Evaluation of Ecological Capability on Yasuj City for Implementation Urban Land Use

 
Introduction
In order to achieve sustainable development, it is necessary to obtain and adopt planning procedures based on Multi Criteria Evaluation of natural environment. Since biophysical (natural) environment has limited ecological capabilities for human use, ecological capability assessment, as an essence for environmental studies and with the aim of preventing existing crises, yields proper grounds for environmental planning. The analysis of land capability and sufficiency for urban development is one of the main categories with which urban planners deal.
The country's political divisions  Yasuj city is center Kohgiluyeh and Boyerahmad,  is located in the eastern part of the province and in the Zagros mountains and cold. The area to the north of the province Esfahan, of the south and East to the province fars and the West and South West Provinces cities Gachsaran and Dehdasht is limited. Yasuj population in the years 1345, 1355, 1365, 1375,1385,1390 respectively 931 people, 4524 people, 29,991 people, 69,133 people, 100,544 people, 108,505 people. Undoubtedly among all cities Kohgiluyeh and Boyerahmad, Yasuj is the only city population and its area considerably, will increase the concentrations of various services. It is due to the special characteristics such as the political and administrative center of the province, the establishment of institutions and government agencies and enjoyment of the services and facilities more than other cities and towns and villages moved to the city, yet has a high population growth. Therefore, the optimal plan based on scientific principles and standards of ecological and Estimation of land for urban development in the future prospects of future problems can be minimized or even prevented.
 
 
Materials and Methods
Extent of the scope of the study, 127/6 square kilometers and 1:100,000 scale used in this study have been selected. To do so, after detecting the ecological resources of the area (scale 1: 100000) the obtained data was introduced to Arc GIS software. Since implementation and applicability of urban land use necessitated synchronized evaluation of numerous criteria or variables, the study utilized spatial multi criteria evaluation method (SMCEM). And therefore, the initial attempts focused on preparation and standardization of the criteria maps. Fuzzy expert system and linear functions were used for the purpose of the study. To analyze land proportion for the development of the expected application, Weighted Linear Combination (WLC) method was utilized and then by combining layers of information and analysis on fuzzy evaluation software can be ecologically relevant maps were prepared. Sustainable and unsustainable resources were identified in a research scale. Also, the criteria and variables were identified for evaluation yasuj city for implementation urban  land use. Overall, data were obtained through twenty-one layers as criteria maps for spatial evaluation of implementation urban land use.
Analytic Hierarchy Process (AHP)
In this research, each criterion or sub criterion was weighing using pair wise comparison method and to selecting the preferred criteria, the preference^,s value table of the saaty is used . To ease the calculating of the weights in purpose of preference degrees and hierarchies the Expert Choice software was used. The operations of AHP, the weights and compared with CR are evaluated. It is a condition of accepting the CR ratio is less than 0/1. Remarkably, in this study, the number of CR 06/0, respectively, which represents the result is acceptable. Weights were calculated by the method of integrated layers methods WLC is used.
 
Weighted Linear Combination (WLC)
Weighted linear combination (WLC) technique was applied to select the best option (site), according to criteria evaluation method. The site which obtained the highest score is identified as the suitable site or class. In this method, the value of each criterion is calculated by the following equation:
A_i =  S_j W_j X_ij
Where, X_ij is the value of i alternative towards j criterion, is a standardized weight as aggregation of all weights is equal to one (S W_J = 1). The calculated weights showed the relative importance of each criterion and preferred alternative is selected by defining of maximum value of A_i ( i = 1, 2,3, … , n). To applying the weighted linear combination (WLC) method.
Finally, Standard raster layers all factors in all three of the physicochemical and biological and socio - economic weights derived from the techniques of analytic hierarchy process multiple groups.
Result:  W₁ S_{1  +}  W₂ S₂ + … + W_i S_i
W_i = Weight Layer                S_i = Layer standard
then Layers of standardized weight criteria for Multi-criteria evaluation analysis of software GIS, Using the orders Raster Calculate Were called. In order to achieve the overall assessment rating based on the proposed mathematical model and order Fuzzy Overlay overlay were tagged.
Urbun Land Use= ([Slop 01] × 0.263) + ([Land Use 01] × 0.162) + ([Quantity Water 01] × 0.150) + ([Soil Type 01]× 0.089) + ([ hypso 01] × 0.072) + ([ Surface Water 01] × 0.05) + ([Vegetation Density 01] × 0.05) + ([ aspect 01] × 0.041) + ([Bed rock 01] × 0.031) + ([Wind power 01] × 0.021) + ([Vegetation type 01] × 0.016) + ([Fault 01] × 0.014) + ([Depth 01] × 0.013) + |([Geo 01] × 0.011) + ([Forest 01] × 0.008) + ([Rain 01] × 0.005) + ([Agriculture 01] × 0.005) + ([temperature 01] × 0.003) + ([River 01] × 0.003) + ([ Airport 01] × 0.001) + ([Indst complex 01] × 0.001)
 
 
Results
Map of the final classification of thevaluation  of  ecological capability on yasuj city for implementation urban  land use in this study shows that that a total of 12736 hectare area of ​​about 3541 acres in the study area has high potential and 5153 acres area has good potential, 1678  hectares of medium power and 1,898 acres low power and 466  acres of the study area is very weak power. Table  1 shows an ecological potential classes of yasuj city for implementation urban  land use.
 
 
 
Table 1: ecological potential classes of yasuj city





potential classes


Area
 (hectare) 


Area
 (square kilometers)




high


3541


35414807/14




Good


5153


51528911/01




Medium


1678


16782526/77




Low


1898


18976520/63




very weak


466  


4660145/622




Total


12736


127362911/2





 
Studies show that in parts of East and South and South West yasuj city by natural constraints such as Zagros Mountains and Dense forests oak and high slope land are confronted. By conducting WLC model, direction are found that conform to the present realities based on field evidences and comparison of obtained results. Limiting factors such as the Zagros heights, high slope, oak mass foret, fault, agriculturad lands, rivers to prevent some of the environmental allocation for the urban development opplication. The mapping final shows regions suitable for physical urban development of the city. The results and finding of this research were applied by urban planners.