莫拉克颱風前後高屏溪流域土壤性質空間變異

Spatial Variation of Soil Properties in Kaoping River Basin Prior and Post Typhoon Morakot

蔡興融(Shing Rung Tsai)

指導教授 ： 江介倫

國立屏東科技大學/工學院/水土保持系所/碩士(2011年)

https://doi.org/10.6346/NPUST.2011.00190

摘要

論文摘要內容：
溪流的河道邊土壤會因為季節及颱風的影響帶來改變，其變因程度大，受到溪流沖刷、溪水暴漲的影響，改變河道邊的土壤理化性質。為了解颱風前後，河道邊土壤上、中、下游的變異。研究區域以高屏溪流域河道邊的土壤理化性質做為調查重點，本研究做統計分析，主成分分析、鄧肯分析及簡單相關，並利用有限觀測值藉由克利金內插繪出分佈圖，其中調查範圍包括了旗山溪、荖濃溪、美濃溪、隘寮溪等支流，做為整個流域的分析對象。進而探討整個流域上的空間分佈、變異在颱風過後的程度及影響的土壤理化性質。
本研究以顆粒密度(Particle Density)、土壤質地(soil texture)、粒徑分析(particle size analysis)、電導度(electrical conductivity)、有機質(organic matter)、全氮(total N)、有效磷(available P)、土壤反應(soil pH)、土壤陽離子交換容量(Cation Exchange Capacity ,CEC)，以上九種土壤理化性質做為調查項目。半變異分析顯示，在颱風前後電導度(EC)臨界值從16提高至80、陽離子交換容量(CEC)從452降至190，兩者土壤性質在颱風前後臨界值高，代表其相關性低，顯示受到颱風程度影響較小，只和特定因子有關；有機質臨界值在颱風後從30降至1.1，因為有機質(OM)在颱風後受到溪流沖刷、土壤搬移及表土的流失會使有機質(OM)流入河中，使得表土有機質(OM)含量趨勢呈現平穩的狀態；有效磷(P)在颱風後臨界值由0.65提高至5.8且相關性由高轉低，這代表有效磷(P)會因為颱風影響，導致在颱風後有效磷呈現不均勻的分佈；全氮(N)、pH在颱風前後臨界值小且相近，顯示這兩種土壤性質在颱風後呈現較微小的變化。克利金分佈圖結果顯示，颱風後以有機質、有效磷、pH、全氮差異最為顯著。說明了颱風期間溪水暴漲並沖刷河岸，使得河岸邊的土壤性質會隨著土壤潰堤而流失或流入河中，並造成整個流域上下游在颱風過後的差異。有機質(OM)在颱風前上游屬於含量較多的趨勢，颱風後呈現和颱風前相反的分佈，下游的含量高於上游；有效磷(P)颱風前也是屬於上游含量較高的趨勢，颱風後呈現下游集中的趨勢；全氮颱風前在平均0.01%以上的數值集中於上游，颱風後0.01%的數值因為被沖刷而集中於下游；pH值在颱風前除了距離出海口近的值偏低，其餘整個流域介於7.8~8.4屬於弱鹼性~中性，颱風後整個流域上、中、下游的pH改變，空間呈現微小的變化。交換性陽離子容量和電導度在颱風前後差異最不明顯，以距離出海口最近的下游數值偏高，顯示這兩種性質在颱風前後不會有產生空間上的變異，因為這兩種土壤性質不會受到河道沖刷或是土壤搬移改變，則是受到特定因子影響而改變。

關鍵字

克利金 ； 土壤性質 ； 空間分佈

並列摘要

Taiwan situates at the subtropical region with frequent typhoons, earthquakes and fragile complex geology. Flourish economy worsens inadequate land uses and even river sides are used to grow crops. The river-side soil is most important of study areas in Kaoping river basin. The statistical analysis used in this study including principal component analysis (PCA), simple correlation and Duncan’s analysis. In this study, Kriging method, GIS was used to map the soil properties of Kaoping river basin prior and post typhoon. Research focuses on the investigation of the chemical and physical properties of soil in Kaoping River basin. The survey covered Chishan River, Laonung River, Meinong River and Ailiao River. By using Kriging Method, the distribution of whole Kaoping River basin was estimated. Furthermore, the spatial distribution and variation after typhoon and the physical and chemical properties of soil in Kaoping River basin were also discussed.
In this study, nine chemical and physical soil properties are used as the research project including particle density, soil texture, particle size analysis, electrical conductivity, organic matter, total N, available phosphorus, pH and cation exchange capacity (CEC). The results showed that after typhoon, the organic matter and phosphorus changed most obviously between the upstream and downstream river and then Total N and pH are followed; cation exchange capacity and electrical conductivity changed the least which showed the two soil properties are less likely to be moved or changed by river erosion. The Semivariogram analysis showed that after typhoon, Conductivity (EC) sill value changed from 16 to 80; cation exchange capacity (CEC) changed from 452 to 190. Both soil properties sill values are high after typhoon which showed low correlation. Typhoon has small effect on it. Only specific factors are related. Organic matter sill value changed from 30 to 1.1. During typhoon, affected by river erosion, topsoil loss and soil movement, organic matter (OM) flowed into the river and the content of OM on topsoil showed steady. Available phosphorus (P) sill value increased from 0.65 to 5.8 and the correlation decreased. It can be said that Available P significantly has changed by the impact of typhoon. Therefore, phosphorus showed uneven distribution after typhoon. The sill value between total nitrogen (N) and pH is small and close which means small change occurred between the two soil properties after typhoon. Kriging maps showed that organic matter, Available phosphorus, pH and total nitrogen have the most significant difference after typhoon. The content of Organic matter (OM) are more in the upstream region, but it decreases after typhoon. Likewise, available phosphorus (P) is more in the upstream region, but after typhoon, it’s found much more in the downstream region. The average value of 0.01% on total nitrogen (N) concentrated in the upstream region before typhoon; on the contrary, it concentrated in the downstream region after typhoon due to the washout. The pH values are between 7.8 ~ 8.4 in Kaoping river basin, except in the river mouth where pH value is lower. The pH value has minor changes in Kaoping river basin. Cation exchange capacity and conductivity have the least variation after typhoon and it accumulates in the downstream region close to the sea mouth which showed the two soil properties have no obvious variation in space because the two properties may not effect by the river erosion or soil movement but only affected by specific factors.

並列關鍵字

Kriging ； soil properties ； Spatial distribution

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