2.2.2 Testing System
The experimental setup mainly consists of a bioretention facility
system, water supply system, and test system. The site layout is shown
in Fig. 4. As shown in Fig. 4(a), the bioretention facility system
consists of a 14-m long bioretention facility belt with three typical
bioretention facilities and a 14 m × 3.5 m simulated municipal road with
compacted loess as the subgrade. The water supply system consists of a
reservoir (5 m × 3 m × 1 m), ② a measuring weir, and ③ a return channel.
The water in the reservoir was pumped to the measuring weir as necessary
during the experiment. An open channel was set at the end of the
bioretention facility belt to form a flow loop with the reservoir.
The test system is mainly composed of ① a test I moisture sensor
section, ② a test II moisture sensor section, ③ a test III moisture
sensor section, and ④ a data collector. The moisture sensor is a CS635
(Campbell Co., USA), and its measurement accuracy is ± 1%. The sensor
was embedded by digging an exploratory well. The influence of water
infiltration on the vertical water content of the site is usually less
than 2 m (Hou et al., 2019b), so a total of 12 soil moisture sensors
were arranged at depths of 1.5 m, 2 m, 2.5 m, and 3 m. The sensor
positions in the test 1 section are shown as an example in Fig. 4(b).
The data collector model is TDS-602 and its fastest sampling speed is
0.02 s.
[Insert Figure 4]