3. Analysis resources of database

level; the highest risk region gets level 9 and the lowest gets level 1, based on the

Pareto ranking is a method for ordering cases on multiple criteria that has become popular in the context of genetic algorithms, where it is particularly valued because it often gives high rankings to those cases that only score heavily on one factor [13]. PR analysis is based on the principle of Pareto optimality. "Pareto optimality" is a formally defined concept used to determine when an allocation is optimal. An allocation is not Pareto optimal if there is an alternative allocation where improvements can be made to at least one participant's well-being without reducing any other participant's well-being. When no further Pareto improvements are possible, the allocation is a "Pareto optimum." A primary factor is selected from each vulnerability indicator. As shown in Figure 2, each point represents a grade of factor 1 and factor 2. If there is no point staying in the first quadrant, and there is no point ranked as high vulnerability degree. By taking same grade range region as a degree and following up the same step, this study can show each region's vulnera-

where Xi is the different indicators' data; M is the average grade, S is the

=ð Þ N � 1

ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi

r� �

<sup>Σ</sup>ð Þ Xi � <sup>M</sup> <sup>2</sup>

<sup>z</sup>‐score <sup>¼</sup> ð Þ Xi � <sup>M</sup> <sup>=</sup><sup>S</sup> (2)

, and N is the number of data

principle to do PR analysis and evaluate each regional vulnerability.

Geographic Information Systems and Science

bility distribution.

standard deviation, S ¼

Figure 2.

62

Concept of PR analysis.

#### 3.1 General introduction of study area

According to the CGS disclosed geological drilling database, the Yunlin and Chiayi areas have relatively complete drilling data and complicated geographical environment. The area of environmental sensitive areas in Chiayi area of Yunlin is as high as 57%.

The strata along the western coast of Taiwan, especially the Chiayi area of Yunlin, are mostly modern alluvial strata. Because of their unconsolidated strata, the soil layers are mostly interbedded layers of sand and clay. In the past, soil liquefaction took place in sites containing particles with a diameter of about 0.01-cm loose fine sand-based and high groundwater level characteristics of the soil. Therefore, this study focuses on the Yushe River alluvial fan plain in Yunlin County, Chiayi County in the Chia-Nan Plain, the grid scale is 100 100 m, as shown in Figure 3.

Figure 3. Study area—the plate area in Yunlin and Chiayi.
