摘要:

This paper gives the data and methods used to calculate the nitrogen and phosphorus loads of the Ngongotaha Stream, near Rotorua, New Zealand. The variations in concentration with time and with flow rate are given in some detail, as examples of what may happen in other streams of the central volcanic plateau, and a novel way to define a flow‐concentration curve is described. Nitrate, ammonia, dissolved reactive phosphorus (DRP), total phosphorus (TP), and total Kjeldahl nitrogen (TKN) concentrations were measured, and mean concentrations in 1976 base flow were found to be 527, 25, 32, 48, and 162 mg m‐3respectively. Nitrate concentrations showed seasonal variations, and although changes occurred during floods, they were not correlated with flow rate. DRP concentrations showed little variation, except that they dropped at the peak of the largest floods. TP was strongly correlated with flow rate during floods, and TP loads could best be calculated by allowing for a curvilinear relationship between concentration and flow rate. The logarithms of the TP load carried by a flood and the peak flow rate of the flood were highly correlated(R= 0.984). The annual loads of nitrate, ammonia, DRP, TP, and TKN were estimated to be 34, 1.3, 2.9, 6.0, and 26 tonnes in 1976.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515977

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Riffles and points of divergence of branch channels in braided rivers are critical controls upon passage of fish and recreational boats because they are points at which depths are at a minimum. Depths on randomly selected riffles were measured in braided reaches of the Ashley, Hurunui, and Rakaia Rivers and related to discharge; minimum depths encountered in extended reaches of these rivers at a range of flows have also been measured. The data can be used to predict minimum available passage depths at a specified flow, or conversely, to predict the discharge required to maintain a specified minimum passage depth. However, presently available estimates of critical minimum depths required for various instream uses (migration of salmonids, jetboating) appear excessively conservative, and minimum depth requirements must be more accurately determined before instream flow needs can be properly assessed.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515978

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

Four drift bottles, cast adrift south of the Subtropical Convergence at 48°S, 156°E in November 1980, landed within 123 days of release at a short stretch of coast north of Banks Peninsula. A high degree of coherence in the responsible drift pattern is indicated. The contemporary surface circulation inferred from satellite‐derived sea‐surface temperature distributions indicates that the bottles were entrained in a meridionally‐converging flow after drifting across the southern Tasman Sea without crossing the Convergence. They were prevented from further eastward drifting because of a marked southward flexing of the Convergence east of the Southland Current during February 1981. Because of local weather and tide effects, the bottles finally beached in Pegasus Bay.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515979

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor

摘要:

The height of widespread tsunami runup about the Bay of Plenty from various volcanic scenarios involving eruptions at White Island is shown to be insignificant in all cases considered, except for Krakatoa‐type explosions. The problem of localised inundation remains unanswered. Some definitions describing volcanic tsunami risk, introduced recently by J. Latter(Bulletin volcanologique1982), are briefly mentioned. All numerical calculations assumed cylindrical symmetry and used a flux‐corrected Lax‐Wendroff algorithm to solve the modified shallow water equations of Peregrine.

ISSN:0028-8330    

DOI:10.1080/00288330.1982.9515980

出版商:Taylor & Francis Group    

年代:1982

数据来源: Taylor