Land surface dynamics and environmental challenges of the Niger Delta, Africa: Remote sensing-based analyses spanning three decades (1986e2013) Claudia Kuenzer a, * , Sybrand van Beijma b , Ursula Gessner a , Stefan Dech a, c a Earth Observation Center, EOC, of the German Aerospace Center, DLR, Oberpfaffenhofen, 82234 Wessling, Germany b Airbus Defence and Space, Europa House, Southwood Crescent, Farnborough, GU14 0NL, United Kingdom c Department of Geography and Geology, University of Wuerzburg, Wuerzburg, Germany Keywords: Niger Delta Remote sensing Oil industry Coastal change Gas flaring abstract The Niger Delta, the largest river delta on the African continent, is one of the most densely populated river deltas globally and hosts the world's third largest mangrove forest. It is a major biodiversity hot spot of our planet. At the same time the delta is home to Africa's largest oil reserves and responsible for a skyrocketing GDP development of Nigeria since the 1970s. Nigeria ranks 13th among all oil producing countries, but oil exploitation also brought with it severe environmental degradation, leading to the delta's nomination for a place on the top 10 list of the “World's Worst Polluted Places Report” in 2013. Despite the outstanding importance of the region for Nigeria, Africa, and the international community most studies published focus mainly on topics of geology, geochemistry, and environmental toxicology. Studies employing earth observation satellite data to assess Niger Delta dynamics are rare. This paper aims at contributing to an overview of Niger Delta geography and environmental threats and challenges, as well as to an understanding of Niger Delta land surface dynamics from 1986 to 2013. Covering the complete delta, we present results of land cover change analyses, results of an assessment of coastline dynamics, as well as the manifestation of oil exploitation activity as expressed via oil access canal dredging and gas flaring, monitored within the 27 year time span investigated. © 2014 Elsevier Ltd. All rights reserved. Introduction: geography of the Niger Delta and socio- ecological threats Geography of the Niger Delta The Niger Delta in Nigeria is Africa's largest river delta and covers an area exceeding 29,900 km 2 (Goudie, 2005) (see Fig. 1). The Niger River discharges on average over 30,000 m 3 of water per second into the Gulf of Guinea. Currently, 20% of Nigeria's popu- lation e over 30 million people e live in the Niger Delta (National Bureau of Statistics, 2013). The largest city in the Delta is Port Harcourt, with a population exceeding one million inhabitants. Delta genesis started in the Cretaceous (Short & Staeuble, 2004) and progressed according to marine transgressive and regressive cycles of differing durations in response to eustatic sea level changes. The horizontal sediment structure of the delta is characterized by different marine and fluvially deposited layers composed of sand, silt, and clay (Abam, 1997). A most compre- hensive and novel stratigraphy and sedimentology of the Niger Delta has recently been published by Reijers (2011). Geo- morphologically, the recent Niger Delta can be categorized into three different regions: the continental part of the delta, the tran- sitional area dominated by land and ocean interactions in the coastal zone, and the delta's marine territories (Ugbe, 2011). This humid region receives between 2400 and 4200 mm of precipitation per year, mainly during the rainy season. Flora and fauna in the delta are very diverse. The largest mangrove forest of Africa e and the third largest globally e can be found in the delta and comprises an area between 5000 and 8600 km 2 depending on the literature source (Fatoyinbo & Simard, 2012; Isebor & Awosika, 1993; Ohimain, 2003). The Niger Delta region is characterized by an extraordinary aquatic and terrestrial biodiversity, above all related to the aforementioned mangrove forest areas, which also provide a substantial number of ecosystem services (Kuenzer & Quoc 2013; Prince & Arokoyu, 2010; Quoc, Oppelt, & Kuenzer, 2012). But not only the near-coastal areas are * Corresponding author. Tel.: þ49 (0)8153 28 3280; fax: þ49 (0)8153 28 1458. E-mail address: claudia.kuenzer@dlr.de (C. Kuenzer). Contents lists available at ScienceDirect Applied Geography journal homepage: www.elsevier.com/locate/apgeog http://dx.doi.org/10.1016/j.apgeog.2014.07.002 0143-6228/© 2014 Elsevier Ltd. All rights reserved. Applied Geography 53 (2014) 354e368