The Importance of the Precipitation and the Susceptibility of the Slopes for the Triggering of Landslides Along the Roads

In order to characterise the influence of the heavyrains on the observed landslides during the 1996–1997hydrological cycle, rainfall records for the last 100years are analysed from 104 stations in easternAndalusia. Regarding the amounts of rain recordedbetween October 1996 and March 1997 in the 104stations studied, 31 presented new all-time records;15 presented values that were 80–100% of thepre-1995 record; 49 stations, 80–50%; and 9stations, < 50%. A map has been devised of thesusceptibility of the materials through which thesouth-eastern Andalusian road network crosses,together with an inventory of the damage caused byinstability phenomena on banks and cuttings of theroad network during the winter of 1996–1997. Therelationships between the rainfall during the studyperiod, the damage caused to the road network and thesusceptibility of the materials affected are analysed.The results indicate that there is a clearcorrespondence between the rainfall recorded and thesusceptibility of the materials with the inventorieddamage. It is concluded that the widespread seriousdamage caused in early 1997 to the roads andsurrounding areas in the Alpujarra region and thecoast of the Province of Granada was mainly caused bythe extraordinarily heavy rains. However, considerablyless damage was observed where the susceptibility ofthe terrain is low, thus highlighting the extremeusefulness of terrain-susceptibility maps for riskprevention and territorial planning.     

Influence of diet and temperature on physiological energetics of Chorus giganteus (Gastropoda: Muricidae) during reproductive conditioning

The influence of two bivalve diets (Mytilus chilensis “chorito” and Tagelus dombeii "navajuela") at three temperatures (13, 15, and 18°C) was studied during the reproductive conditioning of Chorus giganteus (Lesson, 1829). Energy budgets were determined taking into account energy acquisition (ingestion and absorption) and energy expenditure (oxygen consumption, ammonia production, and energy placed into mucus production and egg laying). Relative physiological condition was assessed by calculating the scope for growth index (SFG). Diet and temperature both played key roles in the physiological energetic and reproductive conditioning of this snail. Tagelus was the preferred prey, probably because of its greater vulnerability to predatory attack by C. giganteus. The highest feeding rate was observed at 15°C, coinciding with optimal growth. Absorption efficiency was similar with both diets, despite the differential preference in prey. Temperature had no effect on oxygen uptake, but increased as the snails fed on Tagelus during the reproductive conditioning period. Diet was the main factor affecting SFG, and temperature, although significant, accounted for a lower percentage of variation in SFG. Highest growth rates were observed at 15°C on a Tagelus diet. Reproductive effort, measured as the proportion of the total energy budget of an organism that is allocated to reproduction, was highest at 18°C with a Tagelus diet. Energy would not be allocated for reproduction when the snails were fed with M. chilensis, as SFG was negative at all three temperatures.     

Finding appropriate interpolation techniques for topographic surface generation for mudslide risk zonation

Mudslides and debris flows are now more common problems in tropical regions than landslides. This article addresses the issue of modelling mudslide-susceptible locations using an information value approach. Landsat 7 (ETM+) was employed to create a land-use map with limited field checks. Other parameters considered were lineament, road, soil, stream network and lithology. Topographic parameters such as slope and aspect play a dominant role in slope stability studies. Maps for slope and aspects were developed from a digital elevation model using statistical surface interpolation techniques. This article offers insight into the importance of the selection of suitable surface interpolation techniques. The three surface interpolation techniques evaluated in the study were: inverse distance weighted, Kriging and Spline. These were found to have varied accuracies of interpolation surfaces for all parameters, including elevation, slope and aspect. Surfaces offering the best accuracy were adopted for the information value approach for mudslide susceptibility zonation.     

Constraints influencing stakeholder participation in collective environmental management

Stakeholder participation is crucial for collective environmental management. This article unearths factors that influence stakeholder involvement, with emphasis on their associated origins. The management of a drainage canal in Map Ta Phut industrial estate, Thailand, was studied. Seven types of constraints were identified, namely: (a) distrust, generated from the lack of neutrality; sanction; sincerity; evidence of improvement; and denialism, (b) delay and slowness, created by characteristics of governmental procedures; geographically divided responsibility; the lack of willingness to participate; ineffective communication; limited budget; and misunderstandings, (c) information sharing in inappropriate manners, (d) an entrenched position originating from an allegation, past conflicts, and reminiscence, (e) unfairness and envy emerging from uneven distribution of benefits and inadequate infrastructure, (f) relationship abuse and fear of reprisals, and (g) community spoilage. Avoiding actions that create distrust, promoting activities that strengthen the relationship, sharing not only positive but also controversial information, understanding limitations of other stakeholders, being open-minded and forgiving, and self-evaluation and self-correction are ways to sustain successful stakeholder participation.     

The scattered disk population as a source of Oort cloud comets: evaluation of its current and past role in populating the Oort cloud

We have integrated the orbits of the 76 scattered disk objects (SDOs), discovered through the end of 2002, plus 399 clones for 5 Gyr to study their dynamical evolution and the probability of falling in one of the following end states: reaching Jupiter's influence zone, hyperbolic ejection, or transfer to the Oort cloud. We find that nearly 50% of the SDOs are transferred to the Oort cloud (i.e., they reach heliocentric distances greater than 20,000 AU in a barycentric elliptical orbit), from which about 60% have their perihelia beyond Neptune's orbit (31 AU<q<36 AU) at the moment of reaching the Oort cloud. This shows that Neptune acts as a dynamical barrier, scattering most of the bodies to near-parabolic orbits before they can approach or cross Neptune's orbit in non-resonant orbits (that may allow their transfer to the planetary region as Centaurs via close encounters with Neptune). Consequently, Neptune's dynamical barrier greatly favors insertion in the Oort cloud at the expense of the other end states mentioned above. We found that the current rate of SDOs with radii R>1 km incorporated into the Oort cloud is about 5 yr⁻¹, which might be a non-negligible fraction of comet losses from the Oort cloud (probably around or even above 10%). Therefore, we conclude that the Oort cloud may have experienced and may be even experiencing a significant renovation of its population, and that the trans-neptunian belt—via the scattered disk—may be the main feeding source.     

The high-eccentricity libration theory revisted

Using the local asymmetric expansion of the disturbing function for the planar elliptic restricted three-body problem up to degree 1 ine ₁ we develop a small amplitude libration theory. We review the laws that characterize the mean-motion resonances of asteroids with Jupiter and we obtain other new laws. Special attention is paid to the second forced mode whose equations are reformulated and new consequences of this component are discussed. An analytical expression for the trajectories in the phase space is obtained. The predictions are compared with numerical experiments which confirm the results.     

Flow and patterns of nitrate pollution in groundwater: a case study of an agricultural area in Tsukuba City, Japan

A numerical simulation was applied to first characterize the groundwater flow and patterns of nitrate pollution of a small-agricultural catchment in Tsukuba City, Japan, for a 10-year period. There was a good performance of the flow simulation. In contrast, although the transport model calculated the evolution of the plume, it only provided estimates of solute concentrations. Groundwater contamination increased exponentially during the first 594 days of the simulation, reaching then a near-equilibrium state. Fertilizer applications are responsible for most of the leaching of NO₃⁻ to groundwater, therefore, shifting of crops and the associated agricultural practices may translate into decreases of contamination levels. A series of hypothetical scenarios demonstrated that replacing grasslands by other crops may reduce the contamination levels up to 12%. As the chosen field is a representative of many other agricultural areas in Japan, the approach and results should also be applicable to similar cases around the country.     

Refinement of three-dimensional multilayer models of basins and crustal environments by inversion of gravity and magnetic data

The sensitivity of gravity and magnetic data to deep structures and the broad availability of regional data sets and surveys of high resolution make them suitable for determining detailed three-dimensional (3D) models of the subsurface. However, the sole consideration of gravity and magnetic information cannot properly resolve heterogeneous 3D environments. Advocated to solve this problem, we present an automated refinement technique for three-dimensional multilayer models as conditioned by gravity and magnetic data and by meaningful geometrical and physical constraints. We construct our model by an aggregate of rectangular prisms and aim to estimate their bottom depths, which define the geological layers. We summarize mathematically our concept of refinement in an objective function that includes the misfit to the data, the similitude to an a priori geological–geophysical model, and the smoothness of the relief of the layers. Importantly, our objective function also includes inequality constraints that prevent the superposition of layers and integrate the surface and borehole geology with the multilayer deep model. The objective function is solved using quadratic programming in a stable iterative scheme. The resulting algorithm is tested on synthetic data and applied to crustal and sedimentary basin environments from southern Baja California, Mexico. The assimilation of the geological and geometrical constraints to the inversion process produces models that correlate with the surface geology and reveal the three-dimensional features of the subsurface.     

The impact of deforestation on the hydrological cycle in the western Mediterranean: an ensemble study with two regional climate models

 A deforestation experiment is performed over the western Mediterranean, applying two different RCMs with differing domains and an ensemble technique to obtain a measure of their internal variability. The internal variability is used to assign statistical significance to the results, and also to discuss whether the models are sufficiently free to develop internal mesoscale processes. Considerable internal variability values found for hydrological variables even in autumn and winter seem to support the assumption that the models are free enough to be applied to such a sensitivity study. The combined use of two models, with strongly differing domains, and significance assigned through the use of internal variability should highlight responses to deforestation which are of physical origin and not a result dependent on one particular model. The overall significant response from both RCMs to deforestation is a reduction of evaporation (spring and summer, extending over the whole deforested zone) and a decrease in precipitation (late spring and summer, over some regions). A detailed analysis over subzones shows remarkable agreement between the two models over some of these subzones, showing non-local effects in precipitation response. Received: 8 February 2000 / Accepted: 12 January 2001