background: groundwater nitrate pollution is an important environmental problem in water resources management. in this regard, specific measures aiming at prevention of water pollution will be helpful to managers and decision-makers. identification of aquifers’ vulnerable areas and determination of groundwater protection zones using most widely used models, such as drastic and cd, are one of th...

the mahabad river watershed has been exposed to severe erosion as a result of landuse change. the aim of this study is to quantify the amount of sediment yield and the relationship between land use change and slope. different sources such as geologic and topographic maps, satellite images, hydrometric as well as meteorological data were used to extract and gather the information needed for this...

Visualization is the important means of understanding and explaining the geologic phenomena from the bore huge data sources. In this paper, taking the geologic exploration engineering as research objects, the authors discuss the three-dimensional geologic phenomena, propose a blended data model integrated vector and raster data, analyze the necessity and technique route of visualization, and se...

Contamination of groundwaters with geogenic arsenic poses a major health risk to millions of people. Although the main geochemical mechanisms of arsenic mobilization are well understood, the worldwide scale of affected regions is still unknown. In this study we used a large database of measured arsenic concentration in groundwaters (around 20,000 data points) from around the world as well as di...

[1] Reliable global crustal field anomaly maps produced from magnetic measurements of the CHAMP satellite mission now allow for quantitative geological studies of crustal structure and composition. We have developed a GIS based forward modeling technique to model these anomaly maps. On the basis of the geologic and tectonic maps of the world, laboratory susceptibility values of the occurring ro...

An image processing technique called the cellular neural network (CNN) approach is used in this study to locate geological features giving rise to gravity anomalies such as faults or the boundary of two geologic zones. CNN is a stochastic image processing technique based on template optimization using the neighborhood relationships of cells. These cells can be characterized by a functional bloc...

AASG/USGS Geologic Map Data Model Committee* Gary Raines, Chairman, US Geological Survey, [email protected] Boyan Brodaric, Geological Survey of Canada, [email protected] Jim Cobb, Kentucky Geological Survey, [email protected] Ralph Haugerud, US Geological Survey, [email protected] Greg Hermann, New Jersey Geological Survey, [email protected] Bruce Johnson,...

Geologic uncertainty in underground construction often leads to design and construction conservatism and hence to inflated costs. This paper presents a general model for the probabilistic prediction of tunnel geology, as a basis for developing more effective tunnel design and construction decision support systems. The geologic conditions along the tunnel alignment are modeled by a set of geolog...