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In recent years, natural disasters such as earthquakes, landslides, mudslides, collapses, drought, and extreme temperature occur frequently in Yunnan Jinsha River watershed, causing deterioration of physical environments for human settlements in some areas of the watershed. Although several studies have addressed individual environmental elements in the study area, efforts for integrated analysis of environmental factors and human settlements are still lacking. Therefore, it is important to identify the spatial distribution of physical environments for human settlements to support population distribution planning. This study includes 10 factors (topography, landform, vegetation, elevation, fault, rock, soil, earthquake intensity, temperature, and precipitation) as indicators for the assessment of human settlement suitability based on the analytic hierarchy process and grey correlation methods. Geographic information system functions were used to help understand the spatial distribution of human settlements and the causal factors. This study reveals different spatial units of the watershed suitable for human habitation from the viewpoint of physical environment and provides recommendations for urban planning and siting, land use planning, and disaster mitigation in the watershed.

The paper describes a proposed unified hydro-elasto-plastic model with a solid–fluid transition. The model associates a hydro-elasto-plastic model for partially saturated geomaterials, a Bingham’s viscous law, and the transition criterion between solid and fluid states. The model describes both solid and fluid behaviours of partially saturated geomaterials in a unified framework. In addition, this paper describes a novel Finite Element Method with Lagrangian Integration Points (FEMLIP) formulation for solving hydro-mechanical problems. Based on the equilibrium equation of momentum and the continuity equation of water flow, the formulation was developed and implemented in a FEMLIP tool. Bishop’s effective stress expression and proper water retention diagrams were taken into account. A heuristic column and real rainfall-induced mudflows were also simulated and analysed in this study. The permeability effects of partially saturated soil and the effective cohesion were considered, which included consideration...

Volcanic hazard maps are used to inform planners, policy-makers, and the public of the areas potentially impacted by volcanic hazards. We describe the design and production of a three-dimensional (3D) volcanic hazard map showing lahar travel times at Mount Hood, Oregon. The creation of this map involved the application of innovative techniques, including (a) an analytical model for computing lahar travel time isochrones; (b) a terrain tiling system for 3D modeling software; (c) the modeling of roads, rivers, and other linear features as 3D tubes to improve visibility; and (d) progressive terrain bending to create a top-down perspective in the foreground and an oblique perspective in the background. A user study (documented in a separate article) confirmed that the 3D map effectively shows the extent and travel time of potential lahars, allowing readers to choose better escape routes than with a conventional two-dimensional map.

The town of Leh and its adjoining areas were affected by severe flash floods and mudslides triggered by a cloud burst over the Leh region on 6 August 2010. Identification of the area affected by fl...

During the last 70 years of general climatic amelioration, 18 glacial-lake outburst floods (GLOFs) and related debris flows have occurred from 15 moraine-dammed lakes in Tibet, China. Catastrophic loss of life and property has occurred because of the following factors: the large volumes of water discharged, the steep gradients of the U-shaped channels, and the amount and texture of the downstream channel bed and bank material. The peak discharge of each GLOF exceeded 1000 m(3)/s. These flood discharges transformed to non-cohesive debris flows if the channels contained sufficient loose sediment for entrainment (bulking) and if their gradients were > 1%. We focus on this key element, transformation, and suggest that it be included in evaluating future GLOF-related risk, the probability of transformation to debris flow and hyperconcentrated flow. The general, sequential evolution of the flows can be described as from proximal GLOFs, to sediment-laden streamflow, to hyperconcentrated flow, to non-cohesive debris flow (viscous or cohesive debris flow only if sufficient fine sediment is present), and then, distally, back to hyperconcentrated flow and sediment-laden streamflow as sediment is progressively deposited. Most of the Tibet examples transformed only to non-cohesive debris flows. The important lesson for future hazard assessment and mitigation planning is that, as a GLOF entrains (bulks) enough sediment to become a debris flow, the flow volume must increase by at least three times (the "bulking factor"). In fact, the transforming flow waves overrun and mix with downstream streamflow, in addition to adding the entrained sediment (and thus enabling addition of yet more sediment and a bulking factor in excess of three times). To effectively reduce the risk of GLOF debris flows, reducing the level of a potentially dangerous lake with a siphon or excavated spillway or installing gabions in combination with a downstream debris dam are the primary approaches.

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 informat...

This note examines the environmental, infrastructure and economic impact of the Lapindo mudflow disaster in East Java province. It outlines unsuccessful attempts to staunch the mud volcano, concerns for human health and plans for long-term management of the mudflow. It considers the impact on transport and logistics networks and the additional costs to the East Java economy. The heaviest economic impact has occurred in the region surrounding the mud volcano in Sidoarjo district, but areas to the east and west are also affected. Individual firms in East Java have found means of accommodating their business operations to the mudflow with some provincial government assistance. PT Lapindo Brantas, the company considered responsible for the drilling that led to the mud volcano, has been slow in compensating victims as required by presidential decrees. Delays in finalising compensation appear to be holding back implementation by the national government of critical infrastructure reconstruction work.

Two previously unrecognised debris‐avalanche deposits have been identified on the eastern flanks of Egmont Volcano beneath a thick mantle of tephric and andic soil material that has mostly subdued their topographic expression. The Ngaere Formation is a c. 23 14C ka large volume (>5.85 km3) debris‐avalanche deposit that is widely distributed over 320–500 km2 of the north‐east, south‐east, and south portions of the Egmont ring plain. The second deposit, Okawa Formation, is a c. 105 ka large volume (>3.62 km3) debris‐avalanche deposit that has been mapped over a minimum area of 255 km2 in northern and north‐eastern Taranaki. Both debris‐avalanche formations contain axial facies with hummocks composed mainly of block‐supported brecciated andesitic debris. A less conspicuous marginal facies, texturally resembling a mudflow, is more extensive. A third debris‐avalanche deposit (Motunui Formation) is extensively preserved along the north Taranaki coast where it is truncated by a c. 127 ka wave cut surfac...

Debris flows are often triggered by heavy rainfall and flash floods in mountainous areas. Generally, debris flows are the most disastrous event associated with floods and cause most of the fatalities resulting from flood events. This paper reports a study of debris flows by filed investigations at the Xiaojiang watershed, which is in the upper Yangtze River basin, and flume experiments. Two types of debris flows—viscous debris flows and two-phase debris flows — occur on the Yunnan Plateau in south China. Viscous debris flows consist of clay, silt, sand, and gravel. This kind of flow is non-Newtonian and often develops into roll waves. They sometimes exhibit drag reduction and extremely high super-elevation. The drag reduction is mainly due to the effects of air cushions and the bed smoothening. Two-phase debris flows consist of gravel and boulders and show obvious relative movement between the solid particles and the liquid. Flume experiments show that debris flows may be triggered by torrential ...

We examined the distribution of extreme daily precipitation events (100 mm or more per day) in relation to weather conditions in the county of Nordland, Norway. Precipitation data included 88 weather stations and cover the period January 1964–March 2002. Over this period, extreme precipitation took two forms: frontal precipitation (associated with a warm or cold front) and warm sector precipitation (associated with the air masses between two fronts). Our analyses show that 57% of the extreme daily precipitation situations were classified as warm sector precipitation. This stands in contrast to claims that significant warm sector precipitation will very rarely, if ever, propagate as far north as Nordland. Because extreme precipitation may be linked to the risk of avalanches, earthflows and mudflows, it may be important to re-evaluate the forecasting criteria for heavy rain in north Norway.

The early stage of weathering / soil formation processes from new volcanic mudflow (new lahar materials) brought from Mt. Pinatubo was examined. For this purpose, comparative studies on the physical / chemical characteristics of the new lahar materials and soils formed by the deposition of old lahar materials were conducted. Original soils contained less coarse sand, more silt, and clay than the new lahar materials. Increase in the clay content of the original soils reflected the progression of weathering. The occurrence of a higher leaching process of Fe, Ca, and Mg and of a moderate accumulation of organic matter in the original soils was suggested, based on the differences in the soil elemental composition and chemical properties. Values of base saturation and phosphate absorption coefficient (PAC) of the new lahar materials were 388% and 44, while those of all the original soils ranged 15–160% and 55–894, respectively. With the progression of weathering, the PAC value tended to increase gradu...

This paper presents a numerical model which can be used to simulate phenomena such as flowslides, avalanches, mudflows and debris flows. The proposed approach is la- grangian, and balance of mass and momentum equations are integrated on depth. Depending on the material involved, the model can implement rheological models such as Bingham orfrictional fluids. A simple dissipation law allows the approximation of pore pressure dissipation in the sliding mass. Finally, some applications are presented.

After being dormant for a long time, Mt. Pinatubo volcano located on Luzon island in the Philippines erupted violently on June 15, 1991 (Evangelista 1993). During successive rainy seasons, 1991 to 1993, large mudflows spread on the surrounding areas. The detailed chemical, physical, and mineralogical characteristics of these mudflow materials will be described in another report. In this paper, preliminary application of satellite imagery for the estimation of Mt. Pinatubo mudflow distribution is reported.

An exploratory study is done to modelling of rivers on volcano slopes. Beside the occurrence of mud flows or lahars these rivers are characterised by unsteady supercritical flow and large suspended-sediment concentrations. A fully coupled 1D model is presented for the rivers, provided that lahars do not occur. It can simulate unsteady supercritical flow (Froude numbers between about 1 and 1.8) with volumetric sediment concentrations less than about 10%. The redistribution of the suspended-sediment concentration (i.e., the lag between concentration and transport capacity due to sediment relaxation) causes instabilities of the bed conformable to antidunes. Calculations with a numerical model using Preissmann's implicit scheme, and applied to a river on the Kelud Volcano in Indonesia, show the rapidity of bed-level variations and the upstream propagation and growth of bed disturbances. These results offer a deeper understanding in the problems of the rivers on the Kelud. Furthermore it yields a base for inve...

Debris flows are frequently responsible for deaths and destruction of property in many parts of the world. One method of controlling debris flows is to construct a debris basin in the depositional area of the debris flow path to contain all or part of a debris flow or multiple flows. In this paper, considerations in the design of debris retention basins are discussed and methods of estimating design parameters are reviewed. Failure of debris basins can be disastrous. Homes, roadways, and property can be destroyed in addition to loss of life. While prediction of debris volume and frequency is essential to the basin design, maintenance of the basin is essential to the basin survival. A debris basin cannot function as designed if the basin is not properly maintained. This requires that the basin be emptied of its contents on a regular basis and after major debris flow events so that the basin can contain debris from future flows. Failure to keep the basin free of debris increases the risk of failure.

This paper discusses some of the important factors influencing mobilization of rapid mass-movement (slides, flows) on steep (35°–40°) mountain slopes affected by extreme precipitation. A large area, including the Lofoten islands and the adjoining mainland, was affected by a violent rain-storm on 6 October 1959. The rain caused several slides and mudflows, most of which occurred on slopes exposed to the strong southwesterly winds. The geomorphological effects of the rain-storm can still clearly be seen as almost unvegetated scars in the slopes. One reason for the catastrophic effects of the 1959 rain-storm was the high precipitation during the preceding months (152 % of the normal precipitation in September) which had saturated the soil at the time of the rain-storm. Judging by the morphology of the erosion scars, the rapid mass-movement of soil always started with several successive slides. The slides were often initiated below basin-like, shallow depressions in the upper parts of the slopes or at other p...

The authors describe how remote sensing imagery may be employed in the zonation and mapping of the alluvial fans of the Fergana Basin, USSR. Settlement patterns depicted on these maps can then be analyzed by planners and civil defense personnel with a view toward minimizing risks posed by natural hazards endemic to alluvial fans: mudflows and other seismically triggered mass movements. Translated from: Geografiya i prirodnyye resursy, 1987, No. 3, pp. 50-55.

In the southwest Yukon, valley walls mantled by talus and glacial deposits have been modified by a variety of catastrophic processes. Avalanches, landslides, mudflows, and retrogressive slope failures have been triggered by a variety of internal and external causes. These flow mechanisms produce a range of landforms in the paraglacial environment that dominate the landscape, particularly in the higher mountain zones. Models of rock glacier formation resulting from retrogressive slope failures, high hydrostatic pressures, and avalanche activity are proposed.

A group of complex landslides in the Razorback area, Australia is described. They are located on hillslopes underlain by Triassic shales and sandstones, on grazing land derived from earlier woodland. The slide types range from debris slides and slumps to earthflows and mudflows. Continued landsliding has been reported since the 1880's until the present. The influence of land use and of annual and daily rainfall on triggering of the landslides is discussed.

A method for the compilation of 1:3,000,000-scale maps of natural nival-glacial phenomena is proposed for an area of the High Pamir Range in Soviet Central Asia. Such maps depict the distribution, frequency and intensity/magnitude, and potential impacts of such natural hazards as avalanches, mudslides, “dirty snow” avalanches (combined avalanches-mudslides in late spring), icings (naledy), and glacier pulsations, and are used in the planning of construction and the maintenance of roads and other transportation corridors during winter and spring. Hypothetical examples of the use of the maps are provided. Translated from: Materialy glyatsiologicheskikh issledovanly, USSR Geophysical Committee Publication No. 55. Moscow: Mezhduvedomstvenniy geofizicheskiy komitet, 1986, pp. 213–219.

An episode of unusually intense rainfall triggered over a thousand landslides on Santa Cruz Island, California, during the winter of 1977-78. These included large, deep-seated failures, composite mudflows, and hundreds of shallow soil slips. In this study, landslide occurrence is examined in relation to lithologic, pedologic, topographic, and vegetational conditions. Their effects on soil permeability, water movement patterns, and shear strength are found to be related to landslide morphology and process.

The subfield of engineering geography is viewed as concerned with the interaction of man-made structures and the natural environment. The article focuses on the engineering-geographic problems that may arise in the course of operation of a large mining enterprise, with particular reference to the apatite mines of the Kola Peninsula in northern European Russia. The issues include such natural hazards as snow avalanches, mudflows and flooding of mines, and the problems of huge tailing heaps, some of them situated on mountain slopes and representing a potential rock creep hazard.

Summary The degradational and aggradational features of the valleys of the Cooleman Plain fluviokarst are discussed in relation to karst development, rejuvenation through uplift and climatic change. Aggradation, including mudflow action, as a result of a cold climatic phase, probably that between 30 000 and 15 000 B.P. in the Late Pleistocene, led to blockage of caves and temporary restoration of surface drainage.

Shallow intrusion of dolerite sills into porous and permeable Permian-Triassic strata in the Allan Hills region resulted in steam pressures which exceeded that of the roof rocks causing fracturing and fluidisation of the sediments and the formation of volcanic mudflows and explosion breccias. Shallow dolerite intrusion is suggested by curved and domed sills which were intruded parallel to surfaces of equal vertical rock pressure and magmatic pressure (compensation surfaces) so that they became gently curved to mirror the overlying topography. En echelon sills formed at shallow depths where folding and bedding-plane slip in the sediments was possible. A wedgeshaped clastic sill associated with a clastic dyke extending from it have a matrix similar to that of the mudflow breccias. The clastic sill is considered to be a preserved extension space which formed in front of an intruding dolerite sill. Fracturing of the roof of the extension space resulted in a fluidised mixture of mud, steam, and rock f...

From September 1975 to April 1976 offshore production Platform V in South Pass, Block 28 (East Bay, Louisiana), was instrumented to measure the effect of storm waves on the soft sediments typical of the Mississippi delta (in a project given the acronym SEASWAB). A portion of this project consisted of four identifiable units of instrumentation (see note): (1) an accelerometer package buried 1 m in the sediment to measure three‐dimensional sediment accelerations and an associated pressure transducer, which measured wave‐induced pressures; (2) an array of instruments that included a wave staff, electromagnetic current meter, and a pressure transducer to examine various relationships between wave properties; (3) a wave‐, current‐, and wind‐measuring station 3.35 km inshore of Platform V to determine the transformation of the waves as they moved over the sediments; and (4) a transponder buried in the mud, the position monitored so that long‐term mudflow could be measured. The direct measurement of sea...

Stationary investigations of the mudflows recorded in the Buzau Subcarparthians (southeast of the Carpathian chain) have revealed some peculiarities of both their involvement in slope modeling and their dynamics. The first mudflow investigated carried, in the course of eight years, 21,500 m3 of debris. These deposits gradually reached the mudflow track due to the successive release of some slides and falls in the source area. The second example (48,000 m3 displaced) refers to a mudflow triggered by extreme rainfalls (177.8 mm rain in 24 hours).

The authors urge greater utilization of mountain territories in the south of the USSR for purposes of electric-power generation and recreation. Geographers are expected to make a significant contribution to the planning of development projects involving regulation of water resources, prevention of soil erosion, mudflows and avalanches, and other distinctive mountain phenomena.

Sulebak, Jan R. 1959. Mudflow in the Low Alpine Region. Norsk geogr. Tidsskr. 23, 15-23. A fresh mudflow in the low alpine region at Doraalen, SE Norway, is described and discussed. The discharge of the masses (150—200 m3) started as a slide but continued immediately as a flow. A medial channel, confined by deposits having the form of levees and broad tongue-like accumulations, can be followed along the track. The levees arc situated on slopes ranging from 33g (30°) to 6g (5.5°). The forms are dependent upon the consistency of the material.

The effects of an extreme rainfall triggering debris flows (mudflows) in the mountains S of Abisko, N Sweden, in 1979, are evaluated with regard to geomorphological impact. Several older events of debris flows in the same area during postglacial time are evident in the morphology of the slopes. Where such flows have occurred repeatedly, debris accumulations superficially similar to alluvial cones and referred to as debris flow cones are built. An attempt at dating old flows by means of lichenometry indicated at least four earlier events within the last 2700 years in Nissunvagge. A map of the spatial pattern of known rainfall-triggered mass movements in northern Lappland is presented to support the hypothesis of geomorphic impact of extreme rainfall in three area size classes called regions, cells and spots.