Book Review

In this paper, we examine the applicability of spatial optimization as a generative modelling technique for sustainable land‐use allocation. Specifically, we test whether spatial optimization can be used to generate a number of compromise spatial alternatives that are both feasible and different from each other. We present a new spatial multiobjective optimization model, which encourages efficient utilization of urban space through infill development, compatibility of adjacent land uses, and defensible redevelopment. The model uses a density‐based design constraint developed by the authors. The constraint imposes a predefined level of consistent neighbourhood development to promote contiguity and compactness of urban areas. First, the model is tested on a hypothetical example. Further, we demonstrate a real‐world application of the model to land‐use planning in Chelan, a small environmental amenity town in the north‐central region of the State of Washington, USA. The results indicate that spatial optimization is a promising method for generating land‐use alternatives for further consideration in spatial decision‐making.     

Reassessment of flood frequency using historical information for the River Ouse at York,UK (1200–2000)

Abstract

The reassessment of flood risk at York, UK, is pertinent in light of major flooding in November 2000, and heightened concerns of a perceived increase in flooding nationally. Systematic flood level readings from 1877 and a wealth of documentary records dating back as far as 1263 AD give the City of York a long and rich history of flood records. This extended flood record provides an opportunity to reassess estimates of flood frequency over a time scale not normally possible within flood frequency analysis. This paper re-evaluates flood frequency at York, considering the strengths and weaknesses in estimates resulting from four contrasting methods of analysis and their corresponding data: (a) single-site analysis of gauged annual maxima; (b) pooled analysis of multi-site gauged annual maxima; (c) combined analysis of systematic annual maxima augmented with historical peaks, and (d) analysis of only the very largest peaks using a Generalized Pareto Distribution. Use of the historical information was found to yield risk estimates which were lower and considered to be more credible than those achieved using gauged records alone.

Citation Macdonald, N. & Black, A. R. (2010) Reassessment of flood frequency using historical information for the River Ouse at York, UK (1200–2000). Hydrol. Sci. J. 55(7), 1152–1162.     

A whole-basin, mass-balance approach to paleolimnology

Lake sediments record the flux of materials (nutrients, pollutants, particulates) through a lake system both qualitatively, as changes in the composition of geochemical and biological tracers, as well as quantitatively, through changes in their rate of burial. Burial rates provide a direct link to contemporary (neo-) limnological studies as well as management efforts aimed at load reductions, but are difficult to reconstruct accurately from single cores owing to the spatial and temporal variability of sediment deposition in most lakes. The accurate determination of whole-lake burial rates from analysis of multiple cores, though requiring more effort per lake, can help resolve such problems and improve our understanding of sediment heterogeneity at multiple scales. Partial solutions to these problems also include focusing corrections based on ²¹⁰Pb flux, co-evaluation of concentration profiles, trend analysis using multiple lakes, and trend replication based on a small number of cores from the same lake. Recent multi-core studies demonstrate that no single core site faithfully records the whole-lake time-resolved input of materials, but that as few as five well-placed cores can provide a reliable record of whole-lake sediment flux for morphometrically simple basins. Lake-wide sediment fluxes can be coupled with reconstructed outflow losses to calculate historical changes in watershed and atmospheric loading of nutrients, metals, and other constituents. The ability of paleolimnology to accurately assess the sedimentary flux and extend the period of reference into the distant past represents an important contribution to the understanding of biogeochemical processes and their response to human and natural disturbance.     

Tropical cyclone contribution to extreme rainfall over southwest Pacific Island nations

Southwest Pacific nations are among some of the worst impacted and most vulnerable globally in terms of tropical cyclone (TC)-induced flooding and accompanying risks. This study objectively quantifies the fractional contribution of TCs to extreme rainfall (hereafter, TC contributions) in the context of climate variability and change. We show that TC contributions to extreme rainfall are substantially enhanced during active phases of the Madden–Julian Oscillation and by El Niño conditions (particularly over the eastern southwest Pacific region); this enhancement is primarily attributed to increased TC activity during these event periods. There are also indications of increasing intensities of TC-induced extreme rainfall events over the past few decades. A key part of this work involves development of sophisticated Bayesian regression models for individual island nations in order to better understand the synergistic relationships between TC-induced extreme rainfall and combinations of various climatic drivers that modulate the relationship. Such models are found to be very useful for not only assessing probabilities of TC- and non-TC induced extreme rainfall events but also evaluating probabilities of extreme rainfall for cases with different underlying climatic conditions. For example, TC-induced extreme rainfall probability over Samoa can vary from ~ 95 to ~ 75% during a La Niña period, if it coincides with an active or inactive phase of the MJO, and can be reduced to ~ 30% during a combination of El Niño period and inactive phase of the MJO. Several other such cases have been assessed for different island nations, providing information that have potentially important implications for planning and preparing for TC risks in vulnerable Pacific Island nations.

     

Palaeoclimatic reconstruction from Lateglacial (Younger Dryas Chronozone) cirque glaciers in Snowdonia,North Wales

The cirques of Snowdonia, North Wales were last occupied by glacier ice during the Younger Dryas Chronozone (YDC), c. 12.9–11.7 ka. New mapping presented here indicates 38 small YDC cirque glaciers formed in Snowdonia, covering a total area of 20.74 km². Equilibrium line altitudes (ELAs) for these glaciers, calculated using an area–altitude balance ratio (AABR) approach, ranged from 380 to 837 m asl. A northeastwards rise in YDC ELAs across Snowdonia is consistent with southwesterly snow-bearing winds. Regional palaeoclimate reconstructions indicate that the YDC in North Wales was colder and drier than at present. Palaeotemperature and annual temperature range estimates, derived from published palaeoecological datasets, were used to reconstruct values of annual accumulation and ‘winter balance plus summer precipitation’ using a degree-day model (DDM) and non-linear regression function, respectively. The DDM acted as the best-estimate for stadial precipitation and yielded values between 2073 and 2687 mm a^?1 (lapse rate: 0.006 °C m^?1) and 1782–2470 mm a^?1 (lapse rate: 0.007 °C m^?1). Accounting for the potential input of windblown and avalanched snow onto former glacier surfaces, accumulation values dropped to between 1791 and 2616 mm a^?1 (lapse rate: 0.006 °C m^?1) and 1473–2390 mm a^?1 (lapse rate: 0.007 °C m^?1). The spatial pattern of stadial accumulation suggests a steep precipitation gradient and provides verification of the northeastwards rise in ELAs. Glaciers nearer the coast of North Wales were most responsive to fluctuations in climate during the YDC, responding to sea-ice enforced continentality during the coldest phases of the stadial and to abrupt warming at the end of the stadial.     

Testing resilience thinking in a poverty context: Experience from the Niger River basin

Resilience thinking is an important addition to the range of frameworks and approaches that can be used to understand and manage complex social–ecological systems like small-scale fisheries. However, it is yet to lead to better environmental or development outcomes for fisheries stakeholders in terms of food security, improved livelihoods and ecological sustainability. This paper takes an empirical approach by focusing on the fundamentals of resilience thinking to evaluate its usefulness in developing relevant management interventions in small-scale fisheries in the Niger River Basin in West Africa. The paper presents the outputs of a participatory assessment exercise where both fishery communities and local experts were involved at two different scales. The resilience frame used was designed to facilitate the identification of socially defined thresholds that help delineate the desirability of the current system configuration and provides a diagnosis framework that tailors management solutions to problems in local context. The analysis highlights some key contributions from resilience thinking to the challenge of diagnosis in small-scale fisheries management in developing countries, as well as important contributions that emerge from taking a pragmatic and critical approach to its application.