Is better to be a kayayei than to be unemployed: reflecting on the role of head portering in ghana’s informal economy

The implementation of neoliberal economic reforms with its resultant effects on rural agricultural economies has facilitated the migration of young girls from northern to southern Ghana to seek for alternative livelihoods in the urban informal economy as head porters (Kayayei). Using semi-structured questionnaires and interviews with 45 Kayayei in Makola and Agbogbloshie Markets, Accra, this study examines how migration as a livelihood strategy contributes to an improvement in the living conditions of young girls and their families. The paper also looks more closely into the pathways through which the livelihoods of these young female migrants may contribute to local economic development. The study highlights that Kayayei contribute to local economic development through market exchange and revenue generation, also there is significant perceived positive impact of head portering on standard of living of these young girls through improved access to income, health care and asset accumulation while their families benefit from remittances. The study concludes by advocating for the need to provide access to credit and skills training in enhancing the livelihood of Kayayei.     

Software for producing trichromatic images in astronomy

We present a software package for combining three monochromatic images of an astronomical object into a trichromatic color image. We first discuss the meaning of true colors in astronomical images. We then describe the different steps of our method, choosing the relevant dynamic intensity range in each filter, inventorying the different colors, optimizing the color map, modifying the balance of colors, and enhancing contrasts at low intensity levels. While the first steps are automatic, the last two are interactive.     

Effects of Fe3+ on Dissolution Dynamics of Carbonate Rocks in a Shallow Burial Reservoir

Dissolution of carbonates in acidic fluids, which has attracted much research attention in recent years, is of great significance for the formation of high-quality reservoirs. The dissolution stage under low temperature and low pressure in shallow burial is one of the most important processes of reservoir dissolution and transformation. However, the dissolution dynamics of carbonate rocks in shallow burial and their formation have been controversial for a long time, and there are still disputes in the dissolution processes about how associated minerals and accessory minerals (e.g., pyrite) in carbonate reservoirs influence the formation of secondary pores. Additional metal ions in acidic fluids can change fluid properties and dissolution processes, and consequently affect reservoir quality. However, there are few laboratory studies done on the effect of associated minerals on the dissolution dynamics of carbonates. To clarify the specific impact of Fe-bearing associated minerals and Fe³⁺ on the dissolution of carbonates in shallow burial reservoirs, six samples of typical carbonate rocks in the Zigui area of Hubei Province, China were studied. The dissolution kinetics of carbonates in dilute hydrochloric acid and sulfuric acid solutions containing metal ions (Fe³⁺/Ca²⁺/Mn²⁺) at ambient temperature and pressure (T?=?25 °C, P?=?1 atm) were studied, by laboratory dissolution experiments combined with numerical simulations using PHREEQC. The results show that the Fe³⁺ is of great significance on the dissolution of carbonate rocks, while the influences of Ca²⁺ and Mn²⁺ are relatively weak. The dissolutions degrees of micritic limestone (ZG-L25), dolomitic limestone (ZG-L7) and dolomite (ZG-D9) were better than the other carbonates under the influence of metal ions (Fe³⁺/Ca²⁺/Mn²⁺) in acid solutions. Therefore, the dolomite reservoir of the Cambrian Qinjiamiao Formation, the dolomitic limestone reservoir of the Tianheban Formation and the limestone reservoir of the Triassic Daye Formation in the Zigui area are potential high-quality reservoirs. The carbonate reservoirs associated with Fe-bearing minerals were easier to dissolve and formed secondary pores under shallow burial. This process is beneficial to the formation of high-quality reservoirs. Moreover, the addition of Fe³⁺ into hydrochloric acid solution may be conducive to improving the reservoirs acidizing effect. Furthermore, the results gave innovative results from multiple perspectives of geo-material science and computational geosciences, which may provide new avenues for in-depth study of carbonate dissolution in shallow burial based on water–rock reaction, chemical dissolution, computational simulation, and geological background.

     

Spatio-Geologically Informed Fuzzy Classification: An Innovative Method for Recognition of Mineralization-Related Patterns by Integration of Elemental, 3D Spatial,and Geological Information

Natural Resources Research - Recognition and mapping of mineralization-related patterns in geochemical data is a key computational analysis to achieve a predictive model of prospectivity for...     

Post‐fire thin debris flows: sediment transport and numerical modelling

The creation of a hydrophobic layer in the soil during ?res in semi‐arid environments inhibits the in?ltration of rainfall. This leads to increased rates of runoff and associated sediment transport. When the hydrophobic layer is deposited beneath the soil surface, a perched water table develops which may cause thin (1–2 cm) hillslope failures that are distinguishable from features caused by rilling and sheet?ow. Evidence for these failures was observed after a ?re near Santa Barbara, California. The amount of sediment eroded from some hillslopes was substantial, with 290 kg of sediment per metre width of hillslope delivered to the valley ?oor. The mechanics of these failures are examined with a numerical model that incorporates a stability analysis with subsurface ?ow routing along a typical hillslope pro?le. The model correctly predicts the location of the failures as well as the rainfall amount necessary to trigger them. Copyright © 2003 John Wiley & Sons, Ltd.     

The effect of bidirectional flow on tidal channel planforms

Salt marsh tidal channels are highly sinuous. For this project, ?eld surveys and aerial photographs were used to characterize the planform of tidal channels at China Camp Marsh in the San Francisco Bay, California. To model the planform evolution, we assume that the topographic curvature of the channel centreline is a key element driving meander migration. Extraction of curvature data from a planimetric survey, however, presents certain problems because simple calculations based on equally distanced points on the channel axis produce numerical noise that pollutes the ?nal curvature data. We found that a spline interpolation and a polynomial ?t to the survey data provided us with a robust means of calculating channel curvature. The curvature calculations, combined with data from numerous cross‐sections along the tidal channel, were used to parameterize a computer model. With this model, based on recent theoretical work, the relationship between planform shape and meander migration as well as the consequences of bidirectional ?ow on planform evolution have been investigated. Bank failure in vegetated salt marsh channels is characterized by slump blocks that persist in the channel for several years. It is therefore possible to identify reaches of active bank erosion and test model predictions. Our results suggest that the geometry and evolution of meanders at China Camp Marsh, California, re?ect the ebb‐dominated regime. Copyright © 2004 John Wiley & Sons, Ltd.     

Identification of groundwater potential in hard rock aquifer systems using Remote Sensing,GIS and Magnetic Survey in Veppanthattai,Perambalur, Tamilnadu

Water is an essential natural resource without which life wouldn’t exist. The study aims to identify groundwater potential areas in Vepapanthattai taluk of Perambalur district, Tamil Nadu, India, using analytic hierarchy process (AHP) model. Remote sensing and magnetic parameters have been used to determine the evaluation indicators for groundwater occurrence under the ArcGIS environment. Groundwater occurrence is linked to structural porosity and permeability over the predominantly hard rock terrain, making magnetic data more relevant for locating groundwater potential zones in the research area. NE-SW and NW-SE trending magnetic breaks derived from reduction to pole map are found to be more significant for groundwater exploration. The lineaments rose diagram indicates the general trend of the fracture to be in the NE-SW direction. Assigned normalised criteria weights acquired using the AHP model was used to reclassify the thematic layers. As a result, the taluk’s low, moderate, and high potential zones cover 25.08%, 25.68% and 49.24% of the study area, respectively. The high potential zones exhibit characteristics favourable for groundwater infiltration and storage, with factors as gentle slope of <3°, high lineament densities, magnetic breaks, magnetic low zones as indicative of dykes and cracks, lithology as colluvial deposits and land surface with dense vegetation. The depth of the fracture zones was estimated using power spectrum and Euler Deconvolution method. The groundwater potential mapping results were validated using groundwater level data measured from the wells, which indicated that the groundwater potential zoning results are consistent with the data derived from the real world.     

Assessing agricultural and hydrological drought vulnerability in a savanna ecological zone of Sub-Saharan Africa

Natural Hazards - Despite measures to mitigate drought, study on the extent of agricultural and hydrological drought vulnerability is still neglected in the savanna ecological zone of Nigeria. This...