過去數年間，臺灣地區之山坡地開發案為數甚多。這些開發往往由於水文設計不 當，而造成水患及下游承接水體之水質惡化等問題。雖然坡地開發案之相關主管單位，對坡 地開發之水文設計訂定準則與設計方法，然而這些準則與方法有些部分與水文學之原理相抵 觸者。本文針對坡地開發滯留池設計之現行法規，深入研析，並以範例闡釋現有規範中水文 設計不當之處。 同時，本研究亦證明 SCS 三角形單位歷線法集流時間、降雨延時及尖峰到 達時距等各項時間參數間之關係，以闡明該法之應用限制。最後，針對坡地開發滯留池水文 設計之特性，本文提出一套利用改良式合理化公式，配合單位歷線進行逕流演算之方法。
Developments in hillslope area have increased dramatically over the last two decades in Taiwan. These developments often result in flooding problems and water quality deterioration for the receiving water bodies due to inappropriate hydrologic designs. Although the authoritative agency has established hydrologic design criteria and procedures for hillslope development projects, these criteria violate several basic hydrologic principles, and the design rationale contradicts standard hydrologic design procedures. In this study we thoroughly review the current design criteria and procedures. Demonstrative examples are presented to explain why the established criteria are inappropriate. In particular, we show that application of the SCS unit hydrograph is subject to certain restrictions regarding three time parameters:time of concentration, rainfall duration, and time to peak. Misuse of the SCS unit hydrograph will result in inappropriate design. By considering the special characteristic of hydrologic design in hillslope development project, we propose a new design approach using unit hydrographs based on the modified rational formula. A demonstrative example of this approach is also given.
