Regulating services

The principal contributions of geodiversity in this category in Scotland are through climate regulation, water regulation, water purification and waste treatment, and the regulation of erosion and natural hazards. Other contributions to air quality regulation, disease and pest regulation are principally delivered indirectly through soil processes (cf. Aspinall et al. in prep.) and are not discussed further here. Of note in relation to regulating the distribution of pollinators is the value of exposures in soft sediments that provide nesting sites for burrowing bees and wasps (Whitehouse, 2007, 2008).

3.3.1 Climate regulation

At a global scale, climate is modulated by a range of natural processes and perturbations, including variations in the Earth’s orbital parameters, volcanic eruptions, plate tectonics and mountain building. Geological processes play a key part in the carbon cycle and regulation of greenhouse gases in the atmosphere. Regulation of carbon dioxide is affected by rock weathering and storage in sedimentary rocks and peat bogs. Variations in topography also affect climate at global to local scales. This is particularly applicable to Scotland where regional scale patterns in temperature and rainfall reflect the geographical variations in relief (e.g. McClatchey, 1996). At a smaller scale, the combination of relief, wind exposure, precipitation gradients and other climatic factors produce strong local changes in climate (e.g. between valley bottoms and mountain tops), which in turn is reflected in the diversity of hydrology, soils and habitats. Ecosystems also regulate climate through biogeochemical and biophysical effects (Smith et al., in prep.). Scotland’s organic soils play a major role as a terrestrial sink of carbon (Chapman et al., 2009) and can contribute to climate change mitigation and adaptation (Smith et al., in prep.; Bardgett et al., in prep.).

3.3.2 Water regulation, water purification and waste treatment

Water regulation (including runoff and flooding) and quality are closely related to catchment topography, soils and bedrock geology. The key processes include plant and microbial nutrient uptake, pollutant sequestration in soil and sediment organic matter, breakdown of organic pollutants, acidity buffering and denitrification (Smith et al., in prep.). For example in the Cairngorms, detailed studies have demonstrated critical links between geology, groundwater and surface water chemistry, the influence of catchment characteristics (particularly soil types) on groundwater residence times and contributions to runoff, groundwater-surface water interactions and the influence of groundwater on surface water chemistry and ecology, stream and surface water acidification and the effects of snowmelt on hydrological regime and water quality (Appendix 2).

3.3.3 Erosion and natural hazard regulation

Geodiversity contributes to these regulating ecosystem services through coastal protection, soil erosion and landslide protection and flood protection (Table 3.2).

Table 3.2 The regulating ecosystem services associated with individual hazards. (From Smith et al., in prep.).

Hazard Ecosystem Service (How ecosystems reduce the hazard) Mass movements, coastal

erosion and flooding

Maintenance of the integrity of landsurfaces (regolith and landforms).

Soil erosion Soil retention on the land surface that is evident in two further services: a) maintenance of ‘intact’ soil cover while allowing for gradual evolution (on timescales of natural pedogenesis); b) maintenance of low suspended sediment loads in fluvial systems.

Runoff generation & flooding Water retention and storage and delayed release from the land surface and attenuation of peaks as floodwater passes through river networks.

Coastal and fluvial flooding, land instability, erosion and sediment deposition are all natural geomorphological processes which tend towards various forms of dynamic equilibrium in relation to the prevailing geomorphological and climatic conditions. These processes can be perturbed by natural causes, such as extreme weather events, and disrupted by human changes to the environment, such as urbanisation, afforestation, deforestation, river engineering, floodplain development, mineral extraction, ‘hard’ coastal defences, or any other form of development that interferes with natural processes.

Geomorphological processes frequently impinge on human activity (e.g. through flooding, coastal erosion, siltation, landslips and soil erosion), with resultant economic and social costs (e.g. Winter et al., 2008). Management responses often result in locally engineered solutions such as riverbank and coast protection measures that are unsuccessful or simply transfer the problem elsewhere and in so doing have adverse impacts on the natural heritage. Typically, management timeframes are based on human experience and are not informed sufficiently by the longer-term geological perspective. However, it is this perspective which is vital in assessing natural hazards and implementing sustainable management of natural resources [Box 3.2]. Earth scientists therefore have a key role, particularly in “improving our understanding of the physical processes responsible for natural disasters and for providing reliable data on the frequency and magnitude of past events”

(Clague, 2008, p. 204).

BOX 3.2 Enhancing our knowledge of geodiversity to mitigate hazards

Recently BGS has developed attributed 3D subsurface Quaternary geomorphology and bedrock models of Glasgow and its surrounding area to enhance the understanding of geological and hydrogeological processes (Figure 3.8). Designed to assist planners and engineers to develop strategies for mitigating pollution, controlling flooding and providing the geological basis for regeneration, the model will also aid the identification and management of geodiversity conservation sites.

Figure 3.8 Glasgow’s subsurface Quaternary. (Reproduced with the permission of the British Geological Survey ©NERC. All rights Reserved).

This attributed 3D engineering geology model of the superficial deposits of the Clyde Valley through the eastern part of Glasgow was constructed with modelling software interrogating thousands of borehole records and field data (Entwistle et al., 2008). Draped on a digital terrain model, it aims to provide developers and planners with better understanding of near-surface ground conditions, physical and lithological properties of sediments, groundwater flow pathways and surface drainage. Models such as these can also assist in identifying ground which is prone to flooding and, when linked to spatial datasets of buildings, monuments and key geodiversity exposure sites, may prove valuable in planning the safeguard of these features.

Sustainable solutions involve working with natural processes (e.g. sustainable flood management for rivers under the Flood Risk Management (Scotland) Act 2009 and managed realignment at the coast) and depend on the effective application of earth science knowledge as part of the development of more integrated approaches, such as the maintenance of sediment transport at the coast or natural flow regimes in rivers. This

emphasis on natural approaches and non-structural measures was highlighted in the recommendations of the Millennium Ecosystem Assessment report on Policy Responses Assessment (Mirza et al., 2005) and is well exemplified in shoreline management plans and integrated river catchment management. For example, only a small proportion (2%) of Scotland's coast is artificially defended (Figure 3.9) (EUrosion, 2004). This emphasises the important role the natural coast has as a form of coastal defence. Although the hard coast is likely to remain resilient to accelerations in sea-level rise, the soft coast is likely to be more dynamic. Land uses behind these soft coasts are more vulnerable to rises in sea level. The internal reorganisation of sediment within coastal cells is critical to the health of the soft coast. Any intervention which locks-up or restricts sediment movement is likely to propagate erosion on down-drift sections of coast. Good sediment husbandry informed by coastal sediment budgets is therefore key to managing these dynamic landforms (Orford & Pethick, 2006). Understanding the natural evolution and dynamics of our coastline will become ever more important in the future, as the significant costs and limited life expectancy of traditional coastal defence will increasingly mean that landowners look towards adaptation as the sustainable approach to managing and avoiding the impacts of sea-level rise in many coastal locations (Cooper & McKenna, 2008).

Figure 3.9 The nature of the Scottish coastline (Source: EUrosion, 2004).