河川流量的資料為水工構造物設計、水資源規劃及水資源管理等之根本，因此長期且確實掌握河川流量實為國人研究之首要目標。河川流量量測的關鍵因子之一為河川通水斷面積之估算。此外河川通水斷面積亦為一重要水文因子，不論是流量推估、各項水利工程、各類型模式演算，其都為必要參數。長久以來河川斷面量測必須耗費大量人力、金錢、時間，洪水過程河川底床變動劇烈，流況不佳且量測危險，更加深通水斷面積量測的困難度。憑藉透地雷達經濟、快速有效率、且非接觸水體等優點，本研究利用透地雷達量測河川斷面，以期達到節省經費並增加施測頻率之效果。本研究中以北勢溪流域河川為主，建立透地雷達量測流程，已期達到快速量測之效果。經由各種處理功能率定河川底床波形以增加資料判釋準確性，與傳統鉛錘法比較後結果顯示河川斷面積差異不大，證實此法能夠運用於實際河川通水斷面量測。
Discharge is the basic data used in hydraulic structure design, water resources planning, and water management. Therefore discharge measurement become more and more important for the water management. Good water management is founded on the reliability of discharge measurement depends on the initial field measurement. Steam cross section is the key data to accurately estimate discharge. By the way, hydraulic and hydrological models always need stream cross section data. The conventional method used to measure stream cross section is costly, time-consuming, and dangerous. It is necessary to develop a new method to measure stream cross section. Field experiments were conducted to test the ability of ground penetrating radar (GPR) to measure stream cross section without placing instruments in the stream. Experiments were conducted in three gaging stations in the Beishih River. The results show that GPR is a viable technology for mapping stream cross section geometry and computing discharge.
