Using runoff and percolation model to estimate non-point source losses in tea plantaions

• Main Authors: Chih-Liang Wu, 吳致良
• Other Authors: Ching-Gung Wen
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/77251448567596471292

碩士 === 國立成功大學 === 環境工程學系碩博士班 === 92 === 　　This study deals with the estimation of non-point source (NPS) loads for high mountain tea plantations in a small drainage area. The suitable water quality equations are pre-selected and their parameters are calibrated and verified based on collected precipitation data, runoff discharge and quality data in conjunction with the distributed rainfall-runoff model. The results show that the annual unit pollution load comprises 329.7 kilograms per hectare per year (kg/ha/y) of SS, 24.6 kg/ha/y of TN, 0.82 kg/ha/y of TP, 15.5 kg/ha/y of NO3--N and 0.16 kg/ha/y of PO43--P. 　　Subsurface flow was a significant path to transport dissolved nutrients from excess amounts of fertilizer applied in tea plantations, but these water samples were hardly to collect on site. The subsurface flow and percolation samples from tea plantation in a storm event were collected by a laboratory scale experiment in this study. The result show that nutrient content and antecedent condition of soil are the major factors for the variation of the nutrients loads from subsurface. An optimal regression model can be formulated as: Nitrogen : PTN = 0.57*S-0.04*WSN+1.87 n=6 R2=0.89 Phosphorous : PTP= *PSS+PPO4-P PPO4-P=0.01*S+0.001*WTP+0.01 n=6 R2=0.70 Where PTN is nitrogen loss through percolation,kg-N/ha; S is antecedent condition of soil,mm/hr; WSN is the nutrient content of surface soil,mg-N/g-soil; PTP is phosphorous loss through percolation,kg-P/ha; WSP is the nutrient content of surface soil,mg-P/g-soil; Ra is accumulated rainfall in a sigle event,mm; is the nutrient ratio,kg-P/kg-SS; n is sample size; and R2 is determinate coefficient of regression equations. Finally, the NPS loads of tea plantation from subsurface flow was estimated by these regression equations. The export coefficients of percolation are indicated as: TN=95.81 kg/ha-yr, TP=1.84 kg/ha-yr.