Application of GKSIM Model for Estimating the Changes of Land Use and Land Cover
Takashi Hoshi1), Satoshi Hoshino2), Ichiro Nomura3)
1)Department of Computer and Information Sciences,
Faculty of Engineering, Ibaraki University
4-12-1, Nakanarusawa, Hitachi, Ibaraki, 316-8511, Japan
Tel: (81)-294-38-5133, Fax : 981)-274-37-1429
E-mail : hoshi@ cis.ibaraki.ac.jp
2)Faculty of Agriculture, Okayama University
1-1-1, Tsushimanaka, Okayama,700-8530, Japan
Tel: (81)-86-8372, Fax : (81)-86-251-8388,
E-mail : shoshino@ cc.okayama-u.ac.jp
3)Graduate School of Science and Engineering, Ibaraki University
4-12-1, Nakanarusawa, Hitachi, Ibaraki,316-0034, Japan
Tel : (81)-294-38-8235, Fax: (81)-294-36-3070,
E-mail : nom@cis01.cis.ibaraki.ac.jp
Abstract
The changes of land use and land cover show that a region can achieve the continual growth. Therefore it is an important problem to analyze the mechanism of the changes of land use and land cover to develop the long range estimating model to establish the way of the continual development of the global environment. In this study, it is estimated how land use and land cover in Asian region change. It is suggested that GKSIM model is applied to the long range estimating model of land use and land cover. It is one of point modeling method and Korea is applied to this case. This paper describes about the use of GKSIM model, consider how to modify it and report that the political suggestion can be found by the estimated result of land use and land cover.
1.Introduction
GKSIM model is applied to Korea in Asian region to value the long range changes of land use and land cover. Several data which have surveyed every ten years are used, and the changes of land use and land cover area estimated. If these data are used, one of them will have an enormous effect on estimating the changes of land and land cover. We have to make the effort to minimum the error and to use these data and values the changes of land use and land cover until the year 2050.
2. Theoretifcal background of GKSIM model
Generalized Kane's Simulation(GKSIM) model was designed to improve the faults of Kane's Simulation(KSIM) model [ Y.Sawaragi 91981)] and develop it. The summary and features of both models are explained as follows.
2.1 KSIM model
KSIM model is joint simulation model using cross-impact matrix and has the features of geometric model and algerabraic model.
This model is normalized the change variable i of land use and land cover from 0 to 1. The maximum and the minimum values that variable i can change are set. They are set 1 and 0 respectively. These data are transformed into xi ( I=1,2,…,n) that exists in (0,1)interpolation next x
i
at t+
Dt is expressed by Eq.(2.1).
Xi(t + Dt) =
xi(t)pi(t) 0 £ xi(t) £ 1 (2.1)
a
ij(t) is an effect of x
j on x
i and decided by the specialist usually.
The condition 0<xi(t+
Dt)<1 is always assured in Eq.(2.1) because of
p
i>0 in Eq.(2.2). In other words, it is assured that the estimated value doesn't exceed the limit value.
Though KSIM model is easy to use, it has some faults. For example,
-
It is assumed that system variable changes as well as sigmoidal growth curve does. If it changes discontinuously, it can't be used in KSIM model.
- The limit number of variable is defined.
- Though the subjective variable can be used, sometimes there are insufficient cases by the way of using data on the quantitative analysis.
- A few terms can be used.
- Time scale Dt isn't clearly discussed.
2.2 GKSIM model
GKSIM model has more features than KSIM model does as follows [K. Otsubo (1996-8).
-
Applying GKSIM model makes time scale clear.
- Statistical sampling can be done and so on.
If it is assumed that land use area change rate of the item i at t is r
i(t), land use area xi(t+Dt) of item I at t+Dt is expressed by Eq.(2.3).
xi(t+Dt)=xi(t){1+ri(t)} (2.3)
X
i(t) is the value in (0,1) transformed the survey data ass well as KSIM model and Eq.(2.4) has been formed.
xi(t+Dt)=xi(t){1+ri(t)}
={1- xi(t)}1+ri(t) +0{xi(t)}
0 £xi(t) £ 1, 0{xi(k)} ® 0
|
(2.4) |
If parameters R
i and Q
i are introduced in Eq.(2.4), Eq.(2.5) is written as follows.
xi(t+Dt)=1-Qi{1-xi(t)} Ri{1+ri(t)} (2.5)
SÅ: The sum of the plus effect on x
i(t)
SÅThe sum of the minus effect on x
i(t)
xi(t+Dt)=1-Qi{1-xi(t)} Riwi(t) (2.7)
If Eq.(2.6) is assumed, Eq.(2.7) is written. Cij is an effect of x
i on x
j.
R
i and Q
i are solved by the method of least squares so that Eq.(2.7) may be conformed to the past survey data. Eq.(2.7) is used in GKSIM model.
Past population data, GDP (Gross Domestic Product) data, and these estimated data are necessary to apply GKSIM model to estimating the changes of land use and land cover. If the population in the year 1970,1980,and 1990 are as p(70), p(80), and p(90) respectively, the future population is estimated by Eq.(2.8) and Eq.(2.9).
P(t+Dt)= Ö ap(t)+b (2.8)
If p(90)<p(70) andp(70)-p(80)<p(80)-p(90) are, it is estimated by Eq.(2.9) that is a line passing through p(80) and p(90).
| p(t+Dt)= |
a
-----
p(t) |
+b (2.9) |
As a result, Eq.(2.11) for GDP data as well as Eq.(2.10) is shown. Fig.2.1 and Fig.2.2 show the estimated results respectively.
Fig. 2.1 Change of population in Korea
Fig. 2.2 Change of GDP in Korea
