Qiao Li-fang,Zhang Yi-chuan,Qi An-guo,and Li Xin-zheng

School of Horticulture and Landscape Architecture,Henan Institute of Science and Technology,Xinxiang 453003,Henan,China

Introduction

The urban wetland park is one of the most popular urban green space,and it has important functions such as ecological function,leisure function,educational function and disaster prevention function.Thus it plays an important role in the urban ecosystem.With the rapid-growing economy and the public's increasing demanding for the improvement of environment quality,many cities in China constructed the urban wetland parks to improve the urban environment.However,ranking the huge amounts of landscape planning works of urban wetland park is always difficult without an appropriate classification and the ranking system.An evaluation model for measurement of accessibility of green space was proposed by using GIS (Li et al.,2008).AHP is one of the most thriving methods in the comprehensive evaluation or resources evaluation of the urban wetland parks,forest parks and wetland parks (Yang,2006;Shi et al.,2007;Kang et al.,2005;Zhang,2003).

Hwang (1981) and Yoon (1980) introduced Technique for the Order Preference by Similarity to Ideal Solution (TOPSIS) method based on the idea that the best alternative should have the shortest distance from the positive ideal solution and the farthest distance from the negative ideal solution.

The AHP,proposed by Thomas (Saaty,1980) is one of the most commonly applied multi-criteria decision making techniques.It combines tangible and intangible aspects in order to derive a ratio scale,the abstract scale of priorities,which is valid to make complex decisions.For some complicated decision problems,in order to avoid the mistakes and to improve the accuracy,it is needed to rely on the wisdom of a group of experts to make a decision,so the AHP should be adopted.

AHP may be applied to determine weight and it is a method combing qualitative analysis and quantitative analysis and effective in deciding the weight of each quota to the general goal.This research combined AHP and TOPSIS together and established a classification and ranking model of urban wetland park's planning works.

Materials and Methods

Materials

A total of 30 planning works of urban wetland park designed by senior class major landscape architecture in Henan Institute of Science and Technology were chosen as the appraisal samples.

Selection of influent factors

There are many factors influencing the landscape planning of urban wetland park.The indice which can reflect essentially the landscape planning of wetland parks should be selected (Table 1).

Primitive data

The evaluation set was defined {excellent,good,normal,bad,terrible} and the corresponding interval set = {0.8-1,0.6-0.8,0.4-0.6,0.2-0.4,0-0.2}.Data of each factor was obtained from three teachers'evaluation (Table 2).

To determine factor weights

The determination of weight was taken by three professional teachers (Table 3).The consistency check results met the consistency requirement.

To determine Z* and Z-

According to the normalized matrix,the most superior vector Z*and inferior vector Z-might be obtained,that was:

Z*=(0.04398,0.01154,0.02108,0.01012,0.01585,0.00436,0.00345,0.01096,0.00196,0.01094,0.02558,0.01679,0.00504,0.00930,0.01247,0.00314,0.00784)

Z-=(0.01451,0.00559,0.01296,0.00643,0.01144,0.00307,0.00139,0.00693,0.00106,0.00679,0.01951,0.00917,0.00270,0.00389,0.00617,0.00234,0.00487)

Table1 Model tree of factors influencing landscape planning of urban wetland park

Table2 Original data of influential factors

Table3 Weights of factors

To determine Euclidean distance and Ci

Euclidean distance and Ciresults are shown in Table 4.

Results

By comparison (Table 4),the landscape planning works of urban wetland park can be classified into four categories described as the followings (Table 5).

As we can see form Table 5,these programs could be divided into four categories depending on the value of the relative closeness.The samples numbered 4,25,11,12,26,6,27,10,and 15 had higher landscape quality,and could be provided for experts or policy makers as the optimization basis.

Table4 Results of optimization ranking

Table5 Classification criteria and inclusive samples

Conclusions

AHP-TOPSIS model is simple and easy to be used as a classification and ranking method.The classification and ranking results on the planning works of urban wetland parks had good discrimination.

This method is also practical for the classification and ranking of landscape works of other urban greenbelts.

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