| 1. |
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| 2. |
- Bennett, Elena, et al.
(author)
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Toward a more resilient agriculture
- 2014
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In: Solutions : For a Sustainable & Desirable Future. - : Australian National University. - 2154-0926. ; 5:5, s. 65-75
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Journal article (peer-reviewed)abstract
- In Brief Agriculture is a key driver of change in the Anthropocene. It is both a critical factor for human well-being and development and a major driver of environmental decline. As the human population expands to more than 9 billion by 2050, we will be compelled to find ways to adequately feed this population while simultaneously decreasing the environmental impact of agriculture, even as global change is creating new circumstances to which agriculture must respond. Many proposals to accomplish this dual goal of increasing agricultural production while reducing its environmental impact are based on increasing the efficiency of agricultural production relative to resource use and relative to unintended outcomes such as water pollution, biodiversity loss, and greenhouse gas emissions. While increasing production efficiency is almost certainly necessary, it is unlikely to be sufficient and may in some instances reduce long-term agricultural resilience, for example, by degrading soil and increasing the fragility of agriculture to pest and disease outbreaks and climate shocks. To encourage an agriculture that is both resilient and sustainable, radically new approaches to agricultural development are needed. These approaches must build on a diversity of solutions operating at nested scales, and they must maintain and enhance the adaptive and transformative capacity needed to respond to disturbances and avoid critical thresholds. Finding such approaches will require that we encourage experimentation, innovation, and learning, even if they sometimes reduce short-term production efficiency in some parts of the world.
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| 3. |
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| 4. |
- Collins, Ruairi, et al.
(author)
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Biochemical discrimination between selenium and sulfur 1 : a single residue provides selenium specificity to human selenocysteine lyase
- 2012
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In: PLoS One. - Stockholm : Karolinska Institutet, Dept of Medical Biochemistry and Biophysics. - 1932-6203.
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Journal article (peer-reviewed)abstract
- 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.
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| 5. |
- de Fraiture, C., et al.
(author)
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Can rainfed agriculture feed the world?
- 2009
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In: Rainfed Agriculture. - Wallingford, UK : CABI. - 9781845933890 ; , s. 124-132
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Book chapter (other academic/artistic)
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| 6. |
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| 7. |
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| 8. |
- Dile, Yihun, 1982-
(author)
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Intensifying Agricultural Water Management in the Tropics : A cause of water shortage or a source of resilience?
- 2014
-
Doctoral thesis (other academic/artistic)abstract
- Frequent climatic shocks have presented challenges for rainfed agriculture in sub-Saharan Africa. Appropriate water management practices are among the solutions to the challenges. The role of water harvesting in achieving sustainable agricultural intensification and specified resilience was explored. Suitable areas for water harvesting in the Upper Blue Nile basin were identified. The usefulness of the Curve Number method for surface runoff estimation was evaluated, and was found to perform satisfactorily. The impact of climate change in the Lake Tana sub-basin was studied. A decision support system was developed for locating and sizing of water harvesting ponds in the SWAT model. Methodological developments enabled analysis of the implications of water harvesting intensification in a meso-scale watershed in the Lake Tana sub-basin.Results suggest that water harvesting can increase agricultural productivity, sustain ecosystems and build specified resilience, and thereby contribute to sustainable agricultural intensification. There is considerable potential for water harvesting in the Upper Blue Nile Basin. Rainfall may increase in the Lake Tana sub-basin due to climate change. Supplementary irrigation from water harvesting ponds and better nutrient application increased staple crop production by up to three-fold. Moreover, a substantial amount of cash crop was produced using dry seasonal irrigation. Water harvesting altered the streamflow regime, and reduced sediment loss from the watershed. Water harvesting can play an important role in food security. It showed potential to buffer climatic variability. In the watershed studied, water harvesting will not compromise the environmental water requirements. Instead, increased low flows, and reduced flooding and sediment loss may benefit the social-ecological systems. The adverse effects of disturbance of the natural flow variability and sediment influx to certain riverine ecosystems warrant detailed investigation.
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| 9. |
- Dile, Yihun Taddele, et al.
(author)
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Assessing the implications of water harvesting intensification on upstream-downstream ecosystem services : A case study in the Lake Tana basin
- 2016
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In: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 542, s. 22-35
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Journal article (peer-reviewed)abstract
- Water harvesting systems have improved productivity in various regions in sub-Saharan Africa. Similarly, they can help retain water in landscapes, build resilience against droughts and dry spells, and thereby contribute to sustainable agricultural intensification. However, there is no strong empirical evidence that shows the effects of intensification of water harvesting on upstream-downstream social-ecological systems at a landscape scale. In this paper we develop a decision support system (DSS) for locating and sizing water harvesting ponds in a hydrological model, which enables assessments of water harvesting intensification on upstream-downstream ecosystem services in meso-scale watersheds. The DSS was used with the Soil and Water Assessment Tool (SWAT) for a case-study area located in the Lake Tana basin, Ethiopia. We found that supplementary irrigation in combination with nutrient application increased simulated teff (Eragrostis tef, staple crop in Ethiopia) production up to three times, compared to the current practice. Moreover, after supplemental irrigation of teff, the excess water was used for dry season onion production of 7.66 t/ha (median). Water harvesting, therefore, can play an important role in increasing local-to regional-scale food security through increased and more stable food production and generation of extra income from the sale of cash crops. The annual total irrigation water consumption was similar to 4%-30% of the annual water yield from the entire watershed. In general, water harvesting resulted in a reduction in peak flows and an increase in low flows. Water harvesting substantially reduced sediment yield leaving the watershed. The beneficiaries of water harvesting ponds may benefit from increases in agricultural production. The downstream social-ecological systems may benefit from reduced food prices, reduced flooding damages, and reduced sediment influxes, as well as enhancements in low flows and water quality. The benefits of water harvesting warrant economic feasibility studies and detailed analyses of its ecological impacts.
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| 10. |
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| 11. |
- Dile, Yihun Taddele, et al.
(author)
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INVESTIGATION OF THE CURVE NUMBER METHOD FOR SURFACE RUNOFF ESTIMATION IN TROPICAL REGIONS
- 2016
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In: Journal of the American Water Resources Association. - : Wiley. - 1093-474X .- 1752-1688. ; 52:5, s. 1155-1169
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Journal article (peer-reviewed)abstract
- This study tests the applicability of the curve number (CN) method within the Soil and Water Assessment Tool (SWAT) to estimate surface runoff at the watershed scale in tropical regions. To do this, surface runoff simulated using the CN method was compared with observed runoff in numerous rainfall-runoff events in three small tropical watersheds located in the Upper Blue Nile basin, Ethiopia. The CN method generally performed well in simulating surface runoff in the studied watersheds (Nash-Sutcliff efficiency [NSE] > 0.7; percent bias [PBIAS] < 32%). Moreover, there was no difference in the performance of the CN method in simulating surface runoff under low and high antecedent rainfall (PBIAS for both antecedent conditions: similar to 30%; modified NSE: similar to 0.4). It was also found that the method accurately estimated surface runoff at high rainfall intensity (e.g., PBIAS < 15%); however, at low rainfall intensity, the CN method repeatedly underestimated surface runoff (e.g., PBIAS > 60%). This was possibly due to low infiltrability and valley bottom saturated areas typical of many tropical soils, indicating that there is scope for further improvements in the parameterization/representation of tropical soils in the CN method for runoff estimation, to capture low rainfall-intensity events. In this study the retention parameter was linked to the soil moisture content, which seems to be an appropriate approach to account for antecedent wetness conditions in the tropics.
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| 12. |
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| 13. |
- Dile, Yihun T., et al.
(author)
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Suitability of Water Harvesting in the Upper Blue Nile Basin, Ethiopia : A First Step towards a Mesoscale Hydrological Modeling Framework
- 2016
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In: Advances in Meteorology. - : Hindawi Limited. - 1687-9309 .- 1687-9317.
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Journal article (peer-reviewed)abstract
- 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 6-24% 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.
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| 14. |
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| 15. |
- Dile, Yihun Taddele, et al.
(author)
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The role of water harvesting to achieve sustainable agricultural intensification and resilience against water related shocks in sub-Saharan Africa
- 2013
-
In: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 0167-8809 .- 1873-2305. ; 181, s. 69-79
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Research review (peer-reviewed)abstract
- Poverty alleviation in rural areas is a top priority for social and economic development, particularly against a backdrop of rising populations up to 2050 and to meet growing food demands in a rapidly urbanizing world. Sustainable intensification of agricultural techniques are therefore required, such as water management practices that result in higher agricultural production without causing severe environmental impacts, whilst at the same time improving resilience to drought and dry spells. Water harvesting practices have shown promising results in reducing risks, and improving yields whilst also delivering positive impacts on other ecosystems. However, before large scale implementation of water harvesting, further investigation of local downstream impacts are warranted. We conclude that water harvesting remains a promising option for sustainable agricultural intensification in the water scarce tropics, resulting in both risk reduction and yield improvements.
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| 16. |
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| 17. |
- Flach, Rafaela, et al.
(author)
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Towards more spatially explicit assessments of virtual water flows: linking local water use and scarcity to global demand of Brazilian farming commodities
- 2016
-
In: Environmental Research Letters. - : IOP PUBLISHING LTD. - 1748-9326. ; 11:7, s. 075003-
-
Journal article (peer-reviewed)abstract
- Global consumption of farming commodities is an important driver of water demand in regions of production. This is the case in Brazil, which has emerged as one of the main producers of globally traded farming commodities. Traditional methods to assess environmental implications of this demand rely on international trade material flows at country resolution; we argue for the need of finer scales that capture spatial heterogeneity in environmental variables in the regions of production, and that account for differential sourcing within the borders of a country of production. Toillustrate this, we obtain virtual water flows from Brazilian municipalities to countries of consumption, by allocating high-resolution water footprints of sugarcane and soy production to spatially-explicit material trade flows. We found that this approach results in differences of virtual water use estimations of over 20% when compared to approaches that disregard spatial heterogeneity in sourcing patterns, for three of the main consumers of the analysed crops. This discrepancy against methods using national resolution in trade flows is determined by national heterogeneity in water resources, and differential sourcing. To illustrate the practical implications of this approach, we relate virtual water flows to water stress, identifying where global demand for water coincides with high levels of water stress. For instance, the virtual water flows for Brazilian sugarcane sourced by China were disproportionally less associated to areas with higher water stress when compared to those of the EU, due to EUs much higher reliance on sugarcane from water scarce areas in Northeast Brazil. Our findings indicate that the policy relevance of current assessments of virtual water flows that rely on trade data aggregated at the national level may be hampered, as they do not capture the spatial heterogeneity in water resources, water use and water management options.
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| 18. |
- Garg, Kaushal K., et al.
(author)
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Assessing impacts of agricultural water interventions in the Kothapally watershed, Southern India
- 2012
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In: Hydrological Processes. - : Wiley. - 0885-6087 .- 1099-1085. ; 26:3, s. 387-404
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Journal article (peer-reviewed)abstract
- The paper describes a hydrological model for agricultural water intervention in a community watershed at Kothapally in India, developed through integrated management and a consortium approach. The impacts of various soil and water management interventions in the watershed are compared to no‐intervention during a 30‐year simulation period by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Kothapally receives, on average, 800 mm rainfall in the monsoon period. 72% of total rainfall is converted as evaporation and transpiration (ET), 20% is stored by groundwater aquifer, and 8% exported as outflow from the watershed boundary in current water interventions. ET, groundwater recharge and outflow under no‐intervention conditions are found to be 64, 9, and 19%, respectively. Check dams helped in storing water for groundwater recharge, which can be used for irrigation, as well minimising soil loss. In situ water management practices improved the infiltration capacity and water holding capacity of the soil, which resulted in increased water availability by 10–30% and better crop yields compared to no‐intervention. Water outflows from the developed watershed were more than halved compared to no‐intervention, indicating potentially large negative downstream impacts if these systems were to be implemented on a larger scale. On the other hand, in the watershed development program, sediment loads to the streams were less than one‐tenth. It can be concluded that the hydrological impacts of large‐scale implementation of agricultural water interventions are significant. They result in improved rain‐fed agriculture and improved productivity and livelihood of farmers in upland areas while also addressing the issues of poverty, equity, and gender in watersheds. There is a need for case‐specific studies of such hydrological impacts along with other impacts in terms of equity, gender, sustainability, and development at the mesoscale.
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| 19. |
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| 20. |
- Garg, Kaushal K., et al.
(author)
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Up-scaling potential impacts on water flows from agricultural water interventions : opportunities and trade-offs in the Osman Sagar catchment, Musi sub-basin, India
- 2013
-
In: Hydrological Processes. - : Wiley-Blackwell. - 0885-6087 .- 1099-1085. ; 27:26, s. 3905-3921
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Journal article (peer-reviewed)abstract
- Agricultural water management (AWM) has been shown to improve and secure yields in the tropics and has been suggested as an important way to combat poverty in the region. In this paper, we describe potential impacts on upstream and downstream flows of extensive AWM interventions, using the watershed development programme of the Osman Sagar catchment of Musi sub-basin, Andhra Pradesh semi-arid India, as an example. Various AWM interventions are compared with a non-intervention state and the current state of the study area, using 31 years of data by application of the calibrated and validated ARCSWAT 2005 (Version 2.1.4a) modelling tool. Different AWM interventions contribute to improved livelihoods of upstream smallholder farmers by increasing soil moisture availability and groundwater recharge, which can subsequently be used for irrigation. The result is higher crop production and hence larger incomes. Moreover, lower flow intensities and sediment losses reduced by 30-50%, reducing the risk of flooding and sediment accumulation in the Osman Sagar drinking water reservoir. On the other hand, AWM interventions are predicted to result in reduced total water inflows to the Osman Sagar reservoir from 11% of the total annual rainfall (754mm) recorded at present, to 8% if AWM interventions were implemented at large scale throughout the catchment. A cost-benefit analysis of AWM interventions showed that the highest net economic returns were achieved at intermediate intervention levels (only in-situ AWM).
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| 21. |
- Hoff, Holger, et al.
(author)
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Greening the global water system
- 2010
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In: Journal of Hydrology. - : Elsevier BV. - 0022-1694 .- 1879-2707. ; 384:04-mar, s. 177-186
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Journal article (peer-reviewed)abstract
- Recent developments of global models and data sets enable a new, spatially explicit and process-based assessment of green and blue water in food production and trade. An initial intercomparison of a range of different (hydrological, vegetation, crop, water resources and economic) models, confirms that green water use in global crop production is about 4-5 times greater than consumptive blue water use. Hence, the full green-to-blue spectrum of agricultural water management options needs to be used when tackling the increasing water gap in food production. The different models calculate considerable potentials for complementing the conventional approach of adding irrigation, with measures to increase water productivity, such as rainwater harvesting, supplementary irrigation, vapour shift and soil and nutrient management. Several models highlight Africa, in particular sub-Saharan Africa, as a key region for improving water productivity in agriculture, by implementing these measures. Virtual water trade, mostly based on green water, helps to close the water gap in a number of countries. It is likely to become even more important in the future, when inequities in water availability are projected to grow, due to climate, population and other drivers of change. Further model developments and a rigorous green-blue water model intercomparison are proposed, to improve simulations at global and regional scale and to enable tradeoff analyses for the different adaptation options.
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| 22. |
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| 23. |
- Karlberg, Louise, et al.
(author)
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Exploring potentials and constraints of low-cost drip irrigation with saline water in sub-Saharan Africa
- 2004
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In: Physics and Chemistry of the Earth. - : Elsevier BV. - 1474-7065 .- 1873-5193. ; 29:15-18, s. 1035-1042
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Journal article (peer-reviewed)abstract
- Irrigation with saline water could provide an interesting opportunity to meet increasing food demands without competing with other pressing needs for fresh water such as domestic and industrial water use in water scarce regions. In sub-Saharan Africa, saline groundwater could be a plentiful and under-utilised resource; however, there is a lack of data to confirm this assumption. Saline water is deliberately and successfully used for irrigation of field and garden crops in several countries. The water saving characteristics and the distribution patterns of water in the soil under drip irrigation make this water application technique suitable for use in combination with saline water. Low-cost drip irrigation has already been successfully implemented in sub-Saharan Africa. It is suggested that low-cost drip irrigation with saline groundwater for the cultivation of horticultural crops can be a feasible option under conditions of water shortage, and has the potential to contribute to improved and sustainable crop production for smallholder farmers.
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| 24. |
- Karlberg, Louise, et al.
(author)
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Impacts of agricultural water interventions on farm income : An example from the Kothapally watershed, India
- 2015
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In: Agricultural Systems. - : Elsevier BV. - 0308-521X .- 1873-2267. ; 136, s. 30-38
-
Journal article (peer-reviewed)abstract
- Agricultural water interventions (AWI), e.g. in-situ soil and water conservation strategies, irrigation, and damming of rivers to increase groundwater recharge, have been suggested as important strategies to improve yields in tropical agriculture. Although the biophysical implications of AWIs have been well investigated, the coupling between the biophysical changes and the economic implications thereof is less well understood. In this study we translate the results from a hydrological model, SWAT, on crop yields for different cropping systems with and without agricultural water interventions, to hypothetical farm incomes for a watershed, Kothapally, located in Andhra Pradesh, India. It was found that on average, AWI significantly improved farm incomes by enabling the cultivation of a high value crop during the monsoon season (cotton), supplementary irrigated to bridge dry spells and replacing a traditional crop (sorghum), and also by enhancing the capacity to produce dry season, fully irrigated vegetable crops, in this case exemplified by onion. AWI combined with cotton resulted in more than a doubling of farm incomes compared to traditional sorghum-based systems without AWI during normal and wet years (i.e. for 75% of the years). Interestingly, we observed that the difference between the AWI system and the no intervention system was larger during years of high average rainfall compared to dry years. It was also found that access to irrigation was more important for farm income than crop choice and AWI per se, and thus farms with access irrigation benefitted more from AWI compared to farmers lacking access to irrigation. In conclusion, we suggest that in order to assess equity aspects in terms of farm income generation following the implementation of an AWI project, there is a need for income analyses at the farm level, since income estimates at the watershed level may mask important differences in economic benefits between farms.
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| 25. |
- Karlberg, Louise, 1974-
(author)
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Irrigation with saline water using low-cost drip-irrigation systems in sub-Saharan Africa
- 2005
-
Doctoral thesis (other academic/artistic)abstract
- In the scope of future population support, agricultural productivity, in particular in sub-Saharan Africa, has to increase drastically to meet the UN’s 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.
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| 26. |
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| 27. |
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| 28. |
- Karlberg, Louise, et al.
(author)
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Low-cost drip irrigation of tomatoes using saline water: a suitable technology for southern Africa?
- 2007
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In: Agricultural Water Management. - : Elsevier BV. - 0378-3774 .- 1873-2283. ; 89:1-2, s. 59-70
-
Journal article (peer-reviewed)abstract
- Using saline water for. irrigation increases water productivity by freeing up fresh water that can be allocated to domestic or other uses. Drip irrigation is widely regarded as the most promising irrigation system in combination with saline water. Simple drip irrigation kits that are affordable for smallholder farmers have successfully been implemented for irrigation of vegetable gardens in several countries in sub-Saharan Africa. The possibility of using low-cost drip irrigation with saline water to successfully irrigate a common garden crop, tomatoes, was tested in this study. Two low-cost drip irrigation systems with different emitter discharge rates (0.2 and 2.5 1 h(-2)) were used to irrigate tomatoes (Lycopersicon esculentum Mill. cv. "Daniella") with water of three different salinity levels (0, 3 and 6 dS m(-1)). In addition, plastic mulch to minimise soil evaporation was also compared to a "bare soil" or uncovered treatment. Two consecutive tomato crops (spring and autumn) were produced during two growing seasons, starting from September 2003 and ending in April 2004, at the Hatfield Experimental Farm in Pretoria, South Africa. An average yield of 75 Mg ha(-1) was recorded for all treatments and seasons, which can be compared with the average marketable yield for South Africa of approximately 31.4 Mg ha(-1). Even at the highest irrigation water salinity (6 dS m(-1)), a yield above the average marketable yield was achieved, indicating that low-cost drip irrigation works well in combination with saline water. Furthermore, the study showed that the choice of drip irrigation system with regard to discharge rate is of minor importance when irrigating with saline water. However, combining low-cost drip irrigation with plastic mulch increased the yield by on average 10 Mg ha(-1) for all treatments. For the bare soil treatments, rainfall had an important role in the leaching of salts from the soils. Finally, the study showed that specific leaf area was higher at high irrigation water salinities, which is contrary to results from other studies. To be able to generalise the promising findings from this study, there is a need to mechanistically model the impact of different climates, soils and irrigation management practices, as well as the long-term sustainability of these systems.
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| 29. |
- Karlberg, Louise, et al.
(author)
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Model-based evaluation of low-cost drip-irrigation systems and management strategies using saline water
- 2007
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In: Irrigation science. - : Springer Science and Business Media LLC. - 0342-7188 .- 1432-1319. ; 25:4, s. 387-399
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Journal article (peer-reviewed)abstract
- A drip-irrigation module was developed and included in an ecosystem model and tested on two independent datasets, spring and autumn, on field-grown tomato. Simulated soil evaporation correlated well with measurements for spring (2.62 mm d(-1) compared to 2.60 mm d(-1)). Changes in soil water content were less well portrayed by the model (spring r(2) = 0.27; autumn r(2) = 0.45). More independent data is needed for further model testing in combination with developments of the spatial representation of below-ground variables. In a fresh-water drip-irrigated system, about 30% of the incoming water was transpired, 40% was lost as non-productive evaporative flows, and the remainder left the system as surface runoff or drainage. Simulations showed that saline water irrigation (6 dS m(-1)) caused reduced transpiration, which led to higher drainage and soil evaporation, compared with fresh water. Covering the soil with plastic mulch resulted in an increase in yield and transpiration. Finally, two different drip-irrigation discharge rates (0.2 and 2.5 l h(-1)) were compared; however the simulations indicated that the discharge rate did not have any impact on the partitioning of the incoming water to the system. The model proved to be a useful tool for evaluating the importance of specific management options.
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| 30. |
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| 31. |
- Karlberg, Louise, et al.
(author)
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Modeling carbon turnover in five terrestrial ecosystems in the boreal zone using multiple criteria of acceptance
- 2006
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In: Ambio. - 0044-7447 .- 1654-7209. ; 35:8, s. 448-458
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Journal article (peer-reviewed)abstract
- Estimates of carbon fluxes and turnover in ecosystems are key elements in the understanding of climate change and in predicting the accumulation of trace elements in the biosphere. In this paper we present estimates of carbon fluxes and turnover times for five terrestrial ecosystems using a modeling approach. Multiple criteria of acceptance were used to parameterize the model, thus incorporating large amounts of multi-faceted empirical data in the simulations in a standardized manner. Mean turnover times of carbon were found to be rather similar between systems with a few exceptions, even though the size of both the pools and the fluxes varied substantially. Depending on the route of the carbon through the ecosystem, turnover times varied from less than one year to more than one hundred, which may be of importance when considering trace element transport and retention. The parameterization method was useful both in the estimation of unknown parameters, and to identify variability in carbon turnover in the selected ecosystems.
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| 32. |
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| 33. |
- Karlberg, Louise, et al.
(author)
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Modelling transpiration and growth in salinity-stressed tomato under different climatic conditions
- 2006
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In: Ecological Modelling. - : Elsevier BV. - 0304-3800 .- 1872-7026. ; 190:1-2, s. 15-40
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Journal article (peer-reviewed)abstract
- Models aiming to simulate growth under salinity stress and varied climatic conditions must rely on accurate methods for predicting transpiration and photosynthesis. Traditionally, models have described salinity stress as a decrease in water uptake caused by a low osmotic potential in the soil; however, many physiological studies suggest that reduced plant growth observed under saline conditions could be caused by increased respiration. Explicit calculation of photosynthesis and respiration enables both approaches to be tested and compared in a simulation model. We used an integrated ecosystems model (the CoupModel) to simulate photosynthesis and transpiration over a range of salinities. The model was calibrated and tested on two sets of data (two different seasons) on saline water, drip-irrigated tomato from lysimeter trials in the Arava Valley, Israel. Yields for the spring season were significantly lower than during the first autumn season even though transpiration was higher. As a result, water use efficiency differed by a factor of two between seasons. The model was successful in capturing this large variation, which was caused primarily by high levels of radiation and vapour pressure deficits during spring. For autumn the salinity stress approach in which water uptake was reduced performed well, whereas during spring the increased respiration approach correlated better with measurements. The concept of water use efficiency was found to be a useful tool for interpreting the accumulated effects of climatic and environmental conditions on particular agricultural systems. An attempt to simulate tomatoes grown in production beds indicated that the model set-up was also able to describe conventional cropping systems
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| 34. |
- Karlberg, Louise
(author)
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Modelling Transpiration and Growth of Salinity and Drought Stressed Tomatoes
- 2002
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Licentiate thesis (other academic/artistic)abstract
- 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.
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| 35. |
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| 36. |
- Kijne, Jacob, et al.
(author)
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Opportunities to increase water productivity in agriculture with special reference to Africa and South Asia
- 2009
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Reports (other academic/artistic)abstract
- Our primary goal in this paper is to describe how improvements in water and land management can increase the productivity of water in agriculture, which, broadly defined, means getting more value or benefit from the volume of water used to produce crops, fish, forests and livestock (Kijne et al., 2003). We begin by reviewing water scarcity and water productivity at the global level. We then describe ten Key Messages regarding efforts to improve water productivity in agriculture, with emphasis on Africa and South Asia.
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| 37. |
- Larsen, Casper Grønlund, et al.
(author)
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Transmyringeal ventilation tube insertion for unilateral Menière’s disease : a protocol for a prospective, sham-controlled, double-blinded, randomized, clinical trial
- 2022
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In: Trials. - : Springer Science and Business Media LLC. - 1745-6215. ; 23:1
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Journal article (peer-reviewed)abstract
- Background: Menière’s disease is an idiopathic disorder characterized by recurrent episodes of vertigo lasting more than 20 min, unilateral sensorineural hearing loss, and tinnitus. If vertigo attacks occur frequently, the patient is usually severely incapacitated. Currently, there is no consensus on the treatment of Menière’s disease. The evidence regarding most treatment options is sparse due to a lack of randomized trials together with an often-spontaneous relief over time and a considerable placebo effect. Insertion of a transmyringeal tube is a simple and relatively safe, minimally invasive procedure and previous open-label trials have shown promising results. Study design: This is a prospective, sham-controlled, double-blinded, randomized, clinical trial. Aim: This trial aims to assess the effects of inserting a ventilation tube into the tympanic membrane compared with sham treatment for definite or probable unilateral Menière’s disease according to the criteria formulated by the Classification Committee of the Bàràny Society. Outcomes: The primary outcome will be the number of spontaneous vertigo attacks lasting more than 20 min and time to treatment failure. In addition to the primary outcome, we will assess various secondary outcomes related to hearing, ear fullness, dizziness, and serious adverse events. Sample size: An estimated 104 participants in total or 52 participants in each group will be necessary. The primary analysis will be according to the intention-to-treat principle. The trial will be initiated in 2021 and is expected to end in 2025. Trial status: ClinicalTrials.gov: NCT04835688. Registered on April 8, 2021. Protocol version: 1.8, 26-09-2022. Date of first enrollment: October 1st, 2021. End of study: anticipated January 2025.
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| 38. |
- Näsström, Mats, et al.
(author)
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Projekt: Fastelaboratoriet - VINNEXC
- 2007
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Other publication (pop. science, debate, etc.)abstract
- Fastelaboratoriet är ett VINN Excellence Center för innovation inom Funktionella Produkter. Centret skapades till minne av innovatören Rolf Faste som under många år var verksam vid Stanford University i Kalifornien, USA
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| 39. |
- Rockström, Johan, et al.
(author)
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A safe operating space for humanity
- 2009
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In: Nature. - : Springer Science and Business Media LLC. - 0028-0836 .- 1476-4687. ; 461:7263, s. 472-475
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Journal article (peer-reviewed)
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| 40. |
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| 41. |
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| 42. |
- Rockström, Johan, et al.
(author)
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Managing water in rainfed agriculture : the need for a paradigm shift
- 2010
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In: Agricultural Water Management. - : Elsevier BV. - 0378-3774 .- 1873-2283. ; 97:4, s. 543-550
-
Journal article (peer-reviewed)abstract
- Rainfed agriculture plays and will continue to play a dominant role in providing food and livelihoods for an increasing world population. We describe the world's semi-arid and dry sub-humid savannah and steppe regions as global hotspots, in terms of water related constraints to food production, high prevalence of malnourishment and poverty, and rapidly increasing food demands. We argue that major water investments in agriculture are required. In these regions yield gaps are large, not due to lack of water per se, but rather due to inefficient management of water, soils, and crops. An assessment of management options indicates that knowledge exists regarding technologies, management systems, and planning methods. A key strategy is to minimise risk for dry spell induced crop failures, which requires an emphasis on water harvesting systems for supplemental irrigation. Large-scale adoption of water harvesting systems will require a paradigm shift in Integrated Water Resource Management (IWRM), in which rainfall is regarded as the entry point for the governance of freshwater, thus incorporating green water resources (sustaining rainfed agriculture and terrestrial ecosystems) and blue water resources (local runoff). The divide between rainfed and irrigated agriculture needs to be reconsidered in favor of a governance, investment, and management paradigm, which considers all water options in agricultural systems. A new focus is needed on the meso-catchment scale, as opposed to the current focus of IWRM on the basin level and the primary focus of agricultural improvements on the farmer's field. We argue that the catchment scale offers the best opportunities for water investments to build resilience in small-scale agricultural systems and to address trade-offs between water for food and other ecosystem functions and services.
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| 43. |
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| 44. |
- Rockström, Johan, et al.
(author)
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Planetary Boundaries : Exploring the Safe Operating Space for Humanity
- 2009
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In: Ecology and Society. - 1708-3087. ; 14:2, s. 32-
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Journal article (peer-reviewed)abstract
- Anthropogenic pressures on the Earth System have reached a scale where abrupt global environmental change can no longer be excluded. We propose a new approach to global sustainability in which we define planetary boundaries within which we expect that humanity can operate safely. Transgressing one or more planetary boundaries may be deleterious or even catastrophic due to the risk of crossing thresholds that will trigger non-linear, abrupt environmental change within continental- to planetary-scale systems. We have identified nine planetary boundaries and, drawing upon current scientific understanding, we propose quantifications for seven of them. These seven are climate change (CO2 concentration in the atmosphere <350 ppm and/or a maximum change of +1 W m(-2) in radiative forcing); ocean acidification (mean surface seawater saturation state with respect to aragonite >= 80% of pre-industrial levels); stratospheric ozone (<5% reduction in O-3 concentration from pre-industrial level of 290 Dobson Units); biogeochemical nitrogen (N) cycle (limit industrial and agricultural fixation of N-2 to 35 Tg N yr(-1)) and phosphorus (P) cycle (annual P inflow to oceans not to exceed 10 times the natural background weathering of P); global freshwater use (<4000 km(3) yr(-1) of consumptive use of runoff resources); land system change (<15% of the ice-free land surface under cropland); and the rate at which biological diversity is lost (annual rate of <10 extinctions per million species). The two additional planetary boundaries for which we have not yet been able to determine a boundary level are chemical pollution and atmospheric aerosol loading. We estimate that humanity has already transgressed three planetary boundaries: for climate change, rate of biodiversity loss, and changes to the global nitrogen cycle. Planetary boundaries are interdependent, because transgressing one may both shift the position of other boundaries or cause them to be transgressed. The social impacts of transgressing boundaries will be a function of the social-ecological resilience of the affected societies. Our proposed boundaries are rough, first estimates only, surrounded by large uncertainties and knowledge gaps. Filling these gaps will require major advancements in Earth System and resilience science. The proposed concept of "planetary boundaries" lays the groundwork for shifting our approach to governance and management, away from the essentially sectoral analyses of limits to growth aimed at minimizing negative externalities, toward the estimation of the safe space for human development. Planetary boundaries define, as it were, the boundaries of the "planetary playing field" for humanity if we want to be sure of avoiding major human-induced environmental change on a global scale.
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| 45. |
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| 46. |
- Rockström, Johan, et al.
(author)
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The planetary water drama : Dual task of feeding humanity and curbing climate change
- 2012
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In: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 39
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Journal article (peer-reviewed)abstract
- This paper analyses the potential conflict between resilience of the Earth system and global freshwater requirements for the dual task of carbon sequestration to reduce CO2 in the atmosphere, and food production to feed humanity by 2050. It makes an attempt to assess the order of magnitude of the increased consumptive water use involved and analyses the implications as seen from two parallel perspectives; the global perspective of human development within a safe operating space with regard to the definition of the Planetary Boundary for freshwater; and the social-ecological implications at the regional river basin scale in terms of sharpening water shortages and threats to aquatic ecosystems. The paper shows that the consumptive water use involved in the dual task would both transgress the proposed planetary boundary range for global consumptive freshwater use and would further exacerbate already severe river depletion, causing societal problems related to water shortage and water allocation. Thus, strategies to rely on sequestration of CO2 as a mitigation strategy must recognize the high freshwater costs involved, implying that the key climate mitigation strategy must be to reduce emissions. The paper finally highlights the need to analyze both water and carbon tradeoffs from anticipated large scale biofuel production climate change mitigation strategy, to reveal gains and impact of this in contrast to carbon sequestration strategies.
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| 47. |
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| 48. |
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