The magnitude of soil erosion and sediment load reduction efficiency of check dams under extreme rainstorms is a long-standing concern. The current paper aims to use check dams to deduce the amount of soil erosion under extreme rainstorms in a watershed and to identify the difference in sediment interception efficiency of different types of check dams. Based on the sediment deposition at 12 check dams with 100% sediment interception efficiency and sub-catchment clustering by taking 12 dam-controlled catchments as clustering criteria, the amount of soil erosion resulting from an extreme rainstorm event on July 26, 2017 (named “7·26” extreme rainstorm) was estimated in the Chabagou watershed in the hill and gully region of the Loess Plateau. The differences in the sediment interception efficiency among the check dams in the watershed were analyzed according to field observations at 17 check dams. The results show that the average erosion intensity under the “7–26” extreme rainstorm was approximately 2.03 × 10⁴ t/km², which was 5 times that in the second largest erosive rainfall in 2017 (4.15 × 10³ t/km²) and 11–384 times that for storms in 2018 (0.53 × 10² t/km² - 1.81 × 10³ t/km²). Under the “7–26” extreme rainstorm, the amount of soil erosion in the Chabagou watershed above the Caoping hydrological station was 4.20 × 10⁶ t. The sediment interception efficiency of the check dams with drainage canals (including the destroyed check dams) and with drainage culverts was 6.48 and 39.49%, respectively. The total actual sediment amount trapped by the check dams was 1.11 × 10⁶ t, accounting for 26.36% of the total amount of soil erosion. In contrast, 3.09 × 10⁶ t of sediment were input to the downstream channel, and the sediment deposition in the channel was 2.23 × 10⁶ t, accounting for 53.15% of the total amount of soil erosion. The amount of sediment transport at the hydrological station was 8.60 × 10⁵ t. The Sediment Delivery Ratio (SDR) under the “7·26” extreme rainstorm was 0.21. The results indicated that the amount of soil erosion was huge, and the sediment interception efficiency of the check dams was greatly reduced under extreme rainstorms. It is necessary to strengthen the management and construction technology standards of check dams to improve the sediment interception efficiency and flood safety in the watershed.

长期遭受暴雨袭击的大坝水土流失和减轻沉积物负荷的效率一直是人们长期关注的问题。本文旨在利用止水坝推断出流域极端暴雨下的土壤侵蚀量，并确定不同类型的止水坝截留泥沙的效率差异。根据12个拦河坝的沉积物沉积（截流效率为100％）和子集水区聚类（以12个大坝控制集水区为聚类标准），2017年7月26日极端暴雨事件导致的土壤侵蚀量（称为“在黄土高原丘陵和沟壑区的Chabagou流域，估计有7·26英寸的极端暴雨。根据对17个检查水坝的实地观测，分析了流域检查水坝之间的泥沙截留效率差异。结果表明，“ 7–26”极端暴雨下的平均侵蚀强度约为2.03×10⁴ 吨/千米²，为5倍，在2017年第二大侵蚀性降雨（4.15×10 ³ 吨/千米²）和11-384倍，对于在2018年（风暴0.53×10 ² 吨/千米² - 1.81 ×10 ³ 吨/公里²）。在“ 7–26”极端暴雨下，曹平水文站上方查巴沟流域的土壤侵蚀量为4.20×10 ⁶  t。排水渠（包括被破坏的排水坝）和排水涵洞的防洪坝的截污效率分别为6.48％和39.49％。止水坝截留的实际总泥沙量为1.11×10 ⁶ t，占土壤侵蚀总量的26.36％。相比之下， 下游河道输入了3.09×10 ⁶ t的泥沙，河道内的泥沙沉积为2.23×10 ⁶  t，占土壤侵蚀总量的53.15％。水文站的泥沙输送量为8.60×10 ⁵  t。“ 7·26”极端暴雨下的泥沙输送比（SDR）为0.21。结果表明，在强暴雨条件下，水土流失量巨大，拦沙坝的截沙效率大大降低。有必要加强检查坝的管理和施工技术标准，以提高流域的泥沙截留效率和防洪安全。