Use of USLE/GIS technology integrated with geostatistics to assess soil erosion risk in different land uses of Indagi Mountain Pass—Çankırı, Turkey

The universal soil loss equation (USLE) is an erosion model to estimate average soil loss that would generally result from splash, sheet, and rill erosion from agricultural plots. Recently, use of USLE has been extended as a useful tool predicting soil losses and planning control practices by the effective integration of the GIS-based procedures to estimate the factor values on a grid cell basis. This study was performed for five different lands uses of Indağı Mountain Pass, Cankırı to predict the soil erosion risk by the USLE/GIS methodology for planning conservation measures in the site. Of the USLE factors, rainfall-runoff erosivity factor (USLE-R) and topographic factor (USLE-LS) were greatly involved in GIS. These were surfaced by correcting USLE-R site-specifically using DEM and climatic data and by evaluating USLE-LS by the flow accumulation tool using DEM and watershed delineation tool to consider the topographical and hydrological effects on the soil loss. The study assessed the soil erodibility factor (USLE-K) by randomly sampled field properties by geostatistical analysis. Crop management factor for different land-use/land cover type and land use (USLE-C) was assigned to the numerical values from crop and flora type, canopy and density of five different land uses, which are plantation, recreational land, cropland, forest and grassland, by means of reclassifying digital land use map available for the site. Support practice factor (USLE-P) was taken as a unit assuming no erosion control practices. USLE/GIS technology together with the geostatistics combined these major erosion factors to predict average soil loss per unit area per unit time. Resulting soil loss map revealed that spatial average soil loss in terms of the land uses were 1.99, 1.29, 1.21, 1.20, 0.89 t ha⁻¹ year⁻¹ for the cropland, grassland, recreation, plantation and forest, respectively. Since the rate of soil formation was expected to be so slow in Central Anatolia of Turkey and any soil loss of more than 1 ton ha⁻¹ year⁻¹ over 50–100 years was considered as irreversible for this region, soil erosion in the Indağı Mountain Pass, to the great extent, attained the irreversible state, and these findings should be very useful to take mitigation measures in the site.     

The evaluation of “social risk” due to volcanic eruptions of Vesuvius

A re-evaluation of the demographic risk per number of inhabitants due to volcanic eruptions in the Vesuvius area was made on the basis of the Census data of 2001. We introduced other variables (population density and number of houses) which permit to upgrade the existing models. Using the Geographical Information Systems (GIS) and particularly ArcGIS 9.0 software we have elaborated a land use map, an urbanization map and a series of new risk maps which lead us to obtain a map of what we call “social risk” due to volcanic eruptions, derived from the combination of the data used and the overlay of the maps. We have proposed an integrated model which can be easily updated to follow the evolution of the volcanic risk in the overpopulated Vesuvius area, with the aim of supporting the planning of Civil Protection and Local Authorities, for an evacuation scenarios and the possibility of taking into account the potential infrastructural damages. This methodology can be tested in other volcanic regions.     

Flood risk perceptions and spatial multi-criteria analysis: an exploratory research for hazard mitigation

The conventional method of risk analysis (with risk as a product of probability and consequences) does not allow for a pluralistic approach that includes the various risk perceptions of stakeholders or lay people within a given social system. This article introduces a methodology that combines the virtues of three different methods: the quantifiable conventional approach to risk; the taxonomic analysis of perceived risk; and the analytical framework of a spatial multi-criteria analysis. This combination of methods is applied to the case study ‘Ebro Delta’ in Spain as part of the European sixth framework project ‘Floodsite’. First, a typology for flood hazards is developed based on individual and/or stakeholders’ judgements. Awareness, worry and preparedness are the three characteristics that typify a community to reflect various levels of ignorance, perceived security, perceived control or desired risk reduction. Applying ‘worry’ as the central characteristic, a trade-off is hypothesized between Worry and the benefits groups in society receive from a risky situation. Second, this trade-off is applied in Spatial Multi-Criteria Analysis (SMCA). MCA is the vehicle that often accompanies participatory processes, where governmental bodies have to decide on issues in which local stakeholders have a say. By using risk perception-scores as weights in a standard MCA procedure a new decision framework for risk assessment is developed. Finally, the case of sea-level rise in the Ebro Delta in Spain serves as an illustration of the applied methodology. Risk perception information has been collected with help of an on-site survey. Risk perception enters the multi-criteria analysis as complementary weights for the criteria risk and benefit. The results of the survey are applied to a set of scenarios representing both sea-level rise and land subsidence for a time span of 50 years. Land use alternatives have been presented to stakeholders in order to provide the regional decision maker with societal preferences for handling risk. Even with limited resources a characteristic ‘risk profile’ could be drawn that enables the decision maker to develop a suitable land use policy.     

Liquefaction potential of Quaternary alluvium in Bolu settlement area,Turkey

Groundwater bearing alluvial units in the seismically active settlement areas may bring out probable damage on the urban and built environment due to liquefaction. Bolu settlement area and surroundings are located in the North Anatolian Fault Zone. Geotechnical boreholes were drilled in order to determine the distribution of the geological units, to obtain representative soil samples and to measure groundwater level. Quaternary aged alluvium is the main geological unit in the South of study area. Stiffness and consistency of the soils were determined by Standart penetration test. P and S wave velocities of soil have been measured along the seismic profiles. The index and physical properties of the samples have also been tested in the laboratory. Liquefaction potential and safety factor of the sandy levels in Quaternary aged alluvium were investigated by different methods based on SPT and V _s. Liquefaction seems to be a significant risk in case of an earthquake with a _max = 0.48 g and M _w = 7.5 at different levels of the boreholes. This situation may bring out environmental problems in the future.     

Complexity theory, spatial simulation models, and land use dynamics in the Northern Ecuadorian Amazon

Our research questions and analytical approaches are used to examine coupled human-natural systems in the Northern Ecuadorian Amazon. They are based on complexity theory and extend from our earlier work in Cellular Automata (CA) in which land use/land cover (LULC) change patterns were spatially simulated to examine deforestation and agricultural extensification on household farms. The basic intent is to understand linkages between people and the environment by explicitly considering pattern-process relationships and the nature of feedback mechanisms among social, biophysical, and geographical factors that influence LULC dynamics within the study area. In this research, we describe how our CA modeling approach emphasizes the human dimensions of LULC change by including socio-economic and demographic characteristics at the household-level along with biophysical data that describe the resource endowments of farms, geographic accessibility of farms to roads and communities, and the evolving nature of human-environment interactions over time and space in response to exogenous and endogenous factors.A LULC change scenario is examined by comparing model outcomes generated for a base CA model and an alternative CA model to explore the effects of increases in household income on land use change patterns at the farm level, achieved as a consequence of improved geographic accessibility to roads and communities and increased off-farm employment as a household livelihood strategy. Growth or transitions rules in our CA model, as well as neighborhood associations are sensitive to socio-economic and demographic factors of households, resource endowments of farms, geographic accessibility, and the uncertainty associated with peasant farming in a frontier setting. Model outcomes indicate that increases in household income are associated with more land in pasture and more land being cultivated for crops as a result of greater access to agricultural markets. In addition, more land in secondary forest succession occurs as a consequence of greater access to roads and communities, thereby, affording a better opportunity for off-farm employment and greater levels of household income.     

黄金坪水电站深厚覆盖层跟管钻进工艺研究

结合大渡河黄金坪电站深厚覆盖层帷幕灌浆试验项目需要,对深厚覆盖层跟76 m深套管护壁钻进这一高难度技术进行攻关研究,并提出两级跟管的钻孔结构,圆满实现了试验灌浆孔非灌段跟76 m深套管的目标,为今后类似工程跟管施工提供了重要的参考借鉴作用。     

Monitoring and modelling of urban sprawl using remote sensing and GIS techniques

The concentration of people in densely populated urban areas, especially in developing countries, calls for the use of monitoring systems like remote sensing. Such systems along with spatial analysis techniques like digital image processing and geographical information system (GIS) can be used for the monitoring and planning purposes as these enable the reporting of overall sprawl at a detailed level.     

Land use land cover classification of Orissa using multi-temporal IRS-P6 awifs data: A decision tree approach

An attempt has been made to understand the potential of temporal Advanced Wide Field Sensor (AWiFS) data aboard IRS-P6 (Resourcesat) to generate the land use land cover information along with the net sown area. The temporal data sets were georeferenced, converted to top of atmosphere reflectance and classified using decision tree classifier, See5. Results indicate that the temporal data set could give a better definition of training sites thereby resulting in good overall kappa (kappa = 0.8651) as well as individual classification accuracies. However, co-registration of temporal datasets accuracies also has got a significant influence on the classification accuracy. Temporal variation in cloud infestation and availability of appropriate data sets within the season (before harvest of the crop) has also affected the classification accuracy.     

环北京地区土地利用变化监测与分析

利用1992和2002年2期Landsat卫星影像,对环北京地区土地利用变化和退化情况进行监测,探讨和分析了北京地区土地利用变化、土地退化的特征和规律.结果表明,北京风沙源区土地利用变化的最大特点是耕地显著减少,林地和牧草地明显增加;整个风沙源区的土地退化格局宏观上受大兴安岭向南延长段和阴山山脉东段的地形地貌控制,并且随所处位置的不同而退化程度有较明显的差异.     

Trade-offs between carbon,water, soil and food in Guanzhong-Tianshui economic region from remotely sensed data

It is important to ensure the efficient supply of land ecosystem services when the competition for land is increasing. In this paper we simulated the ecosystem services function under two scenarios, including carbon sequestration, agricultural production, water and soil conservation, and analyzed the tradeoffs among these ecosystem services in Guanzhong-Tianshui region from 2000 to 2050. Then the productive efficiency of ecosystem services was assessed under two scenarios and compared their production possibility frontiers (PPFs). Through the simulation analysis of their optimum allocation, we also provide the scientific evidence to the development of ecosystem. The natural rules were revealed that if these trade-offs emphasize the potential to sequester carbon in the landscape, along with very little loss of agricultural production, much more water is used. It could be identified to adhere to combine the exploitation and utilization, remediation and protection for land to promote the effective circulation of land eco-system, and meet the society’s preferences for land ecosystem service function by adjusting the use of multiple eco-services.