Title: Application of GIS and remote sensing in exploration and environmental management of Námafjall geothermal area, N-Iceland

Abstract

This research is focused on the applications of remote sensing and Geographical
Information System (GIS) as a decision support system in geothermal exploration and
environmental management. The project aim is to find out the best location for drill sites
and site selection for a geothermal power plant in Bjarnarflag geothermal field in
Námafjall high temperature geothermal area in North Iceland.
SPOT Satellite images are used as one of the important environmental, geographical and
surface data sources in the work. Surface exploration data including geological,
geochemical and geophysical survey data are used. GIS (ArcInfo 9.0) has been used in
this work not only as a powerful tool in mapping and spatial visualization but also as a
decision support system for suitability analysis.
Decision making on location of wells and a power plant in analogue methods has been
defined mostly by reservoir engineering, geological, geochemical, hydrological, and
environmental and other information and human errors were unavoidable during decision
making. The proposed project contributes to the environmental and social economical
roles in the decision making process for sustainable locating of well sites and power plant
by effectively making use of GIS as decision support system, firstly to avoid human
errors during decision making and secondly to find new, easy and automated
computerized methods for geothermal exploration (well site selection) and power plant
location.
In geological studies three data layers including geothermal manifestations, volcanic
craters and faults and fractures are overlain and intersected and the common area is
selected as a geologically suitable area. The geologically selected suitable area is overlain
by the weighted geophysical and fractures distance raster maps and a weighted cell base
raster calculation carried out and the suitable area based on exploration data selected.
In the environmental suitability analysis, the vegetation cover and vegetation cover
density maps are first overlain and on the basis of a cell base weighted raster analysis a
suitable area is selected. This map has been overlain by the weighted protected area map,
slope and elevation map with predefined criteria and a special weighting for each one,
and a suitable area has been selected.
In the final well site selection the exploration suitability map and environmental
suitability map have been overlain and a weighted cell base raster analysis carried out.
Based on the final analysis the suitable area has been ranked at three different levels of
suitability and from the first priority sites two sites were selected as well fields for the
first phase of geothermal exploration drilling.
For power plant site selection, three alternative sites have been defined by the project
developer for a proposed power plant and in this work the environmental, natural risk
potential and economical factors have been evaluated. Thirteen different factors in the
two main groups including environmental factors and natural risk and economical factors
are examined. Firstly each site is evaluated based on every factor and a relative value
from 0 to 9, assigned to the sites according to the condition of the site related to the factor
evaluated. Moreover, the 13 defined factors have been evaluated with respect to the
importance of others. In this evaluation, all 13 factors have been given 100% value, but
each one received a special weight with respect to its importance in environmental impact
and economical effects. Finally a simple matrix analysis has been carried out to evaluate
the sites A, B and C. In the result, site A is the best one, scoring 89% of the ideal site
score, site B is second with 76% and site C comes least one with 66% of the score for the
ideal available power plant site in study area.