中文摘要：

为研究适用于小型渠道以及田间进水口的量水设施,该文拟结合小型渠道分水闸设计体型简单的梯形薄壁侧堰,探讨其水力特性影响因素。设计7种堰顶与水平方向夹角（-9°、-6°、-3°、0°、3°、6°、9°）的梯形侧堰,在6种流量工况下进行42组试验,研究侧堰附近水面线、流量系数与其影响因素之间的关系、水头损失等水力特性。结果表明：建立的水面线函数最大相对误差仅为1.85%,满足测流精度要求;建立梯形薄壁侧堰流量与水头、堰高、堰顶角度的关系式,其相对误差绝对值最大为8.97%,满足测流精度要求;分析不同流量下水头损失及壅水高度,侧堰堰顶角度越大,水头损失及壅水高度越大;得到的上游水深与流量以及侧堰堰顶角度的关系式的决定系数可达0.9以上,便于在量水时根据渠道规格以及灌溉流量确定适宜的梯形侧堰堰型。该研究对梯形薄壁侧堰水力特性进行初步探索,为侧堰在灌区末级渠道或田间进水口的推广提供参考。

英文摘要：

Water shortage is one of the problems that limit economic development in China. However, farmers adopt flood irrigation in most irrigated areas for lacking of suitable flow-measurement devices, which leads to water waste. Thus studying convenient and adaptable flow-measurement devices is particularly important. Side weirs have simple structure and high precision. They are installed in the side of channels and directly connected with the small channels without changing the cross-section structures of channels. To explore convenient and adaptable flow-measurement devices used in small channels or water inlets in the field, a simple trapezoidal side weir combined with diversion sluices for small channels was designed. Based on previous researches of rectangular side weirs, different angles of side weir were set at-9 °,-6 °,-3 °, 0 °, 3 °, 6 ° and 9 °. Experiments were conducted in rectangular channel under different discharges up to 40 L/s to study side weirs＇ hydraulic characteristics in Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas in Northwest AF University. Flow profiles, Froude number, discharge coefficient and head loss were obtained from experiments. Water profiles in different locations were compared, which reflected that the flow profiles nearby side weir fluctuated obviously. Based on the dimensionless, the relationship between discharge coefficient and its impact factors were studied. The results showed that side weirs could affect flow in main channel, and the influence range was from side weir to the center of main channel. Flow profiles function derived from this study could be applied in practice, with maximum relative error 1.85%. Moreover, discharges formula was established based on it. Discharge coefficient decreased with increasing ratio between side weir height and flow depth upstream when the crest angles of trapezoidal side weirs were greater than 0° and increased when the crest angles of trapezoidal side weirs were less than 0°. While the relat