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Effects of pasture treatments on runoff characteristics and water quality
|關鍵字:||runoff characteristics;逕流特性;water quality;disturbance;mulching;the treated swine wastewater;nitrogen loading;rainfall event;soil;水質;擾動;敷蓋;豬糞尿處理水;氮肥負荷量;降雨事件;土壤||出版社:||水土保持學系||摘要:||
第一部份旨在利用小型模擬降雨機以評估敷蓋及擾動土壤對建立緩坡草地期間地表逕流之影響。試驗採2×2複因子設計，3重複，共12個1×0.5×0.8 m3之土箱。敷蓋因子含敷蓋及裸露處理及擾動因子含擾動及無擾動處理。在模擬降雨強度50 mm/h下，同一處理進行30 min之乾土測定，中斷30 min後再進行60 min之濕土測定。觀測所得之逕流資料用以分析：起始逕流時間、逕流上升肘之斜率變化及平衡逕流率之斜率變化等三項。試驗結果：二參試因子對建立緩坡草地期間逕流參數之影響為：(1)在乾土測定中：同一敷蓋因子下，敷蓋處理較裸露處理可延遲69.4% 之起始逕流時間、降低18.5% 之上升肘之逕流迴歸係數、降低26.8% 之終端逕流量及降低28.9% 之平均逕流率；及在同一擾動因子下，擾動處理較無擾動處理可延遲375% 之起始逕流時間、降低56.9% 之上升肘之逕流迴歸係數、降低104% 之終端逕流量、及57.3% 之平均逕流率。(2)在濕土測定中：同一敷蓋因子下，敷蓋處理較裸露處理可降低19.1% 之尖峰流量、降低12.2% 之終端逕流量及降低28.9% 之平均逕流率；及在同一擾動因子下，擾動處理較無擾動處理可降低40.8% 之尖峰流量、降低57.3% 之平均逕流率及降低36.9% 之終端逕流量。因此建議在建立緩坡草地時，擾動處理與敷蓋處理可延遲起始逕流時間、減低逕流上升肘之斜率及降低尖峰流量。惟本試驗僅在坡度5%、降雨強度50 mm/h、降雨延時60 min之條件下進行，應用本試驗之結果時，宜注意勿在降雨強度高及降雨延時長之雨季，此會產生不同之結果。
第二部份：旨在為利用小型模擬降雨機來評估施灌豬糞尿處理水及不同乾水距對地表逕流水質之影響。本試驗以4×3複因子設計，共12個1×0.5×0.8 m3之土箱。試驗因子為豬糞尿處理水因子(含固液分離水、厭氣水、排放水及對照組四種處理)及乾水距因子(含施灌豬糞尿處理水後第1、第4及第14天產生逕流)。本試驗在降雨強度50 mm/h之模擬降雨下，俟產生逕流後，持續進行30 min之降雨延時，所得之逕流資料用以分析逕流中之總氮(TN)、NH3-N、NO3--N、總磷(TP)、溶磷(DP)及電導度(EC)等六項。結果顯示：施灌豬糞尿處理水會影響逕流之水質，且逕流濃度隨豬糞尿處理水種類而有所不同，其中以固液分離水處理組之地表逕流水質最差，厭氣水次之，但每公頃之流失量均很低；在施灌豬糞處理水後，第1天發生暴雨之逕流水質顯著高於第4天及第14天之逕流水質。
The purposes of this dissertation were to study the effects of different treatments of pasture in gentle slopeland on runoff characteristics and water quality. The dissertation was divided into three parts of experiment.
The first part of dissertation was using a small-scale rainfall simulator to evaluate the effects of mulching and disturbance of soil on runoff parameters during the period of pasture establishment in gentle slopeland. The 22 factorial experiment design with 3 replications was employed. One factor was coverage with mulching or bare treatment, and the other was disturbance factor with disturbed or undisturbed treatment. A 50 mm/h of rainfall simulation consisted of 2 phases, a dry run of about 30 min followed by a wet run approximately 30 min later. Runoff hydrographs (runoff / applied water 100) were subdivided into 3 components representing: (1) time to runoff initiation; (2) rate of change in runoff percentages in the rising limb; and (3) equilibrium runoff percentage. Under the same coverage factor on the dry run conditions, runoff initiation time was delayed for as much as 69.4%, regression coefficient of runoff rising limb was deflated 18.5%, final flow was lowered 26.8%, and average runoff rate was reduced 28.9% for the mulching treatment as compared to the bare treatment. Under the same disturbance factor, runoff initiation time was delayed for as much as 375%, regression coefficient of runoff rising limb was deflated 56.9%, final flow was lowered 104%, and average runoff rate was reduced 57.3% for the disturbed treatment as compared to the undisturbed treatment. Under the same coverage factor on the wet run conditions, peak flow was lowered as much as 19.1%, final flow was lowered 12.2%, and average runoff rate was reduced 28.9% for the mulching treatment as compared to the bare treatment; and under the same disturbance factor, peak flow was lowered 40.8%, final flow was lowered 57.3%, and average runoff rate was reduced 57.3% for the disturbed treatment compared to the undisturbed treatment. The results suggest that the combination of disturbed and mulching soil can reduce runoff rate and peak flow in gentle slopeland. However, the application of the result to the season having high rainfall intensity and longer storm duration should be avoided.
The second part of dissertation was also using a small-scale of rainfall simulator with a 50 mm/h of rainfall intensity and a 30 min of rainfall duration to evaluate the runoff quality from soil bins receiving effluents of treated swine wastewater. A 43 factorial experiment design was employed. Two factors consisted of type of effluent with four treatments (solid-liquid separation effluent, anaerobic effluent, aerobic effluent and control), and drying interval with three treatments (rainfall was simulated at the first, fourth and fourteenth day after applying the effluents). The results showed that runoff quality from solid-liquid separation effluent was the worst in the treated swine wastewater, and from the first day after applying effluent was also the worst in the three drying interval treatments. However, the percentage of mass loss from applying the treated swine wastewater by surface runoff was small.
The last part of dissertation was using pangolagrass soil columns to determine the effects of the types of effluent of the treated swine wastewater and nitrogen loading rates on the quality of percolation. The 25 factorial design with three replications was employed. The factors were types of effluent (anaerobic and aerobic treatments), and nitrogen loading rates (0, 50, 100, 150 and 200 kg/ha). The investigation was conducted under four rainfall events, which occurred at the 1, 17, 42 and 60 days after application. The most important factors on percolation quality were nitrogen loading rates and following by rainfall event. The results showed that the concentration of total nitrogen, ammonia nitrogen and nitrate nitrogen increased with increasing nitrogen loading rate. No significant difference in quality of the percolation was found between the two types of effluent except for the nitrate nitrogen. Except for nitrate nitrogen, the total nitrogen and ammonia nitrogen were significantly higher after the first rainfall event than others. Also, for the recommendation purpose in the near future, a figure was set up between the application depths and nitrogen concentrations of effluent of the treated swine wastewater in relation to irrigation of nitrogen loading rates.
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