Using Geographic Information Systems and Remote Sensing Data for assessing and managing geoecological risk in mountain areasVahagn Muradyan The survey of the expected damages for a potential disaster essentially consists of risk evaluation. Risk is defined as the expected losses (of lives, persons injured, property damaged, and economic activity disrupted) due to particular hazard for a given area and reference period. Based on mathematical calculations risk is the product of hazard, vulnerability and cost of the elements at risk (WMO, 1999). Most of the data required for disaster management has a spatial component, and also changes over time. Therefore the use of Remote Sensing and Geographic Information Systems(GIS) has become essential regional geoecological disaster management. While GIS has been used as a tool to address specific aspects of risk management, there are few examples of integrated risk management applications. There are obvious advantages in developing a fusion between a philosophy of risk management and the power of GIS as a decision support tool, hence Georisk-GIS as it has been termed. The objective of Georisk-GIS is to aid decision making and problem solving in fields that have a bearing on community safety and sustainability. The work was made using an orthophoto as basis, on which all buildings, land parcels and roads, within the mountain region and its direct surroundings were digitized, resulting in a digital parcel map, for which a number of hazard and vulnerability attributes were collected in the field. As a software while preparing a Georisk-GIS, we employed GIS package ArcGIS 9.2 and ERDAS Imagine 9.1. Assessment and management of regional geoecological risk was performed based on 4 underlying parameters: geoecological potential, geoecological stability, geoecological load, geoecological tension of mountain landscapes. The values of basic parameters of the geoecological risk analysis were calculated as sums of respective indices expressed in scores and multiplied by their significance reflecting coefficients. Conversion of natural unit measurement indices to a single score system is implemented through division of natural value (minimal to maximal) segment into a quantity of equal-size segments (Gorelov 2000), corresponding to the quantity of single-scale scores. In agreement with that rule, a formula was derived of calculation of geoecological potential, stability, load and tension: Mint=K1*(F1)+ K2*(F2)+ K3*(F3)+...+Kn*(Fn), where Mint is an integral assessment of basic indices of geoecological risk analysis;F1...Fn-values of underconsideration indices in scores; n the number of factors; K1..Kn corresponding weight factors. Subsequently, those factors were integrated by “Model Builder” in ArcGIS applying “Weighted Sum” functions. The produced maps enabled us to assess and manage regional georisk. |
