scholarly journals The February 2000 floods on the Letaba River, South Africa: an examination of magnitude and frequency

Koedoe ◽  
2001 ◽  
Vol 44 (2) ◽  
Author(s):  
G.L. Heritage ◽  
B.P. Moon ◽  
A.R.G. Large
Keyword(s):  
Cross Sections ◽  
National Park ◽  
Water Surface ◽  
Peak Flow ◽  
High Flow ◽  
Surface Slope ◽  
The West ◽  
Olifants River ◽  
Resistance Coefficients ◽  
Channel Type

Accurate estimates of the magnitude of the floods that affected southern Africa in February 2000 are difficult to obtain since floodwaters damaged the majority of gauging stations on affected rivers. It is possible to estimate the peak discharge experienced in the Letaba River in the Kruger National Park by simulating the hydraulic and geometric characteristics of the peak flow and relating these to the roughness of the channel. Peak water surface slope data were determined from debris and mudline measurements at breaks in channel type. These data are combined with published high-flow channel resistance coefficients for different channel types to generate peak flow estimates for eleven different cross-sections, located between tributaries to allow for sub-catchment contributions to be estimated. In February 2000 flow peaked at approximately 4000 nWs near to Black Heron Dam (in the west of the park), and increased to approximately POOOm^s just upstream of the confluence with the Olifants River. Comparison with gauge records indicates that the February 2000 peak was higher than any flow during the proceeding four decades.

scholarly journals The February 2000 floods on the Sabie River, South Africa: an examination of their magnitude and frequency

Koedoe ◽  
2001 ◽  
Vol 44 (1) ◽  
Author(s):  
G.L. Heritage ◽  
B.P. Moon ◽  
G.P. Jewitt ◽  
A.R.G. Large ◽  
M. Rountree
Keyword(s):  
Cross Sections ◽  
National Park ◽  
Hydrological Model ◽  
Peak Flow ◽  
Kruger National Park ◽  
Rainfall Runoff ◽  
Major Tributary ◽  
Flood Flow ◽  
Simulated Flow ◽  
Channel Type

The floods that affected much of Southern Africa in February 2000 have been reported as the largest in living memory by many observers. However, the force of the floods damaged the majority of the gauging stations located on the affected rivers, many of which were not constructed to measure flows of such a magnitude. This paper presents an estimation of the peak flood discharge on 6 February 2000 for the bedrock influenced Sabie River in the Kruger National Park, by simulating the hydraulic and geometric characteristics of the peak flow and relating these to the roughness character of the channel. Peak water surface slope data in the form of strandline measurements at channel type breaks along the river were collected for six sites along the Sabie River within the Kruger National Park. Flood conditions within each channel type were considered to approximate to uniform flow. The cross-sections are located between major tributary inputs allowing for approximate sub-catchment flow contributions to be estimated. The results indicate that the flow peaked at around 3000 mVs at the Kruger Gate entrance to the Kruger National Park, increasing to approximately 5500mVs at Skukuza and 7000 mVs at Lower Sabie close to the Mozambique border following inputs from the Sand River sub-catchment. These estimates compare well with the simulated rainfall runoff total of 4300 mVs at Skukuza, however, precipitation inputs over the lowveld appear to indicate that the discharge only rises to 4950 mmVs at Lower Sabie. A flood flow of this magnitude has never been experienced based on the simulated flow data generated by the ACRU hydrological model calibrated against measured flows therefore suggesting a return period in excess of the 60 years of record.

Study on the Flood Volume Investigation for Medium and Small River

2012 ◽  
Vol 599 ◽  
pp. 728-731
Author(s):  
Zhong Du ◽  
Hui Xiu Wu ◽  
Zeng Chuan Dong ◽  
De Shu Sun
Keyword(s):  
Water Surface ◽  
Peak Flow ◽  
Runoff Coefficient ◽  
Ungauged Basins ◽  
Surface Slope ◽  
Remote Sensing Technology ◽  
Flood Volume ◽  
Sensing Technology ◽  
Water Surface Slope ◽  
Statistical Interpolation

The hydrological research of ungauged basins became the new topic of international hydrological plan, the flood investigation can effectively make up for the information insufficient of the contemporary remote sensing technology and traditional statistical interpolation techniques. Take Dasha River rainstorm for example, water surface slope was monitored of 8‰ by slope-area method, the peak flow was calculated of 1830 m3/s. According to the measured multi-peak flood hydrograph simulates single peak hydrograph and five points probable, the flood volume was calculated of 109 million m3, the runoff coefficient is 0.84 and runoff depth is 505 mm. The river basin has 250 mm previous rainfall, and the underlying surface was saturated, so the result indicated that it accord with runoff yield and concentration theory. The method can be extended for medium and small size river.

Managing rivers for conservation and ecotourism in the Kruger National Park

1995 ◽  
Vol 32 (5-6) ◽  
pp. 227-233 ◽  
Author(s):  
F. J. Venter ◽  
A. R. Deacon
Keyword(s):  
National Park ◽  
Good Condition ◽  
Kruger National Park ◽  
Rapid Expansion ◽  
Natural Environments ◽  
The West ◽  
The Past ◽  
Management Actions ◽  
Flow Through ◽  
Three Rivers

Six major rivers flow through the Kruger National Park (KNP). All these rivers originate outside and to the west of the KNP and are highly utilized. They are crucially important for the conservation of the unique natural environments of the KNP. The human population growth in the Lowveld during the past two decades brought with it the rapid expansion of irrigation farming, exotic afforestation and land grazed by domestic stock, as well as the establishment of large towns, mines, dams and industries. Along with these developments came overgrazing, erosion, over-utilization and pollution of rivers, as well as clearing of indigenous forests from large areas outside the borders of the KNP. Over-utilization of the rivers which ultimately flow through the KNP poses one of the most serious challenges to the KNP's management. This paper gives the background to the development in the catchments and highlights the problems which these have caused for the KNP. Management actions which have been taken as well as their results are discussed and solutions to certain problems proposed. Three rivers, namely the Letaba, Olifants and Sabie are respectively described as examples of an over-utilized river, a polluted river and a river which is still in a fairly good condition.

scholarly journals The influence of the 1991/92 drought on the woody vegetation of the Kruger National Park

Koedoe ◽  
1995 ◽  
Vol 38 (2) ◽  
Author(s):  
A.J. Viljoen
Keyword(s):  
National Park ◽  
Woody Species ◽  
Aerial Photographs ◽  
Woody Vegetation ◽  
General Area ◽  
Variable Intensity ◽  
The North ◽  
Olifants River ◽  
Area North ◽  
The Impact

All observations and data related to the impact of the 1991/92 drought on the woody vegetation, excluding the riverine vegetation of major rivers, are summarised. This includes data from a visual estimate of damage from aerial photographs, surveys on selected sites, and general observations. Despite lower rainfall, the area north of the Olifants River (excluding the far-northern part) was less affected than the area south of it, suggesting that the woody vegetation in the north is more adapted to drought. A characteristic of the drought was the localised distribution pattern and variable intensity of damage to the same species in the same general area. Information on 31 species are presented briefly. Although a large number of woody species was to some extent damaged, when the woody vegetation is considered as a whole, the influence of the drought was not very severe.

scholarly journals The implementation of an aquatic toxicity index as a water quality monitoring tool in the Olifants River (Kruger National Park)

Koedoe ◽  
1999 ◽  
Vol 42 (1) ◽  
Author(s):  
V. Wepener ◽  
J.H.J. Van Vuren ◽  
H.H. Du Preez
Keyword(s):  
Water Quality ◽  
Water Quality Index ◽  
National Park ◽  
Quality Index ◽  
Aquatic Toxicity ◽  
Temporal Trends ◽  
Kruger National Park ◽  
Toxicity Index ◽  
Olifants River

Large sets of water quality data can leave water quality managers and decision-makers totally overwhelmed. In order to convey the interpretation of the data in a simplified and understandable manner, the water quality results from bi-monthly surveys undertaken at seven different sampling sites in the Letaba, Olifants, and Selati rivers over a two year period (February 1990 to April 1992) were reduced to index values, using a water quality index. The water quality index (Aquatic Toxicity Index or ATI) revealed spatial and temporal trends. The higher index values, recorded for the sampling sites towards the eastern part of the Kruger National Park (KNP), revealed that the water quality was better than the quality measured in the Olifants River on the western bound-ary. The lowest index values were calculated for the Selati River, with index values consistently below 50. Index values indicate that the water quality in the Selati River was unsuitable for supporting normal physiological processes in fish. The water quality of the Selati River had an immediate impact on the water quality of the Olifants River directly below the confluence. Lower index values recorded at sites further downstream was also attributed to the influence of the Selati River since there are no known point sources of contaminants within the boundaries of the KNP. The index scores also elucidated temporal trends with lower scores evident during winter months. This was due to reduced flow in the Olifants River and a greater contribution of contaminated water from the Selati River. Index values increased following the first seasonal rains due to a dilution effect. Very low index values were recorded at certain sites during flood periods due to increased turbidity, reduced oxygen, and increased metal concentrations.

scholarly journals The geometric parameters of plants on the spur dykes in a selected section of the Odra River

2018 ◽  
Vol 45 ◽  
pp. 00110
Author(s):  
Magda Hudak
Keyword(s):  
Water Surface ◽  
Flow Resistance ◽  
Water Levels ◽  
Flow Conditions ◽  
Plant Structure ◽  
Central Section ◽  
Quantitative Characteristics ◽  
Odra River ◽  
The Impact ◽  
Resistance Coefficients

Spur dykes are structures for regulating rivers. They are designed for medium water levels, when spur dyke tops are above the water surface. In the central section of the Odra River the water level is changeable, and the spur dykes work in different hydrological conditions: as non-submerged and submerged. Correct recognition of the plant structure growing on the spur dykes is of great importance in the context of the subsequent allocation of its measure related to the hydraulic action, among others coefficients of resistance of plant zones and refers mainly to grasses. In hydraulic calculations, it is required to determine the value of flow resistance coefficients. In such a departure, the flow is omitted in the area occupied by vegetation. Therefore, it is necessary to know the quantitative characteristics of overgrowth. Vegetation should be presented in the form of a model reflecting the impact of plants growing on the spur dykes and their impact on the water flow conditions in the river. Literature data are not very numerous and are still awake unsatisfied. The paper presents the results of research on the density of vegetation on the Odra River in the Nowa Sól region.

scholarly journals Andrena Florivaga Eversmann , 1852 (Hymenoptera: Apoidea: Andrenidae) - A New Bee Species of the Genus Andrena in Poland

2013 ◽  
Vol 57 (1) ◽  
pp. 45-50
Author(s):  
Józef Banaszak ◽  
Ewelina Motyka ◽  
Katarzyna Szczepko
Keyword(s):  
National Park ◽  
Morphological Characteristics ◽  
First Record ◽  
General Distribution ◽  
Baikal Lake ◽  
The West ◽  
Central Siberia ◽  
Lake Region ◽  
Time Period ◽  
Pan Traps

Summary The first record of Andrena florivaga Eversmann, 1852 is reported from Poland on the basis of specimens collected in the Kampinos National Park (Mazovian Lowland). Diagnosis, data on localities, biology, and general distribution of the species are provided. One female and five males were caught on a mowed fresh meadow and fallow fields with the use of water pan-traps (Moericke traps), during the 2003 - 2004 time period. The main morphological characteristics distinguishing Andrena florivaga from the very similar Andrena dorsalis Brullé, 1832 species and from the other species of the subgenus Lepidandrena are: in the case of females - the width of facial foveae and colouration of legs, and in the case of males - the length of the first flagellar segment, colouration of clypeus, and pubescence of gonostyles. Andrena florivaga can be found from France in the west, to Central Siberia (Baikal lake region) in the east, and Turkey in the south. Poland is the northernmost locality of the species.

scholarly journals FEDERAL JETTY AND SAND DIKE AT THE ENTRANCE OF FIRE ISLAND INLET, NEW YORK

1986 ◽  
Vol 1 (20) ◽  
pp. 85
Author(s):  
Cyril Galvin ◽  
Charles J. Rooney ◽  
Gilbert K. Nersesian
Keyword(s):  
New York ◽  
Cross Sections ◽  
Good Condition ◽  
Inlet Channel ◽  
The West ◽  
North Shore ◽  
The North ◽  
Fire Island ◽  
Longshore Transport ◽  
Severe Erosion

Prior to construction at Fire Island Inlet, Fire Island was moving westward at more than 200 feet per year, the north shore of the inlet was eroding severely, and navigation in the inlet was difficult. The Federal Jetty, completed in 1941, and the sand dike, built in 1959, have halted the westward migration, eliminated the severe erosion, and partially improved navigation, with minimal maintenance or repair to the structures. There has been a large net accretion of sand east of the jetty and west of the dike, an unknown part of which is at the expense of shores to the west of the inlet. At the State Park on the south side of the inlet interior, erosion accelerated, probably because of the dike. The middle and ocean segments of the 4750-foot Federal Jetty are now (1987) in good condition, although the design implies a stability coefficient for the quarrystone jetty head at time of construction that would now be considered risky. Stability has been promoted by a stone blanket under and east of the jetty, a thick stone apron seaward of the jetty, a low (8 feet MLW) crest, and armor stone that has been partially keyed in place. Damage due to scour, common at other single-jetty inlets, is absent here because longshore transport, which easily overtops the low crest, keeps the inlet channel away from the jetty. Although the two seaward segments of the jetty remain in good condition, the inshore segment of the jetty is in poor condition, despite its apparently sheltered location. The cumulative effects of waves, possibly channeled to the site along recurved spits during storms, have damaged 1200 feet, and tidal scour has destroyed about 230 feet. The damaged segment has a design cross section which is onefifth and one-twelfth the cross sections of the jetty trunk and head.

Sign in / Sign up

Export Citation Format

Share Document