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Abstract

Worldwide, nitrogen (N) deficiency is the main yield limiting factor owing to its losses via leaching and volatilization. Urease inhibitors slow down urea hydrolysis in soil by inhibiting urease enzyme activities whereas gibberellic acid is growth regulator. That is why, we evaluated the role of urease inhibitor [N-(n-butyl)thiophosphorictriamide (NBPT)] and gibberellic acid (GA3) in improving nitrogen uptake and yield of maize under different N levels (120 and 150 kg ha−1) along with control. Both N levels alone and in combination with GA3 and NBPT significantly increased yield and yield components of maize over control. In addition, 150 kg N ha−1 + NBPT + GA3 produced highest biological, grain, and stover yields, 1000 grain weight, plant height, and N uptake exhibiting 33.15%, 56.46%, 27.56%, 19.56%, 23.24%, and 78% increase over 150 kg N ha−1, respectively. The sole use of gibberellic acid or NBPT with each level of N also improved the yield and yield components of maize compared to sole N application and control. Furthermore, application of 120 kg N ha−1 along with NBPT and GA3 performed at par to 150 kg N ha−1 + NBPT + GA3 but it was superior than sole applied 150 kg N ha−1 for all the studied traits. These results imply that application of GA3 and/or NBPT can reduce dependence on urea and improve the yield and N uptake in maize by slowing urea hydrolysis in calcareous soils and shall be practiced.

Introduction

Maize (Zea mays L.) belongs to family Poaceae and is one of the most important cultivated crop in tropical and subtropical region of the world (Nabizadeh et al. 2012; Khan et al. 2014a, b). It is the 3rd largest grain crop in Pakistan following wheat and rice (Harris et al. 2007). Maize is an exhaustive crop needs an adequate amount of essential nutrients for its abundant production, in order to fulfill the demand of the rapid increasing population of the world. Nitrogen (N) is an essential nutrient, is a basic constituent of plant growth, and improves crop production and other nutrients uptake (Zaman et al. 2008a, b; Nasim et al. 2018). Nitrogen is a mobile nutrient, it moves and is lost easily from the soil (Junejo et al. 2011) and is usually deficient in calcarious soils (Adnan et al. 2018a; Snyder et al. 2007; Shah et al. 2012). Worldwide increase in crop yield is directly proportional to synthetic fertilizer application, though the higher N fertilizer has drastically declined nitrogen use efficiency (NUE) (Tilman et al. 2002; Liu et al. 2013; Erisman et al. 2007; Turan 2021a).

Abstract

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1. Introduction

2. Geotourism development and Geoheritage assessment in context of India

3. Description of the Geoheritage sites of Puruliya district, West Bengal (India)

4. Method of Assessment

5. Result and discussion

6. Conclusion

Funding agency

Acknowledgement

References

Abstract

Exploration of geoheritage sites is a new venture in tourism studies. The objective of the study is centred around the Geoheritage site conservation for geological and geomorphological interpretation and introduction of Geotourism involving the local people in Puruliya district. The main litho-unit of Puruliya district belongs to Chhotanagpur Granite Gneissic Complex of Archean era. Nine geological/geomorphological important sites are chosen for assessing their geoheritage values and analysing the Geotourism potential. A modified model of Kubalikova (2013) is adopted for the evaluation of the selected nine important sites, where five important criteria i.e. scientific (intrinsic) values, educational values, economical values, conservation values and added (cultural, ecological and aesthetic) values are considered. The result reveals that sites like Durgabera dam, Bhanratongri hill, Garpanchakot and Jaychandi hill can be assumed as top potential Geotourism site occupying highest geoheritage values, whereas Jabar hill, Poradih hill and Tamakhun old mine are quite low in the context of Geoheritage values. Based on the result, few strategies are suggested which can help to develop Geotourism in the study area and raise awareness about the geoheritage values among the students, general visitors and the local residents of the area.

1. Introduction

Geoheritage and geoconservation are two conceptions deal with the protection and conservation of earth science features. It concerns with rock monuments, fossil parks, geological marvels/features, geomorphological landforms. In a broader sense, geoheritage also includes cultural sites (such as mining sites)/archaeological sites (made of stones) that have an integrated value in response to a particular region. Preservation of natural heritage and associated cultural values to education, interpretation and entertainment is the main aim of Geotourism (Gordon, 2018). Therefore, a link can be established between the two notions Geotourism and Geoheritage. According to Hose and Vasiljević (2012) Geotourism can be defined as “the provision of interpretative and service facilities for geoheritage sites and geomorphosites and their encompassing topography, together with their associated in situ and ex situ artefacts, to constituency-build for their conservation by generating appreciation, learning and research by and for current and future generations” (Antić & Tomić, 2017; Hose, 2012; Kubalíková, 2013). Though it is a widely accepted definition of Geotourism concept, the scope of the concept in this definition has remained narrow in sense. Dowling (2013) truly remarked that “Geotourism is a form of sustainable tourism with a primary focus on experiencing the earth’s geological features in a way that fosters environmental and cultural understanding, appreciation and conservation, and is locally beneficial”. According to Panizza (2009), all the physical attributes over the earth surface, for example, a gorge, a mountain peak, a sea cliff have some kind of cultural values as it belongs to the certain cultural territory. Sometimes the natural heritage sites also become the sacred place for human being and is regarded an important element for geo-cultural understanding. Landscape often considers as a component of expressing architectural design, literature, poems, paintings and so on (Lindberg et al., 1997). So in this context, landscapes (including both geological and geomophological landforms/features) can be considered as a cultural component which not only posses scientific and aesthetic value but also bears an immense cultural value. All these aspects incorporate within the concept of ‘Geoheritage’ for sake of geoconservation of the territorial resources. Geotourism helps to identify the geoheritage resources and try to use for sustainable economic development with active participation of the local community.

The present work attempts to discriminate between the geochemical features of magmatichydrothermal systems involved in the early stages of mineralization in high grade versus low grade porphyry copper systems, using chemical compositions of silicate and sulfide minerals (i.e., plagioclase, biotite, pyrite and chalcopyrite). The data indicate that magmatic plagioclase in all of the porphyry copper systems studied here has high An% and Al content with a significant trend of evolution toward AlAl3SiO8 and Si4O8 endmembers, providing insight into the high melt water contents of the parental magmas. Comparably, excess Al and An% in the high grade deposits appears to be higher than that of selected low grade deposits, representing a direct link between the amounts of exsolving hydrothermal fluids and the potential of metal endowment in porphyry copper deposits (PCDs). Also, higher Al contents accompanied by elevated An% are linked to the increasing intensity of disruptive alteration (phyllic) in feldspars from the high grade deposits. As calculated from biotite compositions, chloride contents are higher in the exsolving hydrothermal fluids that contributed to the early mineralization stages of highly mineralized porphyry systems. However, as evidenced by scattered and elevated log (fH2O)/(fHF) and log (fH2O)/(fHCl) values, chloride contents recorded in biotite could be influenced by post potassic fluids. Geothermometry of biotite associated with the onset of sulfide mineralization indicates that there is a trend of increasing temperature from high grade to low grade porphyry systems. Significantly, this is coupled with a sharp change in copper content of pyrite assemblages precipitated at the early stages of mineralization such that Cu decreased with increasing temperature. Based on EMPA and detailed WDS elemental mapping, trace elements do not exhibit complex compositional zoning or solid solution in the sulfide structure. Nevertheless, significant amounts of Cu and Au are contained in pyrite assemblages as micro- to nano-sized inclusions, especially in the high grade fertile porphyry deposits. However, unexpectedly high concentrations of Te, Se, and Re may be associated with early stage of sulfide mineralization, especially when there is no epithermal lithocap. This may highlights the significance of trace metals partitioning in the sulfides formed at the early stages of mineralization in PCDs.

Introduction

Porphyry Cu ± Mo ± Au mineralization forms in magmatic – hydrothermal systems following the shallow emplacement (5 to 15 km depth) of metal-rich oxidized magma saturated with H2O, S, and Cl (Sillitoe, 2010; Richards, 2011). The deposits are usually centered on volumetrically small cupolas on the top of subjacent larger, batholith-sized intrusions (Hedenquist and Lowenstern, 1994; Sillitoe, 2010). Most porphyry deposits are found above former to active subduction zones in association with subduction-related, calc-alkaline silicic magmas (Richards, 2003; Sillitoe, 2010; Sun et al., 2013). However, it is now recognized that these deposits may also form in collisional settings (e.g., Chen et al., 2015; Richards, 2015a, b). Examples of the latter are the Miocene porphyry Cu–Mo deposits in Gangdese belt on the south Tibetan Plateau (e.g., Hou et al., 2009; Wang et al., 2014a,b), the Eocene Yulong porphyry Cu belt (Liang et al., 2006), and arguable occurrences in Pakistan and Iran (Richards et al., 2012; Asadi et al., 2014). The Cenozoic Urumieh-Dokhtar magmatic arc (UDMA) in Iran is considered as one of the major Cu-bearing belts with high potential for the occurrence of economic world class giant to sub-economic small porphyry Cu ± Mo ± Au mineralization (e.g., Shafiei et al., 2009; Richards et al., 2012; Asadi et al., 2014; Zarasvandi et al., 2013, 2015a; Fig. 1; Table 1). In this belt, high Sr/Y magmas responsible for Cu-mineralization are strictly restricted to the late- stage Miocene magmatism, forming approximately 29 m.y. after the initiation of magmatism along the UDMA (Richards, 2012; Aghazadeh et al., 2015; Zarasvandi et al., 2015a). It is thought that subduction modified juvenile lower arc crust that inherited its arc signature with respect to F, Cl, and Cu is the source of fertile magmatism capable of producing porphyry mineralization in UDMA (Asadi et al., 2014; Zarasvandi et al., 2015b).

Agricultural irrigation has increased the groundwater level in the Heitai terrace (part of the Heifangtai terrace) by 20 m over nearly five decades, which causes 3–5 landslides each year at the edge of the terrace. The Heitai terrace is of great interest in the study of loess-related landslides; but there is no unanimous agreement on the types of either the landslides in this study site or the loess-related slope failures in general. On the basis of aerial images (res. 5 cm), Digital Elevation Model (res. 10 cm), and field investigations, we analyzed the distribution and failure mode of the landslides in Heitai. The geological structure and characteristics of 69 landslides (vol. 5 × 103 –6 × 106 m3 ) are studied. The preliminary results of groundwater recharge in the terrace and formation of the apparent spring lines on the slope surface are analyzed to better understand the failure modes. We divided the landslides in Heitai into two groups based on the location of the failure surface, i.e. loess landslide and loessbedrock landslide, of which the development is governed by the angle between the principle direction of slope deformation and the dip of bedrock bedding. We further analyzed the failure mode of each type observed in Heitai, defined as follows: loess-bedrock planar slide, loess-bedrock irregular slide, loess flowslide, loess slide, and loess flow. The proposed types of loess-related landslide are to be incorporated in the Varnes classification (Varnes, 1978) in consideration of the engineering properties of loess, and to provide backward compatibility for Heitai and potentially other regions in the Loess Plateau of China.

Introduction

The Heitai terrace is formed by the fourth river terrace of the Yellow River in Gansu Province, China (Fig. 1a). More than 50 gullies are formed at the edge of the terrace. The terrace has a surface area of 9 km2 with the maximum length of 5.2 km (W–E) and a width of 2.5 km (NeS). It is part of the Heifangtai terrace with high concentration of loess-related landslides due to surface irrigation started in 1968 (Derbyshire, 2001; Peng et al., 2016; Zeng et al., 2016; Zhou et al., 2014). Loess slope failure is common upon wetting due to its high porosity and collapsibility (Dijkstra et al., 1994; Jiang et al., 2014; Liu et al., 2016; Smalley et al., 2001; Wu et al., 2017; Yuan and Wang, 2009). Irrigation provides 4–6 cycles of groundwater recharge annually, which has increased the groundwater level by 20 m at an average rate of 0.18 m yr−1 (Xu et al., 2014) and caused about 200 landslides along the edge of the terrace (Fig. 1b). Study on the loessrelated landslides in Heitai sustained its popularity due to frequent failures and significant societal impacts. Landslide classification system forms a long-lasting research topic (Alimohammadlou et al., 2013; Casagrande, 1940; Cruden and Varnes, 1996; Görüm et al., 2011; Hungr et al., 2011; Hungr et al., 2014; Hutchinson, 1988; Qi et al., 2010; Varnes, 1978; Wang and Zhou, 1999; Xu et al., 2016). In many cases, defining the landslide type serves as a ‘baseline’ of the problem because it reflects the landslide material and behavior (Hungr et al., 2014). Landslides in loess provide a unique collection of landforms and failure mechanisms that are often undervalued in the global classification systems. Loess is recognized as a unique material, created by aeolian deposition in the Loess Plateau of China, comprising predominantly silt-sized particles that form cemented meta-stable structures with characteristically high void ratios. Landslides in loess are often generalized as a single type of landslide based on the material composition, such as loess flow by Varnes (1978), and loess flowslide by Hungr et al. (2014), under the category of earth flow. In the context of landslide behavior, loess-related slope failure was divided into different types based on either the movement and failure mechanism or the location of the failure surface.

Our understanding of the spatial patterns of landslides in Africa is limited with available landslide studies typically focusing on only one or a few study areas. Moreover, Africa is clearly underrepresented in terms of available landslide inventories. This study aims to produce a first continent-wide landslide susceptibility map for Africa, calibrated with a well-distributed landslide dataset. We reviewed the literature on landslides in Africa and compiled all available landslide inventories (ca. 10,800 landslides), supplemented by additional landslide mapping using Google Earth imagery in underrepresented regions (ca. 7,250 landslides). This resulted in a dataset of approximately 18,050 landslides. Various environmental variables were investigated for their significance in explaining the observed spatial patterns of landslides. To account for potential mapping biases in the dataset, we used Monte Carlo simulations that selected different subsets of mapped landslides to test the significance of the considered environmental variables. Based on these analyses, we constructed two landslide susceptibility maps for Africa: one for all landslide types and one excluding the known rockfalls. In both maps, topography is by far the most significant variable. We evaluated the performance of the fitted multiple logistic regression models using independent subsets of landslides, selected from the total dataset. Overall, both maps perform very well in predicting intra-continental patterns of landslides in Africa and explain about 80% of the observed variance in landslide occurrence. To further test the robustness and sensitivity to mapping biases, we also modelled landslide susceptibility while excluding regions with arid climates, as landslides in these environments are expected to be better preserved over time and therefore likely relatively overrepresented. Despite this potential bias, the effect on the landslide susceptibility model is limited. Based on the constructed database and our analyses we further discuss potential research gaps for landslide prediction in Africa and at continental scales. For example, analysis of the African countries’ mean landslide susceptibility shows a lack of landslide research in various countries prone to landsliding (e.g.: Guinea, Gabon, Lesotho, Madagascar). Apart from the intrinsic value of this landslide susceptibility map as a natural hazard risk management tool, the map and compiled database are highly promising for other applications. For example, we explored the potential significance of landslides as a geomorphic process by confronting our landslide susceptibility map with an available database of measured catchment sediment yield for 500 rivers in Africa. Overall, a significant positive, but relatively weak relation between landslide susceptibility and sediment yield is observed.

Introduction

Studies on landslide risks and fatalities indicate that landslides are present on all continents and are a global threat to humans, infrastructure and the environment (Dilley, 2005; Guzzetti et al., 2012; Haque et al., 2016; Kjekstad & Highland, 2009; Petley, 2012; Sassa & Canuti, 2009; Stanley & Kirschbaum, 2017). While this is certainly also the case for Africa, this continent remains strongly underrepresented in landslide research (e.g. Gariano & Guzzetti, 2016; Kirschbaum et al., 2015, 2010; Maes et al., 2017; Nadim et al., 2006; Petley, 2012; Reichenbach et al., 2018). Also global landslide susceptibility (LSS) maps rely on very few (or no) data of observed landslides in Africa for their calibration (e.g. Hong et al., 2007; Kirschbaum et al., 2009; Nadim et al. 2006; Stanley & Kirschbaum, 2017). Nonetheless, landslides are one of the deadliest natural disasters in Africa (Guha-Sapir et al., 2017). Moreover, their importance and impact are expected to increase due to climate change, with an increase in total precipitation and increasing frequency and intensity of rainstorm events (Gariano & Guzzetti, 2016). This was for instance shown for the Great Lakes region (Shongwe et al., 2011; Souverijns et al., 2016; Thiery et al., 2016), probably one of the most landslide susceptible regions in Africa (Hong et al., 2007; Stanley & Kirschbaum 2017). In addition, Africa is facing a considerable growth in population, which is projected to triple by the end of the 21st century (Gerland et al., 2014). This will likely affect both the frequency and impact of landslide events. For these reasons, earlier studies have urged to fill the gap on landslide research in Africa (e.g. Gariano & Guzzetti, 2016; Jacobs et al., 2016; Maes et al., 2017).

The role of forests in regulating landslide risks is well established but estimates of the economic value of this ecosystem service are limited. In order to incorporate the role of forests for landslide risk mitigation in spatial planning and other decision-making contexts, there is a need for spatially explicit information regarding the value of this service. We develop a methodological framework to combine bio-physical modelling of natural hazard risk and socio-economic exposure in a predictive model to estimate and map of the economic value of forest regulation of landslides. This method is applied in a case study of Adjara Autonomous Republic of Georgia to examine alternative scenarios for forest management and associated land cover change. The approach produces credible spatially explicit results to inform policy decisions regarding investment in forest management; and has the potential for replication in other data scarce regions.

Introduction

It is expected that damages from landslides will increase steadily over the coming years (Dai et al., 2002). Underlying this trend is an increase in human activity in landslide prone areas, which increases risk through two channels: development generally involves deforestation, which increases the probability of landslides occurring; and more human activity generally means more assets that are exposed to damage (Nadim et al., 2006). An additional factor that will drive increasing landslide damage is that climate change is predicted to cause increased precipitation in many areas already prone to landslides and may result in additional areas facing the risk of slope erosion and landslides (Dale et al., 2001; Ciabatta et al., 2016; Crozier 2010). The role of forests in regulating landslide risks is well established (Endo and Tsuruta, 1969; Megahan et al., 1978; Wu and Swanston, 1980; Preston and Crozier, 1999; Jakob, 2000). The economic value of this regulating service has, however, received limited attention in the economic valuation and ecosystem services literature (Chiabai et al., 2011; de Groot et al., 2012; Häyhä et al., 2015). Existing research has tended to focus on the value of forests for timber (Phan et al., 2014; Pohjanmies et al., 2017), non-timber forest products (Schaafsma et al., 2014; Mutoko et al., 2015), water supply (Ojea et al., 2012; Wang et al., 2017), recreation (Zandersen and Tol, 2009) and carbon storage (Triviño et al., 2015). The relatively limited number of studies that do estimate the economic value of landslide regulation by forests tend to be for small-scale study sites (e.g. Olschewski et al., 2012; Dominati et al., 2014). Information on the economic value of forests in regulating landslides is useful for informing forest management decisions (Langner et al., 2017). Quantification of the damage costs of deforestation (or avoided damage costs resulting from reforestation) provides input for the appraisal of investments in conservation and restoration. Mapping ecosystem service values delivers additional information to support decision making, particularly for land use policy development, spatial planning and resource allocation (Schägner et al., 2013; Nahuelhual et al., 2015). In order to incorporate the role of forests for landslide risk mitigation in spatial planning and other decision-making contexts, spatially explicit information related to the value of forest landslide regulation needs to be developed. Many regional governments, especially in the developing world, do not have the resources to create and gather such data in usable forms, in the absence of which, policy attention is not paid to investments in forests as a landslide mitigation measure. While reliable techniques for assessing landslide hazard often require detailed geotechnical information on existing conditions, the high cost of which means they are available only where high risk is already anticipated, more exploratory techniques of hazard and risk can provide frameworks for development planning and environmental protection measures (Gaprindashvili and Van Westen, 2016).

Rain-induced shallow landslide is the major type of landslide that happens on natural terrain in Hong Kong due to its high seasonal rainfall and deep weathering soil profile. The Geotechnical Engineering Office has been in a leading role to steer the risk management of natural terrain landslides in Hong Kong. Recently, the territory-wide rainfall-based landslide susceptibility model (in terms of landslide density per year) has been developed to predict the number of natural terrain landslides that may occur in an anticipated rainfall event. Subsequently, the storm-based landslide density has been transformed to the annual landslide frequency to compile the territory-wide landslide frequency map by incorporating the mean annual frequency of occurrence of different probable rainfall scenarios. The annual rainfall frequency of a particular rainfall scenario is derived from its return period, determined based on the abundant real-time rainfall data at a five-minute interval from 110 automatic raingauges across Hong Kong at an average density of 10 km2 /gauge. The transformation is discussed in this paper, together with the evaluation of the performance of the landslide frequency map. In addition, the potential applications of the map in Hong Kong and the pitfalls of the common evaluation methods are highlighted.

Introduction

“Natural terrain” is commonly used in Hong Kong to denote hillsides that are not significantly modified by human activities. On average, about 300 natural terrain landslides occur every year in Hong Kong and rain-induced shallow landslide is the major type of landslide due to the high seasonal rainfall and deep weathering soil profile. Heavy rainstorms in Hong Kong generally occur during the wet season from April to September and are associated with either low pressure trough or severe tropical cyclones. As a general reference, the mean annual rainfall at the Hong Kong Observatory (HKO)’s Principal Raingauge was 2398.5 mm between 1981 and 2010. Landslides from natural terrain can result in serious consequence to life and property in Hong Kong due to its dense urban development on hillsides. The problem is chronic for the impacts of extreme weather events, slope degradation and ever-increasing population and encroachment of new urban development on steep hillsides. Over the past 35 years, the Geotechnical Engineering Office (GEO) has been in a leading role to steer the risk management of natural terrain landslides in Hong Kong to reduce and contain landslide risk within an as low as reasonably practicable level that meets the needs of the public and facilitates safe and sustainable developments. The slope engineering practice and landslide risk management have evolved in response to experience and through continuous improvement initiatives and technology advances (Wong & Ko 2006).

In 1983, a catastrophic landslide occurred in Saleshan, Dongxiang, Gansu, China, which resulted in the death of 237 people and the destruction of 585 houses. Saleshan landslide was a typical rapid moving landslide in loess area, China, which moved with extremely high speed and long run-out distance on a gentle sliding surface. This paper reviews the characteristics of the landslide and its consequence, analyzes the possible triggers and the processes of development, and back-calculates the kinematic characteristics of the landslide. The digital elevation models (DEMs) of the study area before and after the event were used to analyze the geomorphological characteristics before and after the event. The authors inferred the possible deformation and failure processes of the landslide based on available observations. Direct shear tests were carried out to obtain the parameters of the soil involved in the failure and postfailure process, which was adopted in the following simulation using an energy-based runout model. The velocities of moving materials at a different time stage together with the variation of runout distance and maximum flow height are presented. The authors also compared the calculated results with field observations and previous simulation results. Sensitivity analysis was conducted to understand the effect of internal and basal friction angles on the kinematic characteristics. This study indicates that the Saleshan landslide was a fast-moving landslide with long traveling distance. The landslide lasted more than one minute with a maximum velocity of approximately 25 m/s according to the calculation using the energy runout model, which was consistent with the estimations based on the observation of eyewitness. This study also gives an insight on the progressive failure mechanism and explains the high mobility of Saleshan landslide in details, which provides a reference for hazard zonation for areas along loess platforms.

Introduction Landslides are an important process which posed significant hazards, resulting in fatalities, property damage and degrading farmland (Huang, 2009). From 2004 to 2010, 2620 fatal landslides were recorded, which resulted in a total of 32,222 recorded fatalities (Petley, 2012). In China, most of the landslides occurred in high-altitude regions such as Qinghai-Tibet plateau and southwest area in China (Huang, 2007). According to the statistical data provided by the Ministry of Land and Resources of the People’s Republic of China, landslide geohazards have caused 4,718 fatalities from 2004 to 2016 (Zhang and Huang, 2018). Every year, one-third of the geohazards in China occur on the Loess Plateau (Zhou et al., 2002), with more than 80% involving landslides with slip surfaces shallower than 10 m (Zhuang et al., 2017). The main types of landslides involving substantial amounts of loess include flow, fall and slide (Li et al., 2013; Hungr et al., 2014; Zhang et al., 2012). According to the field investigation, it was found that most of the landslides in the loess area occurred on a slope around 20º – 35º and the flowslides had a long runout distance due to soil liquefaction resulting in a low frictional angle (Zhang et al., 2009; Zhang et al., 2013; Zhang et al., 2014). Since 1900, more than 20 catastrophic landslides have been recorded whose volumes are greater than 20  106 m 3 , several of which occurred in loess area of China (Derbyshire et al., 2000; Wen et al., 2004; Huang, 2007; Wang et al., 2014; Xu et al., 2014; Zhang et al., 2014; Zhang and Wang, 2018) (Table 1). The landslides triggered by Haiyuan Earthquake 1920, are typical examples of these cases which in total resulted in more than 100,000 deaths (Huang, 2007; Wang et al., 2014).

مقاله سال 2016

مدل های عددی تکامل چشم انداز در ابتدا برای بررسی ژئوموفولوژی و هیدرولوژی آبخیز طبییعی گسترش یافته و ابزار رایجی برای بررسی رفتار ژئومورفیک در مقیاس های زمانی و مکانی شدند. همه این مدل ها از یک مدل ارتفاع دیجیتال (DEM) به عنوان نمایشی از سطح چشم انداز استفاده کرده و یک مسئله مهم، کیفیت و وضوح این سطح است. تمرکز ما در اینجا بر چگونگی تولید نتایج مدل جایگزین توسط نوسانات یا زبری سطح DEM می باشد. این تحقیق با تغییر تصادفی ارتفاعات سطح DEM و بررسی اثر آن بر ژئومورفولوژی و نرخ های انتقال رسوب برای یک طراحی بازسازی مطرح شده برای چشم انداز پس از استخراج معدن با استفاده از فهم های چشم انداز متعدد با افزایش اندازه تغییرات تصادفی انجام می شود. در این تحقیق نشان می دهیم که مقدار افزایشی تغییرپذیری تصادفی سطح، تاثیر قابل ملاحظه ای بر انتقال رسوب در مقیاس های زمانی هزار ساله ندارد. با این حال ، تغییر پذیری تصادفی سطحی الگوی زمانی یا تحویل خروجی رسوب را تا اندازه زیادی تغییر می دهد. یک نتیجه قابل توجه این بود که همه شبیه سازی ها در انتهای 10000 سال دوره مدل سازی به طور ژئومورفولوژی مشابه بوده و یک همپایی ژئومورفولوژی را نشان می دهند. با این حال ، الگوهای فرسایش و ته نشست برای شبیه سازی های مکرر با دنباله متفاوتی از آشفتگی های تصادفی متفاوت بودند. موقعیت های جایگزین آشفتگی های تصادفی تاثیری قوی بر الگوهای محلی تکامل و فرسایش دامنه و الگو و رفتار ته نشست دارند. نتایج، بازخوردهای پیچیده ای را نشان می دهند که حتی در یک سیستم مدلسازی شده ساده رخ می دهند.

مقاله سال 2017