Early warning systems development for agricultural drought assessment in Nigeria Oluwatola Adedeji & Adeyemi Olusola & Godstime James & Halilu Ahmad Shaba & Israel Ropo Orimoloye & Sudhir Kumar Singh & Samuel Adelabu Received: 14 July 2020 /Accepted: 3 November 2020 # Springer Nature Switzerland AG 2020 Abstract The existing drought monitoring mechanisms in the sub-Saharan Africa region mostly depend on the conventional methods of drought monitoring. These methods have limitations based on timeliness, objectiv- ity, reliability, and adequacy. This study aims to identify the spread and frequency of drought in Nigeria using Remote Sensing/Geographic Information Systems tech- niques to determine the areas that are at risk of drought events within the country. The study further develops a web-GIS application platform that provides drought early warning signals. Monthly NOAA-AVHRR Path- finder NDVI images of 1 km by 1 km spatial resolution and MODIS with a spatial resolution of 500 m by 500 m were used in this study together with rainfall data from 25 synoptic stations covering 32 years. The spatio- temporal variation of drought showed that drought oc- curred at different times of the year in all parts of the country with the highest drought risk in the north- eastern parts. The map view showed that the high drought risk covered 5.98% (55,312 km 2 ) of the country’s landmass, while low drought risk covered 42.4% (391,881 km 2 ) and very low drought risk areas 51.5% (476,578 km 2 ). Results revealed that a strong relationship exists between annual rainfall and season- integrated NDVI (r 2 = 0.6). Based on the spatio- temporal distribution and frequency of droughts in Ni- geria, drought monitoring using remote sensing tech- niques of VCI and NDVI could play an invaluable role in food security and drought preparedness. The map view from the web-based drought monitoring system, developed in this study, is accessible through localhost. Keywords Drought . NOAA-AVHRR . NDVI . MODIS . Spatio-temporal Introduction Early warning systems are globally becoming a pre- requisite for an effective disaster reduction implementa- tion plan. These are ensembles of toolkits needed to ensure a proactive design that could tackle headlong the impact of natural disasters be it flood, fire, hurricane, drought, dust storm, pest and diseases, etc. The design of early warning systems varies and the components are largely different. However, the basic idea behind a Environ Monit Assess (2020) 192:798 https://doi.org/10.1007/s10661-020-08730-3 O. Adedeji : G. James : H. A. Shaba Department of Strategic Space Applications, National Space Research and Development Agency (NASRDA), Abuja, Nigeria A. Olusola (*) : S. Adelabu Department of Geography, University of the Free State, Bloemfontein, South Africa e-mail: olusolaao@ufs.ac.za I. R. Orimoloye Centre for Environmental Management, University of the Free State, Bloemfontein, South Africa I. R. Orimoloye Department of Geography and Environmental Science, University of Fort Hare, Alice, South Africa S. K. Singh K. Banerjee Centre of Atmospheric & Ocean Studies, IIDS, Nehru Science Centre, University of Allahabad, Prayagraj, Uttar Pradesh 211002, India