Abstract: The rigid constraints of the marine environment and the fierce competition from the sea use of various industries have led to the continuous extrusion of marine aquaculture areas,especially in coastal waters.Therefore,deep-water cage aquaculture(DWCA) has gradually become an emerging industry in mariculture.Thus the spatial planning of DWCA has become a necessary research topic.Suitability evaluation is a process of grading for a certain type of development or utilization,based on analyzing its suitability,which is often used in planning.Changhai County is affiliated to Dalian,Liaoning Province,China.Changhai sea area (38°55'47"N~39°34'10"N) is located in the northern part of the Yellow Sea.This paper constructed the suitability evaluation index system for DWCA and takes Changhai sea area as the case to study the spatial distribution of the suitability of DWCA based on GIS technology.
According to the guiding principle,difference,data availability and comprehensive construction principle of the evaluation index system,11 indicators were selected to establish a system framework based on natural and social factors.The value of the evaluation index weight reflected the degree of influence of the indicator in the evaluation index system,which were determined by the analytic hierarchy process.At last,the weighted comprehensive index method was used to calculate the suitability index.
For natural suitability,some unsuitable areas for DWCA were mainly caused by the low concentration of chlorophyll a and high comprehensive pollution index of water quality.According to the distribution of natural suitability index,the suitability index was the highest in the sea area near Wumang Island,Zhangzi Island,Gexian Island and Guanglu Island,followed by the sea area among Xiaochangshan Island,Wumang Island and Haiyang Island.The suitability of the outer seas of the southeastern part of Changshan Island was higher than that of the northwestern part of the coastal waters.For the social suitability,the distance from town would affect the convenience of aquaculture operations.From the perspective of social suitability index distribution,the degree of suitability was centered on land and islands,and was concentrically distributed to the sea.
The comprehensive evaluation index were obtained through weighted calculating natural and social suitability.The results showed that the suitable sea area for DWCA was 3 527.94 km²,accounting for 32.7% of the total sea area of Changhai County.The most suitable sea area for DWCA was distributed around the western part of Guanglu and Gexian Island,the southern part of Zhangzi Island,the sea area between the Shicheng Island and Wumang Island,and the southern part of the Haiyang island,with an area of 1 248.38 km²,accounting for 11.57%.The higher suitability sea area was widely distributed around Zhangzi Island,Haiyang Island,Wumang Island and Xiaochangshan Island,covering an area of 2 279.56km²,accounting for 21.13%.Due to the combined effects of Chlorophyll concentration and distance from town areas,it was not suitable for DWCA area mainly distributed in sea areas far away from land and islands,with an area of 814.81 km²,accounting for 7.56%.Other sea areas were medium suitability.The study could provide reference for the sea planning and sea area management of aquaculture in Changhai County.