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International Institute for Geo-Information Science and Earth Observation (ITC) 2012

Assessing the potential of geonetcast earth observation and in situ data for drought early warning and monitoring in Tegray, Ethiopia

Ataklti, T.Y. (Tewelde Yideg)

Titre : Assessing the potential of geonetcast earth observation and in situ data for drought early warning and monitoring in Tegray, Ethiopia

Auteur : Ataklti, T.Y. (Tewelde Yideg)

Etablissement de soutenance : University of Twente International Institute for Geo-Information Science and Earth Observation (ITC)

Grade : Master of Science in Geo-Information Science and Earth Observation 2012

Résumé
Rainfall is a one of the most dominant factors governing drought occurrences. Its representing at the global, regional as well as local scale is a major issue in drought assessment and early warning. Observing of rainfall in the Tigray region of Ethiopia requires a combination of satellite rainfall and rain gauge data. However, Tigray has a sparse weather stations network and lack of skilled manpower to collect the meteorological data and to provide quality reports timely. In this study, the potential of GEONETCast satellite rainfall data was evaluated against other satellite rainfall data, currently used in Ethiopia for drought early warning and also In-situ data. Drought and food security early warning is currently done in Ethiopia using the LEAP methodology data calculate rainfall-based water requirement satisfaction (WRSI) and crop yield reduction (YR) indices. In this study, an attempt is made to see whether satellite energy balance ET-based WRSI and YR indices, derived from near real time GEONETCast data could be used to perform an independent evaluation of agricultural drought risk and crop failure in Tigray. Five years (2006 to 2010) meteorological data was collected from Tigray Branch meteorology Office(TBMO) and Ethiopia National Meteorology Agency (NMA). Three years (2008 to 2010) of statistical crop data were obtained from the Tigray Bureau of Agriculture and Rural Development (BoARD). Five month (May to September 2010) of MSGMPE satellite rainfall data were collected, which is produced by EUMETSAT. Daily Evapotranspiration 13 6 images of (DMET) were obtained from LSA SAF. Decadal RFE2.0 rain fall estimates for the same period, daily FEWS NET (ETo from July 15 to November 30, 2010) and GlobCover 20 09 land cover data was used together with field knowledge to classify land cover of the study area. The results of the rainfall inter-comparison of MS GMPE, RFE2.0, TAMSAT and In-situ station data showed that MSGMPE 3-km data permitted a good assessment of areal rainfall in Tigray (for 2010). Further use of MSGMPE can be recommended to gene rate daily or decadal district rainfall amounts with good accuracy. The comparison of the satellite ET-based WRSI and YR from GEONETCast data with LEAP standard output (WRSI and YR) and crop yield statistics from Tigray BoARD, showed that there is potential to use satellite ET from GEONETCast to evaluate crop drought stress and yield reduction in the Tigray region. The GlobCover (2009) dataset did not permit reliable assessment of seasonal rain-fed land cover in the Tigray region, and own field knowledge and other sources were needed to generate rain-fed land cover information. More ground validation for land cover is needed to use these satellite land cover data for operational purposes. It can be conclude that MSG-based satellite rainfall estimation and ET-based drought indices (WRSI and YR) derived from GEONETCast, can help us for decision making in agricultural drought early warning and monitoring in Ethiopia. In this study application is tested especially in areas like Tigray where weather and other monitoring stations are sparsely available, and drought prone areas are very present who require close monitoring for drought and agricultural production and livelihood protection.

Mots clés : satellite rainfall, satellite eva potranspiration, drought, water requirement satisfaction index, crop yield reduction, GEONETCast, LEAP.

Version intégrale (ITC)

Page publiée le 2 avril 2018, mise à jour le 12 octobre 2018