Small Valley Research Articles

Numerical simulations of turbulent flow within and in the wake of a small basin

Small terrain features, such as small valleys, basins, sinkholes, low hills, and outcrops, while generally associated with mountainous regions, can also be found over plains. In this study, we present a numerical investigation of the effect of a small terrain feature (a 30 m high rim) on the mean and turbulent flows inside and downstream of an enclosed basin it surrounds. Results from high‐resolution numerical simulations (10 m isotropic spatial resolution) indicate that small terrain features in the proximity of larger ones can induce relatively large modifications to the mean and turbulent flows. The 30 m high rim is found to have an effect on the mean wind speeds at least 600 m upstream from the basin. The main effect is a 10% reduction in wind speed up to 120 m above ground level due to the upstream blocking effect of the rim. The presence of the rim can also double the turbulent kinetic energy (TKE) both inside and downstream of the basin compared to an otherwise identical basin without a rim. The slopes of the basin play an important role in first creating and then defining the wake, and in intermittent wind regimes most of the scalar transport from near the slope of the basin happens through slope roll vortices that define the edge of the downstream wake region of the basin. Inside the basin, the rim acts to limit momentum transfer in the lower half of the basin, which suggests a mechanical forcing effect induced by the rim on lower basin environments that could interact with thermal buoyancy effects in heated or cooled basins. Some of the wake features resemble wind‐eroded surfaces in the wakes of Martian craters. Results also reveal a critical height level (43 m below the rim height) that acts as the most favored location for TKE production and destruction, which could be important for the top‐to‐bottom turbulence erosion of basin boundary layers. These results stress the importance of resolving small‐scale terrain features, as their effects can be nonlocal.

Algunos criterios topográficos para identificar el origen antrópico de cárcavas

In semi-arid or sub-humid environments, there are isolate gullies or badland areas that could be caused by human activity. In some cases, particularly in cultivated areas, it is possible to identify artificial disturbances of the drainage network whose incision is the responsible for gully development. A detailed study of the gullies and the basic layout of the drainage can show anomalies that are incompatible with a natural evolution. The anomalous layout of a gully that does not follow the axis of a small valley, the existence of gullies that cross obliquely a hillslope, or a sudden change in the path of the gully use to be the most frequent criteria. The identification of one of several anomalies can allow us to deduce the anthropic origin of badland networks originally attributed to a natural origin.

Hidrología superficial en ambientes adhesados, cuenca experimental Guadalperalón

Research was carried out in the Guadalperalón catchment in Extremadura, Spain, between 1990 and 1997 in order to understand the hydrological and erosional processes operating in semi-arid open woodlands with silvo-pastoral landuse (dehesas). The present paper presents a summary of the major results of the project, including investigations of runoff production at different spatial scales, rainfall interception of holm oaks, and the water balance of the catchment. At the hillslope scale variations of runoff generation could be related to existing soil-vegetation units, which are typical for the peneplain landscape of SW Iberia. Low runoff coefficients are observed below tree canopies, in areas with improved pastures, as well as at footslopes and small valley bottoms with fluvio-colluvial sediment fill. Antecedent soil moisture conditions are shown to be of major importance. The shallow and degraded soils have low infiltration capacity, and, additionally, during prolonged droughts, when ground cover is strongly reduced due to continuous grazing, water repellency was observed. Large amounts of overland flow are produced during events preceded by high rainfall amounts and saturated soil conditions. In this situation all spatial units show high runoff coefficients. As a consequence antecedent soil moisture conditions are decisive for runoff production. During years with below average rainfall Hortonian overland flow dominates and water flow is discontinuous with reinfiltration in the sediment fill of footslopes and valley bottoms. During years with above average rainfall these areas become saturated, and large amounts of runoff are produced (saturated overland flow). As a result runoff coefficients vary strongly, with very low values during dry years (1.5%) and moderate values during humid years (15.9%).

Characteristics of cold pools observed in narrow valleys and dependence on external conditions

AbstractObservations from the recent COLd‐air Pooling EXperiment (COLPEX) field campaign are used to relate the intensity of cold pools within two small valleys (O(100 m) depth and O(1 km) width) to flow conditions within the airmass passing over the valley. The temperature structure of the cold pools is examined using transects of ground‐based sensors through the valleys and radiosonde releases from within the valley, in order to evaluate simple two‐dimensional concepts of cold‐pool formation due to sheltering. The cold‐pool spatial and temporal structure is found to be consistent between different nights when strong cold pools occurred. Initially a sharp surface inversion occurs similarly at all points within the valley, with isentropes roughly terrain‐parallel. The inversion layer at the bottom of the valley then grows deeper, spreading over the bottom portion of the valley, and cross‐valley isentropes eventually become horizontal. By defining appropriate measures of the relative temperature drop within the cold pool, and non‐dimensional valley depth diagnosed with respect to the speed and stability of the approaching flow, the measurements are shown to be consistent with previous relationships determined for simple two‐dimensional valleys.

FEEDING HABITS OF THE COMMON CHAMELEON, CHAMAELEO CHAMAELEON (LINNAEUS, 1758) IN THE SOUTHEASTERN IBERIAN PENINSULA

ABSTRACT We present the feeding habits of the common chameleon (Chamaeleo chamaeleon) at Taramay, a small coastal valley in the southeastern Iberian Peninsula. Fecal pellets collected from sexed and measured specimens trapped in the field were used for diet analysis. Thirty-four fecal samples provided a total of 777 identified prey items. All prey were arthropods and the numerically dominant groups were Diptera, Hymenoptera, Orthoptera, and Heteroptera. We failed to find sexual differences in diet preference, but there was a seasonal shift in the prey consumed. Orthoptera, the largest prey type, was consumed less in spring than summer or autumn. Examination of grasshopper phenology in coastal habitats of the southeastern Iberian Peninsula, and of the change in chameleon habitat utilization and mobility during the mating period, verified that the common chameleon appears to consume grasshoppers in approximate proportion to their abundance. Prey consumed were smaller than in previous studies. We believe the...

Mass change study on Arctic glacier Pedersenbreen, during 1936–1990–2009

Pedersenbreen is a small polythermal valley glacier, located in Svalbard, which has been one of the two glaciers monitored by Chinese Arctic expedition members since 2004. This study estimates its area and volume and analyzes its change during 1936–1990–2009, using field collected GPS/GPR data in 2009 and historical topographic maps published by the Norwegian Polar Institute. We have found that Pedersenbreen is just like many other valley glaciers in Svalbard, having experienced a significant recession since the end of Little Ice Age in the early 20th century. The glacier tongue has retreated more than 0.6 km, while ice volume has decreased by approximately 13%. The overall thinning rate of Pedersenbreen has shown acceleration during the recent decades. Further analysis shows that the ice tongue in the downstream area of Pedersenbreen is melting at the highest rate, while a simultaneous accumulation occurred in the upstream. However, as global temperatures increase, the accumulation area is reducing year by year.

Vegetation and hydrogeology along the distribution range of Centaurium somedanum, an endemic plant of mountain calcareous springs

Calcareous springs support bryophyte-dominated habitats relevant to biodiversity and conservation, but not much is known about the ecology of vascular plants restricted to these environments. Here, we investigate vegetation and hydrogeological patterns within the distribution of Centaurium somedanum, a threatened vascular plant endemic to mountain calcareous springs in the Cantabrian range (Spain). We studied the hydrogeological characteristics of the spring systems where this species occurs and identified three types of springs: (a) springs with active travertine deposition in small valleys, (b) springs in rock fall avalanches and (c) springs fed by calcareous water close to geological faults. Vascular plants and bryophytes co-occurring with the study species were sampled in 1-m2 plots to identify major vegetation types and to assess the relationships between species composition and topography. The presence of C. somedanum was associated with vegetation of calcareous spring fens (Caricion davallianae) in geological faults, tufa concretions (Adiantion) in active travertines, and another vegetation type of calcareous flushes (Pinguiculion) that was found in all of the spring types. C. somedanum shows a wider ecological range than other vascular plants of calcareous springs, occupying micro-habitats with similar cover of bryophytes but different from the cover of vascular plants. Although these plant communities are primarily dependent on the hydrology of springs, the variation in species composition is also correlated to the slope and solar radiation at the micro-scale. Our study demonstrates how a vascular plant with a calciphilic character may adapt to tufa-forming niches along the spring-flush-fen gradient, thus allowing it to occupy a wide range of habitats at different altitudes and geohydrological conditions.

杉村楚人冠邸白馬城における庭の構成と維持管理の特徴

Sojinkan SUGIMURA was a journalist of The Asahi Shimbun Company. He got a property which is located near the Teganuma Lake in Abiko, Chiba Pref. in 1912. After that, he named this property Hakuba‐jo, had lived and ended his life until 1945. On this study, we narrowed the garden space of this property and aimed to clarify the feature as an old private garden by analyzing his essays, expense notes, old photographs and old survey maps. Especially, we examined next three aspects: 1) to clarify the location and surroundings as the place of residence, 2) to represent the spatial layout and to sort out garden elements which were made up through his country life, 3) to find his maintenance policy which was between natural growth and actual life. As a result, Hakuba‐jo garden is characterized by the site specific feature and his sense of nature. On one hand, the property is spread from the hilltop to yatsu (small valley), a spring and a distant view of lake were taken in his life with the garden. On the other hand, the garden was covered with a mass of floral, colorful foliaged trees and wild grasses. The maintenance of these garden features were influenced by his ‘rustic taste’ which was confirmed as the natural style garden, the choice of plants, self‐help maintenance, and the gardening lasted thirty years.

Influence of the Material Behavior Law and Damage Value on the Results of an Orthogonal Cutting Finite Element Model of Ti6Al4 V

A finite element model has been developed with Abaqus/Explicit to model the orthogonal cutting of Ti6Al4V. Experiments were carried out to validate its results. The experimental cutting conditions are the same as those used in the finite element model. They lead to the production of a saw-toothed chip, either numerically or experimentally. The comparison of the model results shows that the difference with the experimental RMS cutting force value is quite large (about 40%). Both chips morphologies are similar although the teeth of the simulated one have smaller valleys and lengths. The numerical model could therefore be improved. The aim of this paper is to study the influence of the material behavior law and the damage value on the model results, in order to get closer to the experimental results. It shows that the difference between numerical and experimental cutting forces reduces drastically (it becomes of the order of 2%) for stresses obtained with the modified behavior law similar to those observed in the literature. The teeth of the chip have a larger valley and are therefore closer to the experimental chip. These improvements do not interfere with the physics of the saw-toothed chip formation, which is still the same as the experimental one. An important point is that it turns out that the influence of the material behavior law and of the damage value are almost decoupled within the limits of the variations selected. Indeed, the material behavior law controls the level of the cutting force while the damage value acts mostly on the morphology.

Опыт выявления и отображения основных закономерностей растительного покрова методом картографирования (на материале исследования гольцово-таёжной территории)

Geobotanical mapping of the territory in riverheads Bureya of 4500 sq.km is carried out and the map of a actual vegetation cover of scale 1 : 200 000 is prepared. The legend of the map is presented in the form of the text with three-level hierarchy of classes. At the heart of structure of a legend of the map such regularities of a vegetation cover, as its latitudinal zonality / altitudinal belts, situation in a relief and dynamic series lie. The largest divisions of the legend reflect, first, change of large classes of mesocombinations of vegetation at the level of belts and, secondly, distinction in a boreal - forestry belt between a vegetation cover of tops and slopes of mountains, on the one hand, and the bottoms of river valleys, with another. Divisions of the legend of the second level reflect, first, vegetation changes in the form of high-rise and barrier changes of subbelts, secondly, distinctions of a vegetation cover in different geomorphological conditions (small and average river valleys, northern slopes, etc.). Divisions of the legend of the second level correspond to dynamic series of units of the third level. Essential addition to it are block diagrams of dynamics of a vegetation cover.

小字区域に着目した谷戸の基礎的単位の抽出とその特徴

This paper aims to clarify the standard shape character of Yato-topography by classifying the small valleys whose small administrative unit name includes “Ya” that means valley. In the case study area, there are most Yato-topography with following characteristics, the reclaimable fields area is about 1 ha, the forest area is about 3 ha, the entrance width of vale is about 60m, and the distance from the entrance to the end is about 200m. This study declares that basic Yato that is social units units have these characteristics. In other words, Yato is a unit that has fields for mainly agriculture, whose area is about 1 ha, have forest as the water source whose area is three times larger than the fields. In the conventional method for extracting ato that uses the stream order, the areas of Yato units varies widely because of the influence by the fractal form of vales. In the method using small administrative unit for extracting Yato, the areas of Yato units are certain. Therefore, it is considered that the method in this paper is more appropriate.

When Air Quality Becomes Deleterious—A Case Study for Kigali, Rwanda

Rwanda is a landlocked republic in Equatorial Africa. The capital Kigali (1°57'S, 30°04'E) can be mentioned as a typical African city due to its rising population and the rising rate of motorization. Different pollutants produced e.g. by a highusage rate of mopeds or open fireplaces burning wood for cooking and household chores could be detected. Climatological parameters as well as air pollutants were measured within the urban area. Additionally, highly frequented spatial and temporal mobile measurements of particulate matter were taken during different dry seasons regarding different conditions. These values indicated an urban heat island, which tended to rise for the last four decades. A temporary phenomenon for the air pollution indicators is visible during clear and calm weather situations, e.g. the distinctive relief caused an accumulation within small valleys called “Marais” in the night time. Unfortunately, these are the favourite places for living and agriculture. So there is no infrequence in values of PM10 > 1.000 μg·m-3. The origin of the different airborne particles was verified by using a scanning electron microscope and it could be mentioned that most particles were from the combustion of biomass and traffic.

Temporal and spatial variability of nocturnal cooling in a complex of small valleys in the Kanto Plain during the winter

Temporal and spatial variability of nocturnal cooling in a complex of small valleys in the Kanto Plain during the winter

North as a Sacred Direction? Traces of a Prehistoric North-South Route Across Pembrokeshire

The King’s Quoit dolmen perches precariously halfway up a headland in south Wales. Its location has been an enigma since Victorian times. The monument builders chose not the spectacular sea views of the south-facing slope, but the apparently more mundane inland vista of the north side, with a near horizon comprising a low ridge on the far side of a small valley, now a beach. Previous research by the author into the astronomical possibilities at this site have revealed horizon indicators for cardinal north, in the form of earth mounds which appear to have marked the lower culminations of Deneb and Vega, as they dipped down to the horizon and rose again during the third and fourth millennium BCE. This has led to another discovery, namely, that a still traceable route way of roads and footpaths leads north from this monument across Pembrokeshire, passing close by several Neolithic monuments and settlements as it does so, before reaching a sheltered bay and another, south facing, dolmen on the north coast. The southern end of this possible ancient trackway is located on Carmarthen Bay, and the northern end, on Cardigan Bay. Both bays encompass a lengthy stretch of relatively sheltered coastal and estuarine water.

Potencial Geoturístico do Parque Estadual da Serra do Ibitipoca, Sudeste do Estado de Minas Gerais

The Ibitipoca Mountain is a spectacularly morphostructural feature located between the Santa Rita do Ibitipoca and Lima Duarte cities, southeast Minas Gerais State, between the Parallel 21º38' and 21º44', and Meridians 43º50' and 44º00'. In this environment, was created in 1973 Ibitipoca State Park by Forest Institute of Minas Gerais State, which protects an area of 1,488 ha, with higher altitudes ranging from 1784 m, for the Morro da Lombada and 1722 m of Pico do Pião. This natural feature represents a great declivity of the Serra da Mantiqueira widely flattened with a plateau in the north portion, and a devastated south topography. In the geological context, Ibitipoca Mountain consists mainly of quartzites and coarse grain size, interspersed with layers of fine micaceous quartzites and garnet-sillimanite-biotite schist. The sediments that filled the original sedimentary basin have been metamorphosed in amphibolite facies, and deformed in a compressive tectonic regime resulting from an evolving nappe folding type, with the subsequent development of systems of faults and shear zones of high angle. The result of this tectonic event in sedimentary transitional continent-ocean, associated with erosion action, provided the development of fifteen wonderful and unique caves in quartzites, specially the Bromelias Cave with more development. The geomorphology can be summarized by the occurrence of escarpment plunging toward the river valleys and of Rio do Salto and Córrego da Mata, controlled by major tectonic folding that affected the metasedimentary rocks. The relief of the Ibitipoca Mountain present ruiniform forms, lapies and small valleys that may have been generated by processes of landslides galleries caves or doline. The rocks of PEI have a complex tectonic evolution that result in interesting geoforms. This ancient geological environment shows surprisingly exuberant flora and fauna and exotic caverns and pits that constitute potential areas to Geotourism.

Significance of the fine drainage pattern for submarine canyon evolution: The Foix Canyon System, Northwestern Mediterranean Sea

Submarine gullies are relatively small valleys that occur in a variety of submarine slopes. They are very common in continental slopes and in submarine canyon heads and flanks, where they often form tributary networks. Gullies are smaller than submarine canyons, though there is no standardised size criterion to distinguish between them. Gullies and gully networks have been often viewed as initial steps in the development of larger submarine canyons and more mature drainage networks. The shelf-incising submarine Foix Canyon System (FCS) is located in the northwestern Mediterranean Sea. Numerous, well-developed and morphologically diverse gullies carve its two heads and flanks. The objective of this study is to analyse the drainage network of the FCS and decipher the role of gullies in its evolution. Submarine gully and canyon networks were extracted from swath bathymetry data of 50m grid size using Geographic Information Systems (GIS). A systematic morphometric analysis was carried out on drainage network of the FCS by using the Horton–Strahler method. Our results show that the FCS is formed by 1660 streams, 1000km in total length, which can be classified to six stream orders. To detect relevant morphological changes along valley sections, the drainage density, the stream frequency and the drainage area relief parameters were applied. Furthermore, a branching index (Ib) was developed to characterise the geometry of the submarine drainage network. In the canyon heads Ib values are ~1.7, which correspond to a dendritic network, whereas Ib in the canyon branches displays values of ~2.2 corresponding to a pinnate one. At a finer scale, we have identified two types of canyon flank gullies, namely “rim gullies” and “toe gullies”: (1) rim gullies form large, dendritic networks that extend from the canyon thalweg up to the canyon rim, and (2) toe gullies form smaller pinnate networks restricted to the lower part of the canyon flanks. The formation and development of rim gullies are interpreted as the main process responsible for canyon head growth and across-flank transport of material from the continental shelf. Toe gullies, on the other hand, are the morphological expression of the rejuvenation of rim gullies and the canyon itself. Axial incision and toe gully formation are interpreted as the result of bottom-to-top erosive processes acting at different scales, in response to regional and local changes of the factors controlling the system, respectively. This study helps to identify a variety of gullies and the processes they result from and provides a morphometric methodology to characterise submarine drainage networks at fine resolution scales.

Scaling relationships and concavity of small valley networks on Mars

Valley networks are widely interpreted as the preserved erosional record of water flowing across the martian surface. The manner in which valley morphometric properties scale with drainage area has been widely examined on Earth. Earlier studies assessing these properties on Mars have suggested that martian valleys are morphometrically distinct from those on Earth. However, these earlier measurements were generally made on large valley systems because of the limited topographic data available. In this study, we determine the scaling properties of valley networks at smaller scales than have been previously assessed, using digital elevation models from the High Resolution Stereo Camera (HRSC). We find a Hack’s law exponent of 0.74, larger than on Earth, and our measurements also reveal that individual small valleys have concave up, concave down, and quasi-linear longitudinal profiles, consistent with earlier studies of dissected terrain on Mars. However, for many valleys, widths are observed to increase downstream similarly to how they scale in terrestrial channels. The similarities and differences between valley networks on Mars and Earth are consistent with the idea that valleys on Mars are comparatively immature, and precipitation was a likely mechanism for delivering water to these networks.

토지이용 변화지역의 토양재조사 결과 분석

최근 농경지의 급격한 감소와 더불어 도시화, 경지정리, 도로공사 및 혁신도시 건설 등으로 토지이용의 변화가 심하게 발생되고 있다. 특히, 토지이용 변화심화지역인 경기도 고양시, 충청남도 천안시, 강원도 원주시를 대상으로 토지 이용변화실태, 토양특성변화양상, 토양도수정내용 및 기업도시 등으로 편입되는 지역의 토양환경분석을 하였다. 이에 대한 결과를 요약하면 다음과 같다. 1. 우리나라의 경지면적 (2011년)은 2009년대비 17.3 ha가 감소되었다. 논의 경우 24.2 ha가 감소되었으나, 밭의 경우에는 7.0 ha가 증가하였다. 2. 논의 면적 감소사유로는 논밭전환 (20.7 ha) > 공공시설 (3.2) <TEX>${\geq}$</TEX> 건물건축 (3.2) > 유휴지 (1.3) > 기타 (0.9) 순이며, 밭 면적의 증가원인은 논밭전환 (20.7 ha) > 개간 (4.5) > 복구 (0.3) 순이었다. 논밭전환의 이유는 논농사에서 농가소득이 높은 밭작물 내지 시설작물로 전환하는 것으로 생각된다. 3. 토지이용변화가 심한 해당시군의 농경지감소 (논, 밭, 과수)는 밭토양조사 (1995~1999) 당시와 비교 (2011년)할 때 고양시는 1,466 ha, 천안시 9,708, 원주시 6,980 ha가 감소되었으며, 1999년 대비 45%~25%의 농경지가 급격히 감소되었다. 4. 환경부 토지이용피복도의 통계자료 활용성을 검토하기 위해 농식품부 통계자료와 비교시 지목별로 큰 차이가 있었다. 따라서, 추후 면밀한 검토를 통하여 활용 방안을 마련해야 할 것이다. 5. 원주시의 토양정보 변경내용을 보면 곡간지의 일부 논토양이 밭 또는 과수원으로 토지이용이 변경되었으며, 배수등급의 경우 도로건설 등으로 인해 저습화되는 등 해당 토양의 일부 특성정보가 변경되었다. 특히, 논토양의 경우 시설재배지, 밭, 과수원, 휴경, 성토화 등으로 토지 이용의 변화가 심하였다. 6. 원주시 혁신도시에 편입되는 논토양은 급지가 떨어지는 3~4급지가 대부분으로 3급지 70.8%, 4급지 29.2%이었다. 밭토양 역시 4급지가 88.7%인 토양으로 우량 급지가 혁신도시 건설에 속하지는 않았다. 앞으로 우량농경지 보전을 위해 제도적 장치의 마련이 필요하다고 생각한다. Recently, agricultural lands decrease sharply, which was caused by urbanization, land consolidation, road construction, and innovation city construction, etc. In particular, Goyang, Chenan and Wonju city were had severe land use change. Therefore, we analyzed changes of land use, soil properties, and soil information in order to provide the basic soil information and soil management practice in these cities. The results are summarized as follows. The area of crop cultivated land in Korea (2011) was reduced to 17.3ha compared to ones from the previous year (2009). The paddy field decreased by 24.2 ha but, upland field increased by 7.0 ha. The reasons for the reduction of the paddy field were converting paddy field to upland (20.7 ha) > public facilities (3.2) <TEX>${\geq}$</TEX> building (3.2) > idle land (1.3) > and others (0.9). Other reasons for reduction in the upland field were switching upland to paddy field, (20.7 ha) > land developed (4.5) > and restoration (0.3) respectively. The main reason of converting paddy field to upland was changing from rice to more profitable upland or greenhouse crops. The cropland area (paddy fields, upland, orchard) of Goyang, Cheonan, and Wonju city were reduced to 1,466 ha, 9,708 ha and 6,980 ha respectively. The ratio of cropland area in each city was reduced by 45~25% dramatically compared to upland soil survey project in Korea (1995~1999). These data were compared with MiFAFF statistics data to use for land use cover map of Ministry of environment. But they were differences significantly. Therefore, intensive investigation should be advised throughout the utilization plan. The paddy fields located in small valley in Wonju city were changed into upland or orchard. The drainage classes of soil have been deteriorated because the flows of water were intercepted by road construction and other disturbance to water flows. In particular, paddy fields have been changed to not only upland, orchard, greenhouse cultivation but also to fallow and soil dressing on paddy in Wonju city. The soil suitability classes of paddy field in Wonju innovation city were the 3rd grade for 70.8% of the area and the 4th grade for 29.2%. The soil suitability classes of upland was the 4th grade for 88.7% of the area. Fortunately, good soil suitability classes were not belong to innovation city in Wonju. So, the good farm land should be conserved and revise the related law.

Residential indoor PM2.5in wood stove homes: follow-up of the Libby changeout program

Abstract In 2005 through 2008, a small rural mountain valley community engaged in a woodstove changeout program to address concerns of poor ambient air quality. During this program, we assessed changes to indoor air quality before and after the introduction of a new, lower emission woodstove. We previously reported a >70% reduction in indoor PM2.5 concentrations in homes following the installation of a new Environmental Protection Agency’s-certified stove within the home. We report here on follow-up of the experiences in these and other homes over three winters of sample collection. In 21 homes, we compared pre-changeout PM2.5 concentrations [mean (s.d.) = 45.0 (33.0) μg/m3] to multiple post-changeout measures of PM2.5 concentrations using a DustTrak. The mean reduction (and 95% confidence interval) from pre-changeout to post-changeout was −18.5 μg/m3 (−31.9, −5.2), adjusting for ambient PM2.5, ambient temperature, and other factors. Findings across homes and across years were highly variable, and a subset of homes did not experience a reduction in PM2.5 following changeout. Reductions were also observed for organic carbon, elemental carbon, and levoglucosan, but increases were observed for dehydroabietic acid and abietic acid. Despite overall improvements in indoor air quality, the varied response across homes may be due to factors other than the introduction of a new woodstove. Practical Implications Biomass combustion is a common source of ambient PM2.5 in many cold-climate communities. The replacement of older model woodstoves with newer technology woodstoves is a potential intervention strategy to improve air quality in these communities. In addition to ambient air, woodstove changeouts should improve residential indoor air quality. We present results from a multi-winter study to evaluate the efficacy of woodstove changeouts on improving indoor air quality. Reductions in indoor PM2.5 were evident, but this observation was not consistent across all homes. These findings suggest that other factors beyond the introduction of an improved wood burning device are relevant to improving indoor air quality in wood burning homes.

Balkas – a new look at a common landform of the East European Plain, from a Quaternary perspective

ABSTRACTBalkas (large Quaternary gullies) of the south‐western part of the East European Plain (and their analogues in Central and Western Europe) are considered in terms of their geomorphology, lithology, sedimentology, modern surface processes, stratigraphy and palaeogeography. Features attributed to balkas in comparison with regular gullies and small river valleys are described. Balkas are widespread elements of the modern landscape with the same characteristic gentle‐concave bottom as regular gullies, and with or without weakly incised river channels. Buried gully incisions of different ages (post‐Gelasian) with the same shape are also revealed below modern Balkas. They are infilled by characteristic balka alluvial, slope and even lacustrine‐bog deposits, in places representing compound sequences of fluvial‐aeolian sedimentation. The fluvial part reflects multiple series of ephemeral episodes of increased water and sediment supply within temporary streams. Two conspicuous series supposedly fall within the final stages of the Dnieper (late Middle Pleistocene) and Valdai (Late Pleistocene) glaciations. Different ideas concerning the increase of surface runoff and erodibility of soils that might favour active balkas under conditions of land‐ice decay and permafrost, including its degradation, are discussed. The development of balkas included relatively short phases of incision and accumulation interrupted by much longer periods of inactivity, when they were subjected to surface processes in a subaerial environment or left as a relic. However, during active phases they served as important and powerful depositories and arteries of rill–gully–balka sedimentation systems, collecting and transmitting eroded material to the river valleys. These phases are related to climatic oscillations and were to some degree independent of fluvial processes affecting the permanent streams. Most of the Middle‐Late Pleistocene balkas retained their primary features, having subsequently been incorporated into the erosional network. In contrast, some of them were totally infilled and disappeared from the landscape. Copyright © 2012 John Wiley &amp; Sons, Ltd.