9 use creating surface or called interpolators, create a continuous surface from
sample input point values, and using spline method as interpolators to build a location for placing result of overlay. Spline method is general purpose
interpolation that fits in a minimum curvature surface through the input points. This method is best use for gently varying surface such as elevation.
Interpolation is used to estimate the value of a function between known data points without knowing the actual function. Interpolation methods can be divided
into two main categories: • Global interpolation. These methods rely on a constructing single equation
that fits all the data points. This equation is usually a high degree polynomial equation. Although these methods result in smooth curves, they are usually
not well suited for engineering applications, as they are prone to severe oscillation and overshoot at intermediate points.
• Piecewise interpolation. These methods rely on constructing a polynomial of low degree between each pair of known data points. If a first degree
polynomial is used, it is called linear interpolation. For second and third degree polynomials, it is called quadratic and cubic splines respectively. The
higher the degree of the spline, the smoother the curve. Splines of degree m, will have continuous derivatives up to degree m-1 at the data points.
Kruger, 2008
2.3 Minimum Threshold Criteria for Marine Coastal Suitability
Marine coastal suitability classification is a process and regrouping of marine characteristics in terms of the relative marine suitability or coastal with certain
purpose. Marine coastal suitability class is determined by the highest limiting factor or the minimum threshold criteria in physical marine characteristics.
The process of marine coastal classification can be done with an approach or using method of threshold criteria. In this method each physical marine coastal is
sequentially arranged in accordance to the marine data that needs to be quantified.
10 Physical parameters: depth, salinity, temperature, brightness, dissolve oxygen, and
pH will be developed for a specific use, so in this report the use of minimum threshold criteria to calculation limiting marine coastal suitability.
Marine coastal suitability classification involves the compared marine suitability with other physical parameters. This comparison is part of matching process.
Threshold criteria is expression by the lowercase symbols after the symbol class, example S2s means marine coastal suitability S2 class which threshold criteria
physical parameter is s Figure 2-1.
Figure 2-1. Structure of the suitability classification modify base on, FAO 1976 Figure 2-1,
shows there are three column: order, class and subclass. ‘Order’ presents the possible values of marine coastal condition possibilities, which are
1 Suitable S or 2 not suitable NS. The suitable marine coastal can be further categorized as class whose values can be either S1, S2, or S3 where the values S
i
S
j
, i j indicate that marine coastal with value S
i
is better than S
j
. The suitable
marine coastal subclasses reflect kinds of limitations. Subclass is expressed with the lower case symbol as limiting factor, in this example m andor e are used as
parameter. There are two guidelines for subclass: • The number of subclasses should be kept to a minimum that will satisfactorily
distinguish land within a class likely to differ significantly in their management requirements or potential for improvement due to differing
limitations.
11 • As few limitations as possible should be used in the symbol for any subclass.
One, rarely two, letters should normally suffice. The dominant symbol i.e. that which determines the class should be used alone if possible. If two
limitations are equally severe, both may be given. FAO, 1976
2.4 Simple Additive Weighting SAW for Marine Coastal Suitability
