This paper aims to conduct a comparative evaluation of evapotranspiration (ET) rates in two experimental pilot-scales vertical flow subsurface constructed wetlands carried out in south east of Algeria (Touggourt), planted separately with P. australis (Ph) and T. latifolia (Ty) in two different substrate types with constant hydraulic loading rate under arid climatic conditions. An estimate of crop coefficient (Kc) for the two macrophytes based on climate conditions and the plant growth was also provided. Two kinds of vertical flow subsurface systems has been tested in the hottest period of the year 2018 over five months (April-August): first with fine gravel (G) (experiment 1), and second with sand (S) (experiment 2). During this period, the cumulative ET_Ty-G, ET_Ph-G and ET_Np-G in the 1^st experiment were 206, 276 and 125 mm, whereas in the 2^nd experiment; the cumulative ET_Ty-S, ET_Ph-S and ET_Np-S were 833, 968 and 635 mm, respectively. Comparing these results with cumulative reference evapotranspiration (ET₀), ET₀ value (426 mm) was higher than ET in the 1^st experiment, and lower than in the 2^nd experiment. Cumulative ET values in planted lysimeters were found to be different and higher than unplanted ones. Moreover, the highest accumulated ET value was obtained with P. australis bed which was found to have higher accumulated ET values than T. latifolia bed. Regarding the crop coefficient (Kc), the average seasonal value of Kc in the 1^st experiment was relatively smaller than 2^nd experiment. The Kc _Ph-S value was almost three times the Kc _Ph-G, and Kc _Ty-S values were also almost four times the Kc _Ty-G.

In general, this study demonstrated that ET and Kc are dependent on climate conditions, the macrophytes growth as well as on the type of substrate in which the macrophytes are planted.

本文旨在对在阿尔及利亚东南部 (Touggourt) 进行的两个试验性中试规模垂直流地下人工湿地的蒸发蒸腾 (ET) 速率进行比较评估，分别种植P. australis (Ph) 和T. latifolia ( Ty) 在干旱气候条件下具有恒定水力加载速率的两种不同基质类型。还提供了基于气候条件和植物生长的两种大型植物的作物系数 (Kc) 估计值。在 2018 年最热的五个月（4 月至 8 月）中，两种垂直流地下系统进行了测试：第一种是细砾石（G）（实验 1），第二种是沙子（S）（实验 2） . 在此期间，累积的 ET _Ty-G,第^一次实验中的ET _Ph-G和 ET _Np-G分别为 206、276 和 125 mm，而在^第二次实验中；_{ET Ty-S}、ET _Ph-S和 ET _Np-S的累积值分别为 833、968 和 635 mm。将这些结果与累积参考蒸散量（ET ₀）进行比较，ET _{0值（426 mm）在第}^一次实验中高于ET，在^第二次实验中低于ET。发现种植蒸渗仪中的累积 ET 值与未种植的蒸渗仪不同且更高。此外，P. australis的累积 ET 值最高发现比T. latifolia床具有更高的累积 ET 值。关于作物系数（Kc），第^一次试验中Kc的平均季节值相对小于^第二次试验。Kc _{Ph-S值几乎是 Kc Ph-G}的三倍， Kc _{Ty-S值也几乎是 Kc Ty-G}的四倍。

总的来说，这项研究表明，ET 和 Kc 取决于气候条件、大型植物的生长以及种植大型植物的基质类型。