Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa
Study region: South Africa. Study focus: The use of Areal Reduction Factors (ARFs) to convert average design point rainfall into areal catchment design rainfall is regarded as fundamental input to event-based deterministic design flood estimation methods. The ARF methods currently used in South Afri...
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| Format: | Article |
| Language: | English |
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Elsevier
2023-12-01
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| Series: | Journal of Hydrology: Regional Studies |
| Subjects: | |
| Online Access: | http://www.sciencedirect.com/science/article/pii/S221458182300229X |
| _version_ | 1797390511411036160 |
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| author | Jacobus P.J. Pietersen Ockert J. Gericke Jeffrey C. Smithers |
| author_facet | Jacobus P.J. Pietersen Ockert J. Gericke Jeffrey C. Smithers |
| author_sort | Jacobus P.J. Pietersen |
| collection | DOAJ |
| description | Study region: South Africa. Study focus: The use of Areal Reduction Factors (ARFs) to convert average design point rainfall into areal catchment design rainfall is regarded as fundamental input to event-based deterministic design flood estimation methods. The ARF methods currently used in South Africa are outdated and were neither developed nor verified using local data. This paper presents the development and assessment of a regionalised approach to estimate long duration (≥ 1-day) geographically-centred ARFs using daily rainfall data representative of the 78 homogeneous long duration rainfall clusters associated with the Regional Linear Moment Algorithm and Scale Invariance (RLMA&SI) regionalisation scheme in South Africa. In order to meet the recommended World Meteorological Organisation rainfall station density criteria, the latter clusters were merged into 46 clusters. Subsequently, long duration geographically-centred sample ARFs were estimated using 2 053 circular catchments and 1 779 daily rainfall stations. New hydrological insights for the region: Five ARF regions were deduced from the 46 clusters and a single regional empirical ARF equation, with unique regional calibration coefficients, was derived. The ARF methodology developed and the subsequent findings are not only new to the South African flood hydrology community and practice, but are also probabilistically correct given that the ARF estimates decrease with an increasing catchment area and decrease with a decreasing storm duration and return period, unlike many other methods used internationally. |
| first_indexed | 2024-03-08T23:12:54Z |
| format | Article |
| id | doaj.art-d62ddbbd1ff547fa8e21ae32b18be4f8 |
| institution | Directory Open Access Journal |
| issn | 2214-5818 |
| language | English |
| last_indexed | 2024-03-08T23:12:54Z |
| publishDate | 2023-12-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Journal of Hydrology: Regional Studies |
| spelling | doaj.art-d62ddbbd1ff547fa8e21ae32b18be4f82023-12-15T07:24:09ZengElsevierJournal of Hydrology: Regional Studies2214-58182023-12-0150101542Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South AfricaJacobus P.J. Pietersen0Ockert J. Gericke1Jeffrey C. Smithers2Department of Civil Engineering, Central University of Technology, Free State, Bloemfontein, South Africa; Corresponding author.Department of Civil Engineering, Central University of Technology, Free State, Bloemfontein, South AfricaCentre for Water Resources Research and School of Engineering, University of KwaZulu-Natal, KwaZulu-Natal, South AfricaStudy region: South Africa. Study focus: The use of Areal Reduction Factors (ARFs) to convert average design point rainfall into areal catchment design rainfall is regarded as fundamental input to event-based deterministic design flood estimation methods. The ARF methods currently used in South Africa are outdated and were neither developed nor verified using local data. This paper presents the development and assessment of a regionalised approach to estimate long duration (≥ 1-day) geographically-centred ARFs using daily rainfall data representative of the 78 homogeneous long duration rainfall clusters associated with the Regional Linear Moment Algorithm and Scale Invariance (RLMA&SI) regionalisation scheme in South Africa. In order to meet the recommended World Meteorological Organisation rainfall station density criteria, the latter clusters were merged into 46 clusters. Subsequently, long duration geographically-centred sample ARFs were estimated using 2 053 circular catchments and 1 779 daily rainfall stations. New hydrological insights for the region: Five ARF regions were deduced from the 46 clusters and a single regional empirical ARF equation, with unique regional calibration coefficients, was derived. The ARF methodology developed and the subsequent findings are not only new to the South African flood hydrology community and practice, but are also probabilistically correct given that the ARF estimates decrease with an increasing catchment area and decrease with a decreasing storm duration and return period, unlike many other methods used internationally.http://www.sciencedirect.com/science/article/pii/S221458182300229XAreal design rainfallAreal reduction factorsDesign point rainfallGeographically-centredObserved daily rainfall |
| spellingShingle | Jacobus P.J. Pietersen Ockert J. Gericke Jeffrey C. Smithers Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa Journal of Hydrology: Regional Studies Areal design rainfall Areal reduction factors Design point rainfall Geographically-centred Observed daily rainfall |
| title | Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa |
| title_full | Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa |
| title_fullStr | Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa |
| title_full_unstemmed | Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa |
| title_short | Derivation of long duration geographically-centred areal reduction factors for catchment design rainfall estimation in South Africa |
| title_sort | derivation of long duration geographically centred areal reduction factors for catchment design rainfall estimation in south africa |
| topic | Areal design rainfall Areal reduction factors Design point rainfall Geographically-centred Observed daily rainfall |
| url | http://www.sciencedirect.com/science/article/pii/S221458182300229X |
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