A spatially explicit modeling approach to explore scenarios of sustainable agriculture futures

The transition to agricultural sustainability involves difficult choices and an understanding of the complex trade-offs associated with agricultural activities. Decision support tools and techniques assist in making the informed decisions for a transition to sustainable agriculture. Georgia Basin — Quite Useful Ecosystem Scenario Tool (GB-QUEST) is a computer-based, user-friendly tool that has been developed to look at the future sustainability scenarios of the Georgia Basin in British Columbia. The objective of this paper is to describe the agricultural model that has been developed for implementation in GB-QUEST. We present its framework, spatial methodology for land-use simulation, and the initial results of its application. The agriculture model is a spatial model that examines the social, economic and environmental consequences of user-defined agricultural development strategies. The model simulates changes in the Georgia Basin from the year 2000 to 2040 in decadal steps. User choices of local and global development factors, along with their "worldview" choices, are important inputs in the model that determine the effects on environmental and socio-economic systems. The model has two components — Generation of land-use scenarios, and Development of Indicator models. The first component uses cell-based spatial algorithms to simulate likely changes/conversions in land-use up to the year 2040. The approach used here integrates the functionality of Multi-Criteria Evaluation (MCE) and Cellular Automata (CA) techniques in order to simulate the land-use conversions. It uses Geographic Information Systems (GIS) and remote sensing techniques for creating, storing and deriving the data sets required for the model. The second component develops the indicator models for relating scenario variables to socio-economic and environmental variables such as physical and economic yields, economic operation costs and nutrient surplus per unit area. These indicator models are used to evaluate land-use scenarios generated by the users. The model encourages understanding of sustainability, by allowing one to explore different possible scenarios of the future for their environmental and socio-economic consequences.     

Transmissivity variations in mudstones

Many people in sub-Saharan Africa have to rely on meager water resources within mudstones for their only water supply. Although mudstones have been extensively researched for their low permeability behavior, little research has been undertaken to examine their ability to provide sustainable water supplies. To investigate the factors controlling the occurrence of usable ground water in mudstone environments, an area of Cretaceous mudstones in southeastern Nigeria was studied over a 3 yr period. Transmissivity (T) variations in a range of mudstone environments were studied. The investigations demonstrate that within the top 40 m of mudstones, transmissivity can be sufficient to develop village water supplies (T > 1 m2/d). Transmissivity is controlled by two factors: low-grade metamorphism and the presence of other, subordinate, lithologies within the mudstones. Largely unaltered mudstones (early diagenetic zone), comprising mainly smectite clays, are mostly unfractured and have a low T of < 0.1 m2/d. Mudstones that have undergone limited metamorphism (late diagenetic zone) comprise mixed layered illite/smectite clays, and ground water is found in widely spaced fracture zones (T > 1 m2/d in large fracture zones; T < 0.1 m2/d away from fracture zones). Mudstones that have been further altered and approach the anchizone comprise illite clays, are pervasively fractured, and have the highest transmissivity values (T > 4 m2/d). Dolerite intrusions in unaltered, smectitic mudstones are highly fractured with transmissivity in the range of 1 < T < 60 m2/d. Thin limestone and sandstone layers can also enhance transmissivity sufficiently to provide community water supplies.     

The impact of the assimilation of scatterometer winds on surface wind and wave forecasts

Recent work has demonstrated that surface marine winds from the Bureau of Meteorology's operational Numerical Weather Prediction (NWP) systems are typically underestimated by 5 to 10%. This is likely to cause significant bias in modelled wave fields that are forced by these winds. A simple statistical adjustment of the wind components is shown to reduce the observed bias in Significant Wave Height considerably. The impact of increasing the vertical resolution of the NWP model and assimilating scatterometer data into the model is assessed by comparing the resulting forecast wind and waves to observations. It is found that, in general, the inclusion of scatterometer observations improves the accuracy of the surface wind forecasts. However, most of the improvement is shown to arise from the increased number of vertical levels in the atmospheric model, rather than directly from the use of the observations. When the wave model is forced with surface winds from the NWP model that includes scatterometer data, it is found that the scatterometer assimilation does not reduce the systematic bias in surface wave forecasts, but that the random errors are reduced.     

Relative effects ofLittoraria irrorata andProkelisia marginata onSpartina alterniflora

Spartina alterniflora salt marshes along the southeastern United States are some of the most productive and well studied ecosystems in the world. The role of physicochemical forces in regulatingSpartina growth is well understood, while the importance of grazers remains less clear. Recent studies have shown that the abundant marsh periwinkle,Littoraria irrorata, can exert strong control overSpartina through its grazing activities, but relatively little is known about its relative effects in comparison to other marsh plant consumers. To test the relative importance of snail and insect consumers onSpartina biomass, we conducted a 7-mo field experiment testing top-down regulation ofSpartina with all combinations ofL. irrorata (removed, control, c. 215 periwinkles m⁻²) andSpartina planthopper,Prokelisia marginata (removed, control). Snail removal resulted in a 50% increase inSpartina biomass while removal of planthoppers had no detectable effect. Planthopper density also increased by 50% when snails were excluded. In this South Carolina marsh,L. irrorata exerts a stronger top-down control ofSpartina thanP. marginata. These results indicate trophic cascade regulation ofSpartina salt marsh is more likely to occur through the predator(s)-Littoraria-plant interaction than through the predator(s)-Prokelisia-plant relationship.     

PSDF: Particle Stream Data Format for N-body simulations

We present a data format for the output of general N-body simulations, allowing the presence of individual time steps. By specifying a standard, different N-body integrators and different visualization and analysis programs can all share the simulation data, independent of the type of programs used to produce the data. Our Particle Stream Data Format, PSDF, is specified in YAML, based on the same approach as XML but with a simpler syntax. Together with a specification of PSDF, we provide background and motivation, as well as specific examples in a variety of computer languages. We also offer a web site from which these examples can be retrieved, in order to make it easy to augment existing codes in order to give them the option to produce PSDF output.     

Chained to Development? Livelihoods and global value chains in the coffee-producing Toraja region of Indonesia

ABSTRACT

A popular rural development strategy in recent years has been through the adoption of what has been widely called a ‘value chain approach’, where improved linkages between small producers in underdeveloped rural communities and ‘lead firms’ constitute the foundations for development interventions. Whilst the global value-chain framework can deliver insights into the broad structural processes shaping livelihood possibilities, the adoption of value chains as a development strategy tends to disregard the complexity of smallholder livelihoods that shape poverty alleviation pathways in different contexts. The relationships between global value chains, development interventions, and rural livelihoods are explored in this article through a case study of smallholder coffee farming in the Toraja region of Indonesia. In this case, value-chain interventions in the coffee sector are unlikely to significantly contribute to improved rural welfare due to the diversified reality of local livelihoods, the nuances of how coffee production is embedded within Torajan culture and economy, and excellent prevailing market opportunities. The livelihood framework, therefore, provides an important corrective for the sometimes excessive optimism presented by advocates of a value-chain approach to rural development.     

Reynolds stress and sand transport over a foredune

Reynolds shear stress (RS = –u′ w′) and sand transport patterns over a vegetated foredune are explored using three‐dimensional velocity data from ultrasonic anemometers (at 0 · 2 and 1 · 2 m) and sand transport intensity from laser particle counters (at 0 · 014 m). A mid‐latitude cyclone on 3–4 May 2010 generated storm‐force winds (exceeding 20 m s^–1) that shifted from offshore to obliquely alongshore. Quadrant analysis was used to characterize the spatial variation of RS quadrant components (Q1 through Q4) and their relative contributions were parameterized using the flow exuberance relation, EX_FL = (Q1 + Q3)/(Q2 + Q4). The magnitudes of RS and sand transport varied somewhat independently over the dune as controlled by topographic forcing effects on flow dynamics. A ‘flow exuberance effect’ was evident such that Q2 (ejection‐like) and Q4 (sweep‐like) quadrants (that contribute positively to RS) dominated on the beach, dune toe, and lower stoss, whereas Q1 and Q3 (that contribute negatively to RS) dominated near the crest. This exuberance effect was not expressed, however, in sand transport patterns. Instead, Q1 and Q4, with above‐average streamwise velocity fluctuations (+u′), were most frequently associated with sand transport. Q4 activity corresponded with most sand transport at the beach, toe, and stoss locations (52, 60, 100%). At the crest, 25 to 86% of transport was associated with Q1 while Q4 corresponded with most of the remaining transport (13 to 59%). Thus, the relationship between sand transport and RS is not as straightforward as in traditional equations that relate flux to stress in increasing fashion. Generally, RS was poorly associated with sand transport partly because Q1 and Q4 contributions offset each other in RS calculations. Thus, large amounts of transport can occur with small RS. Turbulent kinetic energy or Reynolds normal stresses (u′², w′²) may provide stronger associations with sand transport over dunes, although challenges exist on how to normalize and compare these quantities. Copyright © 2013 John Wiley & Sons, Ltd.     

Facies and flow regimes of sandstone‐hosted columnar intrusions: Insights from the pipes of Kodachrome Basin State Park

Sandstone‐hosted intrusions are found in a wide variety of environments, but remain poorly understood compared with their mudstone‐hosted counterparts. In particular, they remain largely unrecognized in the subsurface, in part because they are problematic to image in seismic data. This study reports on the facies and fluid flow associated with a 20 000 km³ sandstone intrusion province in Utah, USA. Forming a small portion of this intrusion province, the intrusions cropping out in Kodachrome Basin State Park display a very wide array of facies and morphologies, factors which would make their identification in core a significant challenge. Remobilized sediment is shown to have been injected at least 200 m vertically from its source, with flow prolonged enough to concentrate heavy minerals in placer‐style deposits at the pipe margins. Evidence for lateral pipe migration and for associated broader fluidization regions is also presented. A new approach to estimating flow parameters in injectites is implemented herein, and indicates that previous work has overestimated velocities and flow Reynolds numbers by up to two orders of magnitude. Flow modelling suggests turbulent flow in the pipes that is consistent with field observations of erosive margins and chaotic internal structures. Post‐emplacement, these pipes remained as long‐term fluid conduits, as revealed by their diagenetic history, focussing and facilitating flow of extraformational fluids, despite the relatively high porosity and permeability of the aeolian host strata.     

Learning with Local Help: Expanding the Dialogue on Climate Change and Water Management in the Okanagan Region, British Columbia, Canada

The research activity described in this report is a comprehensive regional assessment of the impacts of climate change on water resources and options for adaptation in the Okanagan Basin. The ultimate goal of the project is to develop integrated climate change and water resource scenarios to stimulate a multistakeholder discussion on the implications of climate change for water management in the region. The paper describes two main objectives: (a) providing a set of research products that will be of relevance to regional interests in the Okanagan, and (b) establishing a methodology for participatory integrated assessment of regional climate change impacts and adaptation that could be applied to climate-related concerns in Canada and other countries. This collaborative study has relied on field research, computer-based models, and dialogue exercises to generate an assessment of future implications, and to learn about regional views on the prospects for adaptation. Along the way, it has benefited from strong partnerships with governments, researchers, local water practitioners, and user groups. Building on the scenario-based study components, and a series of interviews and surveys undertaken for the water management and adaptation case study components, a set of stakeholder dialogue sessions were organized which focused on identifying preferred adaptation options and processes for their implementation. Rather than seeking consensus on the “best” option or process, regional interests were asked to consider a range of available options as part of an adaptation portfolio that could address both supply side and demand side aspects of water resources management in the Okanagan. The Canadian Crown reserves the right to retain a non-exclusive, royalty free licence in and to any copyright.     

Vertical Structure Of Turbulence In Offshore Flow During Rasex

The adjustment of the boundary layer immediately downstream froma coastline is examined based on two levels of eddy correlation data collected on a mast at the shore and six levels of eddy correlation data and profiles of mean variables collected from a mast 2 km offshore during the Risø Air-Sea Experiment. The characteristics of offshore flow are studied in terms of case studies and inter-variable relationships for the entire one-month data set. A turbulent kinetic energy budget is constructed for each case study.The buoyancy generation of turbulence is small compared to shear generation and dissipation. However, weakly stable and weakly unstable cases exhibit completely different vertical structure. With flow of warm air from land over cooler water, modest buoyancy destruction of turbulence and reduced shear generation of turbulence over the less rough sea surface cause the turbulence to rapidly weaken downstream from the coast. The reduction of downward mixing of momentum by the stratification leads to smaller roughness lengths compared to the unstable case. Shear generation at higher levels and advection of stronger turbulence from land often lead to an increase of stress and turbulence energy with height and downward transport of turbulence energy toward the surface.With flow of cool air over a warmer sea surface, a convective internal boundary layer develops downstream from the coast. An overlying relatively thick layer of downward buoyancy flux (virtual temperature flux) is sometimes maintained by shear generation in the accelerating offshore flow.