集水區暴雨尺度對逕流之非線性關係分析

Analysis of Nonlinear Relationship of Storm Scale on Watershed Runoff

李光敦(Kwan-Tun Lee) ； 鍾逸茹(Yi-Ru Chung) ； 黃仁國(Jen-Kuo Huang)

《農業工程學報》 52卷4期 (2006/12) Pp. 25-38

摘要

傳統水文模式均視集水區降雨逕流過程為一線性反應系統，因此集水區於不同暴雨事件所產生之逕流，可以利用集水區水文反應函數，以線性正比與線性疊加方式模擬集水區出口處之逕流匯流情形。然而無論由水力學理論或是實際水文觀測紀錄中，均顯現集水區降雨逕流過程具有明顯的非線性特性。因此傳統線性水文系統假設，是否成為逕流模擬失誤的主因，值得深入探討。本研究首先利用臺灣地區三個集水區之水文紀錄資料，以分析降雨與逕流间之非線性關係。研究中應用線性系統理論之單位歷線模式與線性水庫模式，以及非線性系統理論之可變單位歷線模式與運動波－地貌瞬時單位歷線模式，針對集水區之逕流過程進行模擬與分析；並詳細探討暴雨事件尺度對於逕流非線性現象之影響。研究結果發現，集水區降雨尺度與逕流量之關係呈明顯非線性。較高的降雨量會造成單位歷線尖峰量較高，且產生尖峰到達時刻前移的現象；反之，較低的降雨量則造成較小的單位歷線尖峰量，且延緩尖峰到達時刻。

關鍵字

降雨逕流模擬 ； 線性水文模式 ； 非線性水文模式 ； 尺度效應

並列摘要

Watershed runoff process is usually recognized as a linear system in conventional rainfall-runoff modeling. Consequently, storm runoff can be simulated by using a hydrologic response function applying linear proportionality and linear superposition techniques. Nevertheless, nonlinearity is usually to be observed through watershed hydrologic records analysis and has shown in hydraulic flow equations. It induces a question that if flow nonlinearity is the main reason to result errors in runoff predictions. In this study, hydrologic records from three watersheds in Taiwan were collected for analysis to realize the watershed nonlinear relationships in rainfall-runoff process. The unit hydrograph method and linear reservoir method, which are based on the linear hydrologic theory, and the variable unit hydrograph method and the kinematic-wave based geomorphic instantaneous unit hydrograph method, which are based on the nonlinear hydrologic theory, were used for runoff simulations and to analyze the influences of storm scale on rainfall-runoff nonlinearity. Results show that the relation between storm scale and runoff generation is highly nonlinear. High rainfall intensity generates a larger unit hydrograph peak and a shorter time to peak discharge, which is contradictory to the linear hydrologic theory assuming a unique unit hydrograph for a specified watershed.

並列關鍵字

Rainfall-runoff simulation ； Linear hydrologic model ； Nonlinear hydrologic model ； Scaling effect