Mapping Prosopis Juliflora in West Somaliland with Landsat-8 Satellite Imagery and Ground Information
Prosopis juliflora is a drought-tolerant fast-growing tree species originating from South and Central America with a high invasion potential in arid and semi-arid areas in Africa. It was introduced in Somaliland in the 1980s and is reported to have spread vigorously since. Despite being recognized as a serious issue in the country, the actual scale of the problem is unknown. In this study, we mapped the species in a study area that includes the capital, Hargeisa, using Landsat 8 satellite imagery. During a field campaign in 2015, we collected canopy-level spectral signatures of P. juliflora and native trees to analyse the potential use of spectral data in discriminating the invasive species. P. Juliflora was found to be generally distinguishable because of its greater vigour during the dry season. We tested the accuracy of the random forest classifier and different classification set-ups, varying the spatial resolution (original 30m vs pan-sharpened 15m) and image acquisition dates (during the wet season, the dry season and a combination of the two). Best overall accuracy (84%) was achieved by using pan-sharpened data from the two seasons. About 30 years since its introduction, the invasive species was detected in 9% of the total investigated area with highest occurrence in the proximity of human settlements and along seasonal watercourses. © 2016 The Authors. Land Degradation and Development published by John Wiley & Sons, Ltd.An Assessment of the Surface Water Resources of the Juba-Shabelle Basin in Southern Somalia
The water resources of the Juba and Shabelle rivers in southern Somalia are important for irrigation and food production, but are influenced by seasonal floods. Prior to the outbreak of civil war in 1991, the Somali Ministry of Agriculture successfully operated a hydrometric network covering the Juba and the Shabelle, data from which provided input to a flow forecasting model. The war resulted in the neglect and abandonment of monitoring stations and an enforced cessation of data collection and management. In 2001 and 2002, part of the pre-war hydrometric network was reinstated and water levels were again recorded at some stations. This paper examines the implications of the 11-year hiatus in data collection, and the now much reduced monitoring network, for assessing and managing the surface water resources. The problems faced have relevance to other basins, within Africa and elsewhere, where there has been a similar decline in data collection.Mapping Forest Degradation Caused by the Recent Increase of Charcoal Production in Southern Somalia
Following more than 20 years of civil unrest, environmental information for Southern Somalia is scarce while there is clear evidence that the war economy fueled by the conflict is rapidly depleting the country’s natural resources and especially the woody biomass. Wood charcoal production is one of the most relevant businesses supporting war regimes such as the extreme Islamist group Al Shabaab, which has ruled in Southern Somalia from 2006 to 2012 and is still occupying large areas. In this study we first used Very High Resolution (VHR) satellite imagery of February 2013 for developing a semi-automatic mapping method of charcoal production sites as a proxy of tree loss over a 754 km2 woody area along the Juba river in Southern Somalia. The accuracy of semiautomatic charcoal production site detection varied between 80 and 95% as compared to visual interpretation and reduced significantly the subjectivity and the required time. The analysis was then applied to previous years (2011-2012) for a 52.6 km2 subset of the study area, and led to a tree loss estimation of 8.63%, corresponding to 15,434 trees over the 3 years period. The results are crucial for better understanding the dimension and impact of charcoal production in Southern Somalia and are a first step towards the development of a charcoal production monitoring system.A Framework for National Assessment of Land Degradation in the Drylands: A Case Study of Somalia
Land degradation is a gradual, negative environmental process that is accelerated by human activities. Its gradual nature allows degradation to proceed unnoticed, thus reducing the likelihood of appropriate and timely control action. Presently, there are few practical frameworks to help countries design national strategies and policies for its control. The study presented here developed a framework for the national assessment of land degradation. This framework is envisaged to support governments in formulating policies on land degradation. It uses time-series remote sensing data to identify the rate and extent of land degradation, local experts to identify prevalent degradation types and drivers of the degradation and field observations to validate the overall assessment. Its simplicity, use of freely downloadable input data and self-triangulation of the assessment methods make it suitable for rapid assessment of land degradation on a national scale. It was tested in Somalia, where it exhibited accuracy greater than 60 per cent when assessing land degradation. This framework is relevant for designing national strategies and policies that address land degradation and provides an opportunity for accurate identification of areas to target with comprehensive local assessment. Testing of the framework in Somalia showed that about one-third of the country was degraded because of loss of vegetation cover, topsoil loss and to the decline of soil moisture. Overgrazing, excessive tree cutting and poor agronomic practices in agricultural areas were identified as the primary drivers of the country’s land degradation. These drivers are encouraged by the prevailing communal land tenure practices, poor governance and civil war. Copyright © 2011 John Wiley & Sons, Ltd.Mapping Charcoal Driven Forest Degradation during the Main Period of Al-Shabaab Control in Southern Somalia
Following more than 20 years of civil unrest, environmental information for Southern Somalia is scarce while there is clear evidence that the war economy fueled by the conflict is rapidly depleting the country's natural resources and especially the woody biomass. Wood charcoal production is one of the most relevant businesses supporting war regimes such as the extreme Islamist group Al-Shabaab, which has ruled in Southern Somalia from 2006 to 2012 and is still occupying large areas. In this study, we map and quantify the tree loss suffered by the region due to the rapid increase in illegal charcoal production and export over recent years. Very high-resolution (VHR) satellite imagery is used to visually count charcoal production sites as a proxy of tree loss in two sample areas within the lower Juba region of Southern Somalia. The image interpretation allows mapping the charcoal production sites as well as estimating tree loss rates above 7% over 5 years. The results are crucial for understanding the exact dimension and effects of the loss of woody biomass and for planning conservation and recovery interventions in the concerned area.