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dc.contributor.advisorPiketh, S.J.
dc.contributor.advisorBurger, R.P.
dc.contributor.advisor18002080 - Piketh, Stuart John (Supervisor)
dc.contributor.authorVan Loggerenberg, Jaun
dc.date.accessioned2017-04-07T12:29:46Z
dc.date.available2017-04-07T12:29:46Z
dc.date.issued2016
dc.identifier.urihttp://hdl.handle.net/10394/21230
dc.descriptionMSc (Geography and Environmental Management), North-West University, Potchefstroom Campus, 2016en_US
dc.description.abstractRainfall is highly variable over space and time. The need for an improvement in the quality of rainfall estimates in Africa has never been greater. In this dissertation the variability of rainfall on the Highveld of South Africa will be explored. For this the Mooi River catchment area has been used to characterise rainfall in the area. The first objective was to characterize the rainfall intensity over the Mooi River catchment. Events were identified by a 15min gap between measurements and characterized by the rainfall intensity and duration of each event measured by a Parsivel disdrometer. It has been found that the majority of events in the Mooi River catchment is highly variable, isolated and has a short duration. These events can therefore be named as convective events. Stratiform events are far more evenly distributed and not that variable, has low rain rates and is longer in duration. These events are not that common in the catchment. The second objective involved developing an algorithm to measure rain rates using a siphon tipping-bucket rain gauge. Measuring rain rates with a siphon poses unique challenges. The newly developed algorithm solves two of the biggest problems associated with siphon gauges. Firstly the rain rate for the first 0.2mm of rain is calculated and added before the first tip of an event. Secondly, double tips were identified, the second tip was deleted and the amount of rainfall of that tip was added to the first tip. A 93% correlation was observed using the new algorithm between the tipping-bucket rain gauge and the Parsivel disdrometer at a time scale resampled to 15minutes. The last objective of this study was to improve single-parameter weather radar data in the catchment. For this objective weather radars, rain gauges and the Parsivel disdrometer was used. It is important to firstly fully understand the variability of the rainfall intensity under the coverage area of a radar to implement new innovative methods which can improve radar rainfall estimates. In the Mooi River catchment when using the theoretical Z-R relation to measure rainfall with radar data events with low rain rates are overestimated and events with high rain rates are underestimated. It has been found that the theoretical Z-R relation used by SAWS is relatively well suited for stratiform events in the Mooi River catchment. However the majority of events in the area are convective which the theoretical Z-R relation does not accurately represent. It is recommended that the Z-R relation used by SAWS should be adjusted to suite the majority of convective events in the catchment situated on the Highveld of South Africa more. Instead of using an A coefficient of 200 and a b coefficient of 1.6, Marshall and Palmer relation, the events will be more represented by a Z-R relation with an A coefficient of 179 and a b coefficient of 1.5en_US
dc.language.isoenen_US
dc.publisherNorth-West University (South Africa), Potchefstroom Campusen_US
dc.subjectRain ratesen_US
dc.subjectVariabilityen_US
dc.subjectParsivel disdrometeren_US
dc.subjectWeather radaren_US
dc.subjectSiphonen_US
dc.subjectTipping-bucket rain gaugeen_US
dc.titleSpatial and temporal variability of rainfall intensity over the Mooi River catchmenten_US
dc.typeThesisen_US
dc.description.thesistypeMastersen_US


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