical and Positive T.B. - those arising insidiously,and those in which the lungs gave persistent apical signs following an acute pulmonary attack (Table 3). #12. Influenza was not found to be so common a cause in these alas es as might have been expected.Slighter attacks of gas poisoning may have had something to do with the impairment. #13. Of other pulmonary diseases a group may be made of Pneumonia, Broncho-Pneumonia, and Pleurisy, including the cases of acute onset in the form which have been returned under T.B.(Positive and Clinical) and CPDI - This type of case shows a total of 694. #14.The Maori soldiers were very subject to Tubercle of the lung :their return for a small force is large. They affect the Ratios per 1000 in the Tables to some degree, and they are differentiated in important points. #15. Figures re: Age incidence shew that the acute diseases are more prominent in the years up to 25, for the acute. conditions - The experience of combatant of officers that men between 25 and 35 years of age are the best soldiers is upheld. In the later ages Asthma and Emphysema are more apparent. #16. Indoor and Outdoor occupation are not well defined among the agricultural population of New Zealand,where the towns are, small ,and short working hours allow of open air exercise .The Outdoor population includes a number of men who are much exposed to the weather and develop Bronchitis and Emphysema in their later years, while the figure for Pneumonia is high at all ages