Formation events of shoreline sand waves on a gravel beach

Kilometric-scale shoreline sand waves (KSSW) have been observed in the north-east flank of the Dungeness Cuspate Foreland (southeastern coast of the UK). They consist of two bumps separated by embayments with a 350–450-m spacing. We have analysed 36 shoreline surveys of 2-km length using the Discrete Fourier Transformation (DFT), from 2005 to 2016, and seven topographic surveys encompassing the intertidal zone, from 2010 to 2016. The data set shows two clear formation events. In order to test the role of high-angle waves on the KSSW formation, the 10-year wave series is propagated from the wave buoy located at 43 m depth up to a location in front of the undulations at 4 m depth using the SWAN wave model. The dominating SW waves arrive with a very high incidence angle (～ 80°) while the NE waves arrive almost shore normal. The ratio R, which measures the degree of dominance of high-angle waves with respect to low-angle waves, correlates well with the shoreline DFT magnitude values of the observed wavelength undulations. In particular, the highest R values coincide with the formation events. Finally, a linear stability model based on the one-line approximation is applied to the Dungeness profile and the 10-year propagated wave series. It predicts accurately the formation moments, with positive growth rates in the correct order of magnitude for wavelengths similar to the observed ones. All these results confirm that the shoreline undulations in Dungeness are self-organized and that the underlying formation mechanism is the high-angle wave instability. The two detected formation events provide a unique opportunity to validate the existing morphodynamic models that include such instability.     

Estimating fractional land cover in semi-arid central Kalahari: the impact of mapping method (spectral unmixing vs. object-based image analysis) and vegetation morphology

Focusing on the central Kalahari, this study utilized fractional cover of photosynthetic vegetation (f_PV), non-photosynthetic vegetation (f_NPV) and bare soil (f_BS), derived in situ and estimated from GeoEye-1 imagery using Multiple Endmember Spectral Mixture Analysis (MESMA) and object-based image analysis (OBIA) to determine superior method for fractional cover estimation and the impact of vegetation morphology on the estimation accuracy. MESMA mapped fractional cover by testing endmember models of varying complexity. Based on OBIA, image was segmented at five segmentation scales followed by classification. MESMA provided more accurate fractional cover estimates than OBIA. The increasing segmentation scale in OBIA resulted in a consistent increase in error. Different vegetation morphology types showed varied responses to the changing segmentation scale, reflecting their unique ecology and physiognomy. While areas under woody cover produced lower error even at coarse segmentation scales, those with herbaceous cover provided low error only at the fine segmentation scale.     

Thermal expansion coefficients for indialite,emerald, and beryl

Thermal expansion coefficients ?₁ and ?₃ calculated for the hexagonal minerals indialite, emerald and beryl are, in general, small with ?₃ being negative near room temperature. This unusual behavior leads to low volume coefficients of thermal expansion (β=2?₁+?₃) making these materials ideal ceramic bodies for catalyst carriers in air-pollution control. The temperature at which the c-cell edge length of beryl is a minimum is strongly dependent upon the presence of trace amounts of impurity atoms. This effect is ascribed to changes in the Grüneisen parameters.     

Temporal Extensions of Landscape Ecology Theory and Practice: Examples from the Peruvian Amazon*

The growing overlap between geographic information science (GIScience) and landscape ecology for landscape characterization has led to increasingly sophisticated measures of landscape site and situation. Scale, both temporal and spatial, has been injected into methodologies to improve our ability to derive process from pattern with the hope of defining, monitoring, and modeling ecological landscape function. This article addresses an evolving methodology of longitudinal or panel analysis designed to test the relative importance of thematic versus structural landscape configuration as well as interannual versus intra‐annual change. Landscape typologies for both temporal signature and dominant structural trajectories are offered as guideposts for rethinking dynamic landscape characterization. A case study from the Peruvian Amazon is provided to illustrate interpretive advances available via panel methods that allow for disentangling inter‐ and intra‐annual shifts as well as separating changes in composition versus configuration for improved understanding of landscape dynamics and dynamism.     

Political Ecologies of Dynamic Wetlands: Hydrosocial Waterscapes in the Okavango Delta

Research within geography and related disciplines has directed much attention to the coupled interactions between social and ecological systems. These studies have usefully analyzed the multifaceted, temporal, and scalar dimensions of human–environment interactions and how future environmental change will continue to challenge human resource needs. Political ecology research has also made contributions in this regard, particularly by emphasizing livelihood systems, impacts of conservation and development, agricultural production, and environmental governance. Yet although political ecology research has contributed to socioecological systems scholarship, much of this work has been situated within dryland environments or marine ecosystems that have particular biophysical features. Comparatively, wetland environments that experience dynamic flooding regimes warrant further attention from political ecology. This article engages with the findings from an ongoing research project that is evaluating the impacts of flooding variability for rural livelihoods in the Okavango Delta of Botswana. We outline some of the main findings from this work by concentrating on two themes central to political ecology: access and governance. We conclude by arguing that the Okavango Delta should be understood as a hydrosocial waterscape that encompasses a variety of socioecological relationships within the region, as well as the power relations operating at a variety of scales that both produce and govern them.     

Environmental Perception,Sense of Place,and Residence Time in the Okavango Delta,Botswana

Integral to the geographic discipline are cross-cultural analyses, many of which use languages outside of the researcher’s own. There are few analyses, however, that address issues of translation that are inherently geographic; namely, that language is understood as a manifestation of place and culture. This article argues that the results of environmental interviews must be interpreted through a lens that evaluates how the translation of a word, or even a concept, is understood differentially based on one’s sense of place. Interviews were conducted in three of the Etsha villages situated in the Okavango Delta, Botswana, comparing perceptions of changes in both the local area and the flooding regime. Findings show qualitatively and quantitatively how residents perceive environmental change in light of their residential histories and their production of place. These results highlight that environmental change in an area is perceived in the context of previous residences, including the length of time spent in residence and the environmental characterization of that place. The process of interviewing regarding such change, especially when translation is necessary, should therefore proceed by incorporating inquiries about previous residences and the environments of those areas to correctly contextualize environmental change in a particular area.     

Human–Wildlife Interactions and Environmental Dynamics in the Okavango Delta,Botswana

The Okavango Delta in Botswana hosts abundant wildlife and a human population with diverse livelihoods. Representing a heterogeneous landscape nuanced by spatial and temporal variability, the region has recently seen an expansion of floodwaters with social impacts ranging from livelihood disruption to human displacement. This article reports on in-depth interviews conducted in 2012 regarding these transitions in Mababe, a community in the eastern Okavango Delta, to evaluate how dynamic environmental processes alter perceptions and livelihood responses. We focus on community members’ variable interactions with wildlife in spaces of human–wildlife overlap also experiencing change. While human–wildlife interactions can have negative effects, we find that perpetuating the common narrative of human–wildlife conflict overlooks how disruptions can usher in new relationships between people and animals. In order to move beyond the conflict narrative, we conclude that spatial and temporal context is essential to evaluate effects of dynamic, uneven, and sometimes unpredictable human–wildlife encounters.     

Post-survey Likert constructions: an adaptive method for generalizing perceptions of environmental variability

GeoJournal - Environmental perceptions are inherently based on an individual’s existing knowledge, experiences, and future expectations. Methods for measuring environmental perception,...