| Wetland is a special ecosystem which has various functions. It is the entironment most close to human and is an important part of natural resources. Also it is the ecosystem landscape most being abundant of bio-diversity. It has various functions which includes regulating the weather, storing floodwater to defend the drought, controlling the soil to be eroded, speeding filling to build land, complementing groundwater, reducing environment pollution, and protecting the bio-diversity etc. So it is recognized as"the earth's kidney". Wetland resource has important influence on the economy development and the living environment of a region, the nation and even the globe. Therefore, wetland protecting and continuable utilizing have become the hotspot of international society nowadays.The coastal wetland resource of HeBei province is abundant with various types. It has representative natural wetland such as marsh and marshed meadow as well as man-made wetland such as breeding pond, brine pan and paddyfield. It has onshore wetland such as river, reservoir and pond as well as tideland wetland such as bottomland and lagoon. However because of people's long-term and high-strength exploitation, the area of natural wetland has a great deal of decrease, which is replaced by man-made wetland that can bring direct economic benefits. And the water quality becomes worse, the eutrophication is aggravating and the bio-diversity falls markedly.This paper choosed two periods'landsat TM remote sensing images of 1987 and 2005 of the coastal area of HeBei province, and applied RS and GIS technologies to the interpretation of the dynamic change of the HeBei coastal wetland during 18 years. On the basis of it, it valued the benefit of the wetland in 1987 and 2005 using the Market Value Method, Shadow Project Approach and some other resources economics method, and tried to apply the result of the image analysis to the valuation. Then it analyzed the influence of the wetland changing upon the benefit. With that, using the weighted sum method, we figured out the benefits of unit area for different types of wetlands, and by comparative analysis we found out the way for their exploitation, utilization and protection.The results showed that, (1) The total area of the wetland was increased, but the area of the natural wetland was acutely reduced.During the 18 years from 1987 to 2005, the total area of the HeBei coastal wetland changed from 243738.23 hm2 to 276964.06 hm2, increasing by 13.63%. But the area of the natural wetland changed from 138147.68hm2 to 109632.66 hm2, reducing by 20.64%. And the area of man-made wetland changed from 105590.55 hm2 to 167331.40 hm2, increasing by 58.47%. (2) The total benefit of the coastal wetland had reduced. The entironmental benefit had reduced and the social and economic benefit had increased. The total benefit of the HeBei coastal wetland is 299621172.8 thousand yuan in 1987 and is 254273846.2 thousand yuan in 2005, reducing by 45347326.6 thousand yuan. Compared to the valuation in 1987, the entironmental benefit reduced by 65162082.5 thousand yuan and the social and economic benefit increased by 19814755.9 thousand yuan. (3) The dynamic change of the wetland directly influenced on the benefit. The natural wetland chiefly contributed to the entironmental benefit, especially in the aspect of offering habitat. By contraries, the man-made wetland chiefly contributed to creating abundant social and economic benefit. (4) For the future,we must pay ateention to protect and rehabilitate the natural wetland , and give moderate exploitation and efficient utilization to the man-made wetland, in order to realize the integrated functions of the wetland, and to offer the maximal benefit. |
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