坡地沖蝕防治成本函數之建立與地利分析之應用

APPLIED EROSION CONTROL COST FUNCTION FOR LAND CAPABILITY ANALYSIS

山坡地屬於環境敏感地區，坡地開發不當將造成基地本身及其下游地區之災害性影響。本研究旨在建立沖蝕防治之成本函數，並運用生態規劃方法之觀念與原則，評估山坡地開發中有關土壤沖蝕方面的影響，以作為地利分析之依據。本研究之重點有四：(1)由自然環境因素反映土地開發之難易程度，並以開發成本為量化之評估單位；(2)界定坡地沖蝕之成本型態為區內成本和對下游地區影響之成本；(3)應用沖蝕學理公式推導成本函數；(4)藉由沖蝕成本的高低，評估土地利用之潛能，降低人為主觀判定因素，並強調人為開發與自然環境之和諧性，以達土地永續利用之目的。本研究以台北縣三峽地區為實例，運用地理資訊系統將成本函數之評估準則納入實證分析。研究結果發現，所建立之成本函數可客觀地作為坡地開發地利分析之依據，亦可以用來評估土地使用改變對基地本身及鄰近地區，有關地表沖蝕與連帶成本之影響。此外，藉由沖蝕防治成本函數之運作，可進一步強調地利分析中有關環境之空間相互影響關係。

Due to the environmentally sensitive characterics of hillsides, inadequate land use on hillsides will result in the adverse effects both on-site and off-site. The purpose of this research is to incorporate ecological land use planning approach and develop an erosion control cost function as evaluative criteria for land capability analysis to assess the environmental constraint of soil erosion on hillsides. There are four major points in this study: (1) apply natural factor to assess the difficulties of land development and use erosion control cost function for evaluation; (2) assess costs of erosion control from view points of both on-site and off-site respectively; (3) develop a cost function on the basis of erosion control to eliminate the subjective judgment of evaluation; and (4) assess the land capability using the established cost function for the sustainable development on hillside. Finally, Sanshia area is used as a case study for demonstrating the analysis of land capability using the erosion control cost function and the geographic information system (GIS). As a result, the established cost function can be used to assess both the land capability of hillsides and the impact of development spatially.