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.

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 Continuous modelling of the Bouregreg watershed (Morocco) using the HEC-HMS model

2021 ◽  
Vol 314 ◽  
pp. 05001
Author(s):  
Oussama Laassilia ◽  
Driss Ouazar ◽  
Ahmed Bouziane ◽  
Moulay Driss Hasnaoui
Keyword(s):  
Annual Variation ◽  
Hydrological Model ◽  
Deep Understanding ◽  
Rainfall Runoff ◽  
Unit Hydrograph ◽  
Soil Moisture Accounting ◽  
Change Impact ◽  
Loss Method ◽  
Acceptable Agreement ◽  
Simulated Flow

A deep understanding of the rainfall-runoff mechanism is essential to estimate the runoff generated in a given basin. In this regard, this paper aims to develop a continuous hydrological model of the Bouregreg watershed. The objective of this modelling is to evaluate the inflow to the Sidi Mohamed Ben Abdellah (SMBA) dam, located at the outlet of this basin. To this end, using the HEC-HMS model, the Soil Moisture Accounting (SMA) Loss Method was used to model infiltration losses. The SCS Unit hydrograph (SCS UH) and the Recession method were chosen as transform model and baseflow model, respectively. As a result, the comparison shows an acceptable agreement between observed and simulated flow in terms of streamflow distribution and peak values (NSE=0.57, R2=0.58). During validation, the model retained its ability to sufficiently reproduce the rainfall-runoff mechanism of the studied basin with a slight overestimation of peaks (NSE=0.61, R2=0.60). This study allows to assess and predict the inter-annual and intra-annual variation of the SMBA dam reservoir’ inflows, and therefore to forecast the climate change impact on this basin.

scholarly journals Application of a distributed hydrological model to the design of a road inundation warning system for flash flood prone areas

2010 ◽  
Vol 10 (4) ◽  
pp. 805-817 ◽  
Author(s):  
P.-A. Versini ◽  
E. Gaume ◽  
H. Andrieu
Keyword(s):  
Cross Sections ◽  
Hydrological Model ◽  
Flash Flood ◽  
Warning System ◽  
Flash Floods ◽  
Probability Of Detection ◽  
Distributed Hydrological Model ◽  
Rainfall Runoff ◽  
Erosion Processes ◽  
Stage Of Development

Abstract. This paper presents an initial prototype of a distributed hydrological model used to map possible road inundations in a region frequently exposed to severe flash floods: the Gard region (South of France). The prototype has been tested in a pseudo real-time mode on five recent flash flood events for which actual road inundations have been inventoried. The results are promising: close to 100% probability of detection of actual inundations, inundations detected before they were reported by the road management field teams with a false alarm ratios not exceeding 30%. This specific case study differs from the standard applications of rainfall-runoff models to produce flood forecasts, focussed on a single or a limited number of gauged river cross sections. It illustrates that, despite their lack of accuracy, hydro-meteorological forecasts based on rainfall-runoff models, especially distributed models, contain valuable information for flood event management. The possible consequences of landslides, debris flows and local erosion processes, sometimes associated with flash floods, were not considered at this stage of development of the prototype. They are limited in the Gard region but should be taken into account in future developments of the approach to implement it efficiently in other areas more exposed to these phenomena such as the Alpine area.

scholarly journals Rainfall runoff features of permeable sidewalk pavement

2020 ◽  
Author(s):  
Liyuan Qiu ◽  
Yu Zhang ◽  
Sheng Zhang ◽  
Jingwei Zhao ◽  
Tengfei Wang ◽  
...  
Keyword(s):  
Urban Areas ◽  
Peak Flow ◽  
Precipitation Pattern ◽  
Rainfall Runoff ◽  
Sponge City ◽  
Permeable Pavement ◽  
Total Runoff ◽  
Runoff Model ◽  
Flood Flow ◽  
Catchment Runoff

Abstract In urban areas, the buildings and pavements make it hard for rainwater to infiltrate into the ground. The hardened underlaying sub-crust has increased the total rainfall runoff, pushing up the peak flood flow. Drawing on the construction concept of sponge city, this paper probes deep into the materials in each layer of permeable pavement for sidewalks. Specifically, a runoff model was constructed for sidewalk pavements under rainfall conditions through numerical simulation and model testing. Using the precipitation pattern of Qingdao, China, several combinations of materials were subject to rainfall simulations, revealing how each permeable pavement controls and affects the surface runoff. The results show that the permeability of surface course and sub-crust directly bear on the starting time, peak flow, total runoff and runoff time of sub-catchment runoff; and the latter has a greater impact than the former on sub-catchment runoff.

scholarly journals Evaluation of Permeable Brick Pavement on the Reduction of Stormwater Runoff Using a Coupled Hydrological Model

Water ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2821
Author(s):  
Xiaoran Fu ◽  
Jiahong Liu ◽  
Weiwei Shao ◽  
Chao Mei ◽  
Dong Wang ◽  
...  
Keyword(s):  
Urban Areas ◽  
Hydrological Model ◽  
Peak Flow ◽  
Stormwater Runoff ◽  
Coupled Model ◽  
Potential Effect ◽  
Watershed Scale ◽  
Hydrological Models ◽  
Rainfall Runoff ◽  
Storm Duration

In several cities, permeable brick pavement (PBP) plays a key role in stormwater management. Although various hydrological models can be used to analyze the mitigation efficiency of PBP on rainfall runoff, the majority do not consider the effect of multi-layered pavement on infiltration in urban areas. Therefore, we developed a coupled model to evaluate the potential effect of PBP in reducing stormwater runoff at a watershed scale. Specifically, we compared the hydrological responses (outflow and overflow) of three different PBP scenarios. The potential effects of PBP on peak flow (PF), total volume (TV), and overflow volume (OV) were investigated for 20 design rainstorms with different return periods and durations. Our results indicate that an increase in PBP ratio reduces both PF (4.2–13.5%) and TV (4.2–10.5%) at the outfall as well as the OV (15.4–30.6%) across networks. The mitigation effect of PBP on OV is linearly correlated to storm return period and duration, but the effects on PF and TV are inversely correlated to storm duration. These results provide insight on the effects of infiltration-based infrastructure on urban flooding.

scholarly journals The contemporary geomorphology of the Sabie River in the Kruger National Park

Koedoe ◽  
2000 ◽  
Vol 43 (1) ◽  
Author(s):  
G.L. Heritage ◽  
B.P. Moon
Keyword(s):  
South Africa ◽  
National Park ◽  
Kruger National Park ◽  
Catchment Management ◽  
Morphologic Change ◽  
Areal Extent ◽  
Single Thread ◽  
Number Of Species ◽  
High Degree ◽  
Channel Type

The Sabie River in the Kruger National Park has been described as the most pristine in South Africa. It has remained largely free of direct alteration along its 110 km length within the reserve and as such displays a high geomorphic diversity. This physical vari- ability supports a great diversity of flora and fauna including a number of species endemic to the river. The diversity in fluvial form is the result of a high degree of bedrock influence coupled with a rapidly changing energy regime. Steeper bedrockinfluenced areas alternate with more gently sloping alluvial segments to create a series of channel types ranging from bedrock anastomosing through to alluvial single thread and braided sections. Each channel type is part of a continuum that relates to the degree of alluviation of the river on the bedrock template. Descriptions of the characteristic channel types associated with the Sabie River, together with associated morphologic units are given together with the areal extent of the changing morphology in the Kruger National Park. Each morphologic unit is characterised by size, shape, sedimentology and flow influence. Recent research into the degree and direction of morphologic change in the Sabie River is also summarised in the light of possible catchment management.

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.

Sign in / Sign up

Export Citation Format

Share Document