Geomorphological Factors Research Articles

Simulation of Forestland Dynamics in a Typical Deforestation and Afforestation Area under Climate Scenarios

Forestland dynamics can affect the ecological security of a country and even the global environment, and therefore it is of great practical significance to understand the characteristics of temporal and spatial variations of forestland. Taking Jiangxi Province as the study area, this study first explored the driving mechanism of the natural environment and social economy on deforestation and afforestation using a simultaneous equation model. The results indicate that population size, topographic and geomorphologic factors, climate, and location play leading roles in influencing forestland density fluctuations. Specifically, the population size, economic development level, gross value of forestry production, climate conditions, and government policies are key influencing factors of afforestation. Deforestation is mainly influenced by agricultural population, non-agricultural economy, forestry production, forestry density, location, transportation, and climate. In addition, this study simulated the spatial distribution of land use and analyzed the spatial characteristics and variation trends of forestland area and quality under the Representative Concentration Pathways (RCPs) climate scenarios from 2010 to 2030 using the Conversion of Land Use and its Effects (CLUE) model. The results indicate that forestland declines under the Asia-Pacific integrated model (AIM) climate scenario. The environment tends to be heavily damaged under this kind of scenarios, and measures should be taken in order to protect the environment. Although the model for energy supply strategy alternatives and their general environmental impact (MESSAGE) scenario is to some extent better than the AIM scenario, destruction of the environment will still occur, and it is necessary to restrain deforestation and convert shrub land into forestland or garden land. These results can provide significant information for environmental protection, forest resource exploitation, and utilization in the areas experiencing deforestation and afforestation.

The significance of sand aprons in Holocene atolls and carbonate platforms

Sand aprons are located in the back-reef area of atolls and carbonate platforms and form transport pathways of reef-derived sediment into adjacent lagoons and platform interiors. Though there are studies focusing on sand apron sediment dynamics, the knowledge of Holocene sand apron evolution is limited, because hardly any subsurface data are available. In the current model, antecedent topography, i.e., the elevation of the underlying Pleistocene karst surface and platform area are major factors controlling Holocene sand apron development. Because data on marginal reef thickness in Holocene atolls and carbonate platforms are limited, maximum lagoon depth was also used as proxy for the depth to the underlying Pleistocene surface. Sand apron proportions of 122 atolls and carbonate platforms from the Atlantic, Indian and Pacific Oceans were quantified and correlated to maximum lagoon depth, total platform area and marginal reef thickness, when available. Analyses show significant correlations between sand apron proportions and both maximum lagoon depth (r = −0.420; p = 0.000) and total platform area (r = −0.226; p = 0.012). There is no statistically significant correlation (r = −0.364; p = 0.165) between sand apron proportions and depth to Pleistocene surface at platform margins. It is assumed that the lack in correlation can be explained by the limited data set of 16 atolls. Principal component analyses might allow the separation of Atlantic (Caribbean) from Indo-Pacific atolls, which probably arise from spatial and regional variations in sea-level history, i.e., in the Atlantic (transgressive) and Indo-Pacific region (transgressive–regressive), but more subsurface data are necessary to confirm the interpretation. In general, Holocene sand apron formation started when marginal reefs approached relative sea level some 6–3 kyrs BP. Because accommodation space became limited, depositional systems of sand aprons prograded toward the lagoon. Estimated sedimentation rate data of atoll lagoons show that the accumulation of sand aprons is up to three times higher than lagoonal background sedimentation and therefore suited to fill lagoonal accommodation space and create “filled buckets” in small and intermediately sized platforms (up to hundreds of km2 size), even during times of high-amplitude sea-level fluctuations of an icehouse world. Although we postulate an application of the antecedent topography model to Holocene sand apron development, further factors controlling reef development such as hydrodynamics and carbonate production still influence sand apron development and pattern. This study shows the need for further work and knowledge of the subsurface of carbonate platforms and reef sand aprons, which is still limited. Collectively, hydrodynamic (waves, tides and currents), biologic (carbonate production and distribution of organisms) as well as geomorphological (present-day and antecedent topography) factors should be combined, when generating new models for sand apron development to better understand sand apron history in the geologic past.

Geomorphological diversity of peatland basins in the Łódź region and its significance for the accumulation of biogenic sediments

Abstract An investigation was carried out on peatlands in the Łódź region. Geological and geomorphological studies focused on 31 sites. The peatland basins are located in moraine plateau and valleys. The diversity of basins in these areas was affected by geomorphological processes: glacial, fluvioglacial, slope, aeolian, thermokarst and fluvial. Peatlands in the region formed in different groups of basins: basins in the moraine area, basins of aeolian origin, basins in valleys (with a distinction between active and inactive valleys). Paleoecological analyses of biogenic deposits show that the peatlands developed from the Late Weichselian to the Subatlantic Period. The schemes of creation and development of the peatlands presented in this study prove a strong influence of geological and geomorphological factors.

Geomorphological diversity of peatland basins in the Łódź region and its significance for the accumulation of biogenic sediments

An investigation was carried out on peatlands in the Łodź region. Geological and geomorphological studies focused on 31 sites. The peatland basins are located in moraine plateau and valleys. The diversity of basins in these areas was affected by geomorphological processes: glacial, fluvioglacial, slope, aeolian, thermokarst and fluvial. Peatlands in the region formed in different groups of basins: basins in the moraine area, basins of aeolian origin, basins in valleys (with a distinction between active and inactive valleys). Paleoecological analyses of biogenic deposits show that the peatlands developed from the Late Weichselian to the Subatlantic Period. The schemes of creation and development of the peatlands presented in this study prove a strong influence of geological and geomorphological factors.

ABRASION IN THE EASTERN GULF OF FINLAND COASTAL ZONE AND ITS RELATION TO LONG-TERM TRENDS OF REGIME-FORMING FACTORS

Abrasion in the eastern Gulf of Finland coastal zone is favored by geological and geomorphologic factors, e.g. weakness of Quaternary deposits, sediment deficit, bottom and coastal relief. Extreme abrasion events occur as a result of coincidence of long-lasting western or south-western storms, high water level, and absence of stable sea ice during such events. In the last decade extreme erosion events took place during autumn-winter seasons of 2006-07 and 2011-12.

Conditions of Water Absorption into Soil and Its Infi ltration into Ground Waters at River Basins of Eastern Cuba

The rivers of Eastern Cuba are characterized by small size, different orography, and moistening. Theoretical aspects of the conditions of absorption formation, values of absorption and infi ltration up to the level of the ground water in the river basins of Eastern Cuba are analyzed with the use of the genetic runoff theory and the linear-correlation model. The dependence of the absorption layer from the geomorphological factor makes it possible to distinguish the layer of surface detention from the general absorption layer before the beginning of water formation (the formation of gravitational water) and during the runoff. The dependence of the infiltration layer from the absorption layer turns out to be rather reliable. However, there is some value on the axis of the infiltration layer which characterizes the presence of the hidden infiltration layer when there is no absorption. It is supposed that in this case the surface and underground catchments are distinguished and there is water exchange between separate subterranean flows.

Elements of Climate Evolution in yhe Area Between Prut and Dniester Rivers. Landscape and Pedogenetic Implications

Abstract Component part of the Carpathian-Danubian-Pontic space, the interfluve area between Prut and Dniester is subject to the regional process of climate evolution and change. In what regards the concept of human-influenced pedogenesis, the role of the biological factor is significantly reduced. As a consequence the direction and intensity of the elementary landscape and pedogenetic processes are determined by the relations between climate and the geomorphological factor. In the conditions of a relative stability of the geomorphological factor, the determining role is held by climate. To this is added soil vulnerability to the implications of climate changes, determined by the degree of soil physical degradation but also by a series of intrinsic and external (drainage) factors. This implies the idea of the control and management of the landscape and pedogenetic implications of climate changes by improving soil physical characteristics.

Assessing the Relationship Between River Mobility and Habitat

Human interventions that limit channel mobility such as bank stabilization are frequent in riparian zones in urban or agricultural environments. This is potentially problematic because channel mobility is an important geomorphological and ecological agent that structures natural instream and riparian ecosystems. This study aims to (1) quantify the relationship between mobility and three types of habitat-related features, namely bars, oxbow lakes and log jams, for a 54-km-long reach of the Yamaska Sud-Est River (Quebec, Canada), which runs from the forested Appalachian Mountains to the agricultural St-Lawrence lowlands, and (2) evaluate the impact of human interventions and geomorphological characteristics on these three features. Channel mobility was measured from historical aerial photos for the period 1950–2009. A combination of high-resolution aerial photos, LiDAR digital elevation model, and field observations was used to measure and map sediment bars, oxbow lakes and log jams, as well as several geomorphological characteristics (channel width, slope, sinuosity and floodplain width). A strong link between the mobility and the presence of habitat features is revealed, but local geomorphological contexts result in different mobility patterns responsible for specific habitats. Floodplain to channel width ratio appears as the best geomorphological factor predicting habitat diversity. Human intervention, mostly through bank stabilization, also appears to be a key factor limiting mobility and its related habitats. These results highlight the importance of defining a protected mobility corridor along rivers where geomorphic processes such as bank erosion can freely occur, as it is an essential process that should be integrated in land use planning and river management. Copyright © 2015 John Wiley & Sons, Ltd.

Coupling the Xinanjiang model with geomorphologic instantaneous unit hydrograph for flood forecasting in northeast China

The Xinanjiang (XAJ) model has been successfully applied in humid and semi-humid regions. Considering the geomorphologic factors to accurately estimate floods, this study adopted the geomorphologic instantaneous unit hydrograph (GIUH) method to calculate the surface runoff instead of the experience unit hydrograph (EUH) in the original model. The geomorphologic factors of the case study basin were obtained by using a digital elevation model (DEM) and the Terrain analysis using Digital Elevation Models (TauDEM). Furthermore, the dynamic Muskingum model was used for the channel flood routing. This study focused on the simulation of heavy precipitation and floods over the Chong River, which is a tributary river to the Songhua River on the right bank in northeast China. The detailed steps of the method were shown, up to the estimated value of flood runoff discharges and flood peaks and their comparison with observed values. The average deterministic coefficients (DCs) of model calibration and validation were 0.89 and 0.83, respectively. The results show that the model precision is high and the model is feasible for flood forecasting. Lastly, some methodological perspectives to enhance the method are presented.

Linking land use/land cover with climatic and geomorphologic factors in regional mean annual streamflow models with geospatial regression approach

Estimates of annual streamflow in connection with key natural and anthropogenic factors are necessary and important for different purposes, such as water resource planning and management, sediment and nutrient loading in streams and rivers, hydropower, and navigation. This study is an attempt to use the spatial statistical regression approach to develop regression models for mean annual streamflow at regional scale while adequately dealing with the common spatial dependency issue in input and output variables used in regression models. The proposed modeling approach is illustrated with a case study of the Upper Mississippi River Basin. The R-squared and the Nash–Sutcliffe model efficiency coefficient of the regional model were 0.993 and 0.985, respectively, while those of the sub-regional model were 0.995 and 0.990, respectively. Methodologically, the proposed model provided an effective way to utilize an extensive spatial dataset of various climatic, geomorphologic, and land cover variables for a large region like the Upper Mississippi River Basin to assess and compare the impact of various factors on mean annual streamflow at regional scale. Furthermore, the model was able to handle spatial dependency in data.

最近の豪雨崩壊および既往の地すべりにおける地形・地質要因のGIS解析

最近の豪雨崩壊および既往の地すべりにおける地形・地質要因のGIS解析

The Impact of Geomorphological Factors on Physical Development of Quchan City

Abstract. The physical development of the cities is directly related to the natural context and geomorphological effects. Development of the city in mountainous regions is highly sensitive due to geomorphological limitations and instability of the ranges. The study area in this research is Quchan City which is in the margins of Atrak River in Khorasan Razavi Province. In this study, it is attempted to investigate the physical development limitations of Quchan City in light of its natural context with a focus on geomorphology. The data in this study are topographic, geological, land use and soils maps, the map of Quchan City and field visit, and the given results of this study show that development of Quchan City is influenced by many limiting factors. Among these, the factors of flooding, subsidence and the seismic risk have the most important effects on urban development. Development areas are limited and with geomorphological risks.

Compartimentação Morfopedológica como Subsídio ao Planejamento do Uso da Terra das Bacias dos Rios Claro e dos Bois, Estado de Goiás

conflitos de uso da terra das bacias dos rios Claro e dos Bois, integrantes da alta bacia do rio Araguaia, estado de Goiás, a partir da compartimentação morfopedológica, de modo a identificar os compartimentos mais suscetíveis à ocorrência dos processos erosivos lineares, interpretando as possíveis causas. Utilizou-se análise integrada das principais variáveis da paisagem, ponderando-se a incidência das erosões lineares (ravinas e voçorocas) em relação aos fatores geológicos, geomorfológicos e o padrão de drenagem, a partir de correlação espacial com base em sensoriamento remoto e geoprocessamento, em escala de detalhe. Foram delimitados 4 (quatro) compartimentos morfopedológicos e 395 focos erosivos hídricos lineares de médio e grande porte...Palavras-Chave: Erosão; Assoreamento; Análise Integrada da Paisagem; Alta Bacia do Rio Araguaia.

An Approach to Identify Site Response Directivity of Accelerometer Sites and Application to the Iranian Area

In recent years, several workers have found numerous cases of sites characterised by significant azimuthal variation of dynamic response to seismic shaking. The causes of this phenomenon are still unclear, but are possibly related to combinations of geological and geomorphological factors determining a polarisation of resonance effects. To improve their comprehension, it would be desirable to extend the database of observations on this phenomenon. Thus, considering that unrevealed cases of site response directivity can be “hidden” among the sites of accelerometer networks, we developed a two-stage approach of data mining from existing strong motion databases to identify sites affected by directional amplification. The proposed procedure first calculates Arias Intensity tensor components from accelerometer recordings of each site to determine mean directional variations of total shaking energy. Then, at the sites where a significant anisotropy appears in ground motion, azimuthal variations of HVSR values (spectral ratios between horizontal and vertical components of recordings) are analysed to confirm the occurrence of site resonance conditions. We applied this technique to a database of recordings acquired by accelerometer stations in the Iranian area. The results of this investigation pointed out some sites affected by directional resonance that appear to be correlated to the orientation of local tectonic lineaments, these being mostly transversal to the direction of maximum shaking. Comparing Arias Intensities observed at these sites with theoretical estimates provided by ground motion prediction equations, the presence of significant site amplifications was confirmed. The magnitude of the amplification factors appear to be correlated to the results of HVSR analysis, even though the pattern of dispersion of HVSR values suggests that while high peak values of spectral ratios are indicative of strong amplifications, lower values do not necessarily imply lower amplification factors.

Геоморфологічні чинники розвитку та розміщення населених пунктів Мостиського р-ну Львівської обл.

Historical features of development of settlements of Mostisky district of Lviv region of Ukraine and influence on their formation of geomorphological conditions of terrain are analyzed. Geomorphological factors of placement of settlements were important at the first historical stages of building of terrain in the Middle Ages. The first settlements were concentrated at lower elevations along the valleys. With the expansion of the network of fortified castles, which were built on the hills, rural development held in conjunction with the middle part of the hills. On the low-lying areas are built local elevated areas in the marshes, where people were hiding from enemy Tatar raids. In ХVIII–ХІХ centuries rural building expands again along the valleys, and built palaces and manors were located on the upper parts of the slopes. The new wave of increasing settlements refers to 30th years of the XXth century, the building blocks occupy the middle of the slope of the valleys and the upper beams. In 60–80th years of the XXth century is compacted blocks within settlements, as well as expansion of their neighbourhoods along the rivers and roads, rural industries in conjunction with a top of the slope. Modern building of the beginning of the XXIst century is mainly developed in the middle and upper portions of the slopes. The influence of relief on the modern structure of settlements and the prevailing relief situation of cities and villages of the district are defined in article. Eight types of relief situations of settlements of Mostisky district are identified: the series-line lower-slope, linear lower-slope, compact mid-slope, compact-branched mid-slope, branched mid-slope, circular mid-slope, sectional plains and compact plains. The series-line lower-slope is the prevailing form of settlement with respect to relief on a hill part of area, and in the lowlands – sectional plains. Key words: development of settlements, structure of settlements, a relief situation.

Recognition and Distinction of Hydrological Relations of Tashk and Bakhtegan Lakes Using GIS & RS Techniques

Lakes as close ecosystems on the earth which have special patterns and hydrological relationships in lakes can determine the development or reduction trends of lake ranges, attachment or detachment between them, lakes water balance and also the changes and fluctuations in water regimes, during the time. Therefore, the Tashk and Bakhtegan lakes were studied, based on the regional climate studies and identification the droughness and wetness years, multi-spectral satellite images using the LANDSAT satellite (including the OLI, ETM+, ETM and MSS sensing images) and IRS during the years 1979_2013. Were used and analyzed and also the lake water level fluctuations during different periods were determined. Based on all used models from lakesin studied period, the hydrological relationship between lakes were proved, and the effects of climatic factors and in the stage after that, the effects of geomorphological factors as detachment factors for Bakhtegan and Tashklaked were determined. DOI: 10.5901/mjss.2014.v5n23p2732

Magnetostratigraphy and luminescence dating on a sedimentary sequence from northern East China Sea: Constraints on evolutionary history of eastern marginal seas of China since the Early Pleistocene

Owing to the large and increasing population density in low-lying coastal regions, even small changes in sea level can have substantial societal and economic impacts. Alternations of terrestrial and marine sediments deposited in coastal areas or continental shelves are important and effective indicators of sea-level changes, and thus, have been widely studied in the marginal seas of China over the past 30 years. However, sea-level change results from not only eustatic factors but also tectonic activity. The Zhe-Min (or Zhejiang–Fujian) Uplift (ZMU) was such an important factor in geomorphology, and formed a barrier preventing entry of sea water into the northern marginal seas of China, but its Quaternary history is poorly known.In this study, a new borehole (ECS-DZ1) was drilled in the Zhoushan Islands, northern East China Sea to obtain information on the evolution of the ZMU during the Quaternary. Information from paleomagnetic and luminescence dating was combined with data on sedimentary changes. The main results are: (1) constrained by luminescence ages, the upper sedimentary units were extrapolated to have been deposited since ∼0.2 Ma; (2) paleomagnetic results suggest that the ECS-DZ1 borehole sequence spans from the pre-Olduvai Matuyama reverse chron to the Brunhes normal chron, approximately constraining the age of the basal sedimentary unit to ∼2.0 Ma; (3) a significant hiatus or erosion between two major sedimentary units possibly occurred between the late Early Pleistocene and Middle Pleistocene.As the Zhoushan Islands are within the ZMU and considering previous transgression studies around this region, it is inferred that the ZMU subsided at ∼2.0 Ma, allowing sea water to invade northward in the Yellow Sea basin. The ZMU might have been uplifted again no later than 1.0 Ma, causing a sedimentary hiatus or lacustrine development. After ∼0.2 Ma, the ZMU subsided completely, allowing large transgressions to develop across the northern marginal seas of China in the context of global sea-level changes.

Reconstructing historic Glacial Lake Outburst Floods through numerical modelling and geomorphological assessment: Extreme events in the Himalaya

ABSTRACTRecession of high‐mountain glaciers in response to climatic change frequently results in the development of moraine‐dammed glacial lakes. Moraine dam failure is often accompanied by the release of large volumes of water and sediment, termed a Glacial Lake Outburst Flood (GLOF). Chukhung Glacier is a small (~3 km2) receding valley glacier in Mt. Everest (Sagarmatha) National Park, Nepal. Unlike many Himalayan glaciers, which possess a thick mantle of supraglacial debris, its surface is relatively clean. The glacier terminus has receded 1.3 km from its maximum Holocene position, and in doing so provided the space for an ice‐contact moraine‐dammed lake to develop. The lake had a maximum volume of 5.5 × 105 m3 and drained as a result of breaching of the terminal moraine. An estimated 1.3 × 105 m3 of material was removed from the terminal moraine during breach development. Numerical dam‐breach modelling, implemented within a Generalised Likelihood Uncertainty Estimation (GLUE) framework, was used to investigate a range of moraine‐dam failure scenarios. Reconstructed outflow peak discharges, including failure via overtopping and piping mechanisms, are in the range 146–2200 m3 s‐1. Results from two‐dimensional hydrodynamic GLOF modelling indicate that maximum local flow depths may have exceeded 9 m, with maximum flow velocities exceeding 20 m s‐1 within 700 m of the breach. The floodwaters mobilised a significant amount of material, sourced mostly from the expanding breach, forming a 300 m long and 100 m wide debris fan originating at the breach exit. moraine‐dam. These results also suggest that inundation of the entire floodplain may have been achieved within ten minutes of initial breach development, suggesting that debris fan development was rapid. We discuss the key glaciological and geomorphological factors that have determined the evolution of a hazardous moraine‐dammed lake complex and the subsequent generation of a GLOF and its geomorphological impact. © 2014 The Authors. Earth Surface Processes and Landforms published by John Wiley & Sons Ltd.

Chapter 10 The rock coast of South and Central America

Abstract The great variety of climatic conditions, tidal ranges and wave regimes of South and Central America act on a complex geology and tectonic framework. Many of the rock and cliffed coasts of South America are strongly controlled by the occurrence of extensive Cenozoic and Pleistocene sediments that crop out at the coast. Geology and the different uplift rates are a major factor in the whole coastal geomorphology of South and Central America, and consequently are a very important control of the processes and landforms of rock coasts. This chapter covers several aspects of the rock coast of South and Central America, with special attention to the combination of tectonic movements and Quaternary Pleistocene–Holocene sea-level changes.

Geomorphological factors predict water quality in boreal rivers

AbstractWater quality is the outcome of numerous landscape factors in the catchment. In addition to land use, soil deposits, bedrock and topography are central in different catchment processes and thus important in predicting water quality. In this study, we explored the influence of geomorphological factors at the catchment scale on water quality in 32 boreal rivers in Finland. Water quality was studied through total phosphorus, total nitrogen, pH and water colour, whereas geomorphological factors covered variables from topography, bedrock and surficial ground material (Quaternary soil deposits). Spearman's rank correlation test was used to study the correlations between variables. The relationship between water quality and geomorphology was analysed using novel multivariate methods by fitting of geomorphological vectors and smooth surfaces onto a non‐metric multidimensional scaling (NMDS) scattergram. Hierarchical partitioning (HP) was used to assess the relative importance of geomorphological variables on water quality.Quaternary soil deposits, especially the covers of clay‐silt and till soils, were important factors in relation to phosphorus and nitrogen based on both NMDS and HP analyses. For example, clay‐silt cover explained over 40% of the variation in these nutrients according to HP. The variation in river water pH was best explained by the covers of sand and open bedrock terrain as well as by catchment topography. Geomorphological variables differed in their effect and relative significance, and thus several geomorphological attributes need to be considered when examining variation in water quality. In conclusion, these results demonstrate that geomorphological factors can be used to predict physical–chemical water quality in a cost‐efficient manner in boreal rivers. NMDS was successfully applied in water quality analyses at the catchment scale. Copyright © 2014 John Wiley & Sons, Ltd.