Identifying residence times and streamflow generation processes using ?18O and ?2H in meso-scale catchments in the Abay/Upper Blue Nile, Ethiopia

Measurements of the stable isotopes oxygen-18 (18O) and deuterium (2H) were carried out in two meso-scale catchments, Chemoga (358 km2) and Jedeb (296 km2) south of Lake Tana, Abay/Upper Blue Nile basin, Ethiopia. The region is of paramount importance for the water resources in the Nile basin. Stable isotope composition in precipitation, spring water and streamflow were analyzed (i) to characterize the spatial and temporal variations of water fluxes; (ii) to estimate the mean residence time of water using a sine wave regression approach; and (iii) to identify runoff components using classical two component hydrograph separations at a seasonal time scale. The results show that the isotopic composition of precipitation exhibit marked seasonal variations, which suggests different sources of moisture generation for the rainfall in the study area. The Atlantic–Indian ocean, Congo basin, and the Sud swamps are the likely the potential moisture source areas during the main rainy (summer) season. While, the Indian–Arabian, and Mediterranean Sea moisture source areas during little rain (spring), and dry (winter) seasons. The spatial variation of the isotopic composition is affected by the amount effect and to less extent by altitude and temperature effects. A mean altitude effect of ?0.12\u89 (100 m)?1 for 18O and ?0.58\u89 (100 m)?1 for 2H were discernable in precipitation isotope composition. The seasonal variations of the isotopic signature of the spring water exhibit a damped response as compared to the river waters, which shows that the spring water has longer residence times than the river water. Results from the hydrograph separation at a seasonal time scale indicate the dominance of event water with an average of 71% and 64% of the total runoff during the wet season in the Chemoga and Jedeb catchment, respectively. The stable isotope compositions of streamflow samples were damped compared to the input function of precipitation for both catchments and this damping was used to estimate mean residence times of stream water of 4.1 and 6.0 months at the Chemoga and Jedeb catchment outlet, respectively. Short mean residence times and high proportions of event water components suggest catchment management measure aiming at reduction of overland flow/soil erosion and increasing of soil water retention and recharge to enable sustainable development in these agricultural dominated catchments.Water ManagementCivil Engineering and Geoscience

Volunteering in Community Sports Associations: A Literature Review

This review paper focuses on volunteers in community sports associations (CSAs). Such associations are a major context of sports volunteering across Europe, Canada and Australia—the countries in which a multitude of sports clubs are represented by governing bodies of sport. Their importance is not only in the large numbers of volunteers involved but also in the benefits of such associations to society. The clearest of these is the provision of opportunities to take part in sport, at a cost subsidized by the efforts of volunteers and thus contributing to physical health. However, the benefits extend more broadly to the quality of life and the rewards the volunteers themselves receive from association. Many community sports associations have a significant number of members who, while they do not actually play sport themselves, provide opportunities for others and also enjoy the social rewards of membership. The review is structured in the following sections: 1. Introduction. 2. The number of sports clubs, club membership, and volunteering. 3. Explaining a trend toward individual participation in sport and volunteering, and a reduction in the number of CSAs. 4. Conceptualizing community sports associations and volunteering. 5. Motivations of sports volunteers. 6. Challenges facing community sports clubs’ volunteers and leaders. 7. Management and leadership of volunteers in CSAs: Applying a rational systems approach, and the pros and cons of formality. 8. Community sports associations and social capital. 9. The relationship between CSAs and event volunteering. 10. Conclusions