Plateau Top Research Articles

Topography and rainfall coupled landscape evolution of the passive margin of Sahyadri (Western Ghats), India

The passive margin of the Indian peninsula, revered as Sahyadri (Western Ghats) from time immortal, stretches along the western margin of the Indian Craton. It acts as an orographic barrier, and the frontal part of this continental-scale escarpment receives most of the rainfall, whereas the plateau top remains dry; this makes a case to study the processes of landform evolution in a climatically active and tectonically quiescent region. In our study, we demonstrated the modification of the Sahyadri with the annual forcing of the Indian Summer Monsoon (ISM). Seven major perennial river basins having higher drainage density and flowing on a lithologically varied terrain were studied using the SRTM 30 m data. The morphometric studies carried out in these basins, and the topographical analyses of the region offer the development of drainage systems on varied lithological terrain with diverse geological history. We demonstrated how the drainage basin erosion is moderated by the headward erosion by the streams as forced by the runoff water, probably by local base-level fluctuations and the forcing of ISM. The modification of the basin margin, i.e., drainage divide migration, is primarily affected by precipitation, whereas the lithological and structural factors have a second-order control on the overall retreat of the water divide.

Bottom currents on a pelagic carbonate platform: Mounds and sediment drifts in the Jurassic succession of the Sciacca Plateau, Western Sicily

AbstractThe stratigraphic succession in the San Vincenzo Gorge (Saccense Domain, western Sicily) documents deposition on a vast pelagic carbonate platform, the Sciacca Plateau, during the Middle and Late Jurassic. This succession caps a peritidal limestone (Inici Formation), which underwent extension during the Western Tethyan Early Jurassic rift phase, and displays a set of unique features, which have never been previously reported on a Tethyan drowned platform. The upper part of the Bositra limestone (late Bajocian‐early Oxfordian p.p.) comprises elongate convex‐up, mound‐shaped bodies, made of thin‐shelled bivalve wacke‐ to grainstone, a few tens of metres across and producing a topographic relief of up to 10 m. Planar beds within the mound cores are seen to thin out laterally with tangential downlaps along sections perpendicular to the mounds' longer axes, and the mounds are in lateral association with concave‐up bedsets. Following halt of the Bositra‐dominated deposition and demise of mound accretion, the draping units inherited an antiformal geometry. The mounds are interpreted as being part of a sediment drift, produced by bottom currents sweeping the Plateau top, the source areas being sediment‐depleted sectors now documented by extremely condensed and hiatus‐ridden sections, with parallel‐sided beds. Following draping and partial levelling of the submarine relief by the Knobbly limestone (?middle Oxfordian/early Kimmeridgian‐late Kimmeridgian), the Coquina limestone is locally a thick (>20 m) ammonite/brachiopod rudstone (Tithonian p.p.). This unit displays evidence for lateral accretion, with large‐scale clinoforms dipping up to 12°, and is interpreted as a mud‐poor, bioclastic‐gravel drift, with the action of bottom currents being apparently linked with a bloom of cephalopods. This is an early‐cemented deposit, where clotted, micropeloidal fabrics document the calcification of microbial communities and are followed by growth of early diagenetic fibrous calcite. The description and interpretation of the mounded Bositra limestone and of the clinostratified Tithonian limestone are the main focus of this paper. The San Vincenzo Gorge outcrop displays similarities with pelagic shelves, like the Upper Chalk basin of northern Europe.

Remote sensing and GIS application for land resources appraisal of Ridhora watershed in Nagpur district, Maharashtra

Accomplishment about morphological, physical and chemical characteristics of soil is an essential requirement for successful crop endowment and achievement in an area. Captivating this concept into jurisdiction, twelve representative soil series were exposed and mapped as series and complex with phases on 1: 50000 scales based on landform-soil relationship in Ridhora watershed of Nagpur district of Maharashtra. Six major landform units viz. plateau top, escarpment, isolated mound, pediment, upper valley and lower valley, were identified and delineated. Based on image interpretation, seven major land use/land cover were identified, i.e. cultivated land, wasteland with scrub, dense forest, moderately dense forest, degraded forest and habitation. Cultivated land is again classified into single and double crop based on temporal data. Soils on very gently sloping plateau top and moderately to steeply sloping escarpments and isolated hillocks are very shallow, somewhat excessively drained and classified as Typic Ustorthents. whereas soils on very gently sloping undulating land, foot slope, alluvial plain and valley are moderately deep to very deep, moderately well drained to well drained, very dark gray to very dark grayish brown in colour, calcareous and have clay textural class and qualify for Typic/Vertic Haplustepts. These soils were grouped into IIIes, IIIesf, IVs, IVsf, VIs, VIIe, VIIs and 2st, 3s, 3st, 4s, 4st and 5t land capability and irrigability subclasses, respectively. The land suitability evaluation indicates that Kachari sawanga-3 (99.69 ha), Bhiwari-2 (66.46), Ridhora-2 (358.04 ha) and Subkund-2 (238.70) series soils are highly suitable for cultivation of cotton, sorghum, soybean, pigeonpea, wheat, chickpea, groundnut and citrus whereas Kokarda-2 (180.00 ha), Mendhe pathar (120.00 ha), Kachari sawanga-2 (26.06 ha) and Bhiwari-1 (17.38 ha) series soils are not suitable for cultivation of cotton, sorghum, soybean, pigeon pea, wheat, chickpea, groundnut and citrus. Suitable conservation measures and interventions have been suggested to improve the productivity of these soils.

Lithoecotopes and Vegetation on Dumps of the Central Mining and Ore Enrichment Combine (the central zone of Kryvbass)

In the article, characteristics of development of vegetation communities under conditions of mine rock dumps of the Central Mining and Ore Enrichment Combine or their rocky components (lithoecotopes) were determined, namely only lithophilic vegetation. We сlassified various lithoecotopes and characterized vegetation communities of varying complexity growing on plateau tops, terraces and slopes, depending on specifics of their constituent rocks and typological features. In accordance with the state of lithoecotopes, including all typological characteristics and the geochemical nature of the rocks, plant lithophilic communities growing on the dumps of the Central Mining and Ore Enrichment Combine, were characterized by significant differences in analytical (floristic and ecomorphic composition, occurrence, layerage, aspect, abundance, cover) and synthetic (similarity, constancy) signs. A detailed survey of the state of plants and their communities within the lithoecotopes has allowed us to establish that their distribution and development have clearly expressed dependence on substrate and relief-exposure,which can be used in phytocoenic and phytocenotic melioration of such technogenic ecotopes. Native overgrowth of all dumps has a shrub-tree forest and grassy pattern in accordance with the typological characteristics and rock composition. In general, taxonomic composition of plant communities growing on the dumps of the Kryvbas central zone is characterised by 153 species belonging to 31 families, of which 66 species are petrophytes, and 18 species are typical only for zone surveyed.

26Al/10Be ratios reveal the source of river sediments in the Kimberley, NW Australia

AbstractWe use cosmogenic 10Be and 26Al in both bedrock and fluvial sediments to investigate controls on erosion rates and sediment supply to river basins at the regional scale in the Kimberley, NW Australia. The area is characterised by lithologically controlled morphologies such as cuestas, isolated mesas and extensive plateaus made of slightly dipping, extensively jointed sandstones. All sampled bedrock surfaces at plateau tops, ridgelines, and in the broader floodplain of major rivers over the region show similar slow lowering rates between 0.17 and 4.88 m.Myr‐1, with a mean value of 1.0 ± 0.6 m.Myr‐1 (n=15), whilst two bedrock samples collected directly within river‐beds record rates that are one to two orders of magnitude higher (14.4 ± 1.5 and 20.9 ± 2.5 m.Myr‐1, respectively). Bedrock 26Al/10Be ratios are all compatible with simple, continuous sub‐aerial exposure histories. Modern river sediment yield lower 10Be and 26Al concentrations, apparent 10Be basin‐wide denudation rates ranging between 1.8 and 7.7 m.Myr‐1, with a median value of 2.6 m.Myr‐1, more than double the magnitude of bedrock erosion rates. 26Al/10Be ratios of the sediment samples are lower than those obtained for bedrock samples. We propose that these depleted 26Al/10Be ratios can largely be explained by the supply of sediment to river basins from the slab fragmentation and chemical weathering of channel gorge walls and plateau escarpments that result in diluting the cosmogenic nuclide concentration in river sediments measured at the basin outlets. The results of a mass‐balance model suggest that ~60–90% of river sediment in the Kimberley results from the breakdown and chemical weathering of retreating vertical sandstone rock‐walls in contrast to sediment generated by bedrock weathering and erosion on the plateau tops. This study emphasises the value of analysing two or more isotopes in basin‐scale studies using cosmogenic nuclides, especially in slowly eroding post‐orogenic settings. © 2019 John Wiley & Sons, Ltd.

Characterization and Classification of Different Rice Growing Soils with Special Emphasis on Soil Organic Carbon Stock in Rajnagar Block of Birbhum District, West Bengal

Characterization and classification of rice growing soils of rainfed region of West Bengal is having an utmost importance for developing optimal agricultural land use planning. In the context of ever increasing food demand under dwindling agricultural land availability, rainfed areas have got the attention for enhancing food grain production for the national food basket. Hence, in the present study, we made an effort to characterize six rice growing soils placed in six different landform situations (plateau top, dissected plateau, plateau fringe, undulating upland, alluvial plains and valley fill) and classify accordingly for resource inventory of Rajnagar block, Birbhum district, West Bengal. Results depicted that, rice is grown mainly in Alfisols and Inceptisols in this block with varying morphological and physico-chemical characteristics. The soils are moderately deep to very deep with sandy loam to clay loam surface texture. Soils of plateau top, dissected plateau, plateau fringe, undulating upland, alluvial plains and valley fill were classified as Typic Haplustalfs, Aeric Endoaqualfs, Typic Haplustalfs, Typic Haplustepts, Aeric Endoaquepts, Typic Haplustalfs, respectively. The double crop rice ecology (rice-mustard) showed significantly (P=0.05) higher surface soil organic carbon (SOC) stock in surface as compared to the other monocrop rice ecologies. Among all the landforms compared, soils of valley fill region had the highest surface SOC stock (14.5 Mg ha-1) followed by plains (10.4 Mg ha-1), plateau fringe (7.7 Mg ha-1), plateau top (8.1 Mg ha-1), dissected plateau (7.2 Mg ha-1) and upland (6.9 Mg ha-1). Significantly (P=0.05) higher total profile SOC stock suggested a better soil health in valley fill and plains as compared to other areas that enhances our understanding about the need of the implementation of carbon management based land use planning for higher future productivity of these soils under environmental sustenance.

Evaluation of the Effect of Radius of Curvature on the Rounded Edge Diffraction Loss Computed by Hacking Method for a Plateau

In this paper, the effect of the radius of curvature on the diffraction loss of rounded edge obstruction is presented. The study is conducted for C-band microwave link with a plateau in its path. The plateau has flat to that spans about 1922 m. Two different approaches are used to determine the radius of curvature of the rounded edged fitted to the plateau top. Among the two methods employed, the ITU-R 526-13 method overestimated the radius (about 12,374,693.37 m) as against 59,031.42 m estimated by the second method at the same C-band frequency of 4 GHz. Also, high radius of curvature by the ITU-R 526-13 method gave very high diffraction loss value for the plateau. Furthermore, with the ITU-R 526-13 method, the radius of curvature does increase with increase in frequency. In all, the results indicate that the ITU-R 526-13 method is not particularly suitable for estimating the radius of curvature for the rounded edge when applied to a plateau. In addition, a more accurate method is required to estimate the radius of curvature for computing rounded edge diffraction loss.

<b>Principle and geomorphological applicability of summit level and base level technique using Aster Gdem satellite-derived data and the original software Baz

This article presents principle and geomorphological applicability of summit level technique using Aster Gdem satellite-derived topographicdata. Summit level corresponds to thevirtualtopographic surface constituted bylocalhighest points, such as peaks and plateau tops, and reconstitutes palaeo-geomorphology before the drainage erosion. Summit level map is efficient for reconstitution of palaeo-surfaces and detection of active tectonic movement. Base level is thevirtualsurface composed oflocallowest points, as valley bottoms. The difference between summit level and base level is called relief amount. Thesevirtualmapsareconstructed by theoriginalsoftwareBaz. Themacroconcavity index, MCI, is calculated from summit level and relief amount maps. The volume-normalised three-dimensional concavity index, TCI, is calculated from hypsometric diagram. The massifs with high erosive resistance tend to have convex general form and low MCI and TCI. Those with low resistance have concave form and high MCI and TCI. The diagram of TCI vs. MCI permits to distinguish erosive characteristics of massifs according to their constituent rocks. The base level map for ocean bottom detects the basement tectonic uplift which occurred before the formation of the volcanic seamounts.

Stream flow unaffected by Eucalyptus plantation harvesting implicates water use by the native forest streamside reserve

Study region: Tropical Atlantic Forest region, Brazil. Study focus: The temporal and spatial dynamics of soil water, water table depth and stream flow in relation to precipitation and the harvesting and regrowth cycle of a Eucalyptus grandis hybrid plantation in a headwater catchment. This landscape contains a mosaic of eucalypt plantation grown for pulpwood on plateau tops and native forest reserves in gullies. Instead of harvesting the native forest to test this effect, we conducted a virtual experiment using a soil and hydrological model (HYDRUS). New hydrological insights: Plantation harvest had little effect on steam flow, despite a 6-11 m rise in water table level under the plantation area. This result suggests that the native forest reserve intercepted groundwater moving laterally between the plantation and the stream. Measured and simulated runoff coefficients were similarly low (5% and 3%, respectively), but simulated removal of the native forest led to an increase to 38%. Therefore, plantation management in this type of landscape is likely to have little impact on stream flows where there is an intact native rainforest reserve beside the stream.

Cadastral-level soil mapping in basaltic terrain using Cartosat-1-derived products

Lack of topographic details in cadastral maps and limited terrain information in coarse-resolution digital elevation models (DEMs) are limitations in understanding the soil–environment relationship, identification of soil patterns, and their boundaries. The present study describes the technique of cadastral-level soil mapping using Cartosat-1-derived products. A high-resolution DEM with a posting of 10 m generated from a Cartosat-1 stereo pair was used to derive terrain attributes. Based on erosional and depositional processes, five major landforms, namely plateau top, escarpment, pediment (erosional), alluvial plain, and narrow valley (depositional), have been delineated using 3D perspective viewing of the landscape and 10 m contours generated from the DEM. The pediments and alluvial plain were further divided into upper and lower pediments and alluvial plain based on elevation. A detailed slope map has been generated from the DEM and reclassified into seven slope classes, namely nearly level (0–1%), very gently sloping (1–3%), gently sloping (3–5%), moderately sloping (5–10%), strongly sloping (10–15%), moderately steep to steep (15–25%), and steep to very steep (25–50%). Five land-use/land-cover classes, namely single crop, double crop, wasteland with and without scrub, and degraded forest have been delineated using Cartosat-1-sharpened IRS-P6 LISS-IV data. The landforms, slope, and land-use/land-cover maps were integrated in a GIS framework and 45 precise physiography–land-use (PLU) units were derived. Nine soil series were identified in major landforms. Soils of plateau top, escarpment, and pediment associated with a low weathering front are very shallow to shallow in depth, have moderate to severe erosion, slight stoniness, and clay texture, whereas soils of alluvial plain, developed in Deccan basaltic alluvium, are deep to very deep (>150 cm), fine textured with shrink–swell potential, and calcareous in nature. Different phases of soil series were identified based on tone, texture, and pattern variations in the satellite image. A detailed soil map has been developed from the PLU map using soil series information and augur observations through the PLU–soil relationship. The combined use of the high-resolution DEM and satellite data has immensely helped in understanding the soil-forming environment, identification of soil patterns, and their boundaries for precise and faster mapping compared to conventional soil mapping.

Logging Intensity Impact on Small Oak Seedling Survival and Growth on the Cumberland Plateau in Northeastern Alabama

Ground disturbance caused by forest harvest operations can negatively impact oak regeneration. On the Cumberland Plateau, for successful regeneration, managers often must rely on very small (less than a ft in height) oak advance reproduction that is susceptible to disturbance by harvesting equipment. Furthermore, sites on the Plateau top are often harvested when conditions are too wet to permit operations elsewhere, increasing the risk to small seedlings that may be more easily pulled from the moist soil. This study was designed to assess the effect of unrestricted and restricted harvesting equipment traffic on small oak advance reproduction under a clearcutting prescription. A feller-buncher and grapple skidding were used to harvest sites under “free access,” resulting in unrestricted traffic on the sites, or under “trail access,” with restricted site traffic. Six hundred eighty-seven oak seedlings were permanently tagged (preharvest); species, height, and basal diameter were recorded and have been remeasured 1, 2, and 8 years postharvest. Fifty-two percent of the tagged seedlings survived after 8 years. The survival rate for seedlings exposed to restricted traffic did not differ from that for seedlings exposed to unrestricted traffic. No evidence of seedlings being pulled out of the ground was observed. After three growing seasons, there was no significant difference in visual site disturbance between the two treatments. After eight growing seasons, the status of the reproduction suggests that little damage was incurred under unrestricted equipment traffic.

Contributions of vulnerable hydrogeomorphic habitats to endemic plant diversity on the Kas Plateau, Western Ghats

BackgroundThe Western Ghats of India are known to be a major biological hotspot that supports plant diversity and endemism. On the Kas Plateau, a lateritic plateau of the northern Western Ghats, we examined mesoscale distributions of endemic, rare, or locally significant plant species in forest habitats or on the plateau and its escarpments, and assessed the edaphic and hydrological parameters of seasonal plateau microhabitats.FindingsAlmost two thirds of over 100 phytogeographically significant species occur on the plateau top; these represent 26 plant families and 43 genera. About 80% of the species are restricted to the upper plateau and its escarpments.ConclusionSince botanically critical plateau habitats are generally small, dependent on seasonal monsoon moisture, and determined by drainage-related parameters that can be altered by anthropogenic activities, they are highly vulnerable. Maintenance of appropriate microhabitats should be a key consideration for conservation of regionally significant plant biota.

Synergetic Use of Satellite Image and DEM for Identification of Landforms in a Ridge-Valley Topography

Multispectral satellite image and digital elevation model (DEM) have emerged as the primary data sources for the mapping of landforms. They offer an opportunity to gain a fresh insight into the geomorphology of an area through landform identification using spatial, temporal, spectral and radiometric resolution of satellite images, and through the synergetic approach using DEM derivatives such as profile, slope, hill shading, contour pattern and 3-D flythrough visuals. This paper demonstrates an integrated study of Resourcesat-1 LISS III (23.5 m) image with ASTER DEM (30 m) for the identification of landforms in a rugged topography where conventional field based methods are difficult to adopt due to terrain inaccessibility. Satellite image aided by 3-D visualisation helped in accurate identification of landforms such as hogback, cuesta, plateau top and intermontane valley. The results showed that although denudational processes are active in this area, structural imprints of the strata that is mostly of proterozoic era, are still preserved.

Mapping of Lateritic Soils of Midlands in Kerala Using Resourcesat-1 LISS-III and SRTM DEM Data

Lateritic soils of Mathamangalam, Kannur District, located in midlands of Kerala, were morphologically studied, characterized, classified and mapped at 1:50,000 scale using remote sensing techniques. The terrain of the study area being hilly and covered with perennial vegetation, soil-landscape model was applied. For this purpose physiographic information was inferred from SRTM DEM, Resourcesat-1 LISS-III satellite image and topographical maps. The interpreted units were validated in the field and characterized through soil-site examination, soil profile study and soil analysis. The study indicated that the lateritic soils of midlands of Kerala vary in physical, chemical and morphological properties in relation to micro-relief. Soils developed on moderately steeply sloping side slopes (15–30% slope) are deep, moderately well drained with gravelly clay textured, where as the soils developed on moderately slopping side slope (10–15% slope) are very deep and well drained. The soils of valleys are very deep, moderately well drained with fine texture. Very gently sloping (1–3%) laterite plateau tops have extremely shallow soils associated with rock outcrops. These soils mainly belong to Order Ultisols followed by Inceptisols and Entisols. These were further grouped up to Family and Series level by tentatively establishing seven soil series. This study helps in understanding the behaviour of lateritic soils of midlands of Kerala, which can be useful in generation of interpretative maps and in optimizing the land use.

Carbono orgânico, nitrogênio total, biomassa e atividade microbiana do solo em duas cronosseqüências de reabilitação após a mineração de bauxita

A mineração é uma das atividades antrópicas que causa grande impacto nos ecossistemas e o grau de degradação depende da intensidade de interferência no solo, do volume explorado e do rejeito produzido. Os microrganismos do solo e sua atividade, por participarem de funções-chave, podem fornecer indicações sobre o real estado de reabilitação de áreas mineradas. O objetivo deste trabalho foi avaliar o impacto da atividade de mineração em duas cronosseqüências com diferentes estratégias (revegetação) de reabilitação em solos de área de mineração de bauxita sobre diversos atributos: C de compostos orgânicos (CO), N total do solo (Nt), biomassa microbiana, atividade enzimática e respiração do solo. O estudo foi desenvolvido em áreas pertencentes a Alcoa S/A, em dois ambientes distintos: (a) em áreas com vegetação típica de campo, predominantemente herbácea, em altitude inferior a 1.000 m, e (b) em áreas de montanhas, no topo do planalto, incluindo remanescentes de cobertura vegetal nativa representada por floresta subtropical subcaducifólia, a uma altitude de 1.600 m, denominadas serra, com características diferenciadas quanto à estratégia e ao tempo de reabilitação, variando de áreas recém-mineradas à áreas com 19 anos de reabilitação. Coletaram-se amostras compostas com três repetições em oito áreas no campo e nove na serra, em duas profundidades (0-10 e 10-20 cm), no inverno e verão. A mineração de bauxita provocou grande impacto nos atributos estudados, causando reduções nos seus valores de até 99 %. Tanto no campo como na serra, os teores de CO, de Nt, a biomassa microbiana e a atividade enzimática aumentaram com as diferentes estratégias de reabilitação. Entretanto a resposta dos atributos estudados foi diferenciada em função do tempo de reabilitação. A biomassa microbiana e a atividade enzimática apresentaram recuperação muito rápida, atingindo valores semelhantes aos das áreas de referência a partir do primeiro ano, enquanto para o CO e o Nt estes só foram alcançados de modo consistente em períodos mais longos de reabilitação (18 anos). O coeficiente metabólico (qCO2) foi indicativo do estresse provocado pela mineração, mas não diferenciou os diferentes tempos de reabilitação. Os resultados deste estudo mostram que os atributos essenciais ao funcionamento adequado do solo são recuperáveis pela revegetação.

Landscape analysis for pedo-geomorphological characterization in part of basaltic terrain, central India using remote sensing and GIS

In the present study, an attempt has been made to analyse IRS-ID LISS-III satellite data in conjunction with field observations for geomorphological mapping and pedo-geomorphological characterisation in Mohgaon area of Nagpur district, Maharashtra. Analysis of satellite data reveals distint geomorphological units viz., plateau top, isolated mounds, linear ridges, escarpments, plateau spurs, subdued plateau, rolling plains, pediments, narrow valleys and main valley floor. Soil profiles, studied on different identified landforms, showed variation in site and morphological charactaristics. Moderate soil erosion occurs on plateau top, isolated mouds, plateau spurs, rollinmg plains and pediments. Severe erosion was identified on escarpments and subdued plateau and narrow valleys suffer very slight erosional hazards. Moderately well drained soils were found on rolling plains, pediments, narrow valleys and main valley floor. Well drained soils were noticed on plateau top and plateau spurs. Very shallow soils were found on the plateau top and isolated mounds. Shallow soils are found in linear ridges, escarpments, plateau spurs and rolling plains. Moderately deep and deep soils are found on subdued plateau, pediments and main valley floor. The landform-soil relatioinship reveals that the soils on the plateau top and isolated mounds are very shallow, well drained, clay textured. The soils on the narrow valleys and main valley floor are deep, moderatly well drained, and clayey in texture. It also indicates that landform-soil processes are governed by physiographic position, drainage, slope and erosion conditions of the area. The present study reveals that the analysis of remotely sensed data in conjunction with field observations in GIS will be of immense help in geomorphology mapping, analysis of landform-soil relationships and generation of their geo-spatial database.

IRS-1C data application in watershed characterization and management

Watershed characterization and management aims at the optimum utilization of land and water resources on a sustained basis. For a precise inventory of a watershed, components like drainage density and pattern, slope percentage and direction, physiography, soils, land use and land cover, were visually interpreted using the geocoded false colour composites (FCCs) of IRS-1B LISS II and IRS-1C LISS III at 1:50 000 scale. The land use and land cover study indicates that the major land utilization types are single crop (28.8%); double crop (14.3%); scrub land (43.1%); degraded notified/open forest (7.2%); rock outcrop (3.8%) and water bodies (2.8%). The dominant soils are loamy-skeletal, Lithic Ustorthents; loamy-skeletal, Lithic Ustochrepts; fine calcareous, Typic Ustochrepts; fine, Vertic Ustochrepts, and very fine, Typic Haplusterts. The soils are grouped into IIIs, IIIes, IVes and VIes land capability classes; N1, N2, S1, S2 and S3 soil site suitability classes and Wt 1.2, Wt 1.3, Wt 2.5, Wt 3.4 and Wt 3.5 soil degradation classes. Based on soil types, percentage slope, drainage density, bifurcation ratio and constant channel maintenance ratio, the soil conservation modules like field bunding, contour bunding, Nala lining and Nala plug/cement check dams were erected. Soil conservation modules, particularly field bunding/ contour bunding improved the moisture status in soils of subdued plateau and upper pediment and resulted in a better harvest of crops under monocropping. Grading and terracing of lower pediments helped to harvest run-off into farm ponds for further recycling of water for agro-horticultural crops. Nala lining and Nala plug/cement check dams in the valley regions have helped in improving the irrigation potential for crops under double cropping system and agroforestry on the plateau top by further reducing the denudation process.

Physiographic analysis of witness-tree distribution (1765–1798) and present forest cover through north central Pennsylvania

This study analyzed witness-tree data recorded from 1765 to 1798 with respect to landform in four major physiographic provinces represented through north central Pennsylvania. These data were also compared with present-day forest composition to evaluate broad changes that occurred 200 years after European settlement. In the Allegheny High Plateau, Tsugacanadensis (L.) Carr. represented 40–47% of witness trees in mountain coves and stream valleys, but only 9% on plateau tops, which comprised 45% Fagusgrandifolia Ehrh. Pinusstrobus L. represented ≤4% frequency across all landforms. The original forests of the Allegheny Mountains were dominated by mixed Quercus, Acer, Castaneadentata (Marsh.) Borkh., and Pinus and had significant T. canadensis only in stream valleys. The presettlement forests of the Allegheny Front and the Ridge and Valley provinces had a similar mix of Quercus, Pinus, Castanea, and Carya, with increased P. strobus on the more mesic sites and Pinusrigida Mill, on the xeric ridges. Comparisons of presettlement with present-day forest composition indicate a dramatic reduction of T. canadensis (32% to 4%) and F. grandifolia (33% to 12%) in the High Plateau and increases in Acer (11% to 37%), Quercusrubra L. (0% to 10%), Prunusserotina Ehrh. (1% to 6%), and Betula (5% to 10%). Other units exhibited reductions in P. strobus, P. rigida, Quercusalba L., and Carya spp. and increases in Quercusprinus L., Q. rubra, Acerrubrum L., and P. serotina. Castaneadentata had its greatest abundance on higher elevation sites in each physiographic unit, and the elimination of this species this century apparently facilitated the increase in Q. prinus and Q. rubra on ridge sites. South of the Allegheny Plateau, increases in A. rubrum, P. serotina, and other mixed-mesophytic species may be in response to fire exclusion this century. The results of this study indicate the importance of landform and physiography on presettlement forest composition as well as the dramatic changes that have occurred as a result of altered disturbance regimes following European settlement.

Mobile Microwave Radiometer Observations: Spatial Characteristics of Supercooled Cloud Water and Cloud Seeding Implications

Abstract Previous studies of the spatial distribution of supercooled liquid water in winter storms over mountainous terrain were performed primarily with instrumented aircraft and to a lesser extent with scans from a stationary microwave radiometer. The present work describes a new technique of mobile radiometer operation that was successfully used during numerous winter storms that occurred over the Wasatch Plateau of central Utah to determine the integrated depth of cloud liquid water relative to horizontal position on the mountain barrier. The technique had the advantage of being able to measure total liquid from the terrain upward, without the usual terrain avoidance problems that research aircraft face in cloudy conditions. The radiometer also collected data during several storms in which a research aircraft could not be operated because of severe turbulence and icing conditions. Repeated radiometer transects of specific regions of the plateau showed significant variability in liquid water depth over 30–60-min time periods, but also revealed that the profile of orographically generated cloud liquid was consistent, regardless of the absolute quantities. Radiometer liquid depth generally increased across the windward slope of the plateau to a peak near the western edge of the plateau top and then decreased across the relatively flat top of the plateau. These observations were consistent with regions where maximum and minimum vertical velocities were expected, and with depiction of cloud liquid by accretional ice particle growth across the mountain barrier. A comparison of data from the mobile radiometer and a stationary radiometer verified the general decrease in liquid depth from the windward slope to the top of the plateau and also showed that many liquid water regions were transient mesoscale features that moved across the plateau. Implications of the results, relative to the seeding of orographic clouds, were that seeding aerosols released from valley-based generators could at times be inhibited by stable conditions from reaching appropriate super-cooled liquid water regions and, as found by others, the region of cloud most likely to be encountered by an AgI seeding agent released from the ground was also relatively warm compared to the ice-forming capability of the particular agent used in these experiments. Also, one convective case study that exhibited relatively warm temperatures in the cloud layer indicated that, even in conditions that permit vertical transport to supercooled liquid zones, sufficient time for ice particle growth and fallout from seeded plumes on this plateau may be lacking.

Stream chemistry in the eastern United States: 2. Current sources of acidity in acidic and low acid‐neutralizing capacity streams

We examined anion composition in National Stream Survey (NSS) data in order to evaluate the most probable sources of current acidity in acidic and low acid‐neutralizing capacity (ANC) streams in the eastern United States. Acidic streams that had almost no organic influence (less than 10% of total anions) and sulfate and nitrate concentrations indicative of evaporative concentration of atmospheric deposition were classified as acidic due to acidic deposition. These acidic streams were located in small (<30 km2) forested watersheds in the Mid‐Atlantic Highlands (an estimated 1950 km of stream length) and in the Mid‐Atlantic Coastal Plain (1250 km). Acidic streams affected primarily by acidic deposition but also influenced by naturally occurring organic anions accounted for another 1180 km of acidic stream length and were located in the New Jersey Pine Barrens, plateau tops in the Mid‐Atlantic and Southeast Highlands, and the Florida Panhandle. The total length of streams acidic due to acid mine drainage in the NSS (4590 km) was about the same as the total length of acidic streams likely affected by acidic deposition (4380 km). Acidic streams whose acid anion composition was dominated by organics were located in Florida and the Mid‐Atlantic Coastal Plain. In Florida, most of the acidic streams were organic dominated, whereas about half of the streams in the Mid‐Atlantic Coastal Plain were organic dominated. Organic‐dominated acidic streams were not observed in the Mid‐Atlantic and Southeast Highlands.