37 research outputs found
Suitability of Water Harvesting in the Upper Blue Nile Basin, Ethiopia: A First Step towards a Mesoscale Hydrological Modeling Framework
Extreme rainfall variability has been one of the major factors to famine and environmental degradation in Ethiopia. The potential for water harvesting in the Upper Blue Nile Basin was assessed using two GIS-based Multicriteria Evaluation methods: (1) a Boolean approach to locate suitable areas for in situ and ex situ systems and (2) a weighted overlay analysis to classify suitable areas into different water harvesting suitability levels. The sensitivity of the results was analyzed to the influence given to different constraining factors. A large part of the basin was suitable for water harvesting: the Boolean analysis showed that 36% of the basin was suitable for in situ and ex situ systems, while the weighted overlay analysis showed that 6â24% of the basin was highly suitable. Rainfall has the highest influence on suitability for water harvesting. Implementing water harvesting in nonagricultural land use types may further increase the benefit. Assessing water harvesting suitability at the larger catchment scale lays the foundation for modeling of water harvesting at mesoscale, which enables analysis of the potential and implications of upscaling of water harvesting practices for building resilience against climatic shocks. A complete water harvesting suitability study requires socioeconomic analysis and stakeholder consultation
Advances in water resources research in the Upper Blue Nile basin and the way forward: A review
The Upper Blue Nile basin is considered as the lifeline for âŒ250 million people and contributes âŒ50âŻGm3/year of water to the Nile River. Poor land management practices in the Ethiopian highlands have caused a significant amount of soil erosion, thereby threatening the productivity of the Ethiopian agricultural system, degrading the health of the aquatic ecosystem, and shortening the life of downstream reservoirs. The Upper Blue Nile basin, because of limited research and availability of data, has been considered as the âgreat unknown.â In the recent past, however, more research has been published. Nonetheless, there is no state-of-the-art review that presents research achievements, gaps and future directions. Hence, this paper aims to bridge this gap by reviewing the advances in water resources research in the basin while highlighting research needs and future directions. We report that there have been several research projects that try to understand the biogeochemical processes by collecting information on runoff, groundwater recharge, sediment transport, and tracers. Different types of hydrological models have been applied. Most of the earlier research used simple conceptual and statistical approaches for trend analysis and water balance estimations, mainly using rainfall and evapotranspiration data. More recent research has been using advanced semi-physically/physically based distributed hydrological models using high-resolution temporal and spatial data for diverse applications. We identified several research gaps and provided recommendations to address them. While we have witnessed advances in water resources research in the basin, we also foresee opportunities for further advancement. Incorporating the research findings into policy and practice will significantly benefit the development and transformation agenda of the Ethiopian government
The Quadruple Squeeze: Defining the safe operating space for freshwater use to achieve a triply green revolution in the Anthropocene
Humanity has entered a new phase of sustainability challenges, the Anthropocene, in which human development has reached a scale where it affects vital planetary processes. Under the pressure from a quadruple squeezeâfrom population and development pressures, the anthropogenic climate crisis, the anthropogenic ecosystem crisis, and the risk of deleterious tipping points in the Earth systemâthe degrees of freedom for sustainable human exploitation of planet Earth are severely restrained. It is in this reality that a new green revolution in world food production needs to occur, to attain food security and human development over the coming decades. Global freshwater resources are, and will increasingly be, a fundamental limiting factor in feeding the world. Current water vulnerabilities in the regions in most need of large agricultural productivity improvements are projected to increase under the pressure from global environmental change. The sustainability challenge for world agriculture has to be set within the new global sustainability context. We present new proposed sustainability criteria for world agriculture, where world food production systems are transformed in order to allow humanity to stay within the safe operating space of planetary boundaries. In order to secure global resilience and thereby raise the chances of planet Earth to remain in the current desired state, conducive for human development on the long-term, these planetary boundaries need to be respected. This calls for a triply green revolution, which not only more than doubles food production in many regions of the world, but which also is environmentally sustainable, and invests in the untapped opportunities to use green water in rainfed agriculture as a key source of future productivity enhancement. To achieve such a global transformation of agriculture, there is a need for more innovative options for water interventions at the landscape scale, accounting for both green and blue water, as well as a new focus on cross-scale interactions, feed-backs and risks for unwanted regime shifts in the agro-ecological landscape
Biochemical Discrimination between Selenium and Sulfur 1: A Single Residue Provides Selenium Specificity to Human Selenocysteine Lyase
Selenium and sulfur are two closely related basic elements utilized in nature for a vast array of biochemical reactions. While toxic at higher concentrations, selenium is an essential trace element incorporated into selenoproteins as selenocysteine (Sec), the selenium analogue of cysteine (Cys). Sec lyases (SCLs) and Cys desulfurases (CDs) catalyze the removal of selenium or sulfur from Sec or Cys and generally act on both substrates. In contrast, human SCL (hSCL) is specific for Sec although the only difference between Sec and Cys is the identity of a single atom. The chemical basis of this selenium-over-sulfur discrimination is not understood. Here we describe the X-ray crystal structure of hSCL and identify Asp146 as the key residue that provides the Sec specificity. A D146K variant resulted in loss of Sec specificity and appearance of CD activity. A dynamic active site segment also provides the structural prerequisites for direct product delivery of selenide produced by Sec cleavage, thus avoiding release of reactive selenide species into the cell. We thus here define a molecular determinant for enzymatic specificity discrimination between a single selenium versus sulfur atom, elements with very similar chemical properties. Our findings thus provide molecular insights into a key level of control in human selenium and selenoprotein turnover and metabolism
Irrigation with saline water using low-cost drip-irrigation systems in sub-Saharan Africa
In the scope of future population support, agricultural productivity, in particular in sub-Saharan Africa, has to increase drastically to meet the UNâs millennium development goals of eradicating extreme poverty and hunger by 2015. Water availability in the root-zone limits crop production in large parts of the developing world. As competition for fresh water increases, water of lower quality, for example saline or polluted water, is often used for irrigation. Low-cost drip systems are suitable for saline water irrigation because they effectuate a minimisation of salt accumulation, leaf burn and peaks in salt concentration. Nonetheless, all types of saline water irrigation contain the risk for causing soil salinisation. Thus, in order to achieve long-term sustainability of these systems, appropriate management strategies are needed. The choice of management practices may be influenced by local conditions such as climate, soil and irrigation water salinity. A litera-ture review showed that there is a potential for saline water irrigation in sub-Saharan Africa in water scarce areas. Low-cost drip irrigation with saline water (6 dS m-1) was successfully used to irrigate two consecutive crops of tomato in semi-arid South Africa. An integrated ecosystems model was developed to simulate long-term yield and salt accumulation in a drip-irrigated agricultural system for a range of salinities, climates and management techniques. Crop, salt and water balance data from two field experiments conducted in Israel and South Africa, respectively, were used to parameterise and test the model. Emphasis was placed on testing the usability of the model as a tool for evaluating the importance of certain plausible management options of low-cost, drip-irrigation systems. Therefore, particular focus was directed towards correctly describing soil salinity stress on plant growth and soil evaporation from a distributed (wetted and dry) surface. In addition, the model was developed to function for different climates without having to change any other parameters or variables except for the actual climatic data. Simulations were subsequently run over a 30-year period to study long-term yield and salt accumulation in the soil profile for two sites in South Africa, demonstrating the applicability of the model. Model simulations showed that high soil salinities reduced crop growth and thus increased both drainage and soil evaporation. Further, covering the soil with a plastic sheet led to a reduction of soil evaporation and a subsequent increase in both transpiration and drainage. Rainfall was crucial for the leaching of salts from the soil, and thus in regions with low levels of rainfall, a higher leaching fraction of supplied saline irrigation water has to compensate for the lack of rain. However, a high leaching fraction also causes large amounts of salt leaching, which could potentially pollute underlying groundwater and downstream ecosystems. This risk can be mitigated using mulching, which minimises non-productive water losses, thereby lowering irrigation water needs. The choice of irrigation water salinity, frequency of irrigation and soil coverage may differ between the farmer and the regional water manager due to different preferences. Furthermore, the study highlighted how environmental variables such as water use efficiency and radiation use efficiency can be used as indicators of system performance. Whereas the latter is first and foremost a general stress indicator, water use efficiency more precisely describes specific factors such as plant size, allocation patterns and evaporative demand, which will affect the exchange of carbon dioxide and water through the stomata.QC 2010110
Modelling Transpiration and Growth of Salinity and Drought Stressed Tomatoes
Irrigation with saline waters is an agricultural practicethat is becoming increasingly common as competition for freshwater increases. In this thesis the mechanisms behind salinityand drought stress has been studied using data from fieldexperiments in combination with a modelling tool, theCoupModel. Measurements from field experiments on salinity,boron toxicity and drought stressed tomatoes grown during twoclimatically different seasons in the Arava desert, Israel,showed a linear relationship between relative growth andevapotranspiration, for all treatments and seasons. Data fromthe spring was used to concurrently simulate growth andtranspiration, hence accounting for feedback mechanisms betweenthe plant and the environment. Salinity stress was modelled asan osmotic effect (reduction of water uptake at high soilsalinities, W approach) or a toxicity effect (direct reductionof photosynthesis with soil salinity, G approach). Goodagreement between simulated growth and transpiration wasachieved with both salinity stress approaches, with twoexceptions. When growth and transpiration were simulated withthe W approach at different salinity levels, transpiration wasunderestimated at high stress. The G approach resulted in anunderestimation of growth at high water stress under moderatesalinity. A direct decrease of photosynthesis leads to adecreasing water-use efficiency with salinity while water-useefficiency remains constant with salinity when the salinitystress is modelled as a reduction in water uptake. Measurementsshowed decreasing water-use efficiency for the salinitygradient, explaining why the W approach was not applicable. Itwas not possible to detect any considerable differences betweenthree different approaches for water uptake tested in thestudy. Keywords:Water-use efficiency; osmotic effect; iontoxicity; semi-arid.NR 2014080
âYou can outrun most things but you can never outrun yourself⊠and the soul always catches up with you eventuallyâ : A qualitative interview study on elders perceptions of mental health
Studien syftade till att öka kunskapen om Ă€ldres syn pĂ„ psykisk ohĂ€lsa utifrĂ„n frĂ„gestĂ€llningen: Hur upplever Ă€ldre psykisk ohĂ€lsa? Ă
tta semistrukturerade intervjuer genomfördes (Ă„ldrar mellan 66â84, M=75,25) och analyserades utifrĂ„n tematisk analys. Fyra teman identifierades: Det Ă€r inte lĂ€tt att vara gammal, Ett harmoniskt Ă„ldrande, Det finns ju roligare saker att prata om och Man fĂ„r nog bra vĂ„rd om man vĂ€l kommer till. Resultaten visade att utanförskap till följd av Ă„lder upplevdes pĂ„verka den psykiska hĂ€lsan negativt och att sociala sammanhang och en meningsfull tillvaro verkar hĂ€lsofrĂ€mjande. Vidare beskrevs en dubbelhet i attityder dĂ€r en mer accepterande instĂ€llning till psykisk ohĂ€lsa utvecklats i samhĂ€llet men att det fortfarande Ă€r skamfyllt för individen. Avslutningsvis beskrevs en kluvenhet till vĂ„rd för psykisk ohĂ€lsa dĂ„ den upplevs relevant men otillgĂ€nglig. Studien pĂ„visar behovet av att tillgĂ€ngliggöra resurser för Ă€ldres psykiska ohĂ€lsa samt att ta Ă€ldres förestĂ€llningar i beaktning i vĂ„rdprocessen.The aim of the current study was to promote knowledge surrounding eldersâ views on mental health, by employing the research question: How do elders perceive mental health? Eight semi-structured interviews were conducted (ages 66-84, M=75.25) and analyzed using thematic analysis. Four themes were identified: Hardships of being old, Harmonious aging, There are more amusing subjects and Thereâs good care once you get there. Results indicated an experience of age-related exclusion having negative effects on mental health, while social inclusion and a fulfilling everyday life promoted good health. Furthermore, split attitudes were expressed regarding mental health issues, where society has become increasingly accepting but the individual still may find it shameful. Finally, an ambivalence toward mental health care was discerned where it was perceived as necessary but inaccessible. The study highlights the need to allocate resources to mental health care for elders and to consider their perspectives in the caring process
Preschool Digitalization : A Qualitative Study Of Preschool Teacher's Perceived Competence
Svensk titel: Förskolans digitalisering - En kvalitativ studie om förskollÀrares upplevda kompetens. Engelsk titel: Preschool Digitalization - A Qualitative Study of Preschool Teachers' Perceived Competence. Studiens syfte Àr att öka förstÄelsen för huruvida förskollÀrare uppfattar sin digitala kompetens som tillrÀcklig för att kunna bidra till att ge barnen en adekvat digital kompetens utifrÄn gÀllande styrdokument. Den metod som vi valde att anvÀnda oss av i studien Àr webbenkÀter dÀr respondenterna fÄr öppna frÄgor dÀr de besvarar med egna tankar, kÀnslor och Äsikter för att göra en kvalitativ studie. Dessa webbenkÀter har genomförts med hjÀlp av Google formulÀr. Resultatet visar hur flertalet förskollÀrare sjÀlva upplever att de inte har den rÀtta kompetensen inom de digitala verktygen de möter i förskolan samt att det handlar om ett personligt intresse frÄn förskollÀraren att höja sin kompetens. I resultatredovisningen redogörs för förskollÀrarnas upplevelser kring digitala kunskaper och deras kompetens nÀr det gÀller digitala verktyg
Preschool Digitalization : A Qualitative Study Of Preschool Teacher's Perceived Competence
Svensk titel: Förskolans digitalisering - En kvalitativ studie om förskollÀrares upplevda kompetens. Engelsk titel: Preschool Digitalization - A Qualitative Study of Preschool Teachers' Perceived Competence. Studiens syfte Àr att öka förstÄelsen för huruvida förskollÀrare uppfattar sin digitala kompetens som tillrÀcklig för att kunna bidra till att ge barnen en adekvat digital kompetens utifrÄn gÀllande styrdokument. Den metod som vi valde att anvÀnda oss av i studien Àr webbenkÀter dÀr respondenterna fÄr öppna frÄgor dÀr de besvarar med egna tankar, kÀnslor och Äsikter för att göra en kvalitativ studie. Dessa webbenkÀter har genomförts med hjÀlp av Google formulÀr. Resultatet visar hur flertalet förskollÀrare sjÀlva upplever att de inte har den rÀtta kompetensen inom de digitala verktygen de möter i förskolan samt att det handlar om ett personligt intresse frÄn förskollÀraren att höja sin kompetens. I resultatredovisningen redogörs för förskollÀrarnas upplevelser kring digitala kunskaper och deras kompetens nÀr det gÀller digitala verktyg
âYou can outrun most things but you can never outrun yourself⊠and the soul always catches up with you eventuallyâ : A qualitative interview study on elders perceptions of mental health
Studien syftade till att öka kunskapen om Ă€ldres syn pĂ„ psykisk ohĂ€lsa utifrĂ„n frĂ„gestĂ€llningen: Hur upplever Ă€ldre psykisk ohĂ€lsa? Ă
tta semistrukturerade intervjuer genomfördes (Ă„ldrar mellan 66â84, M=75,25) och analyserades utifrĂ„n tematisk analys. Fyra teman identifierades: Det Ă€r inte lĂ€tt att vara gammal, Ett harmoniskt Ă„ldrande, Det finns ju roligare saker att prata om och Man fĂ„r nog bra vĂ„rd om man vĂ€l kommer till. Resultaten visade att utanförskap till följd av Ă„lder upplevdes pĂ„verka den psykiska hĂ€lsan negativt och att sociala sammanhang och en meningsfull tillvaro verkar hĂ€lsofrĂ€mjande. Vidare beskrevs en dubbelhet i attityder dĂ€r en mer accepterande instĂ€llning till psykisk ohĂ€lsa utvecklats i samhĂ€llet men att det fortfarande Ă€r skamfyllt för individen. Avslutningsvis beskrevs en kluvenhet till vĂ„rd för psykisk ohĂ€lsa dĂ„ den upplevs relevant men otillgĂ€nglig. Studien pĂ„visar behovet av att tillgĂ€ngliggöra resurser för Ă€ldres psykiska ohĂ€lsa samt att ta Ă€ldres förestĂ€llningar i beaktning i vĂ„rdprocessen.The aim of the current study was to promote knowledge surrounding eldersâ views on mental health, by employing the research question: How do elders perceive mental health? Eight semi-structured interviews were conducted (ages 66-84, M=75.25) and analyzed using thematic analysis. Four themes were identified: Hardships of being old, Harmonious aging, There are more amusing subjects and Thereâs good care once you get there. Results indicated an experience of age-related exclusion having negative effects on mental health, while social inclusion and a fulfilling everyday life promoted good health. Furthermore, split attitudes were expressed regarding mental health issues, where society has become increasingly accepting but the individual still may find it shameful. Finally, an ambivalence toward mental health care was discerned where it was perceived as necessary but inaccessible. The study highlights the need to allocate resources to mental health care for elders and to consider their perspectives in the caring process