頁籤選單縮合
| 題 名 | 雙層暗渠系統之排水及洗鹽效果 |
|---|---|
| 作 者 | 王百祿; | 書刊名 | 農業工程學報 |
| 卷 期 | 26:2 1980.06[民69.06] |
| 頁 次 | 頁66-80 |
| 關鍵詞 | 系統; 洗鹽; 排水; 暗渠; 雙層; |
| 語 文 | 中文(Chinese) |
| 中文摘要 | 本試驗之目的在於探討雙層暗管系統應用於具高不透水層鹽分地之排水及洗鹽效果,以供今後鹽分地改良及暗管系統設計之參考。試驗地點設於蒜頭糖廠鰲鼓農場,土壤屬坋質壤土,暗管間距25公尺,於地表下1.00及1.50公尺交互埋設,所獲主要結果摘述如下: (1)雙層暗管系統試區土壤經雨水自然淋洗後,pH值變化甚小,土壤電導度可自15.67降至3毫姆歐以下,交換性鈉百分率及吸鈉比均迅速下降,洗鹽效果良好,無形成無鹽鹼土之可能性。 (2)雙層暗管系統之排水尖峰流量在同一水頭下高出一般平行暗管五倍以上,水位下降極為迅速,排水效果十分良好。 (3)在土壤剖面中具有較高位置不透水層之鹽分地,可採用雙層暗管排水系統改良。 |
| 英文摘要 | In 1970, the Dutch type subsurface drainage system, which uses small slotted PVC tube as laterals in a depth of 150-200 cm below soil surface, was introduced and tested for reclamation of salt-affected soils in four TSC- owned plantations. After a certain period of leaching, the salt content in the soil decreased and cane yields increased significantly. Because of high leaching efficiency and low initial cost, this system has been widely installed in the saline plantation. However, in some areas, an impermeable soil layer, which contains high percentage of compacted silt, is found located in the depth between 100 to 250 cm from surface. When the drains were placed amid or below such layer, the leaching efficiency was low because excess soil water flow into the drains with slow rate. If the drains were installed above the shallow impermeable layer, a desirable water table could not be maintained, and the high evaporation rate caused salt accumulation on soil surface during dry season. Therefore, conventional mono-level subsurface tile drainage system can not be used to achieve long-term reclamation of salt-affected soil in those areas. In order to reclaim those saline soils effectively by means of increasing leaching efficiency and lowering water table simultaneously, a bi-level drainage system was tested in 1977 in Ao-Ku sugarcane plantation with conventional mono-level tile system used as a check. In the bi-level system, the shallow drain with a depth of 100 cm was interplaced with a deep drain of 150 cm, spaced 25 meters apart. For the conventional parallel system, the drains were installed at 150 cm depth spaced 30 meters apart. After a heavy rainfall, it was found that peak discharge rate was 21.6mm/day for the bi-level and 3.9mm/day for conventional system. For days later, discharge rate of the bi-level system decreased to about 2mm/day. Such results indicated that bi-level subsurface drains remove much more soil water than conventional paralleled drains after heavy rain. Deboer equation was chosen to compare the drainage efficiency of both systems. The results indicated that theoretical time distribution of maximum water table was in good agreement with field data actually observed. Hydraulic conductivity calculated from theoretical equation was found to be very close to those obtained by auger hole method in the field. The results showed that DeBoer equations is most satisfactory for designing the bi-level drainage system. Leaching efficiency of both system was studied by periodical determination of electric conductivity of soil saturation extract sampled from various depth of soil. Desalinization proceeded more rapidly in the bi-level system than in the monolevel system. After five months of leaching, electric conductivity (EC) of top 0-15 cm soil in the bi-level system decreased from 15.67 to 3mmhos/cm, while in the conventional mono-level system, it dropped from 22 to 18 mmhos/cm. EC were even increased in deep soil layers of the latter system. Such results may be caused by a low discharge rate of mono-level drain system. The salt in the top layer moved down and accumulated in the bottom layers. High evaporation rate during summer also be responsible for the salt increased. Similar pattern of change in exchangeable sodium percentage and sodium adsorption ratio was also observed during the same leaching period. Change in soil pH ware very small. A linear relationship was found between drain discharge and entrance resistance. Methods of management of subsurface drain system in fine textured soils are also discussed. |
本系統中英文摘要資訊取自各篇刊載內容。