Operating yields of an aquatic weed harvester and a long-arm hydraulic excavator in aquatic macrophyte control in Piraquara II reservoir, southern Brazil

ABSTRACT Eutrophication of water bodies has caused environmental imbalance, changing population dynamics, as the excessive growth of aquatic macrophytes. The mechanical methods are the most used to control these communities. The aim of this study was to evaluate the operational yield of a harvesting boat and a long-arm hydraulic excavator (in group and individually) in the removal of floating aquatic weeds (and their Nt and Pt contents) in Piraquara II Reservoir, in Southern Brazil. The duration of each of the 100 operational cycles (including loading, transport and unloading of trucks), besides other activities were measured through timing. The hydraulic excavator presented right yields in the removal of weeds from the water body as compared to other studies reported in the literature. However, the adding of the harvesting boat led to an increase of productivity (about 115%). The average yield was 35.57 ± 0.27 m3/h or 284.67 m3/day. Applying area, mass and volume relations for the studied site, this is equivalent to 3273.7 m2/day (considering 11.5 m2/m3) or 142.28 humid tons/day (humid density of 0.5 ± 0.08; n = 30). Therefore, for similar situations, both equipment (mainly in a joint operation) are recommended to aquatic weed infestation control.

摘要：水体富营养化已引发生态失衡，改变了种群动态，伴随水生大型植物的过度滋生。机械防治是当前管控此类水生植物群落的主流手段。本研究以巴西南部皮拉夸拉二世水库为研究区域，旨在评估水生杂草收割船与长臂液压挖掘机（分别作业、联合作业两种模式）清除漂浮水生杂草（及其总氮（Total Nitrogen, Nt）与总磷（Total Phosphorus, Pt）含量）的作业效率。研究通过计时统计，对100个作业循环（含卡车装载、运输与卸载环节）及其他配套作业的耗时开展了测定。相较于文献报道的同类研究，长臂液压挖掘机在水体杂草清除作业中表现出了良好的作业效率；但搭配收割船联合作业后，整体作业效率提升约115%。本研究测得平均作业效率为35.57±0.27立方米/小时，单日作业量可达284.67立方米。结合研究区域的面积、质量与体积换算关系，该作业量等效为每日清除3273.7平方米的杂草（按11.5平方米/立方米换算），或每日清除142.28湿吨（湿密度为0.5±0.08，样本量n=30）。因此，针对类似场景，推荐采用两种设备联合作业（尤以联合运作为佳）开展水生杂草入侵防控工作。