Mark E. Dickson

Improving ecosystem service frameworks to address wicked problems

Complex problems often result from the multiple interactions between human activities and ecosystems. The interconnected nature of ecological and social systems should be considered if these “wicked problems” are to be addressed. Ecosystem service approaches provide an opportunity to link ecosystem function with social values, but in practice the essential role that social dynamics play in the delivery of outcomes remains largely unexplored. Social factors such as management regimes, power relationships, skills, and values, can dramatically affect the definition and delivery of ecosystem services. Input from a diverse group of stakeholders improves the capacity of ecosystem service approaches to address wicked problems by acknowledging diverse sets of values and accounting for conflicting world views. Participatory modeling can incorporate both social and ecological dynamics into decision making that involves stakeholders, but is itself a complex social undertaking that may not yield precise or predictable outcomes. We explore the efficacy of different types of participatory modeling in relation to the integration of social values into ecosystem services frameworks and the generation of four important elements of social capital needed to address wicked problems: enhancing social learning and capacity building; increasing transparency; mediating power; and building trust. Our findings indicate that mediated modeling, group mapping, and mental/conceptual modeling are likely to generate elements of social capital that can improve ecosystem service frameworks. Participatory simulation, system dynamic modeling, and Bayesian belief networks, if utilized in isolation, were found to have a low likelihood of generating the social capital needed to improve ecosystem services frameworks. Scenario planning, companion modeling, group model building, and participatory mapping all generate a moderate to high level of social capital elements that improve the capacity of ecosystem service frameworks to address wicked problems.

Geomorphological Evolution of Lord Howe Island and Carbonate Production at the Latitudinal limit to Reef Growth

Abstract Lord Howe Island is a volcanic island, rising to over 800 m, draped with Late Quaternary submarine and subaerial carbonate sediments. The island and neighbouring islets lie within a chain of seamounts and is presently at or close to the latitudinal limit to coral reef growth. Lord Howe Island and adjacent Balls Pyramid, composed of the basalts erupted around 6 million years ago, sit near the middle of broad shelves on separate peaks of one major volcanic edifice. The central part of the Lord Howe Island is covered by calcarenite that was deposited primarily as dunes (eolianite), but with isolated beach units. Uranium-series, amino acid racemisation, and thermoluminescence dating indicate that many of these were deposited during marine oxygen isotope stage 5. Eolianite units stratigraphically below the beach deposits are of penultimate interglacial, or in places perhaps older, age. Different suites of erosional landforms are associated with different lithologies. Towering plunging cliffs characterise the resistant Mount Lidgbird Basalt, in some cases fringed with large talus slopes. On less resistant lithologies or where nearshore topography means greater wave force as a result of waves breaking, there are shore platforms. Slumping cliffs abut broad erosional platforms on the poorly lithified calcarenite. A fringing reef on the western side of Lord Howe Island, the southernmost coral reef in the Pacific, is dominated by coral and coralline algae. Carbonate sediments veneering the shelf around the islands contain a more temperate biota. Located at the southern limit of reef-forming seas, but apparently having undergone erosion for much of its history outside of reef seas, Lord Howe Island provides insights into marine planation of volcanic islands close to what has been termed the Darwin Point. It represents the initial stages of fringing reef development on a volcanic island. Middleton and Elizabeth Reefs, north of Lord Howe Island, have the morphology of coral atolls and appear to be gradually subsiding. The Darwinian sequence, fringing reef to atoll, appears particularly compressed in this chain of islands. However, a fossil reef in water depths of around 30 m on the shelf around Lord Howe Island, of unknown age, implies a more complex history.

Beach Volume on an Eroding Sand–Gravel Coast Determined Using Ground Penetrating Radar

Abstract Mixed sand and gravel beaches form a wedge of protective sediment at the base of eroding cliffs. In profile these beaches are typically steep with a prominent storm berm. If the volume of beach sediment is insufficient, storms strip beach sediments seaward, exposing the cliff toe to wave attack. The beach volume is thus crucial to the protection of sea cliffs. In this article we describe a method of calculating alongshore variation in the volume of mixed sand and gravel beaches using ground penetrating radar (GPR). Eighteen sites were studied along 50 km of the east coast of South Island, New Zealand. The method was underpinned by an ability to map the boundary between beach sediments and underlying Pleistocene alluvial-fan sediments. This was achieved by studying the radar facies, particularly landward-dipping overwash deposits and seaward-dipping beach erosion surfaces. The method was ground-truthed in three ways: (1) a stream provided a clean section through one site that was imaged by radar; (2) a storm stripped beach sediment from three sites exposing the substrate, which was then surveyed and compared with radar profiles; (3) excavations in a previous study at nine sites were used to combine the stratigraphy with the radar images. GPR proved highly effective in this environment, revealing thin beaches in the south of the study area that thicken northward in the direction of alongshore sediment transport. Cliff height decreases northward such that there is a transition from beaches in front of cliffs, to beaches that overtop low cliffs, to barriers in front of a coastal lagoon.

Managing changing risks to infrastructure systems

Civil engineering infrastructure systems are vulnerable to the effects of natural hazards such as flooding, landslides, windstorm and coastal erosion. Risk analysis provides a rational approach to analysing the threat these phenomena pose and identifying efficient options for system management. This paper presents a general formulation of the risk-analysis problem for an engineering system subject to environmental loads. However, most of the variables that determine system behaviour may be subject to long-term change, for example due to climate change or structural deterioration. The uncertainties in appraisal of infrastructure over extended timescales can be considerable, so a framework is presented for systematic analysis of uncertainties and robust decision making.

Feedback structure of cliff and shore platform morphodynamics

It has been suggested that studies of geomorphological systems should identify potential system feedbacks, determine their direction of influence, and assess their relative importance. In this paper we show how a core set of processes and feedback loops can be distilled from existing literature on rock coast morphodynamics. The structure has been represented using Causal Loop Diagrams and a methodology to estimate the strength of a single feedback loop is presented. The backwearing erosion rate (cliff horizontal erosion) has been found to be controlled by at least four feedback loops; three balancing (cliff toe wave energy depletion, ground-water pore pressure diminution and cliff deposit protection) and one positive loop (abrasion enhancement). The downwearing erosion rate (vertical erosion) has been found to be controlled by at least three balancing feedback loops (weathering limited, shear depletion, cover-protection). Mean sea level directly influences the downwearing rate, through the water depth relative to the wave base, and indirectly influences the backwearing erosion rate through the wave energy dissipation that determines the amount of energy reaching the cliff toe. The offshore wave non-linearity parameter is proposed to capture the complex interaction between waves and shore platform geometries. The strength of the cliff toe energy depletion loop is assessed by reasoning on its causal pathway and found to be O(−10−10 to −10−4) for poorly lithified rock coasts. By understanding how the individual and overall feedback strengths are influenced by different future environmental and human intervention scenarios we could provide better assessment at the time scales needed for coastal management.

Chapter 13 The rock coast of New Zealand

Abstract Arthur Bloom once wrote, in a statement of posthumous appreciation of Sir Charles Cotton, that no New Zealand geomorphologist could ever really be away from the coast (Bloom 1974). It is true to that sentiment that, despite being few in number, geomorphologists working in New Zealand have made a significant and enduring contribution to our understanding of rocky coasts. In large part that contribution can be traced to the countries’ spectacular geographical setting and associated variety of rock coast landforms. In this chapter we summarize the geographical setting in which New Zealands rocky landscape is situated and describe the various lithological and process controls on landscape evolution. The remainder of the chapter provides a perspective on the contribution made by geomorphologists studying New Zealands rocky coast. That review is centred on three methodological epochs: (a) explanatory description; (b) emerging emphasis on measurement; and (c) process-based studies.

Observation of Wave Transformation on Macro-tidal Rocky Platforms

ABSTRACT Poate, T.G.; Masselink, G; Austin, M.; Dickson, M.E., and Kench, P., 2016. Observations of Wave Transformation on Macro-Tidal Rocky Platforms. In: Vila-Concejo, A.; Bruce, E.; Kennedy, D.M., and McCarroll, R.J. (eds.), Proceedings of the 14th International Coastal Symposium (Sydney, Australia). Journal of Coastal Research, Special Issue, No. 75, pp. 602–606. Coconut Creek (Florida), ISSN 0749-0208. Correctly predicting the transformation of ocean waves across rocky platforms has direct implications for cliff stability modelling, coastal defences and long-term coastal evolution. Wave transformation across rocky intertidal platforms is dependent on the morphological characteristics of the platform, including platform width, slope and roughness, and forcing characteristics, including wave and tide conditions. In this paper we present early observations from four field studies providing detailed measurements of wave processes across contrasting rocky platform sites with wave conditions between Hs = 0.5 m and Hs = 1.9 m, water depths between h = 0.5 m and h = 6.8 m and variable platform morphology. Results show that the relative wave height in the surf zone H/h is generally larger than in previous studies (H/h is c. 0.6, instead of 0.3–0.5) and wave dissipation greater for sites with considerable roughness.

Digital Grain Size Analysis of a Mixed Sand and Gravel Beach

Abstract PENTNEY, R.M. and DICKSON, M.E., 2012. Digital grain size analysis of a mixed sand and gravel beach. A new technique to estimate the properties of sediment from digital images is investigated. Sediment was obtained from mixed sand and gravel beaches in Hawke Bay, New Zealand. Samples were manually sieved, and grain size distributions were compared to those obtained from digital images. Digital image analysis provided variable estimates of the grain size distribution (R2  =  0.21−0.74), with much poorer estimates obtained when images contained grain sizes beyond the range of sediments imaged for the calibration catalogue. A reasonable approximation of the mean grain size of a sample was returned from digital analyses when compared with the mean grain size obtained from sieving (R2  =  0.68), provided all sediment sizes within images fitted within the calibration catalogue. This paper discusses limitations of the technique when applied to mixed sand and gravel beaches, and possibilities for overcoming these (e.g., increasing sampling quantity). It is clear that a deeper understanding of the morphodynamics of mixed sand and gravel beaches requires methods capable of detailing the dynamic fluctuations of grain assemblages. Digital image analysis provides a very promising alternative to laborious and time-consuming manual sieving, and it is hoped that this paper provides a useful additional data set to help in the further refinement of methods for digital image analysis.

The Role of Bed Roughness in Wave Transformation Across Sloping Rock Shore Platforms

We present for the first time observations and model simulations of wave transformation across sloping (Type A) rock shore platforms. Pressure measurements of the water surface elevation using up to 15 sensors across five rock platforms with contrasting roughness, gradient, and wave climate represent the most extensive collected, both in terms of the range of environmental conditions, and the temporal and spatial resolution. Platforms are shown to dissipate both incident and infragravity wave energy as skewness and asymmetry develop and, in line with previous studies, surf zone wave heights are saturated and strongly tidally modulated. Overall, the observed properties of the waves and formulations derived from sandy beaches do not highlight any systematic interplatform variation, in spite of significant differences in platform roughness, suggesting that friction can be neglected when studying short wave transformation. Optimization of a numerical wave transformation model shows that the wave breaker criterion falls between the range of values reported for flat sandy beaches and those of steep coral fore reefs. However, the optimized drag coefficient shows significant scatter for the roughest sites and an alternative empirical drag model, based on the platform roughness, does not improve model performance. Thus, model results indicate that the parameterization of frictional drag using the bottom roughness length-scale may be inappropriate for the roughest platforms. Based on these results, we examine the balance of wave breaking to frictional dissipation for rock platforms and find that friction is only significant for very rough, flat platforms during small wave conditions outside the surf zone.

Simulating the shore and cliffs of North Norfolk

This chapter describes geomorphic modelling of the main Norfolk study area, the 50 km of the coast between Blakeney Spit and Winterton Ness, specifically the eroding cliffs, shore platforms, beaches, dunes and coast protection structures. The models represent both the natural eroding coastal system and past and future management interventions. Numerical experiments are also used to explore the possible dynamics of this coast if it were in a natural state.