Wetlands are valuable ecosystems providing a variety of important ecosystem services such as food supply and flood control. Due to increasing anthropogenic influences and the impact of climate ...change, wetlands are increasingly threatened and degraded. An effective monitoring of wetlands is therefore necessary to preserve and restore these endangered ecosystems. Earth Observation (EO) data offer a great potential to support cost-effective and large-scale monitoring of wetlands. Current state-of-the-art methods for wetland mapping, however, require large training data and manual effort and can therefore only be locally applied. The focus of this study is to evaluate a methodology for large-scale and highly automated wetland mapping based on current EO data streams. For this purpose, an algorithm for water and wetness detection based on multi-temporal optical imagery and topographic data is presented. Suitable spectral indices sensitive to water and wetness were identified using feature selection methods based on mutual information between optical indices and occurrence of water and wetness. In combination with the Topographic Wetness Index (TWI), these were used to derive monthly water and wetness masks using a dynamic thresholding approach. Aggregating all observations corrected for seasonal bias yielded flooding and wetness frequencies and the Water Wetness Presence (or Probability) Index (WWPI) as an indicator for wetland occurrence or a pre-inventory. To demonstrate the applicability of the proposed method, the algorithm is demonstrated at three study sites with different wetland types in Kenya/Uganda, Algeria, and Austria using Sentinel-2 MultiSpectral Instrument (MSI) imagery. For all sites, the overall accuracy was above 92%. User's and producer's accuracies were higher for water (>96%) than for wetness (>75%). Due to the high degree of automation and low processing time, the proposed method is applicable on a large scale and has already been applied during the production of the Copernicus High Resolution Water-Wetness Layer and within the European Space Agency (ESA) project GlobWetland Africa.
•A highly automated algorithm for water and wetness detection is proposed.•Tile-based image thresholding is applied to spectral and topographic indices.•Water is automatically detected with very high accuracy across different regions.•The Water and Wetness Probability Index provides a basic wetland inventory.
We compiled published and newly-obtained data on the directly-measured atmospheric deposition of total phosphorus (TP), filtered total phosphorus (FTP), and inorganic phosphorus (PO4-P) to open land, ...lakes, and marine coasts. The resulting global data base includes data for c. 250 sites, covering the period 1954 to 2012. Most (82%) of the measurement locations are in Europe and North America, with 44 in Africa, Asia, Oceania, and South-Central America. The deposition rates are log-normally distributed, and for the whole data set the geometric mean deposition rates are 0.027, 0.019 and 0.14 g m(-2) a(-1) for TP, FTP and PO4-P respectively. At smaller scales there is little systematic spatial variation, except for high deposition rates at some sites in Germany, likely due to local agricultural sources. In cases for which PO4-P was determined as well as one of the other forms of P, strong parallels between logarithmic values were found. Based on the directly-measured deposition rates to land, and published estimates of P deposition to the oceans, we estimate a total annual transfer of P to and from the atmosphere of 3.7 Tg. However, much of the phosphorus in larger particles (principally primary biological aerosol particles) is probably redeposited near to its origin, so that long-range transport, important for tropical forests, large areas of peatland and the oceans, mainly involves fine dust from deserts and soils, as described by the simulations of Mahowald et al. (Global Biogeochemical Cycles 22, GB4026, 2008). We suggest that local release to the atmosphere and subsequent deposition bring about a pseudo-diffusive redistribution of P in the landscape, with P-poor ecosystems, for example ombrotrophic peatlands and oligotrophic lakes, gaining at the expense of P-rich ones. Simple calculations suggest that atmospheric transport could bring about significant local redistribution of P among terrestrial ecosystems. Although most atmospherically transported P is natural in origin, local transfers from fertilised farmland to P-poor ecosystems may be significant, and this requires further research.
In this study, historical surface solar radiation (1850–2005) and future photovoltaic power output (2006–2100) are analyzed to investigate the spatial distribution and long-term variation in global ...solar energy based on the Coupled Model Intercomparison Project Phase 5 (CMIP5) models and the Global Energy Balance Archive (GEBA) database. The results show that global mean surface solar radiation significantly decreased by 0.014 W m−2 year−1 in 1850–2005. According to the Model for Interdisciplinary Research on Climate (MIROC5), surface solar radiation significantly decreased by 3.42 W m−2 year−1 in 1951–1992 and increased by 4.75 W m−2 year−1 in 1993–2005. Global dimming and brightening were observed before and after the 1990s, respectively. The transition of surface solar radiation from dimming to brightening in Europe and the southeastern United States was detected in the 1980s. Stations in Northeast China, Japan, Southeast Africa, the Middle East, and the west coast of India all showed renewed decreasing trends after the 1990s. The direct and indirect effects of anthropogenic aerosols and cloudiness in different periods and regions were the main causes of the changes. To better understand the utilization of global solar energy, global potential photovoltaic power outputs were estimated in future scenarios with an empirical model. Significant increases in potential photovoltaic power are expected in East Asia, Europe, Central Africa and Central America in 2006–2100. The largest increase is expected in central China, where increases are occurring at 3 kWh m−2 year−1. Significantly decreasing potential photovoltaic power is observed in North Africa, the Middle East, Central Asia and Australia. The greatest decrease is observed in the Tibetan Plateau area (approximately −3.0 kWh m−2 year−1 in 2006–2100). With respect to the global distribution of potential photovoltaic power output, large quantities of photovoltaic power are distributed in the northern and southern parts of Africa, the Middle East, the Tibetan Plateau area, the west coasts of North and South America and most of Australia. The yearly mean sum photovoltaic power in these regions is larger than 2000 kW h m−2. Due to the long-term decreasing photovoltaic power (0.67 kWh m−2 year−1) expected worldwide in 2006–2100, effective and rational utilization of solar energy is of great importance.
Annual PV power for 34 CMIP5 model mean and MIRCO5 in historical experiments, RCP4.5 and RCP8.5 scenarios. Display omitted
•Global mean Surface downwelling shortwave radiation decreased during 1850–2005.•The predicted global mean potential photovoltaic power will decrease from 2006 to 2100.•High photovoltaic power is located in North Africa, Middle East, Central Asia and Australia.•Photovoltaic power in East Asia, Europe, Central Africa and America will increase in future.
Extended kin networks are an important social and economic resource in Africa. Existing research has focused primarily on intergenerational ties, but much less is known about "lateral" ties, such as ...those between siblings. In contexts of high adult mortality (i.e., fewer parents and grandparents) sibling interdependencies may assume heightened importance, especially during the transition to adulthood.
In this paper, we extend the resource dilution perspective that dominates research on sibling relationships in early childhood and propose an alternate framework in which siblings represent a source of economic support that contributes positively to educational outcomes at later stages of the life course.
We draw upon longitudinal data from young adults (age 15-18) in southern Malawi to assess the scope and magnitude of economic transfers among sibship sets. We then explore the relationships between sibship size, net economic transfers between siblings, and four measures of educational progress.
First, exchanges of economic support between siblings are pervasive in the Malawian context and patterned, especially by birth order. Second, economic support from siblings is positively associated with educational attainment, as well as with the odds of being at grade level in school, both contemporaneously and prospectively.
During young-adulthood, economic support from siblings acts as a buffer against the negative association between sibship size and schooling outcomes that has been documented at earlier ages.
We question the established notion that siblings unilaterally subtract from resource pools, and argue that sibling support may be consequential for a wide range of demographic outcomes in a variety of cultural contexts. Our findings point to the need for additional research on the importance of lateral kinship ties across cultural settings and throughout the life course.
There has been a growing interest in jatropha- and sugarcane-based biofuels across Sub-Sahara Africa. Biofuel expansion in the region reflects policy concerns related to energy security, poverty ...alleviation and economic development. However, biofuels have also been linked to numerous environmental and socioeconomic impacts such as GHG emissions, water availability/pollution, deforestation, biodiversity loss, poverty alleviation, energy security, loss of access to land and food security to name just a few. Yet there is (a) an insufficient understanding of these impacts (and their synergies) in Sub-Sahara Africa, and (b) a lack of policies that could regulate the biofuel sector and ensure its viability while at the same time preventing its negative impact. The aim of this literature review is to synthesize the current knowledge about biofuel impacts in Africa and to identify priority policy areas that should be targeted for enhancing biofuel sustainability in the continent. The findings of this review indicate that biofuel impacts can be positive or negative depending on several factors such as the feedstock, the environmental/socio-economic context of biofuel production, and the policy instruments in place during biofuel production, use and trade. In most cases there are significant trade-offs but at least part of the negative impacts can be mitigated through careful planning. The incomplete and piecemeal understanding of these trade-offs combined with agronomic, institutional and market failures are currently the most important barriers for the viability and sustainability of biofuel investments in the continent.
•The impact of FDI inflows on industrialization in Africa is analyzed.•Panel data from 49 countries over the period from 1980 to 2009 are used.•FDI did not have a significant impact on the ...industrialization process.•It is inferred that it is due to the over-reliance on natural resources.•Inadequate government interventions may also explain this result.
This paper examines the relationship between inward foreign direct investment (FDI) and the industrialization process in Africa. It uses panel data from 49 countries over the period of 1980–2009. The results indicate that FDI did not have a significant impact on the industrialization of these countries, while other variables, such as the size of the market, the financial sector, and international trade were important. This study concludes that the role of FDI in the transformation agenda, which is currently being discussed in Africa, should be carefully analyzed to maximize the impact of these capital inflows.
Abstract
The development of wind energy in West Africa is essential to meet the rising energy needs due to population growth and societal development. However, only few studies have investigated the ...changes in turbine hub-height wind characteristics over the region under changing climate. This study aims at assessing the impact of climate change on wind power density (WPD) over West Africa using the simulations from the newly developed Coupled Model Intercomparison Project version 6 (CMIP6) models. The CMIP6 near-surface wind speed and directions simulations for the historical climate (1985–2014) were compared with ERA5 reanalysis data using multiple descriptive statistics. Relative to ERA5 reanalysis, the CMIP6 models alongside their multimodel ensemble mean (EnsMean) realistically reproduce the near-surface wind characteristics (i.e. wind speed and directions) across most subregions of West Africa, although noticeable biases still exist. Overall, the CMIP6 EnsMean performs better than most individual models at capturing the near-surface wind speed over the region. Under global warming, we find a robust projected increase (about 70%) in WPD over the Guinea coast subregion of West Africa, especially in June–July–August season. The December–January–February and March–April–May seasons show alternating projected WPD increase and decrease, with predominantly robust projected decrease over the Sahel subregion. The projected increase over the Guinea coast has strong temporal qualities, with the end of the century (2070–2099) changes showing stronger magnitude compared to the mid-century (2040–2069) changes, and thus may provide a commercially viable renewable energy source.
On 20 May 2014, Malawi arranged tripartite elections for president, parliament and local councils. The elections were remarkable for several reasons, seen from both an African and a Malawian ...perspective. Despite an uneven electoral playing field, the elections were highly competitive, ultimately leading to the country's second turnover of power when opposition challenger Peter Mutharika defeated the incumbent president, Joyce Banda. The electoral results also show a return to regionalistic voting patterns and a continuing weakening of political parties, as independent candidates emerged as the largest group in parliament. Although the results were generally credible, the election remains controversial. Several stakeholders questioned the general integrity of the process, and significant logistical problems on election day might have harmed public trust in the electoral authorities. Am 20. Mai 2014 wurden in Malawi gleichzeitig Präsidentschafts-, Parlaments- und Gemeinderatswahlen abgehalten. Der Wahlausgang war bemerkenswert, und zwar sowohl aus nationaler als auch aus kontinentaler Perspektive. Trotz ungleicher Ausgangsbedingungen für die Kandidaten waren die Wahlen hochkompetitiv und führten im Ergebnis zum zweiten Machtwechsel in der Geschichte des Landes: Der Herausforderer der Opposition, Peter Mutharika, konnte der amtierenden Präsidentin Joyce Banda eine Niederlage bereiten. Die Wahlergebnisse zeigten zudem eine Rückwendung zu regionalistischem Wahlverhalten und die weitere Schwächung der politischen Parteien: Nach der Wahl stellten unabhängige Abgeordnete die größte Gruppe im Parlament. Im Großen und Ganzen verliefen die Wahlen glaubwürdig, dennoch wurden sie kontrovers beurteilt. Einige Interessengruppen stellten die Integrität des Wahlprozesses infrage, und die Tatsache, dass es am Wahltag zu erheblichen logistischen Problemen kam, könnte das Vertrauen der Öffentlichkeit in die verantwortlichen Institutionen beschädigt haben.
Sparse gauge networks in Sub-Saharan Africa (SSA) limit our ability to identify changing precipitation extremes with in situ observations. Given the potential for satellite and satellite-gauge ...precipitation products to help, we investigate how daily gridded gauge and satellite products compare for seven core climate change precipitation indices. According to a new gauge-only product, the Rainfall Estimates on a Gridded Network (REGEN), there were notable changes in SSA precipitation characteristics between 1950 and 2013 in well-gauged areas. We examine these trends and how these vary for wet, intermediate, and dry areas. For a 31 year period of overlap, we compare REGEN data, other gridded products and three satellite products. Then for 1998-2013, we compare a set of 12 satellite products. Finally, we compare spatial patterns of 1983-2013 trends across all of SSA. Robust 1950-2013 trends indicate that in well-gauged areas extreme events became wetter, particularly in wet areas. Annual totals decreased due to fewer rain days. Between 1983 and 2013 there were positive trends in average precipitation intensity and annual maximum 1 d totals. These trends only represent 15% of SSA, however, and only one tenth of the main wet areas. Unfortunately, gauge and satellite products do not provide consensus for wet area trends. A promising result for identifying regional changes is that numerous satellite products do well at interannual variations in precipitation totals and number of rain days, even as well as some gauge-only products. Products are less accurate for dry spell length and average intensity and least accurate for annual maximum 1 d totals. Tropical Rainfall Measuring Mission Multi-satellite Precipitation Analysis (3B42-V7) and Climate Hazards center Infrared Precipitation with Stations (CHIRPS v2.0) ranked highest for multiple indices. Several products have seemingly unrealistic trends outside of the well-gauged areas that may be due to influence of non-stationary systematic biases. Social media abstract. Sparse data show increasing Africa rainfall extremes and satellite products fill some missing pieces.
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