梯田可分阶式与波式两种,在黄土高原,除少数埂地外,地形坡度大都在7°以上,故主要应修阶式梯田。流出水量的估算梯田的流出水量应由五至十年一遇的最大净徑流量来估算,同时还湏考虑全年泥沙的最大淤积量(这些数字我們已經推算求得,如表1及表2所示)。因为暴雨可能發生于泛期的末期,为了使梯田埂于修成后一年內不須加高,梯田的流出水 Terraces can be stepped and wave two, in the Loess Plateau, with a few land, the terrain gradient mostly in more than 7 °, so the main should be a step terrace. Estimation of Outflows The outflow of water from terraces should be estimated from the maximum net runoff in five to ten years and the maximum siltation throughout the year (these figures have been derived by calculation as shown in Table 1 and Table 2). Because heavy rains may occur at the end of the flood season, outflow of terraced fields is not required