Estimation of the Crop Evapotranspiration (ETC) in Horizontal Subsurface Flow Constructed Wetlands (HSSF-CWs) is of great importance for hydrological modeling of these systems. The objective of this work was to obtain the Crop Coefficient (KC) values of Vetiver (Chrysopogon zizanioides) and Tifton 85 (Cynodon spp.) grasses when grown in HSSF-CWs whose porous medium was saturated with solutions containing different nutrients concentrations. The water balance was performed every day in order to determine the KC of the grasses. It was verified that the KC values of the Vetiver grass were independent of the nutrient availability, expressed in terms of Electrical Conductivity (EC) of the nutrient solution. The KC value in the initial growth phase (Phase I) was 0.99, independent of the seasons. In Phase II, the KC were 0.95 and 1.36 for autumn and spring, respectively, and for Phase III were 1.12 in autumn and 1.60 in spring. In relation to the Tifton 85 grass, the KC values showed a quadratic behavior as a function of the EC, where the KC estimation models were obtained by the cluster analysis in Phase II and III. For Phase I, the KC value was 1.17, independent of the EC and the time of year.

中文翻译：

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香根草和提夫顿草的蒸散作用是在水平地下流动的湿地中生长的85种草。

水平地下流人工湿地（HSSF-CWs）中农作物蒸散量（ETC）的估算对于这些系统的水文建模非常重要。这项工作的目的是获得香根草（Chrysopogon zizanioides）和Tifton 85（Cynodon spp。）草的HSFC-CW的作物的作物系数（KC）值，该草的多孔介质充满了不同养分浓度的溶液。为了确定草的KC，每天进行水平衡。经证实，香根草的KC值与养分利用率无关，以养分溶液的电导率（EC）表示。初始生长阶段（第一阶段）的KC值为0.99，与季节无关。在第二阶段，KC为0.95和1。秋季和春季分别为36，秋季为3.12，春季为1.60。相对于Tifton 85草，KC值显示出EC的二次行为，其中KC估计模型是通过第二阶段和第三阶段的聚类分析获得的。对于第一阶段，KC值为1.17，与EC和一年中的时间无关。