The Use of Seasonal Climate Forecasting in Policymaking: Lessons from Northeast Brazil

This article examines the use of seasonal climate forecasting in public and private efforts to mitigate the impacts of drought in Ceará, Northeast Brazil. Here, forecasts have been directed towards small scale, rainfed agriculturalists as well as state and local level policymakers in the areas of agriculture, water management, and emergency drought relief. In assessing possibilities and constraints of forecast application in Ceará, the present analysis takes into account three types of variables: (a)characteristics of the forecasts; (b) policymaking systems; and (c)institutional environments. We conclude that, on the one hand, several factors in the Ceará case have limited the effectiveness of seasonal climate forecast use. First, the current level of skill of the forecasts is inadequate for the needs of policy development and farmer decisionmaking. Second, forecast information application has been subject to distortion, misinterpretation and political manipulation. Third, focus on the forecast as a product until recently neglected to take into account end users' needs and decisionmaking behavior. On the other hand, climate forecasting has the potential to offer a dramatic opportunity for state and local level bureaucracies to embark on a path of proactive drought planning.     

Socio-spatial polarization and the (re-)distribution of deprived groups in world cities: A case study of Hong Kong

This paper draws on theoretical discussions of world cities to analyze socio-spatial polarization and (re-)distribution of deprived groups in Hong Kong in the 2000s. Intensifying global economic restructuring processes have induced socio-economic polarization, thereby producing deprived groups although the spatial outcomes may depend on the city-specific context. When local policies do not counteract the polarization trend, a spatial manifestation of widening socio-economic gaps can be expected. Intensified pro-growth policies adopted since Hong Kong’s return to Chinese rule in 1997 and during its economic recession in the early 2000s have worsened the impact of globalization-induced socio-economic and spatial restructuring. Census data from 2001 and 2011 show increasingly differentiated socio-economic profiles at the district level. The analysis offered in this study also points to a decreased socially mixed society in 2011 when the deprived groups lived in districts with less presence of the advantaged population.     

Interaction between nulls and emission in the pulsar B0834+06

We present a detailed study of the single pulses of the bright radio pulsar B0834+06, and offer evidence that the dominant periodic modulation in this pulsar's emission governs the occurrence of nulls. The nulls of B0834+06 constitute approximately 9 per cent of the total pulses and we demonstrate that they do not occur at random in the pulse sequence. On the contrary, they are found to occur preferentially close to the minimum of the pulsar's emission cycle, whose period jitters around a central value of P ₃≈ 2.17 rotation periods. It is likely that the intrinsic duration of the nulls averages about 0.2 times the pulsar rotation period. Surprisingly, the clearly distinct population of nulls and partial nulls of B0834+06 exhibit a two-peak profile slightly broader than that of the normal emission. This is in contrast to the profile of extremely weak normal pulses, which is narrower than the overall profile. A flow/counterflow model for the pulsar's two components can reproduce the essential observed features of the emission in its dominant mode, with nulls occurring at the point where the minima of the two systems are aligned. This suggests that the observed nulling rate is determined by the chance positioning of our sightline with respect to the system. If the flow is interpreted as part of a circulating carousel, a fit yields a best estimate of 14 'sparks'.     

The influence of river training on mountain channel changes (Polish Carpathian Mountains)

The purpose of this paper is to explain the influence of river training on channel changes in mountain rivers. Also considered are the causes of failure of different training schemes. The research was conducted on the regulated Mszanka and Porębianka Rivers, belonging to the Raba River drainage basin in the Polish Flysh Carpathian Mountains. Channel mapping carried out in 2004 drew attention to the contemporary morphology of the channels and the development of their dynamic typology. General changes in channel morphometry and land cover were identified by comparing cartographic sources from various years. Archive material from Cracow's Regional Water Management Authority (RZGW) was used to analyse the detailed channel changes caused by each regulation structure. The material consisted of technical designs of individual training works, as well as plans, longitudinal profiles and cross-sections of trained channel reaches. A series of minimum annual water stages at the Mszana Dolna gauging station was used to determine the tendency of channel bed degradation over 53 years. During the first half of the 20th century, the middle and lower courses of the Mszanka and Porębianka Rivers had braided patterns. The slopes, mostly covered with crops, were an important source of sediment delivery to the river channels. Today, both channels are single-threaded, narrow and sinuous. Downcutting is the leading process transforming the channels. They cut down to bedrock along about 60% of their lengths. The main type of channel is an erosion channel, which occurs also in the middle and lower courses of the rivers. The channel sediment deficit is an important cause for river incision. Sediment supply to the channels was reduced after a replacement of crops on the slopes by meadows or forests. Gravel mining has also caused channel downcutting. The rapid channel changes began after 1959, as systematic training was introduced. Channel regulation seems therefore to be a major factor determining channel adjustment. Debris dams and groynes were built before 1980 and these caused the greatest change of channel pattern, increase of channel gradient and magnitude of river incision. After that date the measures mostly involved drop structures. From then on, the rate of downcutting decreased considerably, but has not ceased. The rivers continued to incise until bedrock was exposed or training structures were destroyed. After that, a tendency to lateral migration and local braiding were observed in the deepened channel. The channels displayed a tendency to return to their morphology and dynamic from before the training. The results demonstrate that river training distorts the equilibrium of channel systems. A channel becomes divided into artificial reaches, which later follow different evolutionary patterns. Most training schemes on mountain channels are ineffective in the long term, as river managers seem to consider a channel at a reach scale only. Individual channel reaches, however, are not independent but rather form a system that must be managed at the entire channel scale.     

The decrease in shear stress and increase in transport rates subsequent to an increase in sand supply to a gravel-bed channel

It is generally accepted that a gravel-bed river will aggrade if the supply of sediment to the river is increased. In a series of flume experiments using constant discharge and gravel feed rate, sand feed rates were increased to 6.1 times that of gravel. The slope of the bed decreased with increasing sand supply, indicating that the increased sediment load could be transported at the same rate due to a decrease in shear stresses. These results extend previous experiments to a wider range of boundary conditions. A recent surface transport model is used to predict the changes in bed composition and transport using the same sediment supply composition and feed rates as in the laboratory experiments. This model reasonably predicts a decrease in the reference shear stresses of the sand and gravel fractions as the sand supply is increased. An increase in sand supply can increase the mobility of gravel fractions in the stream bed, which can lead to bed degradation and preferential evacuation of these sediments from the river.     

Valley-marginal sand dunes in the south-west Kalahari: their nature, classification and possible origins

This paper considers the nature, classification and possible origin of a variety of desert sand dunes which occur in association with ephemeral drainage features in the south-west Kalahari. The dune forms, which we term valley-marginal dunes, are found at the top of valley flanks, and are narrow, elongate forms with arcuate and straight planform elements which mirror the course of extant and ancient channels. Following a discussion of the major schemes used to classify different dune types, we describe the morphology and situation of these valley-marginal dunes. We suggest that whilst the basic morphometry of these dunes is similar to many other dune types, the topographic setting in which they occur is relatively unusual. We conclude that valley-marginal dunes are a previously unrecognized landform which cannot be fitted into current classificatory schemes. It is suggested that one reason for this may be the lack of an explicit temporal dimension in most dune classifications.     

The application of terrestrial laser scanning to aeolian saltation cloud measurement and its response to changing surface moisture

Saltation is the dominant form of aeolian transport of sand sized grains, yet its heterogeneous spatial and temporal distribution, and inherent feedback and interaction with the surface over which sand is transported, hinders large scale quantification. In this letter we present preliminary data on saltation cloud characteristics quantified using terrestrial laser scanning (TLS). These data, together with surface moisture and surface roughness patterns, elucidate the importance of saltation in the development of protodunes on a drying beach, and indicate the potential usefulness of TLS in examining aeolian processes in both beach and desert environments. Copyright © 2010 John Wiley & Sons, Ltd.     

Lake District pioneers – the earliest footprints on land

New evidence reveals that the first arthropods colonized dry land over 450 million years ago, more than 20 million years before the appearance of vascular plants. Traditionally, it was thought that animals only emerged on to land after plants had become established, thus providing a plentiful new food source. The earliest known terrestrial trace fossils occur in volcanogenic sediments from the English Lake District. The trace fossils are thought to have been made on land by a small millipede-like creature. These rocks contain no other fossils.