Biophysical resources characterization of a watershed using remote sensing and geographical information system
2005
Baskoro, D.P.T.
A study was conducted at Sta. maria, Romero, Pangil, Pagsanjan-Balanac, and Sta. Cruz watersheds, all from Laguna Province [Philippines], to evaluate the potential use of remote sensing and Geographical Information System (GIS) for characterizing the biophysical resources. PC-based GIS softwares were used in the analysis, processing and mapping of spatial data. Satellite images were used for mapping land cover. Fuzzy technique that involves the generation of membership maps was applied for mapping land attributes as the basis for soil erosion estimation and land suitability assessment. Integration of existing land use and water body into image improved land cover classification. The classification result indicated that coconut was the most extensive land use for all the watersheds, followed by mixed woody and forest. Annual crops and built-up area cover only a small portion of the study area. Fuzzy technique was found to be able to express wel l the continuous nature of the biophysical resources in the watersheds. Validation with observed land attributes values indicated that root mean square error was significantly lower in fuzzy method than that in conventional method. Areas with soil erosion rate at acceptable level occupied 55% of the study area. Severe to very severe erosion were expected only in small portions, found in the steep to extremely steep slopes. Suitable area for rice and other annual crops with suitability index 0.5-1 are about 57% of the study area, mainly found in level to gentle slopes. Suitable area for coconut covers about 68%. The dominant plant growth limiting factors are slope steepness, erosion hazard, and soil pH.
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