A study on the Estimation of Soil Erosion of Terraced Field under Different Cultivation Types
水稻梯田 ； 通用土壤流失公式 ； 土壤沖蝕指標模式 ； 台灣可容許土壤流失量 ； terraced paddy field ； Universal Soil Loss Equation(USLE) ； Soil Erosion Index Model (SEIM) ； soil loss tolerance in Taiwan
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因本土化水稻梯田試驗研究之重要性，故在新竹縣新埔地區設立水稻梯田試驗區，在選定的降雨事件中，透過分區之降雨量、逕流量、沖蝕量等量化數據的收集，評估在不同耕作型態下各降雨因子與土壤沖蝕量的關係，並探討不同作物情況下對土壤沖蝕量的影響。研究結果顯示利用現地收集之降雨逕流及懸浮載SS觀測值推算陡坡水稻梯田正常耕種下沖蝕量為0.77 ton/ha/yr、棄耕佈滿雜草的情況下沖蝕量為0.74 ton/ha/yr、在轉作情況下沖蝕量為4.15 ton/ha/yr，顯示在水稻梯田地形中其沖蝕量較其他陡坡低，且沖蝕量也低於台灣可容許土壤流失量T=12~18 ton/ha/yr，所以水稻梯田具有相當的水土保持功能。再以通用土壤流失公式(USLE)和土壤沖蝕指標模式(SEIM)來推估試驗地的土壤沖蝕量時，發現其推估值有高估的現象。又在試驗田區的量測中得知單場沖蝕量分別與單場逕流量、單場降雨量、最大30分鐘降雨強度、單場總降雨動能及單場降雨沖蝕指數呈正相關，但在正常耕作下，田面情況差異甚大，因此相關性比起棄耕和轉作情況下來的低。最後因田面作物情況不同，本論文有探討田面作物情況和沖蝕量間的關係。
Regarding the importance of localized study on terraced paddy field, this study established an experimental site of terraced paddy field in Hsin-pu area in Hsin-chu County. In the selected rainfall events, this study collected the quantization data of rainfall, run-off, erosion of each local area and evaluated the relationship of every rainfall factor and soil erosion under different cultivation types; meanwhile, this study also explored the influence of different crops on the soil erosion. By utilizing the collected on-site data of the rainfall runoff and SS observed value of suspend load, the study result showed that the estimated erosion of sloping paddy field under normal cultivation was 0.77 ton/ha/yr, the erosion of abandoned sloping paddy field was 0.74 ton/ha/yr, and the erosion of sloping paddy field under alternative upland cropping pattern usage was 4.15 ton/ha/yr. It revealed that the erosion of paddy field was less than other slopes and the erosion was also less than the allowable soil loss of Taiwan—T=12~18 ton/ha/yr. Therefore, the paddy field has the function of water and soil conservation. In addition, when the researcher utilized the Universal Soil Loss Equation (USLE) and Soil Erosion Index Model (SEIM) to estimate the soil erosion of the experimental area, the estimated value was found to be overestimated. Besides, it was also found in the survey of experimental field that the individual erosion has positive correlation with the individual runoff, individual rainfall, maximum rainfall intensity in 30 minutes, individual total rainfall kinetic energy and individual rainfall erosion index. However, there was great difference in paddy field surface under normal cultivation, so the correlation was lower than that of the abandoned field and the field under alternative upland cropping pattern usage. Lastly, because the different crops of field surface resulted in difference situation, this study explored the relationship between the crops on the field surface and erosion.
工程學 > 土木與建築工程