Driver Pressure Research Articles

Socio-ecological accounting: DPSWR, a modified DPSIR framework, and its application to marine ecosystems

In contrast to institutionally focussed environmental accounting, socio-ecological accounting frameworks organise information concerned with human–environment interactions at scales relevant to ecosystem change and thus encapsulate information more relevant to ecosystem-based management. The DPSIR (Driver–Pressure–State–Impact–Response) framework has been used to identify relevant information in a number of ecosystem contexts but suffers limitations in terms of its definitional clarity and conceptual foundations, which undermine comparability between studies. These limitations are addressed in the DPSWR (Driver–Pressure–State–Welfare–Response) framework, which defines information categories based on a synthesis of concepts in DPSIR and its predecessors so as to more clearly identify the object of measurement in each category and isolate information relating to social systems. Consequently, its categories dealing with social systems are better suited to assessing anthropocentric trade-offs in environmental decision-making, such as through cost–benefit analysis. A conceptual input–output analysis is used to highlight measurement issues connected with the inter-relations between information categories, particularly with regard to scale, and the application of the framework is illustrated by reference to issues affecting marine ecosystems included in a Europewide study for the European Commission. However, DPSWR's definitions are designed to be sufficiently general as to support application in other ecosystem contexts.

Analysis of marine environmental problems in a rapidly urbanising coastal area using the DPSIR framework: a case study in Xiamen, China

Coastal regions are among the most rapidly urbanising places in the world. Rapid urbanisation along the inland coast, if not planned properly, may cause severe environmental consequences. Such situations are particularly true for China due to its rapid economic and social development. We used the Drivers–Pressures–State–Impact–Responses (DPSIR) conceptual framework to assess the factors that contribute to the degradation of the marine environment adjacent to Xiamen, which is one of the most rapidly developing coastal cities in China. Based on the DPSIR conceptual framework, we selected representative indicators to resolve the complicated cause and effect relationships associated with environmental problems. Furthermore, local responses, such as marine functional zoning, and pollution and waste management, were taken as triggers to drive the DPSIR cycle again to further analyse the effects of local response initiatives or activities for decision makers and stakeholders. Finally, we conclude that considerable progress in improving the analysis system could be achieved by establishing a unified information sharing system, by improving indicator development for marine environmental problem assessment, and by geographically and functionally expanding management initiatives to the regional level, including watershed areas.

An integrated analysis of the marine social–ecological system of the Strait of Georgia, Canada, over the past four decades, and development of a regime shift index

A Driver–Pressure–State–Impact conceptual model of the Strait of Georgia, Canada, was developed as a framework to characterise the low frequency temporal (regime-like) patterns of variability in this system since 1970, and to identify suitable indicators of these changes. Thirty-seven time series, including both bio-physical (“natural”) and human variables, were assembled with sufficiently few missing years to permit multivariate statistical analyses. Principal component analyses identified regime-like shifts that correspond to those generally accepted for the NE Pacific (late 1970s; mid-1990s), plus an additional shift in the mid-1980s. Redundancy analyses identified significant relationships in which the natural and human explanatory driver/pressure variables accounted for 72% of the variability of the state/impact response variables. Partitioning this variance among the natural and human drivers/pressures attributed 4% to the natural drivers/pressures alone and 16% to the human drivers/pressures alone, but 53% to the interactions between natural and human drivers and pressures. Both sets of driver and pressure variables (natural and human) are therefore necessary to account for the patterns of variability of the state and impact variables in the Strait of Georgia. Redundancy analysis was also used to identify a reduced set of driver/pressure variables which accounted for a large proportion of the variability in the state and impact response variables: sea surface temperature, wind speed, the North Pacific Gyre Oscillation index, human population surrounding the Strait of Georgia, recreational fishing effort, and the number of hatchery releases of Chinook salmon (Oncorhynchus tshawytscha) into the Strait. A structural change analysis was used to identify significant changes in these six explanatory variables, and to identify regime shift years (including their 95% confidence intervals). A regime shift index for the Strait of Georgia was then constructed using a probabilistic causal network model. This model predicted the observed regime shift behaviour with a success rate of >70%. These six explanatory variables are proposed as leading indicators for low frequency changes (regime shifts) in the Strait of Georgia marine social–ecological system for use within a broader monitoring program.

Cascade units for neon isotope production by rectification

The basics of neon isotope separation by the distillation method at T = 28 K are discussed. The required numbers of transfer units at the top and bottom column sections are calculated for different loads. The experimental characteristics of packed rectification columns are presented and examples of the cascade are discussed. A configuration for a cryogenic circuit based on a high-pressure throttle neon cycle with intermediate nitrogen cooling is presented. The necessity for and the technical feasibility of creating a driver pressure difference between the columns for different stages are demonstrated.

Human head–neck computational model for assessing blast injury

A human head finite element model (HHFEM) was developed to study the effects of a blast to the head. To study both the kinetic and kinematic effects of a blast wave, the HHFEM was attached to a finite element model of a Hybrid III ATD neck. A physical human head surrogate model (HSHM) was developed from solid model files of the HHFEM, which was then attached to a physical Hybrid III ATD neck and exposed to shock tube overpressures. This allowed direct comparison between the HSHM and HHFEM. To develop the temporal and spatial pressures on the HHFEM that would simulate loading to the HSHM, a computational fluid dynamics (CFD) model of the HHFEM in front of a shock tube was generated. CFD simulations were made using loads equivalent to those seen in experimental studies of the HSHM for shock tube driver pressures of 517, 690 and 862kPa. Using the selected brain material properties, the peak intracranial pressures, temporal and spatial histories of relative brain–skull displacements and the peak relative brain–skull displacements in the brain of the HHFEM compared favorably with results from the HSHM. The HSHM sensors measured the rotations of local areas of the brain as well as displacements, and the rotations of the sensors in the sagittal plane of the HSHM were, in general, correctly predicted from the HHFEM. Peak intracranial pressures were between 70 and 120kPa, while the peak relative brain–skull displacements were between 0.5 and 3.0mm.

Influence of Crosswind to Automobile Interior Aerodynamic Noise

After a brief introduction about aerodynamic noise generation and transmission mechanisms, the influence of crosswind to vehicle interior aerodynamic noise for a production automobile sedan was investigated through full-scale aeroacoustic wind tunnel tests. Through analysis of sound pressure level of vehicle interior driver ear position and pressure fluctuation level on vehicle side window glass under different yaw angles, the following results are obtained: The frequency characteristics of vehicle interior aerodynamic noise vary as yaw angle changes under one certain wind speed. Whether on the leeside or by windward, sound pressure level increases as yaw angle goes up. Under the same yaw angle, interior noise level on the leeside is higher than that by windward. Test results between pressure fluctuation level on side window glass and vehicle interior aerodynamic noise of driver ear position show good correlation

Eutrophication Assessment in Basque Estuaries: Comparing a North American and a European Method

Eutrophication in marine ecosystems is an important problem that requires an accurate assessment. Although Basque estuaries (northern Spain) have historically been under high anthropogenic pressure, no specific eutrophication assessment method had been applied in these waters. In this study, a method employed in the Basque Country (BC) to assess the “risk of failing to achieve good ecological status” under the requirements of the Water Framework Directive (WFD) was adapted to exclusively assess the risk of eutrophication. This method is based on the driver–pressure–state–impact–response approach. The results from this method (called WFD-BC method) were compared to the results from Assessment of Estuarine Trophic Status (ASSETS; a specific method developed in the US to assess estuarine trophic status in a pressure–state–response approach). The nutrient pressure was better characterized with the WFD-BC method due to the local hydrographic conditions (i.e., small and river-influenced estuaries) that were not well accommodated by the ASSETS method. In contrast, the WFD-BC results for assessment of state generally reflected worse conditions than the results from the ASSETS method due to the different indicators employed and the way these are integrated in the WFD-BC method. Overall, the WFD-BC method showed a good potential to assess eutrophication. However, to improve it, a lower weight for the benthos and macroalgae is recommended for evaluating state.

Development of a Small Diameter Shock Tube and Measurement of Basic Characteristics

In this study, we developed a diaphragmless driver section with two pistons to generate the shock wave in small diameter tubes. An optical system using a He-Ne laser is constructed for the definition of a main piston opening time. The trajectories of main piston are measured under the several initial driver pressures. Additionally, the motion equation for the main piston is derived from a simple motion model. Moreover, the laser differential interferometer is constructed for the contactless measurement of the shock waves. The shock waves generated by our diaphragmless driver section, propagating in 2 and 3 mm inner diameter tubes are measured by the laser differential interferometer. The Mach number of the shock wave and the density ratio across the shock wave can be calculated by the interference signal obtained from the shock wave measurement. Additionally, the Mach number distributions along the axial direction of the tubes and the relation between the shock wave location and time (shock wave diagram) are obtained. Consequently, it is attributed to the fact that the friction effect between the test gas and the inner wall of the tubes becomes larger with decreasing the inner diameter of the tube.

Present and future environmental impacts on the coastal zone of Berau (East Kalimantan, Indonesia), a deductive scenario analysis

Using the drivers–pressures–state–impact–responses (DPSIR) analytical framework, local stakeholder respondents and experts were interviewed to construct and prioritize a causality network that links ecosystem state of the coastal waters of Berau (East Kalimantan, Indonesia) with societal drivers of change. Particularly on the perceived top priority drivers and pressures, consensus among respondents was considerable. The constructed network was found to be consistent with literature findings from elsewhere in SE Asia. This causality network was then confronted with a local articulation of the SRES scenarios (IPCCs Special Report on Emissions Scenarios: A1, A2, B1, B2), and four plausible trajectories of future change were deduced over a period of 20 years, until 2030. Our scenario articulations differed greatly in the projected immigration influx into the region, in local economic growth and in institutional strength of governance. Under business-as-usual conditions, it is foreseen that fisheries will continue to overexploit the resource, and inland and mangrove deforestation, as well as sediment and sewage loading of the coastal waters, will increase, leading to declines in coral and seagrass extent and depleted fisheries. Scenarios with continued immigration (~A1, A2) will probably aggravate this pattern, whereas those with reduced immigration (~B1, B2) would appear to lead to considerable improvements in the state of the coastal waters of Berau.

Population pressure and environment in the context of growth: evidence from an Indian city

This article analyses the Indian city of Delhi using the contrasting concepts of resilience and agglomeration economies. Delhi is an expanding system that is changing because of economic, social and ecological driving forces. The driver–pressure–state–impact–response (DPSIR) framework is used in this article. We measure the extent of population pressure at the ward level [population pressure index (PPI)] by applying the statistical stochastic frontier function framework. We then examine the association between the PPI and the variables representing well-being and the overall ecosystem. There are overlaps between PPI and poor well-being indicators. However, some areas have a poor environmental state even though their population pressure is not at the frontier. This seems to have resulted from population growth spilling over to areas not fit for human habitation. Further migration of people in response to growth and employability may worsen the levels of well-being. However, appropriate interventions and investment in basic amenities can stop such severe welfare losses and help the city maintain its role as the engine of growth.

Free-piston driver optimisation for simulation of high Mach number scramjet flow conditions

The University of Queensland (UQ) is currently developing high Mach number, high total pressure scramjet flow conditions in its X2 and X3 expansion tube facilities. These conditions involve shock-processing a high-density air test gas followed by its unsteady expansion into a low-pressure acceleration tube. This relatively slow shock-processing requires the driver to supply high pressure gas for a significantly greater duration than normally required for superorbital flow conditions. One technique to extend the duration is to operate a tuned free-piston driver. For X2, this involves the use of a very light piston at high speeds so that, following diaphragm rupture, the piston displacement substitutes for vented driver gas, thus maintaining driver pressure much longer. However, this presents challenges in terms of higher piston loading and also safely stopping the piston. This article discusses the tuned driver concept, the design of a very lightweight but highly stressed piston, and details the successful development of a new set of tuned free-piston driver conditions for X2.

Development of spatial water resources vulnerability index considering climate change impacts

This study developed a new framework to quantify spatial vulnerability for sustainable water resources management. Four hydrologic vulnerability indices – potential flood damage (PFDC), potential drought damage (PDDC), potential water quality deterioration (PWQDC), and watershed evaluation index (WEIC) – were modified to quantify flood damage, drought damage, water quality deterioration, and overall watershed risk considering the impact of climate change, respectively. The concept of sustainability in the Driver–Pressure–State–Impact–Response (DPSIR) framework was applied in selecting all appropriate indicators (criteria) of climate change impacts. In the examination of climate change, future meteorological data was obtained using CGCM3 (Canadian Global Coupled Model) and SDSM (Statistical Downscaling Model), and future stream run-off and water quality were simulated using HSPF (Hydrological Simulation Program — Fortran). The four modified indices were then calculated using TOPSIS, a multi-attribute method of decision analysis. As a result, the ranking obtained can be changed in consideration of climate change impacts. This study represents a new attempt to quantify hydrologic vulnerability in a manner that takes into account both climate change impacts and the concept of sustainability.

Managing the Marine Environment: Is the DPSIR Framework Holistic Enough?

Ever increasing and diverse use of the marine environment and consequent impacts on marine life, habitats and landscapes make prominent the need for policy and policy‐making procedures that promote resilience and sustainability. In this paper, we focus on the Drivers–Pressures–State Changes–Impacts–Responses (DPSIR) framework, which seeks to represent and hence enable the management of key relationships formed between natural systems, designed systems and social systems. The DPSIR framework is widely used to assess and manage the impact of policy changes and associated problems; however, a change is evident in recent applications of the approach: an expert‐driven, evidence‐focussed mode of use is giving way to the use of the framework as a heuristic device to facilitate engagement, communication and understanding between different stakeholders. In this paper, an assessment is made of how holistic DPSIR practice is in the context of the marine environment and we argue that the paradigmatic turn from realist to interpretivist reveals the DPSIR approach's multiparadigmatic and holistic potential. Copyright © 2011 John Wiley & Sons, Ltd.

Effect of primary jet geometry on ejector performance: A cold-flow investigation

The following cold-flow study examines the interaction of the diffracted shock wave pattern and the resulting vortex loop emitted from a shock tube of various geometries, with an ejector having a round bell-shaped inlet. The focus of the study is to examine the performance of the ejector when using different jet geometries (primary flow) to entrain secondary flow through the ejector. These include two circular nozzles with internal diameters of 15 mm and 30 mm, two elliptical nozzles with minor to major axis ratios of a/ b = 0.4 and 0.6 with b = 30 mm, a square nozzle with side lengths of 30 mm, and two exotic nozzles resembling a pair of lips with axis ratios of a/ b = 0.2 and 0.5 with b = 30 mm. Shock tube driver pressures of P 4 = 4, 8, and 12 bar were studied, with the pressure of the shock tube driven section P 1 being atmospheric. High-speed schlieren photography using the Shimadzu Hypervision camera along with detailed pressure measurements along the ejector and the impulse created by the ejector were conducted.

A rapid opening sleeve valve for a diaphragmless shock tube

This paper describes a novel pneumatically operated diaphragmless shock tube valve that is capable of generating well-formed shock waves within a driven tube which has a length to diameter ratio of 122. Its development was motivated by the requirement for an automated shock tube—an application for which the conventional bursting diaphragm method is not suited. The valve operates reliably, without any need for adjustment to its setup, over a wide range of driver pressures. Shock waves of up to Mach 2.4 have been generated in test gas at atmospheric pressure. A model for assessing the performance of the valve was developed and calibrated with experimental data. It indicated that opening times in the region of 0.5 ms were attained. By comparison, the opening time of a burst diaphragm is approximately 0.2–0.3 ms. Features of the valve include a streamlined flow path, which helps optimise the efficiency of the shock tube, automated operation and a test turn around time of the order of a few minutes.

The Niger Delta wetlands: threats to ecosystem services, their importance to dependent communities and possible management measures

The Niger Delta wetlands are changing rapidly, raising concern for the wetlands' health and for communities relying upon its ecosystem services. Knowledge on ecosystem service provision is important for effective ecosystem and livelihoods management, but is currently lacking for the Niger Delta. We synthesised literature and used the ‘Drivers–pressure–state–impact–response’ (DPSIR) framework to structure information on changes in the wetlands' ecosystem services and implications for dependent communities. The wetlands' ecosystem services are being eroded through oil and gas exploration, dredging, invasive plant infestation and wetland reclamation. This is exacerbated by rising demand for oil, population growth and weak governance. Mass fish migration, water pollution and reduction of wetland area are also evident, impacting ecosystem services and traditional livelihood systems. This has caused poverty; people have to buy goods that previously could be obtained from the wetlands. Effective wetland management will be aided by: recognition of ecosystem services' contributions to community well-being; understanding how benefits are distributed over time, space, stakeholder; and how these changes in response to pressures. Since key pressures in the wetland are anthropogenic, understanding the role of institutions in relation to the Niger Delta's ecosystem services is imperative.

Diaphragmless shock wave generators for industrial applications of shock waves

The prime focus of this study is to design a 50 mm internal diameter diaphragmless shock tube that can be used in an industrial facility for repeated loading of shock waves. The instantaneous rise in pressure and temperature of a medium can be used in a variety of industrial applications. We designed, fabricated and tested three different shock wave generators of which one system employs a highly elastic rubber membrane and the other systems use a fast acting pneumatic valve instead of conventional metal diaphragms. The valve opening speed is obtained with the help of a high speed camera. For shock generation systems with a pneumatic cylinder, it ranges from 0.325 to 1.15 m/s while it is around 8.3 m/s for the rubber membrane. Experiments are conducted using the three diaphragmless systems and the results obtained are analyzed carefully to obtain a relation between the opening speed of the valve and the amount of gas that is actually utilized in the generation of the shock wave for each system. The rubber membrane is not suitable for industrial applications because it needs to be replaced regularly and cannot withstand high driver pressures. The maximum shock Mach number obtained using the new diaphragmless system that uses the pneumatic valve is 2.125 ± 0.2%. This system shows much promise for automation in an industrial environment.

Experimental studies on coaxial vortex loops

An experimental study has been conducted on the formation and propagation of coaxial vortex loops using a shock tube facility. The study aimed at evaluating the flow characteristics of pairs of corotating vortex rings that generate the leapfrogging phenomenon. The driver and driven gas of the shock tube were air. Three driver pressures were used (4, 8, and 12 bars) with the driven gas being at ambient conditions. The Mach numbers of the shock wave generated inside the shock tube were 1.34, 1.54, and 1.66, respectively. The sudden expansion present at the diaphragm location effectively decreased the Mach number value of the traveling shock wave. Results showed that a pair of vortex rings staggered with respect to time and with the same direction rotation lead to leapfrogging. Results also indicated that the number of leapfrogging occurrences is related to the Reynolds number of the vortex ring pairs with a decrease in leapfrogs at higher Reynolds numbers.

Ecological–economic assessment of aquaculture options: Comparison between abalone monoculture and integrated multi-trophic aquaculture of abalone and seaweeds

Integrated multi-trophic aquaculture (IMTA) possesses ecological and socio-economic advantages, relative to single-species aquaculture. The promotion of a sustainable aquaculture industry requires that decision-makers, ecosystem managers and farmers have sufficient quantitative information associated with its implementation from both public and private perspectives. The present paper applies the Differential Drivers–Pressure–State–Impact–Response (ΔDPSIR) methodological approach to an ecological and economic comparison between mono-aquaculture and IMTA. Data from a South African 240-ton year − 1 abalone farm were used as a case study. Three operation schemes were considered: abalone monoculture in a flow-through system; and two IMTA schemes, which recycle water and replace 10% and 30% of kelp consumption with on-farm-grown seaweed. The analysis indicates a decrease in the aquaculture generated ecological pressures with the incorporation of seaweeds, mainly a reduction in nitrogen discharges into the adjacent coastal ecosystem (by 3.7 to 5.0 tons year − 1 ), a reduction in harvest of natural kelp beds (by 2.2 to 6.6 ha year − 1 ) and a reduction of GHG emissions (by 290 to 350 tons CO 2e year − 1 ). Adopting an IMTA configuration raised farm profits by 1.4 to 5%. The corresponding overall gain from using IMTA in the case study is several folds larger than the net gain in profit, and is estimated between 1.1 and 3.0 million U.S. dollar per annum. This range of values reflects the gains of adopting IMTA on (i) economic value of the aquaculture, i.e. farm's profit, (ii) value of environmental externalities, and (iii) implementation costs. The analysis suggests that the value of the benefits to the public by adopting the IMTA configurations can be larger than the gains in farm's profitability.

Structuring problems in sustainability science: The multi-level DPSIR framework

Sustainability science needs approaches that allow for the integration of knowledge across disciplines and scales. This paper suggests an approach to conceptualize problems of unsustainability by embedding the Drivers–Pressure–State–Impact–Response (DPSIR) scheme within a multi-level institutional framework represented by Hägerstrand’s system of nested domains. The proposed taxonomy helps to decipher and to better understand key casual chains and societal responses at the appropriate spatial levels for particular sustainability problem areas. To illustrate the scheme more concretely the example of recent problem-solving efforts for Baltic Sea eutrophication driven by Swedish agriculture is examined. The discussion focuses on how the scheme fulfills the four research strategy requirements within the field of sustainability science and how the scheme is distinct from alternative approaches.