Can soil piping impact environment and society? Identifying new research gaps

Soil piping is a widespread, although often overlooked land degradation process. So far, subsurface soil erosion studies have been focused on the importance of soil piping in hydrological and geomorphological processes, and factors controlling piping processes. Nowadays, the environmental changes being caused by the Anthropocene have clearly demonstrated that society depends on soil more than ever before, so the traditional studies of soil erosion processes need to be redefined. In that sense, geomorphologists face to overcome new piping-related problems. In this article we identify new possible areas of research: (i) soil pipes and pipe collapses (PCs) as natural hazards, (ii) role of soil piping in carbon cycle, (iii) soil pipes and PCs and their relationships with biodiversity, and (iv) piping-affected areas as geodiversity sites. Only better recognition of natural hazards driven by soil piping, such as land subsidence and degradation, landslides, flooding and off-site sediment effects may result in better prevention and control measures in piping-affected areas. Moreover, in the context of Global Change the role of soil piping in carbon cycle should be raised. Land-use and land-cover changes, as well as climate change may affect piping dynamics in different morphoclimatic regions and soil loss due to piping may lead to carbon loss. Soil pipes and PCs are closely interlinked with biodiversity, both positively and negatively. Piping erosion may directly and indirectly destroy vegetation and animals, although in some cases piping erosion may create new habitats and provide favourable conditions for some species. However, soil piping is not only an environmental and societal problem, but it may also contribute to the world geodiversity, which is clearly observed in badland sites. Piping erosion may have a significant impact on environment and society, thus further research with new questions is essential to provide knowledge for sustainable development.     

The effect of tides and storms on the sediment transport across a Dutch barrier island

Under natural conditions, barrier islands might grow vertically and migrate onshore under the influence of long‐term sea level rise. Sediment is transported onshore during storm‐induced overwash and inundation. However, on many Dutch Wadden Islands, dune openings are closed off by artificial sand‐drift dikes that prevent the influx of sediment during storms. It has been argued that creating openings in the dune row to allow regular flooding on barrier islands can have a positive effect on the sediment budget, but the dominant hydrodynamic processes and their influence on sediment transport during overwash and inundation are unknown. Here, we present an XBeach model study to investigate how sediment transport during overwash and inundation across the beach of a typical mesotidal Wadden Sea barrier island is influenced by wave, tide and storm surge conditions. Firstly, we validated the model XBeach with field data on waves and currents during island inundation. In general, the XBeach model performed well. Secondly, we studied the long‐term sediment transport across the barrier island. We distinguished six representative inundation classes, ranging from frequently occurring, low‐energy events to infrequent, high‐energy events, and simulated the hydrodynamics and sediment transport during these events. An analysis of the model simulations shows that larger storm events cause larger cross‐shore sediment transport, but the net sediment exchange during a storm levels off or even becomes smaller for the largest inundation classes because it is counteracted by larger mean water levels in the Wadden Sea that oppose or even reverse sediment transport during inundation. When taking into account the frequency of occurrence of storms we conclude that the cumulative effect of relatively mild storms on long‐term cross‐shore sediment transport is much larger than that of the large storm events. © 2017 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.     

Climate change and community resilience in Samoa

Being resilient in the face of climate change seems especially important for island societies, which face the effects of rising temperatures, unpredictable rainfall, changing wind patterns and sea level rise. To date, most studies of adaptation and resilience among Pacific island communities have used indicators and methods rooted in Western science and neo-classical economics. These have been criticized as being locally irrelevant and inadequate to appreciate the dynamic nature and social structures of island communities and their capacity to adapt. This paper challenges the paradigm that defines resilience as a return to equilibrium, by using a non-equilibrium, cultural ecological lens. The non-equilibrium view of resilience sees the social systems of island nations as highly dynamic and undergoing persistent adaptation in the face of changing environmental factors. Field-based research undertaken in eight villages in Samoa found that, through constant exposure to environmental change over extended periods of time, communities have become resilient and are in a position to adapt to future changes. In developing future policy in relation to climate change, Pacific island governments need to develop a more nuanced understanding of islanders’ perceptions and historical actions in the context of both their physical locations and their dynamic socio-cultural systems.     

The impact of a storm surge on business establishments in the Houston MSA

This paper examines the possible storm surge damage from a major hurricane to hit the Houston Metropolitan Statistical Area (MSA.) Using storm surge analysis on a unique data set compiled from the Texas Workforce Commission (QCEW), the paper estimates the expected industry-level damage for each county in the Houston MSA. The advantages of using GIS to analyze the expected storm surge damage estimation is that it provides an accurate estimation of the number of affected employees and probable wages losses, by industry and county, based on QCEW data. The results indicate that the ‘Basic Chemical Manufacturing’ and ‘Oil and Gas Extraction’ industries incur the highest employee and payroll losses while the ‘Restaurants and Eateries’ has the largest establishment damage if a major hurricane were to hit the Houston MSA.     

Assessment of institutional capacity to adapt to climate change in transboundary river basins

Responses to climate change in transboundary river basins are believed to depend on national and sub-national capacities as well as the ability of co-riparian nations to communicate, coordinate, and cooperate across their international boundaries. We develop the first framework for assessing transboundary adaptive capacity. The framework considers six dimensions of transboundary river basins that influence planning and implementation of adaptation measures and represents those dimensions using twelve measurable indicators. These indicators are used to assess transboundary adaptive capacity of 42 basins in the Middle East, Mediterranean, and Sahel. We then conduct a cluster analysis of those basins to delineate a typology that includes six categories of basins: High Capacity, Mediated Cooperation, Good Neighbour, Dependent Instability, Self-Sufficient, and Low Capacity. We find large variation in adaptive capacity across the study area; basins in Western Europe generally have higher capacities to address the potential hazards of climate change. Our basin typology points to how climate change adaptation policy interventions would be best targeted across the different categories of basins.     

Dynamic tensile strength of terrestrial rocks and application to impact cratering

Abstract— Dynamic tensile strengths and fracture strengths of 3 terrestrial rocks, San Marcos gabbro, Coconino sandstone, and Sesia eclogite were determined by carrying out flat‐plate (PMMA and aluminum) impact experiments on disc‐shaped samples in the 5 to 60 m/sec range. Tensile stresses of 125 to 300 MPa and 245 to 580 MPa were induced for gabbro and eclogite, respectively (with duration time of ?1 μs). For sandstone (porosity 25%), tensile stresses normal to bedding of ?13 to 55 MPa were induced (with duration times of 2.4 and ?1.4 μs). Tensile crack failure was detected by the onset of shock‐induced (damage) P and S wave velocity reduction. The dynamic tensile strength of gabbro determined from P and S wave velocity deficits agrees closely with the value of previously determined values by post‐impact microscopic examination (?150 MPa). Tensile strength of Coconino sandstone is 20 MPa for a 14 μs duration time and 17 MPa for a 2.4 μs duration time. For Sesia eclogite, the dynamic tensile strength is ?240 MPa. The fracture strength for gabbro is ?250 MPa, ?500 MPa for eclogite, and ?40 MPa for sandstone. Relative crack‐induced reduction of S wave velocities is less than that of post‐impact P wave velocity reductions for both gabbro and eclogite, indicating that the cracks were predominantly spall cracks. Impacts upon planetary surfaces induce tensile failure within shock‐processed rocks beneath the resulting craters. The depth of cracking beneath impact craters can be determined both by seismic refraction methods for rocks of varying water saturation and, for dry conditions (e.g., the Moon), from gravity anomalies. In principle, depth of cracking is related to the equations‐of‐state of projectile and target, projectile dimension, and impact velocity. We constructed a crack‐depth model applicable to Meteor Crater. For the observed 850 m depth of cracking, our preferred strength scaling model yields an impact velocity of 33 km/s and impactor radius of 9 m for an iron projectile.     

Sealing Features of Fluid-Rock System and its Control on Acidic Dissolution in Cretaceous Sandstone Reservoirs, Kuqa Subbasin

The Cretaceous Bashijiqike Formation is the main gas-bearing strata in the northern structural deformation zone of Kuqa subbasin. The acidic dissolution of this formation arose at 5–4Ma, which corresponds to the late burial stage of the Bashijiqike Formation. Variability of interlayer due to rock composition is negligible. Differentiation of acidic dissolution in sandstones was controlled by difference in amount of exogenous acid fluid from underlying strata. For the absence of sedimentary and structural carrier system between the isolated sandstone reservoirs, most fluid-rock systems show relative sealing feature during later burial stage by sealing feature of formation pressure, geochemical characteristics of formation water and content of diagenetic products in sandstones. Variation of sealing effects for different fluid-rock systems is obvious. The pressure coefficient is inversely proportional to acidic dissolved porosity of sandstone reservoirs, indicating that the variation of sealing effects for fluidrock system mainly controls the differentiation of acidic dissolution.