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Universiteit Gent (2011)

Assessment of rain erosivity and aridity in Central Tanzania

CHAMPUNGA Rashidi Ahamadi

Titre : Assessment of rain erosivity and aridity in Central Tanzania

Auteur : CHAMPUNGA Rashidi Ahamadi

Université de soutenance : Universiteit Gent

Grade : Master of Science (MS) Physical Land Resources 2011

To understand the factors causing land degradation and desertification processes a precise study on rainfall characteristics is important. In this study therefore secondary meteorological data including daily rainfall and temperature for 10 successive years (2000-2009) were collected from 13 meteorological stations in 7 different administrative regions named : Mwanza, Shinyanga, Dodoma, Tabora, Arusha, Singida and Northern part of Iringa region, all located in Central part of Tanzania. The meteorological data were used to assess aridity of drylands prone to desertification. Three different aridity indices methodologies including : Index of De Martonne (1926), Index of Thornthwaite (1948), UNEP (1997) and the Bagnouls-Gaussen Index (BGI) were used in this study. The results from this assessment have revealed three types of climate in Central Tanzania : humid climate, dry sub-humid climate and semiarid climate. The humid climate includes three regions of Mwanza, Tabora and Shinyanga. The dry sub-humid climate includes Singida and Arusha regions while the semi-arid climate includes Dodoma and Iringa region. In order to quantify the relative distribution of the rainfall patterns, a statistical derived index known as the Precipitation Concentration Index (PCI) was used. The results indicate that the rainfall distribution is affected by seasonal effects, strongly confined by a typical dry or wet period. Further, the rainfall aggressiveness and erosivity were assessed according to the Modified Fournier Index (MFI) and CORINE (1995) methodology, respectively. A specific empirical erosion model as proposed by Morgan (1986) is also used for assessment of erosivity in addition to the CORINE (1995) methodology. The results revealed a variation in rainfall aggressiveness between high to very high and strong rainfall erosivity in all regions. Finally, the correlation analysis was performed between MFI and the USLE erosivity factor R=EI30. The result show a highly significant relationship between MFI and the USLE erosivity factor R=EI30 in five regions out of seven. This leads to the conclusion that Central Tanzania is characterised by high aggressive and erosive types of rainfall which is the cause of serious experienced soil degradation and desertification.

Source : Pedon 23 - Physical Land Resources - Universiteit Gent

Page publiée le 31 décembre 2015, mise à jour le 12 décembre 2017