New Path Equations in Absolute Parallelism Geometry

The Bazanski approach, for deriving the geodesic equations in Riemannian geometry, is generalized in the absolute parallelism geometry. As a consequence of this generalization three path equations are obtained. A striking feature in the derived equations is the appearance of a torsion term with a numerical coefficients that jumps by a step of one half from equation to another. This is tempting to speculate that the paths in absolute parallelism geometry might admit a quantum feature.Comment: 4 pages Latex file Journal Reference: Astrophysics and space science 228, 273, (1995

Is dark matter an extra-dimensional effect?

We investigate the possibility that the observed behavior of test particles outside galaxies, which is usually explained by assuming the presence of dark matter, is the result of the dynamical evolution of particles in higher dimensional space-times. Hence, dark matter may be a direct consequence of the presence of an extra force, generated by the presence of extra-dimensions, which modifies the dynamic law of motion, but does not change the intrinsic properties of the particles, like, for example, the mass (inertia). We discuss in some detail several possible particular forms for the extra force, and the acceleration law of the particles is derived. Therefore, the constancy of the galactic rotation curves may be considered as an empirical evidence for the existence of the extra dimensions.Comment: 11 pages, no figures, accepted for publication in MPLA; references adde

Integrated modeling for assessing water-energy-land nexus - Application of a hydrological and hydro-economic modeling framework for the Zambezi basin

Water demands for agricultural, industry, domestic and environmental uses in arid and semiarid regions continue to grow, while available surface and ground water resources remains the same or could even decline because of climate change. Decision makers need tools to support the implementation of sustainable water management policies. Hydro-economic modeling could be used for this task, because of its capacity to integrate key biophysical and socio economic components within a unified framework. However, linking a hydro-economic model with a high-resolution hydrological model is needed in order to incorporate an adequate representation of present and future elements of the water balance. Here we show the coupling of the Extended Continental-scale Hydro-economic Optimization model(ECHO), an integrated economic-technological modeling tool for application to long-term transboundary river basin planning with the Community Water Model (CWATM), a high-resolution global hydrological model. The trajectories of run-off and baseflow are simulated at high resolution (5’, daily) with CWATM and processed to define average inflow scenarios (monthly) for the sub-basin units represented in ECHO. Estimates of industrial, domestic and agricultural water withdrawals, return flows and environmental flow requirements are also taken from the hydrological simulations. Based on this, the ECHO model assesses the cost-effective combination of solutions that could address water scarcity at basin level. Solutions in this context represent transformative policies, basin-wide infrastructure configurations, and investment strategies that enable sustainable development. As an example the novel framework is applied to the Zambezi basin, the largest river basin in Southern Africa, covering 1.4 million square km across eight countries and home to about 40 million people. CWATM provides projections of water availability and demand till 2050 at high spatial resolution under alternative socio-economic and climatic scenarios, while ECHO provides information on the least-cost combination of water management options that can satisfy those water demands subject to available water resources at basin level

Multi-model and multi-scenario assessments of Asian water futures: the Water Futures and Solutions (WFaS) initiative

This paper presents one of the first quantitative scenario assessments for future water supply and demand in Asia to 2050. The assessment, developed by the Water Futures and Solutions (WFaS) initiative, uses the latest set of global climate change and socioeconomic scenarios and state-of-the-art global hydrological models. In Asia, water demand for irrigation, industry and households is projected to increase substantially in the coming decades (30-40% by 2050 compared to 2010). These changes are expected to exacerbate water stress, especially in the current hotspots such as north India and Pakistan, and north China. By 2050, 20% of the land area in the Asia-Pacific region, with a population of 1.6-2 billion, is projected to experience severe water stress. We find that socioeconomic changes are the main drivers of worsening water scarcity in Asia, with climate change impacts further increasing the challenge into the 21st century. Moreover, a detailed basin-level analysis of the hydro-economic conditions of 40 Asian basins shows that although the coping capacity of all basins is expected to improve due to GDP growth, some basins continuously face severe water challenges. These basins will potentially be home to up to 1.6 billion people by mid-21st century

Water Futures and Solution - Fast Track Initiative (Final Report)

The Water Futures and Solutions Initiative (WFaS) is a cross-sector, collaborative global water project. Its objective is to apply systems analysis, develop scientific evidence and identify water-related policies and management practices, working together consistently across scales and sectors to improve human well-being through water security. The approach is a stakeholder-informed, scenario-based assessment of water resources and water demand that employs ensembles of state-of-the-art socio-economic and hydrological models, examines possible futures and tests the feasibility, sustainability and robustness of options that can be implemented today and can be sustainable and robust across a range of possible futures and associated uncertainties. This report aims at assessing the global current and future water situation

Improving Water Resources Management on Global and Region Scales – Evaluating Strategies for Water Futures with the IIASA’s Community Water Model

Half of the planet’s population is severely impacted by severe water issues including absent or unreliable water supply, sanitation, poor water quality, unmitigated floods and droughts, and degraded water environments. In recent years, global water security has been highlighted not only by the science community but also by business leaders as one of the greatest threats to sustainable human development for different generations. How can we ensure the well-being of people and ecosystems with limited water, technology and financial resources? To evaluate this, IIASA’s Water Futures and Solutions Initiative (WFaS) is identifying a portfolios of robust and cost-effective options across different economic sectors including agriculture, energy, manufacturing, households, and environment and ecosystems. Options to increase water supply and accessibility are evaluated together with water demand management and water governance options. To test these solution-portfolios in order to obtain a clear picture of the opportunities but also of the risks and the trade-offs we have developed the Community Water Model (CWATM) which joins IIASA’s integrated assessment modeling framework, coupling hydrology with hydro-economics (ECHO model), energy (MESSAGE model) and land use (GLOBIOM model). CWATM has been developed to work flexibly with varying spatial resolutions from global to regional levels. The model is open source and community-driven to promote our work amongst the wider water and other science community worldwide, with flexibility to link to other models and integrate newly developed modules such as water quality. In order to identify the solution portfolios, we present a global hotspots assessment of water-related risks with the ability to zoom in at regional scale using the example of the Lake Victoria basin in E. Africa. We show how socio-economic and climate change will alter spatial patterns of the hydrological cycle and have regional impacts on water availability. At the same time, we assess water needs for humans and environment to identify the population and regions that are vulnerable to changes linked to extremes such as water scarcity, droughts and floods. Different solution-portfolios to facilitate regional water management planning will be further discussed

The Water Futures and Solutions Initiative of IIASA

The Water Futures and Solutions Initiative (WFaS) is a cross-sector, collaborative global project. Its objective is to developing scientific evidence and applying systems analysis to help identify water-related policies and management practices that work together consistently across scales and sectors to improve human well-being through water security. The Water Futures and Solutions (WFaS) initiative has produced a consistent and comprehensive projection for global possible water futures. Focusing on the near future until the 2050s, WFaS assessed how water future changes over time, employing a multi-model projection

Global assessment of water challenges under uncertainty in water scarcity projections

Water scarcity, a critical environmental issue worldwide, has primarily been driven by a significant increase in water extractions during the last century. In the coming decades, climate and societal changes are projected to further exacerbate water scarcity in many regions worldwide. Today, a major issue for the ongoing policy debate is to identify interventions able to address water scarcity challenges in the presence of large uncertainties. Here, we take a probabilistic approach to assess global water scarcity projections following feasible combinations of Shared Socioeconomic Pathways (SSPs) and Representative Concentration Pathways (RCPs) for the first half of the 21st century. We identify – alongside trends in median water scarcity - changes in the uncertainty range of anticipated water scarcity conditions. Our results show that median water scarcity and the associated range of uncertainty are generally on the increase worldwide, including many major river basins. Based on these results, we develop a general decision-making framework to enhance policymaking by identifying four representative clusters of specific water-policy challenges and needs