Drought propagation in the hydrological cycle in a semiarid region: a case study in the Bilate catchment,Ethiopia

Hydrogeology Journal - Drought is a temporal decrease in water availability and occurs in all climatic regions. Droughts propagate through the hydrological cycle, e.g., meteorological drought...     

Identification of the influencing factors on groundwater drought and depletion in north-western Bangladesh

Groundwater drought is a specific type of hydrological drought that concerns groundwater bodies. It may have a significant adverse effect on the socio-economic, agricultural, and environmental conditions. Investigating the effect of different climatic and anthropogenic factors on groundwater drought provides essential information for sustainable planning and management of (ground) water resources. The aim of this study is to identify the influencing factors on groundwater drought in north-western Bangladesh, to understand the forcing mechanisms. A multi-step methodology is proposed to achieve this objective. The standardised precipitation index (SPI) and reconnaissance drought index (RDI) have been used to quantify the aggregated deficit between precipitation and the evaporative demand of the atmosphere, i.e. meteorological drought. The influence of land-cover patterns on the groundwater drought has been identified by calculating spatially distributed groundwater recharge as a function of land cover. Groundwater drought is defined by a threshold method. The results show that the evapotranspiration and rainfall deficits are determining meteorological drought, which shows a direct relation with groundwater recharge deficits. Land-cover change has a small effect on groundwater recharge but does not seem to be the main cause of groundwater-level decline (depletion) in the study area. The groundwater depth and groundwater-level deficit (drought) is continuously increasing with little correlation to meteorological drought or recharge anomalies. Overexploitation of groundwater for irrigation seems to be the main cause of groundwater-level decline in the study area. Efficient irrigation management is essential to reduce the growing pressure on groundwater resources and ensure sustainable water management.     

Potential application of remote sensing systems to the African rift system

Interdisciplinary interpretation of satellite and geologic-geophysical data can be applied to East Africa as a cost-effective means of regional tectonic evaluation. All available data sources: geologic and geophysical maps and remote sensing images should be used. Remote sensing methods are very efficient for the “synoptic overlook” necessary to pinpoint areas for more detailed investigation.The use of satellite imagery is a way of applying and testing structural frameworks for mineral potential as surface reflections of deep tectonic features can be recognized. Mineralization can be correlated with tectonic lineaments that are probably related to persistent discontinuities in the upper mantle. The outlining of these discontinuities would be of value in the search for the understanding of riftogenesis and in the search for mineralization.This paper is a review of such work with a specific example from Canada, and how the approach can be applied to Africa for continuing research on recent crustal movements.