A hillslope hydrology approach for catchment‐scale slope stability analysis

Regional analysis of slope stability is often constrained by availability of data. Model requirements for input data cannot be met at the desired spatial resolution because data are either site‐speci?c or non‐existent. Faced with these dif?culties it has often been the practice to assume that certain parameters are uniform throughout the area of interest. An alternative approach proposed here allows a more detailed discrimination of slope stability conditions. Based on the principles of hillslope hydrology, hydrologic information can be generated at suf?cient resolution to allow higher resolution slope stability analysis. Measurements from an instrumented network in a small area have been used to establish index‐based models for topographic and climate‐related controls of piezometric response. The ability to relate groundwater levels to rainfall and topographic parameters provides a means of up‐scaling to larger catchments and ultimately the opportunity to generate a catchment‐wide prediction of the distribution, magnitude and frequency of rainstorm‐generated groundwater levels. The example provided in this study uses the topography index of TOPMODEL in GIS to predict the spatial patterns of groundwater elevation for seasonal soil moisture conditions and given rainfall inputs. This allows modelling of catchment‐wide response of soil water to rainstorms with different return periods (representing different magnitudes), and is an essential prerequisite for a probabilistic regional slope stability analysis. Copyright © 2004 John Wiley & Sons, Ltd.     

Linking watershed disturbance with nearshore sedimentation and the shell beds of Lake Tanganyika (Mahale Mountains,Tanzania)

Extensive deposits of shell-rich sediments in the nearshore environment of Lake Tanganyika, Africa, form a unique habitat for a diverse group of endemic gastropods, crustaceans, fish and sponges, among other organisms. Anthropogenic alteration of the lake’s hinterland from deforestation, fires, and agriculture threaten this crucial habitat through sediment pollution of the littoral environment. This study examines the sedimentology of these nearshore shell beds along a study area north of the Mahale Mountains (Tanzania) to test whether varying levels of watershed disturbance, determined by analysis of satellite imagery, within three moderately sized watersheds (>?100 km²) results in sedimentological differences offshore. The results show that shell beds adjacent to disturbed watersheds (Lagosa and Rukoma) contain more fine-grained sediment compared to shell beds offshore of the undisturbed watershed (Katumbi). Widespread burning, clearance, and land cultivation, and rains of the wet season are causal factors that result in significant differences in fine-grained sedimentation, larger sediment plumes offshore, and increased shoreline progradation. In areas most affected by sedimentation, sponges are largely absent, and shell coverage, which is a measure of fish-nesting capabilities, is lower. The discovery of a small population of live Neothauma tanganyicense offshore of the Katumbi river suggests that the presence of shell-bed forming gastropods in front of a relatively low disturbance watershed, and their conspicuous absence offshore of the other two watersheds, could be related to recent watershed disturbance and increased sedimentation. The increased fine-grained sedimentation and limited shell production by the reduced modern gastropod populations may signal that the shell-bed ecosystem of Lake Tanganyika is at risk.     

Climate change risks for severe storms in developing countries in the context of poverty and inequality in Cambodia

Least developed countries are generally regarded as particularly sensitive to climate change due to among other vulnerable locations and low adaptation capabilities. In the present study, we address climate change hazards in least developed countries by presenting a methodological framework, which is suitable for the estimation damage costs as a function of risk aversion, equality, income distribution and climate scenario using state-of-the-art climate model projections. As a case study, the methodology is applied to study severe storms in Cambodia based on two future climate scenarios and data on historical damages from storm events, which are used as a proxy in performing a sensitivity analysis on all input parameters. For the assumptions and parameter ranges used here, the study shows a high sensitivity to the income distribution (reflected by discount rates) and risk aversion and smaller effects from equality measures and extreme wind climate scenario. We emphasize that the assumptions on risk aversion reflecting consumption smoothing possibilities of low-income households clearly depicts that climate risks can be particularly high as a consequence of poverty and therefore recommend that context-specific vulnerabilities and equity concerns in climate risk studies should be included when making assessments for least developed countries.     

UV-B susceptibility and photoprotection of Arctic Daphnia morphotypes

UV-B tolerance and susceptibility of high Arctic morphotypes of the Daphnia pulexl D. tenebrosa complex were assessed by in situ experiments at Ny-Ålesund, Svalbard (79°N). Animals from local ponds were exposed to ambient light plus additional UV-B from lamps in a greenhouse facility. Taxonomic affinities did not appear as major determinants of UV susceptibility, but a major difference in UV-B tolerance was seen between morphotypes with pigmented carapaces and those without, the latter being far more susceptible. Assays on levels of carotene and the anti-oxidant enzymes catalase and superoxide dismutase did not reveal clear-cut differences between populations, and could not account for the higher tolerance in pigmented populations. Levels of glutathione transferase were higher in the transparent population, however. In the absence of blue light and UV, laboratory reared animals did not reconstitute their carapace melanization after moulting, indicating that short-wave light is the cue for melanin synthesis. Tests on melanized individuals and individuals of the same population reared indoors through 1-2 moults supported the major role of melanin for UV protection. Periods with high UV exposure during hatching of ephippia could induce shifts in morphotype or clonal dominance.     

Comparative effects of herbicides on photosynthesis and growth of tropical estuarine microalgae

Pulse amplitude modulation (PAM) fluorometry is ideally suited to measure the sub-lethal impacts of photosystem II (PSII)-inhibiting herbicides on microalgae, but key relationships between effective quantum yield [Y(II)] and the traditional endpoints growth rate (mu) and biomass increase are unknown. The effects of three PSII-inhibiting herbicides; diuron, hexazinone and atrazine, were examined on two tropical benthic microalgae; Navicula sp. (Heterokontophyta) and Nephroselmis pyriformis (Chlorophyta). The relationships between Y(II), mu and biomass increase were consistent (r(2)0.90) and linear (1:1), validating the utility of PAM fluorometry as a rapid and reliable technique to measure sub-lethal toxicity thresholds of PSII-inhibiting herbicides in these microalgae. The order of toxicity (EC(50) range) was: diuron (16-33nM)>hexazinone (25-110nM)>atrazine (130-620nm) for both algal species. Growth rate and photosynthesis were affected at diuron concentrations that have been detected in coastal areas of the Great Barrier Reef.     

Ocean urea fertilization for carbon credits poses high ecological risks

The proposed plan for enrichment of the Sulu Sea, Philippines, a region of rich marine biodiversity, with thousands of tonnes of urea in order to stimulate algal blooms and sequester carbon is flawed for multiple reasons. Urea is preferentially used as a nitrogen source by some cyanobacteria and dinoflagellates, many of which are neutrally or positively buoyant. Biological pumps to the deep sea are classically leaky, and the inefficient burial of new biomass makes the estimation of a net loss of carbon from the atmosphere questionable at best. The potential for growth of toxic dinoflagellates is also high, as many grow well on urea and some even increase their toxicity when grown on urea. Many toxic dinoflagellates form cysts which can settle to the sediment and germinate in subsequent years, forming new blooms even without further fertilization. If large-scale blooms do occur, it is likely that they will contribute to hypoxia in the bottom waters upon decomposition. Lastly, urea production requires fossil fuel usage, further limiting the potential for net carbon sequestration. The environmental and economic impacts are potentially great and need to be rigorously assessed.     

How Chinese Financial Centers Integrate into Global Financial Center Networks: An Empirical Study Based on Overseas Expansion of Chinese Financial Service Firms

The increasing globalization of the Chinese economy has been enabled by both Chinese financial institutions operating globally as well as international firms operating within China. In geographical terms, this has been organized through a number of strategic cities serving as gateways for the exchange of financial functions, products and practices between China and the global economy. Drawing on location data of financial service firms in China listed on stock exchanges in Shenzhen, Shanghai and Hong Kong, this paper shows that Chinese financial firms are expanding globally and how Chinese financial centers are positioned and connected in the urban networks shaped by these financial service firms. It is found that Hong Kong, China, holds strategic positions in the integration of Chinese cities into global financial center networks, and that establishing a foothold in global financial centers such as New York and London has been a priority for Chinese financial institutions. The increasing capital flows directed by Chinese financial institutions suggests a shifting global financial geography, with numerous Chinese cities playing increasingly important roles within global financial center networks.     

The science of European marine reserves: Status,efficacy, and future needs

The ecologically and socio-economically important marine ecosystems of Europe are facing severe threats from a variety of human impacts. To mitigate and potentially reverse some of these impacts, the European Union (EU) has mandated the implementation of the Marine Strategy Framework Directive (MSFD) in order to achieve Good Environmental Status (GES) in EU waters by 2020. The primary initiative for achieving GES is the implementation of coherent networks of marine protected areas (MPAs). Marine reserves are an important type of MPA in which no extraction is allowed, but their usefulness depends upon a number of ecological, management, and political factors. This paper provides a synthesis of the ecological effects of existing European marine reserves and the factors (social and ecological) underlying their effectiveness. Results show that existing European marine reserves foster significant positive increases in key biological variables (density, biomass, body size, and species richness) compared with areas receiving less protection, a pattern mirrored by marine reserves around the globe. For marine reserves to achieve their ecological and social goals, however, they must be designed, managed, and enforced properly. In addition, identifying whether protected areas are ecologically connected as a network, as well as where new MPAs should be established according to the MSFD, requires information on the connectivity of populations across large areas. The adoption of the MSFD demonstrates willingness to achieve the long-term protection of Europe's marine ecosystems, but whether the political will (local, regional, and continent wide) is strong enough to see its mandates through remains to be seen. Although the MSFD does not explicitly require marine reserves, an important step towards the protection of Europe's marine ecosystems is the establishment of marine reserves within wider-use MPAs as connected networks across large spatial scales.     

Marine species mortality in derelict fishing nets in Puget Sound, WA and the cost/benefits of derelict net removal

Derelict fishing gear persists for decades and impacts marine species and underwater habitats. Agencies and organizations are removing significant amounts of derelict gear from marine waters in the United States. Using data collected from repeated survey dives on derelict gillnets in Puget Sound, Washington, we estimated the daily catch rate of a given derelict gillnet, and developed a model to predict expected total mortality caused by a given net based on entanglement data collected upon its removal. We also generated a cost:benefit ratio for derelict gear removal utilizing known true costs compared to known market values of the resources benefiting from derelict gear removal. For one study net, we calculated 4368 crab entangled during the impact lifetime of the net, at a loss of $19,656 of Dungeness crab to the commercial fishery, compared to $1358 in costs to remove a given gillnet, yielding a cost:benefit ratio of 1:14.5.