Precipitation type estimation and validation in China

The results from three methods aimed at improving precipitation type(e.g., rain, sleet, and snow) estimation are presented and compared in this paper. The methods include the threshold air temperature(AT), threshold wet bulb temperature(WBT) and Koistinen and Saltikoff(KSS) methods.Dot graphs are plotted to acquire the threshold air temperature or the threshold wet bulb temperature using daily averaged air temperature, wet bulb temperature and precipitation data at 643 stations from 1961 to 1979(precipitation types are not labeled in the database from 1980 to present) in China. The results indicate that the threshold AT or WBT methods are not able to differentiate rain, sleet and snow in the most regions in China; sleet is difficult to differentiate from other precipitation types based on the two threshold methods. Therefore, one threshold AT and WBT method was used in this study to differentiate rain and snow. Based on GaussianKriging interpolation of threshold air temperature(T0and wet bulb temperature(Tw), the T0 and Tw contour lines and contour surfaces are calculated for China.Finally, a comparison between the KSS, AT and WBT methods are provided in which the KSS method is calculated based on air temperature and relative humidity. The results suggest that the KSS method is more appropriate for water phase estimation than are the other methods; the maximum precision for rain and snow is 99% and 94%, respectively. The AT method performs better than the WBT method when the critical air temperature is 2°C.     

Estimation of rainfall thresholds for shallow landslides in the Sierra Madre Oriental,northeastern Mexico

Landslides induced by prolonged rainfalls are frequent mass movements along the northeastern portion of the Sierra Madre Oriental in Mexico, causing significant damage to infrastructure. In this work, we have studied the connection between rainfall and landslides in the Santa Rosa Canyon, a catchment located in the northeastern Mexico. A landslide database triggered by major storms and hurricanes that have hit the region over the past 30 years was analyzed. A total of 92 rainfall events in the Santa Rosa Canyon were studied to determine the amount of precipitation needed to trigger shallow landslides. For each event the duration(D, in hours) and the cumulated rainfall event(E, in mm) were determined by using historical rainfall data from weather stations located near the study area. We have proposed an ED threshold for rainfall-induced landslides with durations 0.5 D 120 hours to address the conditions that trigger these events in the study area. On analyzing the obtained threshold, it has been established that almost 60 mm of a daily rainfall accumulation is required to trigger shallow landslides in the study area. This estimation is consistent with other calculations made for areas close to the Santa Rosa Canyon. Finally, we validated the predictive capability of the threshold with a different set of rainfall data that did not result in landslides performing a straightforward receiver operating characteristic analysis. A good approach was obtained, especially for rainfall events with daily measurements. Results could be used as input information in the design of a landslide early warning system for the northeastern Mexico, and replicated for other landslide prone areas in the region.     

Optimization of groundwater level monitoring network using GIS-based geostatistical method and multi-parameter analysis: A case study in Wainganga Sub-basin,India

Groundwater is one of the most important resources, its monitoring and optimized management has now become the priority to satisfy the demand of rapidly increasing population. In many developing countries, optimized groundwater level monitoring networks are rarely designed to build up a strong groundwater level data base, and to reduce operation time and cost. The paper presents application of geostatistical method to optimize existing network of observation wells for 18 sub-watersheds within the Wainganga Sub-basin located in the central part of India. The average groundwater level fluctuation (GWLF) from 37 observation wells is compared with parameters like lineament density, recharge, density of irrigation wells, land use and hydrogeology (LiRDLH) of Wainganga Sub-basin and analyzed stochastically in Geographic Information System (GIS) environment using simple, ordinary, disjunctive and universal kriging methods. Semivariogram analyses have been performed separately for all kriging methods to fit the best theoretical model with experimental model. Results from gaussian, spherical, exponential and circular theoretical models were compared with those of experimental models obtained from the groundwater level data. Spatial analyses conclude that the exponential semivariogram model obtained from ordinary kriging gives the best fit model. Study demonstrates that ordinary kriging gives the optimal solution and additional number of observation wells can be added utilizing the error variance for optimal design of groundwater level monitoring networks. This study describes the use of Geostatistics methods in GIS to predict the groundwater level and upgrade groundwater level monitoring networks from the randomly distributed observation wells considering multiple parameters such as GWLF and LiRDLH. The method proposed in the present study is observed to be an efficient method for selecting observation well locations in a complex geological set up. The study concludes that minimum 82 wells are required for proper monitoring of groundwater level in the study area.     

Outlining a stepwise,multi-parameter debris flow monitoring and warning system: an example of application in Aizi Valley,China

In recent years, the increasing frequency of debris flow demands enhanced effectiveness and efficiency of warning systems. Effective warning systems are essential not only from an economic point of view but are also considered as a frontline approach to alleviate hazards. Currently, the key issues are the imbalance between the limited lifespan of equipment, the relatively long period between the recurrences of such hazards, and the wide range of critical rainfall that trigger these disasters. This paper attempts to provide a stepwise multi-parameter debris flow warning system after taking into account the shortcomings observed in other warning systems. The whole system is divided into five stages. Different warning levels can be issued based on the critical rainfall thresholds. Monitoring starts when early warning is issued and it continues with debris flow near warning, triggering warning, movement warning and hazard warning stages. For early warning, historical archives of earthquake and drought are used to choose a debris flow-susceptible site for further monitoring. Secondly, weather forecasts provide an alert of possible near warning. Hazardous precipitation, model calculation and debris flow initiation tests, pore pressure sensors and water content sensors are combined to check the critical rainfall and to publically announce a triggering warning. In the final two stages, equipment such as rainfall gauges, flow stage sensors, vibration sensors, low sound sensors and infrasound meters are used to assess movement processes and issue hazard warnings. In addition to these warnings, community-based knowledge and information is also obtained and discussed in detail. The proposed stepwise, multi-parameter debris flow monitoring and warning system has been applied in Aizi valley China which continuously monitors the debris flow activities.     

Interpreting sedimentation dynamics at Longxi catchment in the Three Gorges Area,China, using Cs-137 activity,particle size and rainfall erosivity

Reservoir sedimentation dynamics were interpreted using Cs-137 activity,particle size and rainfall erosivity analysis in conjunction with sediment profile coring.Two sediment cores were retrieved from the Changshou reservoir of Chongqing,which was dammed in 1956 at the outlet of Longxi catchment in the Three Gorges Area using a gravity corer equipped with an acrylic tube with an inner diameter of 6 cm.The extracted cores were sectioned at 2 cm intervals.All sediment core samples were dried,sieved(2 mm) and weighed.137 Cs activity was measured by γ-ray spectrometry.The particle size of the core samples was measured using laser particlesize granulometry.Rainfall erosivity was calculated using daily rainfall data from meteorological records and information on soil conservation history was collated to help interpret temporal sedimentation trends.The peak fallout of 137 Cs in 1963 appeared at a depth of 84 cm in core A and 56 cm in core B.The peaks of sand contents were related to the peaks of rainfall erosivity which were recorded in 1982,1989,1998 and 2005,respectively.Sedimentation rates were calculated according to the sediment profile chronological controls of 1956,1963,1982,1989,1998 and 2005.The highest sedimentation rate was around 2.0 cm?a~(-1) between 1982 and 1988 when the Chinese national reform and the Household Responsibility System were implemented,leading to accelerated soil erosion in the Longxi catchment.Since 1990 s,andparticularly since 2005,sedimentation rates clearly decreased,since a number of soil conservation programs have been carried out in the catchment.The combined use of 137 Cs chronology,particle size and rainfall erosivity provided a simple basis for reconstructing reservoir sedimentation dynamics in the context of both physical processes and soil restoration.Its advantages include avoiding the need for full blown sediment yield reconstruction and the concomitant consideration of core correlation and corrections for autochthonous inputs and reservoir trap efficiency.     

网络聊天监控系统的研究和实现

Internet给人们提供了越来越方便的信息交流方式。由于Internet的虚拟化，人们对网络空间法律意识的淡薄，以及Internet提供的服务功能的安全和监管问题，也日渐突出。分析了Internet提供的网络聊天服务功能的现状和存在的问题，在此基础上，提出了一套较为完善的网络聊天监控与安全管理的解决方案，并实现了对用户进行网络聊天内容的监控管理应用。     

Comprehensive drought monitoring in Yunnan Province,China using multisource remote sensing data

Development of drought monitoring techniques is important for understanding and mitigating droughts and for rational agricultural management. This study used data from multiple sources, including MOD13 A3, TRMM 3 B43, and SRTMDEM, for Yunnan Province, China from 2009 to 2018 to calculate the tropical rainfall condition index(TRCI), vegetation condition index(VCI), temperature condition index(TCI), and elevation factors. Principal component analysis(PCA) and analytic hierarchy process(AHP) were used to construct comprehensive drought monitoring models for Yunnan Province. The reliability of the models was verified, following which the drought situation in Yunnan Province for the past ten years was analysed. The results showed that:(1) The comprehensive drought index(CDI) had a high correlation with the standardized precipitation index, standardized precipitation evapotranspiration index, temperature vegetation dryness index, and CLDAS(China Meteorological Administration land data assimilation system), indicating that the CDI was a strong indicator of drought through meteorological, remote sensing and soil moisture monitoring.(2) The droughts from 2009 to 2018 showed generally consistent spatiotemporal changes. Droughts occurred in most parts of the province, with an average drought frequency of 29% and four droughtprone centres.(3) Monthly drought coverage during 2009 to 2014 exceeded that over 2015 to 2018. January had the largest average drought coverage over the study period(61.92%). Droughts at most stations during the remaining months except for October exhibited a weakening trend(slope 0). The CDI provides a novel approach for drought monitoring in areas with complex terrain such as Yunnan Province.     

Probabilistic seismic landslide hazard assessment: a case study in Tianshui,Northwest China

Probabilistic analysis in the field of seismic landslide hazard assessment is often based on an estimate of uncertainties of geological, geotechnical,geomorphological and seismological parameters.However, real situations are very complex and thus uncertainties of some parameters such as water content conditions and critical displacement are difficult to describe with accurate mathematical models. In this study, we present a probabilistic methodology based on the probabilistic seismic hazard analysis method and the Newmark's displacement model. The Tianshui seismic zone(105°00′-106°00′ E, 34°20′-34°40′ N) in the northeastern Tibetan Plateau were used as an example. Arias intensity with three standard probabilities of exceedance(63%, 10%, and 2% in 50 years) in accordance with building design provisions were used to compute Newmark displacements by incorporating the effects of topographic amplification.Probable scenarios of water content condition were considered and three water content conditions(dry,wet and saturated) were adopted to simulate the effect of pore-water on slope. The influence of 5 cm and 10 cm critical displacements were investigated in order to analyze the sensitivity of critical displacement to the probabilities of earthquake-induced landslide occurrence. The results show that water content in particular, have a great influence on the distribution of high seismic landslide hazard areas. Generally, the dry coverage analysis represents a lower bound for susceptibility and hazard assessment, and the saturated coverage analysis represents an upper bound to some extent. Moreover, high seismic landslide hazard areas are also influenced by the critical displacements. The slope failure probabilities during future earthquakes with critical displacements of 5 cm can increase by a factor of 1.2 to 2.3 as compared to that of 10 cm. It suggests that more efforts are required in order to obtain reasonable threshold values for slope failure. Considering the probable scenarios of water content condition which is varied with seasons, seismic landslide hazard assessments are carried out for frequent, occasional and rare earthquake occurrences in the Tianshui region, which can provide a valuable reference for landslide hazard management and infrastructure design in mountainous seismic zones.     

Defining a mountain landscape characterized by grazing using actor perception,governmental strategy,and environmental monitoring data

In multi-functional mountainous landscapes worldwide, conservation of natural values is a major task. Here, pro-active policies can be a way forward. National Environmental Quality Objectives(EQO) to solve environmental problems for future generations, however, often wrestle with being too visionary and lacking specificity, which complicates their implementation. The EQO "A Magnificent Mountain Landscape" that has been adopted by the Swedish Parliament in 1999 to preserve the pristine mountain environment in Sweden, experiences all these flaws. To aid its implementation, we studied the conditions and processes needed to define, to evaluate, and to preserve its goals across the Swedish mountain chain, using one of its milestone targets(a landscape characterized by grazing) as a study system. Applying qualitative and quantitative methods, we analyzed three types of data: 1) referral responses to the governmental strategy document, 2) interviews with relevant actors, and 3) environmental monitoring data(reindeer position data). Nationally,our results suggest a need for geographical differentiation to match regional/local conditions. Regionally, difference in both perception and definition of the milestone target among the actors hinders the formulation, monitoring, and evaluation of a common goal. Next to a culture-nature divide, we found that a "within as a user" and "from the outside as an observer" perspective influenced suggested definitions. Moreover, we found a need for better defining whether the goal is maintaining current conditions or restoring previous ones. Our result supports the use of animal position data as a decision support tool to monitor and to aid evaluation of the target. Given the number of actors involved and conflicts of interests present, we suggest the application of a structured decision process to accomplish agreements on a common goal. Here, environmental monitoring data can aid a "landscape assessment step" as a natural part in the decision process to target landscape management actions resourcefully and effectively.     

Dam-break flood simulation under various likely scenarios and mapping using GIS: Case of a proposed dam on River Yamuna, India

The precision modeling of dam break floods can lead to formulation of proper emergency action plan to minimize flood impacts within the economic lifetime of the assets.Application of GIS techniques in integration with hydrological modeling for mapping of the flood inundated areas can play a momentous role in further minimizing the risk and likely damages.In the present study,dam break analysis using DAMBRK model was performed under various likely scenarios.Probable Maximum Flood (PMF)calculated for a return period of 1000 years using deterministic approach was adopted for dam break analysis of the proposed dam under various combinations of breach dimensions.The available downstream river cross-sections data sets were used as input in the model to generate the downstream flood profile.Dam break flow depths generated by the DAMBRK model under various combinations of structural failure are subsequently plotted on Digital Elevation Model(DEM)of the downstream of dam site to map the likely affected area.The simulation results reveals that in one particular case the flood without dam may be more intense if a rainfall of significant intensity takes place.     

Debris flow warning threshold based on antecedent rainfall: A case study in Jiangjia Ravine, Yunnan, China

Debris flows in Jiangjia Ravine in Yunnan province,China are not only triggered by intense storms but also by short-duration and low-intensity rainfalls.This reflects the significance of antecedent rainfall.This paper tries to find the debris flowtriggering threshold by considering antecedent rainfall through a case study in Jiangjia Ravine.From 23 debris flow events,the I-D(Intensity-Duration) threshold was found,which is very close to the line of 95th percentile regression line of rainfall events,representing that 95% of rainfalls can potentially induce debris flows and reflects the limitation of I-D threshold application in this area.Taking into account the effect of antecedent rainfall,the debris flowtriggering threshold for rainfall quantity and intensity is statistically and empirically derived.The relationships can be used in debris flow warning system as key thresholds.Coupling with the rainfall characteristics in this area,new thresholds are proposed as triggering and warning thresholds.     

A homogeneous linear estimation method for system error in data assimilation

In this paper, a new bias estimation method is proposed and applied in a regional ensemble Kalman filter (EnKF) based on the Weather Research and Forecasting (WRF) Model. The method is based on a homogeneous linear bias model, and the model bias is estimated using statistics at each assimilation cycle, which is different from the state augmentation methods proposed in previous literatures. The new method provides a good estimation for the model bias of some specific variables, such as sea level pressure (SLP). A series of numerical experiments with EnKF are performed to examine the new method under a severe weather condition. Results show the positive effect of the method on the forecasting of circulation pattern and meso-scale systems, and the reduction of analysis errors. The background error covariance structures of surface variables and the effects of model system bias on EnKF are also studied under the error covariance structures and a new concept ‘correlation scale’ is introduced. However, the new method needs further evaluation with more cases of assimilation.     

Assessing tourism sustainability in hill towns: Case study of Shimla,India

Hill towns form a popular niche in tourism destinations. They are renowned for their natural beauty and distinctive cultural traditions. Unplanned development can lead to a loss in opportunity to access the potential of these resources or cause their damage. Development decisions need to adopt a sustainable approach that balances tourism growth with the preservation of the natural and cultural assets. The present research details a comprehensive assessment tool to study the sustainability of tourism in hill towns with a focus on Shimla, a popular hill destination in India. The tool specifies seven dimensions of sustainable tourism; 1) Tourism Assets;2) Tourism Activity; 3) Tourism Related Linkages; 4)Tourism Related Leakages; 5) Environmental and Social Sustainability; 6) Infrastructure; and 7)Attractiveness. Primary data were collected through questionnaire surveys of local households and arriving tourists. Visual survey is conducted to map built-environment and land-use. Secondary data were gathered from government reports and scholarly articles. A framework of indicators and sub-indicators was developed to analyze the data at two levels – city and ward. While the appraisal of the city provides an overall view of the performance of the tourism industry, at the ward level a comparative analysis was carried out to reveal sector related potentials and issues. The study reveals the imbalanced tourismconcentration in the core of the city as compared to other wards and the gap between tourist potential and infrastructure development. These are addressed through planning recommendations for more balanced development with a focus on eco-tourism.The research helps develop a framework which paves way to sustainable tourism development in Indian hill towns.     

Extreme rainfall events and associated natural hazards in Alaknanda valley, Indian Himalayan region

Introduction The Himalaya is considered to be the youngest mountains on the earth, and is tectonically very active, and hence inherently (geologically) vulnerable to hazards. Extreme rainfall events, landslides, debris flows, torrents and flash floods due…     

Deformation characteristics and thresholds of the Tanjiawan landslide in the Three Gorges Reservoir Area,China

Since the first impoundment of the Three Gorges Reservoir(TGR) in China in 2003, more than 5000 landslides including potential landslides were identified. In this paper, a deep-seated active landslide in TGR area was analyzed. Fourteen years’ monitoring data and field investigations from 2006 to 2020 were used to analyze the deformation characteristics, influencing factors, and meteohydrological thresholds. The landslide showed a none-overall periodic movement pattern featuring acceleration duri...     

Tourism dependence and poverty alleviation thresholds in Chinese ethnic tourism

Questions persist on the relationship between tourism dependence and economic growth in ethnic tourism areas. This study addresses such gaps by constructing a threshold regression model based on socio-economic data from 2006 to 2019 for nine sites in Enshi Prefecture of central China. Arc GIS and other open-source data were also used to visualize changing tourism resources in the region. Findings suggest that tourism dependence(the ratio of tourism-based GDP to overall GDP) significantly promote...     

Logs and snags in a shola forest of Kerala, India

Introduction Dead wood is an important structural and functional component of a forest ecosystem(Fridman and Welheim 2000). Recent studies also indicate that dead wood is important for maintaining both plant and animal diversity in different forest ecosystems (Grove 2001) as it serve as an energy source (Bray and Gorham 1964) and habitat for an array of organisms. Dead wood can also help reduce erosion, increase soil organic matters (McFee and Stone 1966), and suitable conditions for seedli…     

基于Web GIS的广西雷电实时监测系统

以Web GIS技术为依托,将基础地理信息数据与闪电定位数据、雷达回波图相结合,建立了具有存储、应用、开发、分析及各种图形处理的INTERNET雷电定位实时监测系统,实现对闪电定位数据、雷达回波图的网络发布.系统可以对雷电天气发生发展进行实时监测、定位、跟踪并确定强雷电天气的落区,为各级气象台站预报员准确分析、判断、预报雷雨系统的移动及强度变化提供了较科学、直观的分析工具.     

Shifting cultivation in Mizoram,India: An empirical study of its economic implications

Shifting cultivation is the major occupation and the main source of income of the marginal farmers(Jhumias) in Mizoram. At present, net area sown in Mizoram State is only 5.5%, of which, 16.9% area is devoted to shifting cultivation. Meanwhile, about 54% people, living in the rural areas, are engaged in practicing it. This paper examines economic implications of shifting cultivation in Mizoram, the eastern extension of the Himalaya. A total of 16 villages from eight districts(two villages from each district), were selected for case study, based on their location and distance from the district's headquarter. Household level survey was conducted and a purposive random sampling method was employed to select households with 34.2% sampling size. The case study reveals that production and yield of the principal crops grown under shifting cultivation has decreased during the last 17 years(2000-2017), whereas, there is a slight increase in area sown. It further shows that although, a large group of Jhumias are practicing shifting cultivation and growing subsistence cereals, yet, their economic viability is significantly less than cash crops. As a result, a large section of people in rural areas are living below poverty line. The study suggests that for sustainable livelihood, cash crops can replace subsistence crops and shifting cultivation can be converted into permanent cultivation through terracing the Jhum plots.     

FARMLAND AND URBAN AREA DYNAMICS MONITORING INCHINA USING REMOTE SENSING AND SPATIALSTATISTICS METHODOLOGY

1 INTRODUCTIONGlobal change research involves much geo-objectsand geo-process, such as climate and environmentalchange, substance and energy cycling, land-use/land-cover change (LUCC), interactivity between human and nature, etc.. So it need cooperation frommany research communities including international research programs groups such as IGBP (InternationalGeosphere-Biosphere Programme IPCC (Intergovemmental Panel on Climate Change), IHDP (InternationalHuman Dimension Program o…