**3. Experimental laboratory**

1-min time step. Suction lysimeters designed by IGSNRR are placed at the same depth of water potential sensors to collect pore water from unsaturated soil. The pore water is trans-

In the catchment, a total of 13 water runoff and erosion plots were set up at both sides of the channel representing different type of vegetation. Eight plots (5 × 20 m) from P1 to P8 are located at southern hill slope of the channel. The plots are characterized by different vegetations, which are corns/wheat, bare, grasses, shrubs, paper mulberries, peanuts, peaches, apricots, *Phyllanthus urinarias*, and *Angelica keiskei*. Each runoff plot is located at a slope of 15°. The plot borders 50 cm above the soil surface are made of concrete and sufficiently embedded into the soil. At the downslope end of each plot is a trough, connected to a drum for storage of

In addition, a rainfall simulation system designed by IGSNRR is set up on the P1 and P2 plots. The system includes a submersible pump, electromagnetic flowmeters, sprinkler nozzles, and spray pipes (**Figure 6**). The sprinkler nozzle is installed at a height of 6.0 m so that the drops could reach a horizontal distance of at least 10 m to cover the whole 2 plots. Three rain gauges are positioned at every plot to monitor the simulated and natural rainfalls. A

runoff. Two collecting tanks of the same size are used for each runoff plot.

ported to the bottle through Teflon pipe.

**Figure 6.** Schematic layout of water runoff and erosion plots.

*2.2.8. Water runoff and erosion plot*

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Experimental Hall of Water and Soil Process is located in the geographical museum of IGSNRR. It is 80 m long, 18 m wide, and 22 m high. It is a new integrated water cycle experiment platform, based on the new technology integrated control, measurement, sensors, information processing, developed from China's first artificial rainfall runoff laboratory, slope erosion laboratory, and fluvial geomorphology laboratory in the 1950s. It includes artificial rainfall system, experimental sink of runoff and erosion, river simulation system, and transformation dynamical processes experimental device among precipitation, vegetation water, surface water, soil water, and groundwater.

#### **3.1. Artificial rainfall system**

The artificial rainfall system finished in December 2015 is set up at the height of 18 m in the hall. It includes three rainfall zones: Z1, Z2, and Z3 (**Figure 7**). The total area is 370 m2 . The rainfall can be achieved in each separate zone or in all three zones at the same time. The system consists of variable speed pumps, stainless pipes, control center, laser rainfall monitor, and sets of solenoid valves and spraying nozzles (**Figure 7**). Every set of solenoid valves and spraying includes three valves and three nozzles which can be combined to produce 12–300 mm/h rain and mobile storm. A pressure-compensated flow control valve and a pressure gauge are located at the same altitude of the nozzle allowing a precise control of water pressure and consequently the constancy of rain kinetic energy. The artificial rainfall system is automatically regulated in the control center. The calibration tests showed that the uniformity of the rainfall intensities was greater than 85%.

The rate of motion is as slow as 30–70 mm/day. The multi-function automatic measuring bridge is placed above the system to move from the upstream to the downstream. It can automatically measure water flow, water depth, and cross-section of the modeled river. At the end, there is a

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**Figure 8.** Schematic layout of the river simulation system (top) and one type of crustal shape (bottom).

It consists of two metal rectangular boxes, 10 m long, 3 m wide, and 0.8 m high, and each one is located under artificial rainfall zone 1 and zone 2 (**Figure 9**). The interval area, 1 m wide, is kept between the two boxes in order to easily assemble them into a bigger one. The slope of the experimental sink could be adjusted automatically from 0 to 35°. One 5 cm hole is cut into the downslope end of each plot. A short metal stub pipe is welded on to the hole to form an outlet. Two water flow monitors [14] are horizontally set up in front of the each box for the measurement of the runoff. The box outlet and flow monitor are fitted together with a flexible PVC pipe. The monitor should have lids to prevent direct rainfall from entering them. For simulated rainfalls, runoff volume measurements and sediment sample collection are per-

**3.4. Transformation dynamical processes experimental device among precipitation,** 

consists of two sections joined together, the up section and the down section.

The transformation dynamical processes experimental device among precipitation, vegetation water, surface water, soil water, and groundwater (TDPEDPVSSG) finished in July 2014 is a complex equipment to study the water process among the five different types of water (**Figure 10**). It is hermetically sealed in the house (7 m long, 5 m wide, and 7.5 m high) and

big tank where the recycled water can be pumped to the upstream.

**vegetation water, surface water, soil water, and groundwater**

**3.3. Experimental sink of runoff and erosion**

formed every 5 s and 5 min, respectively.

**Figure 7.** Schematic layout of artificial rainfall system: (a) three zones, (b) laser rainfall intensity monitor, and (c) four component sections.

Laser rainfall intensity monitor is installed at the mid-height of nozzles. It is composed of an array of laser transmitters and receivers (**Figure 7**). It achieves the rain non-touch measurement using orthogonally multiplexed laser beams according to the light attenuation law. The measurement error is less than 2%.

#### **3.2. River simulation system**

The river simulation system is 38 long, 6 m wide, and 1 m high (**Figure 8**). The borders are made of concrete and sealed with the ground to prevent water leaching from them. The crustal lifting simulation system is installed in the middle [13]. It is composed of 12 square steel blocks (2 × 2 m). Each block is supported by four stainless steel-threaded rods, which can be adjusted up and down. The 12 square blocks can be automatically motioned to form 82 types of crustal shape.

**Figure 8.** Schematic layout of the river simulation system (top) and one type of crustal shape (bottom).

The rate of motion is as slow as 30–70 mm/day. The multi-function automatic measuring bridge is placed above the system to move from the upstream to the downstream. It can automatically measure water flow, water depth, and cross-section of the modeled river. At the end, there is a big tank where the recycled water can be pumped to the upstream.

#### **3.3. Experimental sink of runoff and erosion**

Laser rainfall intensity monitor is installed at the mid-height of nozzles. It is composed of an array of laser transmitters and receivers (**Figure 7**). It achieves the rain non-touch measurement using orthogonally multiplexed laser beams according to the light attenuation law. The

**Figure 7.** Schematic layout of artificial rainfall system: (a) three zones, (b) laser rainfall intensity monitor, and (c) four

The river simulation system is 38 long, 6 m wide, and 1 m high (**Figure 8**). The borders are made of concrete and sealed with the ground to prevent water leaching from them. The crustal lifting simulation system is installed in the middle [13]. It is composed of 12 square steel blocks (2 × 2 m). Each block is supported by four stainless steel-threaded rods, which can be adjusted up and down. The 12 square blocks can be automatically motioned to form 82 types of crustal shape.

measurement error is less than 2%.

120 Hydrology of Artificial and Controlled Experiments

**3.2. River simulation system**

component sections.

It consists of two metal rectangular boxes, 10 m long, 3 m wide, and 0.8 m high, and each one is located under artificial rainfall zone 1 and zone 2 (**Figure 9**). The interval area, 1 m wide, is kept between the two boxes in order to easily assemble them into a bigger one. The slope of the experimental sink could be adjusted automatically from 0 to 35°. One 5 cm hole is cut into the downslope end of each plot. A short metal stub pipe is welded on to the hole to form an outlet. Two water flow monitors [14] are horizontally set up in front of the each box for the measurement of the runoff. The box outlet and flow monitor are fitted together with a flexible PVC pipe. The monitor should have lids to prevent direct rainfall from entering them. For simulated rainfalls, runoff volume measurements and sediment sample collection are performed every 5 s and 5 min, respectively.

#### **3.4. Transformation dynamical processes experimental device among precipitation, vegetation water, surface water, soil water, and groundwater**

The transformation dynamical processes experimental device among precipitation, vegetation water, surface water, soil water, and groundwater (TDPEDPVSSG) finished in July 2014 is a complex equipment to study the water process among the five different types of water (**Figure 10**). It is hermetically sealed in the house (7 m long, 5 m wide, and 7.5 m high) and consists of two sections joined together, the up section and the down section.

**Figure 9.** Schematic layout of experimental sink of runoff and erosion.

The down section has two weighable lysimeters. Each lysimeter has a rectangle stainless steel tank with a surface area of 6 m2 (3 m long, 2 m wide) and a depth of 3 m. It is designed to have enough depth to accommodate the rooting depth of most plants and control the groundwater level. A drainage discharge and water supply system at the bottom is designed to facilitate the fluctuation of groundwater level. The gap between the concrete wall and the stainless container is less than 2 cm to avoid alteration of the energy balance of the system. This gap has been covered with a flexible and impermeable rubber film in the surface. Each lysimeter tank rests on a base frame that transmits the weight through a lever system with a counterweight to an electronic load cell. The lever arm reduces the majority of the total mass of tank and soil to a small fraction of some kilograms that are measured by load cell. It measures those soil mass with an accuracy of 60 g which corresponds to a precipitation or water column of 0.01 mm. The output signal of the sensor is transmitted to a computer located in the control room. The frequency of data collection is 30-min interval.

Inc., USA), dielectric water potential (MPS-2, Decagon Devices, Inc., USA), and suction lysimeter designed by IGSNRR are installed in side of the tank at the depths of 20, 43, 53, 63, 73, 83,

**Figure 10.** Schematic layout of the transformation dynamical processes experimental device among precipitation,

cally controlled. The temperature and humidity are generally controlled by air conditioner and humidifier. The light (0–30,000 LUX) is produced by 12 high-pressure sodium lamps above the

can be automati-

are ±1°C, ±5%, and

is emitted from the steel CO2

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The up section is a phytotron where the temperature, humidity, light, and CO2

cylinder tank. The precision of controlling temperature, humidity, and CO2

92.5, 110.5, 130.5, 150.5, 180.5, 210.5, 240.5, and 275.5 cm.

vegetation water, surface water, soil water, and groundwater.

±100 ppm, respectively.

lysimeter, which can be adjusted up and down manually. CO2

In the northern lysimeter, the silt loam is homogeneously placed. However, in the southern lysimeter, three horizons of soil (silt loam and silty sandy loam) are placed, and each horizon depth is 1 m. The type of soil structure is prevalent in this region of North China. Fourteen sets of soil moisture, temperature, and electrical conductivity sensor (5TE, Decagon Devices,

**Figure 10.** Schematic layout of the transformation dynamical processes experimental device among precipitation, vegetation water, surface water, soil water, and groundwater.

The down section has two weighable lysimeters. Each lysimeter has a rectangle stain-

designed to have enough depth to accommodate the rooting depth of most plants and control the groundwater level. A drainage discharge and water supply system at the bottom is designed to facilitate the fluctuation of groundwater level. The gap between the concrete wall and the stainless container is less than 2 cm to avoid alteration of the energy balance of the system. This gap has been covered with a flexible and impermeable rubber film in the surface. Each lysimeter tank rests on a base frame that transmits the weight through a lever system with a counterweight to an electronic load cell. The lever arm reduces the majority of the total mass of tank and soil to a small fraction of some kilograms that are measured by load cell. It measures those soil mass with an accuracy of 60 g which corresponds to a precipitation or water column of 0.01 mm. The output signal of the sensor is transmitted to a computer located in the control room. The frequency of data

In the northern lysimeter, the silt loam is homogeneously placed. However, in the southern lysimeter, three horizons of soil (silt loam and silty sandy loam) are placed, and each horizon depth is 1 m. The type of soil structure is prevalent in this region of North China. Fourteen sets of soil moisture, temperature, and electrical conductivity sensor (5TE, Decagon Devices,

(3 m long, 2 m wide) and a depth of 3 m. It is

less steel tank with a surface area of 6 m2

122 Hydrology of Artificial and Controlled Experiments

**Figure 9.** Schematic layout of experimental sink of runoff and erosion.

collection is 30-min interval.

Inc., USA), dielectric water potential (MPS-2, Decagon Devices, Inc., USA), and suction lysimeter designed by IGSNRR are installed in side of the tank at the depths of 20, 43, 53, 63, 73, 83, 92.5, 110.5, 130.5, 150.5, 180.5, 210.5, 240.5, and 275.5 cm.

The up section is a phytotron where the temperature, humidity, light, and CO2 can be automatically controlled. The temperature and humidity are generally controlled by air conditioner and humidifier. The light (0–30,000 LUX) is produced by 12 high-pressure sodium lamps above the lysimeter, which can be adjusted up and down manually. CO2 is emitted from the steel CO2 cylinder tank. The precision of controlling temperature, humidity, and CO2 are ±1°C, ±5%, and ±100 ppm, respectively.
