Performance of the Global Forecast System's medium-range precipitation forecasts in the Niger river basin using multiple satellite-based products

Accurate weather forecast information has the potential to improve water resources management, energy, and agriculture. This study evaluates the accuracy of medium-range (1–15 d) precipitation forecasts from the Global Forecast System (GFS) over watersheds of eight major dams (Selingue Dam, Markala Dam, Goronyo Dam, Bakolori Dam, Kainji Dam, Jebba Dam, Dadin Kowa Dam, and Lagdo Dam) in the Niger river basin using NASA's Integrated Multi-satellitE Retrievals (IMERG) Final Run merged satellite gauge rainfall observations. The results indicate that the accuracy of GFS forecast varies depending on climatic regime, lead time, accumulation timescale, and spatial scale. The GFS forecast has large overestimation bias in the Guinea region of the basin (wet climatic regime), moderate overestimation bias in the Savannah region (moderately wet climatic regime), but has no bias in the Sahel region (dry climate). Averaging the forecasts at coarser spatial scales leads to increased forecast accuracy. For daily rainfall forecasts, the performance of GFS is very low for almost all watersheds, except for Markala and Kainji dams, both of which have much larger watershed areas compared to the other watersheds. Averaging the forecasts at longer timescales also leads to increased forecast accuracy. The GFS forecasts, at 15 d accumulation timescale, have better performance but tend to overestimate high rain rates. Additionally, the performance assessment of two other satellite products was conducted using IMERG Final estimates as reference. The Climate Hazards Group InfraRed Precipitation with Station data (CHIRPS) merged satellite gauge product has similar rainfall characteristics to IMERG Final, indicating the robustness of IMERG Final. The IMERG Early Run satellite-only rainfall product is biased in the dry Sahel region; however, in the wet Guinea and Savannah regions, IMERG Early Run outperforms GFS in terms of bias.

Desertification in the Sahel Region: A Product of Climate Change or Human Activities? A Case of Desert Encroachment Monitoring in North-Eastern Nigeria Using Remote Sensing Techniques

In Nigeria, desertification has become one of the most pronounced ecological disasters, with the impacts mostly affecting eleven frontline States. This has been attributed to a range of both nat-ural and man-made factors. This study applied a remote sensing-based change detection and indicator analysis to explore land use/land cover changes and detect major conversions from ecologically active land covers to sand dunes. Results indicate that areas covered by sand dunes (a major indicator of desertification) have doubled over the 25 years under consideration (1990 to 2015). Although about 0.71 km2 of dunes have been converted to vegetation, indicative of the success of various international, national, local, and individual afforestation efforts, conversely about 10.1 km2 of vegetation were converted to sand dunes, implying around 14 times more de-forestation compared to afforestation. Juxtaposing the progression of sand dune with climate records of the study area and examining the relationship between indicators of climate change and desertification suggested a mismatch between both processes as increasing rainfall and lower temperatures observed in 1994, 2005, 2012, and 2014 did not translated into positive feedbacks for desertification in the study area. On average, our results reveal that sand dune is progressing at a mean annual rate of about 15.2 km2 in the study area. Based on this study’s land cover change, trend and conversion assessment, visual reconciliation of climate records with land cover data, statistical analysis, observations from ground-truthing, as well as previous literature, it can be inferred that desertification in Nigeria is less a function of climate change, but more a product of human activities driven by poverty, population growth and failed government policies. Further projections by this study also reveal a high probability of more farmlands being converted to sand dunes by the year 2030 and 2045 if current practices prevail.

Fighting Violent Extremism With Narrative Intervention: Evidence From a Field Experiment in West Africa

Violent extremism is one of the major challenges of our time. A cluster-randomized controlled trial with two arms (treatment vs. control) conducted in 132 villages in the Sahel region of Burkina Faso ( N = 2,904 participants) examined whether a narrative intervention in the format of a radio drama can shift behavioral intentions, beliefs, and attitudes in contexts of violent extremism. Individuals in intervention villages participated in weekly listening sessions to the radio drama (6 months’ content) over 12 weeks. Compared with the control condition, the narrative intervention reduced justification of violence, increased behavioral intentions to collaborate with the police, and increased prioritization of addressing violent extremism. The intervention did not influence beliefs about or attitudes toward the police (e.g., trust, fairness) or beliefs about police–community collaboration. Content analysis of the narrative intervention and participants’ reception and discussion of the intervention provide insights on the processes driving the intervention’s influence.

A Survey of Tick Infestation and Tick-Borne Piroplasm Infection of Cattle in Oudalan and Séno Provinces, Northern Burkina Faso

In this study, cattle farms located in Oudalan and Séno, two provinces in the Sahel region, northern Burkina Faso, were surveyed. Cattle owners were interviewed, cattle were examined for tick infestation, and ticks as well as blood samples were collected during the dry season (October). Blood DNA samples were tested for Babesia and Theileria infections using nested PCRs and sequencing. A total of 22 herds, 174 Zebu cattle were investigated at 6 different sites. Overall, 76 cattle (43.7 %) from 18 farms (81.8%) were found infested with ticks. Cattle in Séno, adult cattle (>5 years) and those owned by the Fulani ethnic group were significantly (p < 0.05) more likely to be tick-infested. A total of 144 adult ticks belonging to five species namely: Hyalomma impeltatum, Hyalomma impressum, Hyalomma rufipes, Rhipicephalus evertsi evertsi, and Rhipicephalus guilhoni were collected from the animals. Piroplasms were detected in the blood DNA of 23 (13.2%) cattle. The cattle in Séno and adult cattle were significantly more likely to be piroplasm-positive. Five pathogens diversely distributed were identified. Theileria mutans (12/174), Babesia bigemina (5/174), Theileria annulata (3/174), and Theileria velifera (3/174) were detected for the first time in northern Burkina Faso, whereas Babesia occultans (1/174) was found for the first time in cattle in West Africa. The analysis of the sequences, including B. bigemina RAP-1a, T. annulata Tams1 genes, and the 18S rRNA genes of all the five protozoa, revealed identities ranging from 98.4 to 100% with previously published sequences. Phylogenetic analysis based on the 18S rRNA gene sequences located north Burkina Faso piroplasms in the same clade as isolates from Africa and other regions of the world. Notably, T. mutans sequences were distributed in two clades: the T. mutans Intona strain clade and the Theileria sp. (strain MSD)/ Theileria sp. B15a clade, suggesting the presence of at least two strains in the area. These findings indicate that the control of ticks and tick-borne diseases should be taken into account in strategies to improve animal health in the Sahel region.

Sectarianization, Identity, and How Terrorism Prevails: The Case of Al-Qaeda in the Islamic Maghreb (AQIM) in the Sahel Region of Africa

Various patterns have emerged as a result of globalization when it comes to controlling the kind of threats that a country may face, particularly non-traditional ones. One of them is terrorism, which occurences concentrated in specific places of the world, with North and Sub-Saharan Africa dominating for a variety of reasons. While there are other operational areas contested by various terrorist groups, the Sahel is one of the most well-known, with Al-Qaeda in the Islamic Maghreb (AQIM) being one of the most infamous terrorist groups. Legacies of weak and corrupt governments and institutions, unenforced border security, historical disadvantages, and crippled economies may serve as catalysts for such groups' growing influence, but this paper would argue that the use of sectarianism as a tool of identity mobilization is one of the reasons for AQIM's prevalence as a terrorist group.

Jihadist Insurgencies in the Sahel

Over the last decade, jihadist violence has expanded and intensified throughout the Sahel region. Jihadi groups, including Boko Haram, Islamic State West Africa Province, Jama’at Nusrat al-Islam wal-Muslimin (JNIM), Katiba Macina, and al-Qaeda in the Islamic Maghreb (AQIM), have established strongholds in many places in the central Sahel, as well as in and around the Lake Chad Basin. As they strengthen their presence, Sahelian jihadists have introduced new changes in local social relations and practices, experimented with new forms of governance, and attempted to insert themselves into the local political economy. Yet, as they gain ground and conquer new spaces, their governance model has also shown its limits: their presence has increasingly fueled deadly communal violence, and infighting among jihadi groups has become recurrent and deadly. This chapter analyses the factors and dynamics behind this surge of jihadi violence in the Sahel. It attempts to situate the global jihadi discourse within the spectrum of Islamic ideologies and discourses and elaborates on the dynamics, both at the state and local levels, that have favored the emergence of jihadi groups.

SECURITY DYNAMICS IN NORTH AFRICA AND SAHEL REGION IN THE FIRST HALF OF 2021

The first half of 2021 was marked by the continued spread of the Sars-CoV-2 virus throughout the African continent, by the desperate attempts of the UN and regional powers to implement the Ceasefire Agreement in Libya and keep security situation under control, and increasing the number of illegal migrants to Europe. The COVID-19 pandemic did not reduce terrorist acts in the Sahel region, nor did it stop the wave of small immigrant boats to Spain and Italy from Africa. But the coronavirus pandemic has led to the closure of many African borders, bringing the economies of those countries to the brink of bankruptcy and deteriorating the humanitarian situation in North Africa and the Sahel region. The international community has difficulty monitoring the situation in the area, especially the humanitarian crisis and illegal migration, which is seriously affecting security in its vicinity.

Use of the standardized precipitation and evapotranspiration index (SPEI) from 1961 to 2019 to characterize the drought trend in northern Senegal: Study of the spatiotemporal dynamics in the Ferlo watershed

The study and analysis of the dynamics of the earth's climate is one of the scientific themes that has developed mostly at the recent years. This mobilized several scientists to study, describe or characterize the climate through several methods. These methods derived from climate science have given convincing results of high scientific significance, and above all through the appreciable quality of the indicators provided. In this context, and in order to appreciate this drought trend, we are using in the framework of this study of the Standardized Index of Precipitation and Evapotranspiration (SPEI) during the period 1961-2019. Indeed, the frequency and recurrence of drought are harmful events for the traditional production system in the Sahel region. Thus, the objective of this study is to identify the multiscale distribution of droughts. The results obtained define different types of droughts as well as their prevalence. These generally indicate the prevalence of slightly wet and slightly dry traits and are followed by moderately dry and moderately wet indices over all the stations studied. However, it should be noted a periodic occurrence of more or less long droughts which resulted in the preponderance of meteorological and agricultural droughts with occurrences mainly located in the periods 1974-1989 at Linguère station (1974-1989 and 1993- 2009), in Louga, between 1962-1973 and 1974-1982 in Podor, and, at the end between 1961-1970, 1974-1985 and 1993-2000 in Matam. In addition, the drought sequences are manifested earlier at the level of the stations of Matam and Podor. On other hand, at Linguère and Podor stations, the extreme drought indices were higher for all time scales chosen (SPI_1months, SPI_3 months and SPI_12 months).

Seasonal forecasts of the Saharan heat low characteristics: a multi-model assessment

The Saharan heat low (SHL) is a key component of the West African Monsoon system at the synoptic scale and a driver of summertime precipitation over the Sahel region. Therefore, accurate seasonal precipitation forecasts rely in part on a proper representation of the SHL characteristics in seasonal forecast models. This is investigated using the latest versions of two seasonal forecast systems namely the SEAS5 and MF7 systems from the European Center of Medium-Range Weather Forecasts (ECMWF) and Météo-France respectively. The SHL characteristics in the seasonal forecast models are assessed based on a comparison with the fifth ECMWF Reanalysis (ERA5) for the period 1993–2016. The analysis of the modes of variability shows that the seasonal forecast models have issues with the timing and the intensity of the SHL pulsations when compared to ERA5. SEAS5 and MF7 show a cool bias centered on the Sahara and a warm bias located in the eastern part of the Sahara respectively. Both models tend to underestimate the interannual variability in the SHL. Large discrepancies are found in the representation of extremes SHL events in the seasonal forecast models. These results are not linked to our choice of ERA5 as a reference, for we show robust coherence and high correlation between ERA5 and the Modern-Era Retrospective analysis for Research and Applications (MERRA). The use of statistical bias correction methods significantly reduces the bias in the seasonal forecast models and improves the yearly distribution of the SHL and the forecast scores. The results highlight the capacity of the models to represent the intraseasonal pulsations (the so-called east–west phases) of the SHL. We notice an overestimation of the occurrence of the SHL east phases in the models (SEAS5, MF7), while the SHL west phases are much better represented in MF7. In spite of an improvement in prediction score, the SHL-related forecast skills of the seasonal forecast models remain weak for specific variations for lead times beyond 1 month, requiring some adaptations. Moreover, the models show predictive skills at an intraseasonal timescale for shorter lead times.