Mapping Meaning: Critical Cartographies for Participatory Water Management in Taita Hills,Kenya

Participation of local people is often neglected in natural resource management, which leads to failure to understand the social aspects and historical construction of environmental problems. Participatory mapping can enhance the communication of local spatial knowledge for management processes and challenge the official maps and other spatial representations produced by state authorities and scientists. In this study, we analyze what kind of social meanings can be revealed through a multimethod participatory mapping process focusing on water resources in Taita Hills, Kenya. The participatory mapping clearly complicates the simplified image of the physical science mappings, typically depicting natural water supply, by addressing the impacts of contamination, inadequate infrastructure, poverty, distance to the sources, and restrictions in their uses on people's access to water. Moreover, this shared exercise is able to trigger discussion on issues that cannot always be localized but still contribute to place making. Local historical accounts reveal the social and political drivers of the current water-related problems, making explicit the political ecology dynamics in the area.     

Comparing landslide inventory maps

Landslide inventory maps are effective and easily understandable products for both experts, such as geomorphologists, and for non experts, including decision-makers, planners, and civil defense managers. Landslide inventories are essential to understand the evolution of landscapes, and to ascertain landslide susceptibility and hazard. Despite landslide maps being compiled every year in the word at different scales, limited efforts are made to critically compare landslide maps prepared using different techniques or by different investigators. Based on the experience gained in 20 years of landslide mapping in Italy, and on the limited literature on landslide inventory assessment, we propose a general framework for the quantitative comparison of landslide inventory maps. To test the proposed framework we exploit three inventory maps. The first map is a reconnaissance landslide inventory prepared for the Umbria region, in central Italy. The second map is a detailed geomorphological landslide map, also prepared for the Umbria region. The third map is a multi-temporal landslide inventory compiled for the Collazzone area, in central Umbria. Results of the experiment allow for establishing how well the individual inventories describe the location, type and abundance of landslides, to what extent the landslide maps can be used to determine the frequency-area statistics of the slope failures, and the significance of the inventory maps as predictors of landslide susceptibility. We further use the results obtained in the Collazzone area to estimate the quality and completeness of the two regional landslide inventory maps, and to outline general advantages and limitations of the techniques used to complete the inventories.     

Probabilistic landslide hazard assessment at the basin scale

We propose a probabilistic model to determine landslide hazard at the basin scale. The model predicts where landslides will occur, how frequently they will occur, and how large they will be. We test the model in the Staffora River basin, in the northern Apennines, Italy. For the study area, we prepare a multi-temporal inventory map through the interpretation of multiple sets of aerial photographs taken between 1955 and 1999. We partition the basin into 2243 geo-morpho-hydrological units, and obtain the probability of spatial occurrence of landslides by discriminant analysis of thematic variables, including morphological, lithological, structural and land use. For each mapping unit, we obtain the landslide recurrence by dividing the total number of landslide events inventoried in the unit by the time span of the investigated period. Assuming that landslide recurrence will remain the same in the future, and adopting a Poisson probability model, we determine the exceedance probability of having one or more landslides in each mapping unit, for different periods. We obtain the probability of landslide size by analysing the frequency–area statistics of landslides, obtained from the multi-temporal inventory map. Assuming independence, we obtain a quantitative estimate of landslide hazard for each mapping unit as the joint probability of landslide size, of landslide temporal occurrence and of landslide spatial occurrence.     

Palaeohydraulics revisited: palaeoslope estimation in coarse-grained braided rivers

Methods for estimating palaeoslope from fluvial deposits have been available for some time, but new data and improved understanding of the relevant physical processes afford the possibility of improving existing methods, and the emerging field of quantitative stratigraphy provides a new context for the results. Here we focus on deriving palaeoslope estimates for coarse-grained fluvial deposits. These estimates can be used in basin analyses to constrain the magnitude of the slope change necessary for a given deflection of palaeocurrents, to constrain temporal and spatial variation in basin subsidence rate, and to provide a surface datum for use in sediment-backstripping calculations. The algorithm we derive to estimate palaeoslope applies to rivers that self-adjust through variations in channel width to maintain a temporally and spatially averaged bed shear stress equal to some constant multiple of the critical shear stress for initial motion of bed sediment. Data from modern coarse-grained rivers with minimal bank cohesion and form resistance suggest that this boundary shear stress is equal to about 1.4 times the critical shear stress for movement of the median-sized clast of the surface layer. The key sedimentological criteria for recognition of systems appropriate for this type of analysis are: (1) field relations suggesting that channel banks formed in effectively noncohesive gravel (i.e. free of clay-size sediment and plant roots); (2) absence of significant volumes of dune-derived cross-stratification; and (3) absence of indicators of extremely rapid, flash-flood-type deposition. The basic input data for a palaeoslope calculation are spatially averaged estimates of palaeodepth and median grain size. The most important aspect of data collection is that the depth and grain-size estimates should be determined independently by random sampling over the whole outcrop. Joint analysis of data from appropriate modern rivers and of errors associated with palaeodepth and grain-size estimates indicates that in coarse-grained braided-river deposits, palaeoslope can be estimated to within a factor of 2.     

Coupled atmospheric and marine palaeoclimatic reconstruction for the last 35 ka in the Sele Plain–Gulf of Salerno area (southern Italy)

Planktonic foraminifera and pollen data from core GNS84-C106 (Gulf of Salerno, Tyrrhenian Sea) were analysed through the Modern Analogue Technique, Constrained Cluster Analysis and relative variation biplots. A long period of mild climate, centred around 25 ka BP, is evident in both marine and continental reconstructions. The cooling phase from 17 to 14.7 ka BP, correlated to the H1 Heinrich event, is indicated by a sea surface temperature (SST) decrease, which roughly coincides with the cold-arid phase identified by annual and January temperatures. A rapid increase in atmospheric temperatures and precipitation, culminating at 13.8 ka BP, marks the BA cronozone. The corresponding increase in summer and winter SSTs, of 11 and 6.5 °C, respectively, occurred over 600 years. The beginning of the YD, centred around 12.5 ka BP, is marked by a decrease in summer and winter SSTs of, respectively, 4.5 and 3.5 °C in one century. The atmospheric evidence of the YD is primarily reflected in low January temperatures, reaching −6 °C, the lowest values ever experienced in the analysed time interval. The Late Glacial–Holocene transition is clearly recorded in both the continental and marine realms. From 11.5 to 9 ka BP, atmospheric temperatures record a period of substantial stability followed by a drop at 8.9 ka BP, which chronologically fall within the first RCC event (9–8 ka BP) of Mayewski et al. [2004. Holocene climate variability. Quaternary Research 62, 243–255], in correspondence with a phase of relatively high seasonality, indicated by foraminifera.     

Molecular Line Emission from Accretion Disks Around YSOs

In this work, we model the expected molecular emission from protoplanetary disks, modifying different physical parameters, such as dust grain size, mass accretion rate, viscosity, and disk radius, to obtain observational signatures in these sources. Having in mind possible future observations, we study correlations between physical parameters and observational characteristics. Our aim is to determine the kind of observations that will allow us to extract information about the physical parameters of disks. We also present prospects for molecular line observations of protoplanetary disks, using millimeter and submillimeter interferometers (e.g., SMA or ALMA), based on our results.     

Transport dynamics of mass failures along weakly cohesive clinoform foresets

This study addresses the initiation mechanisms of mass failures on clinoform foresets. Previous studies have created mass flows by releasing dense water–sediment mixtures into standing water, thus imposing the initial conditions for the mass failures rather than allowing them to form on their own. Para‐meters such as the density, composition and initial momentum of the failures are pre‐determined, precluding observation of the factors that set them initially. This study uses a new experimental method that allows a range of mass failures to self‐generate. Building a clinoform using a cohesive mixture of walnut‐shell sand and kaolinite allows the foreset to build up and fail episodically, generating mass failures. Slopes undergo a series of morphological changes prior to failure, creating a concave shape that becomes exaggerated as deposition continues. This morphology leaves the slope in a metastable state. Once the slope is destabilised, failure is initiated. This study investigates the effect of clinoform progradation rates on failure size and frequency by conducting experiments over a range of water and sediment discharge rates. Neither failure size nor failure frequency changes with discharge rate; instead, increases in sediment supply are taken up by changes in the partitioning of sediment between the steep upper foreset and the more gradual delta‐front apron (toeset) below. Sediment is delivered to the delta‐front apron by a form of semi‐continuous slow creep along the foreset. This slow creep is a failure mode that has not received sufficient attention in the submarine mass‐flow literature. The independence of failure size and frequency from sediment supply rate suggests that the presence of mass‐failure deposits does not provide information on the rate of sediment delivery. If these relations hold at field scales, this would imply that individual mass failures are relatively insensitive to changes in water and sediment supply.