**2. Practice on the WHES: I–Nandadish, a natural CZEB**

#### **2.1. The constructions of Nandadish**

Nandadish catchment is a forest watershed with a surficial drainage area of 7897 m<sup>2</sup> . Before its setting, a geological exploring was made by using of 69 drillings distributed in an area covering not only the surficial watershed drainage area from its surficial divides but more area outside. The bedrock elevation of every drill was then measured, so the hypsographic map of the bedrock can be made, together with that of ground surface, the isopachous map of its Quaternary deposit can then be get as well (**Figure 1**). Also from eight drillings with depth penetrating through the bedrock with core sampling for the formation and lithology explorations, no fault, no fracture, and obvious fissures were found from this igneous stratum of andesitic and tuffaceous facies with a thin-weathered layer. It is good for our idea of *controlled-nature*. The depths of its quaternary regolith resting on the bedrock have a range of 1–7 m with an average of 2.46 m (**Figure 1**). It is deeper near the upper divide but only ca 1 m in thickness near the outlet, making the catchment easy to close via a concrete wall installed to the bedrock at the outlet. The vadose zone consists of brunisolic soil of heavy loam, medium Practice on the Watershed Hydrological Experimental System Reconciling Deterministic… http://dx.doi.org/10.5772/intechopen.79357 255

**1. Introduction**

254 Hydrology of Artificial and Controlled Experiments

A framework of watershed hydrological experimental system (WHES) is suggested raised from the theoretical study on the complex hydrological system. It is defined as an experimental system to dialog with the complex watershed hydrological nature, to drive the opening of various doors of their black boxes aimed at revealing mechanisms hidden deep in the system with some degree of organization. In fact, the organization of the WHES is trying to reconciling the deterministic and stochastic extremes for the watershed hydrological complex system,

As a trial of the suggested WHES, the Chuzhou WHES is ongoing for tests. The constituent parts of the WHES can be resolved into four categories as the "macros", "mesos", "micros," and the "nucleus". "Macros" are composed by pure natural EBs at high level of complexity and randomness; "micros" by pure artificial chain at low level; they are two extreme levels in WHES, while the "mesos" are the chain of intermediate phase; actually, it will play the critical role, the "golden mean," in WHES as described in Chapter 11. The "nucleus" are water isotopes and solute isotopes from all chains of macros, mesos, and micros by overall sampling; it characterizes the internal linkages between them, and reveals their interrelated processes;

In Chuzhou WHES, there are two extremes in the intermediate "meso" blocks (Figure 8a in Chapter 11): One is the controlled-natural Nandadish based on the strategy of constrain complexity, another one is the artificial-natural Hydrohill on that of add complexity. Nandadish is designed to meet with the idea on Critical Zone Experimental Block with an intention trying to replace the current Experimental basins suggested by the Representative and Experimental Basin Programme of the first International Hydrology Decade (IHD) since 1965. These two

typical experimental meso-mediation blocks of Chuzhou WHES are reviewed here.

Nandadish catchment is a forest watershed with a surficial drainage area of 7897 m<sup>2</sup>

its setting, a geological exploring was made by using of 69 drillings distributed in an area covering not only the surficial watershed drainage area from its surficial divides but more area outside. The bedrock elevation of every drill was then measured, so the hypsographic map of the bedrock can be made, together with that of ground surface, the isopachous map of its Quaternary deposit can then be get as well (**Figure 1**). Also from eight drillings with depth penetrating through the bedrock with core sampling for the formation and lithology explorations, no fault, no fracture, and obvious fissures were found from this igneous stratum of andesitic and tuffaceous facies with a thin-weathered layer. It is good for our idea of *controlled-nature*. The depths of its quaternary regolith resting on the bedrock have a range of 1–7 m with an average of 2.46 m (**Figure 1**). It is deeper near the upper divide but only ca 1 m in thickness near the outlet, making the catchment easy to close via a concrete wall installed to the bedrock at the outlet. The vadose zone consists of brunisolic soil of heavy loam, medium

. Before

**2. Practice on the WHES: I–Nandadish, a natural CZEB**

"opposites are complementary" as the basic Chinese philosophy have revealed.

actually, it is an essential condition of in WHES.

**2.1. The constructions of Nandadish**

**Figure 1.** (a) Hypsographic map of the ground surface of Nandadish; (b) hypsographic map of the bedrock surface; and (c) Isopachous map of the deposit thickness (including surficial soil).

and clay loams; saprolite with prismatic and block structures, horizontal and vertical fissures and cracks developed in the upper regolith. The altitude difference of watershed approaches 12.9 m with a surface slope ranging from 6.7 to 17.1%.

Aimed at a CZ hydrological experimental block aforementioned, the main construction tasks as sketchily shown in **Figure 2a** are threefold: (1) To change its original trench into the layered

**Figure 2.** (a) Schematic diagram of Nandadish showing the locations of main construction tasks; (b) original view of the main troughs and the catchment coverages during 1980; 1-trough for rainfall, which is served for separation of "channel rainfall" from surface runoff collected from trough 2, 2-for surface runoff (SR); (c) original view of the branch troughs with a watching gallery for the students practice to seeing the real processes of different runoff components during rainfall event; 1-trough for rainfall, 2-for surface runoff (SR), 3, 4-for subsurface runoff (SSR) from troughs at different depths; (d) measuring structures under construction for different troughs, 1-for rainfall (V-notch sharp crested weir), 2-for SR (V weir and rectangular sharp crested weir), 3-for SSR (V weir and rectangular weir), 4-for SSR (V weir), 5-for total runoff (V weir and rectangular weir, not shown); (e) a part of the underground "block divider" with 0.3 m above the ground surface; (f) the change of runoff compositions within time span of 20 years compared with July 1989 and July 2009 using same measuring structures with different catchment coverages.

troughs aimed at collecting different runoff components for direct monitoring and sampling as well. From the natural surficial topography, a main trench and a branch trench are set up both with four layered troughs with locations shown in **Figure 2a**, the general view is shown in **Figure 2b** and **c**; (2) These troughs are led to discharge measuring structures separately within an underground building, the original view of four measuring structures under construction corresponding to troughs, respectively is shown in **Figure 2d**; (3) For setting of a *controlled-natural* entity, it needs to close all the underground surroundings until bedrock, the "block divider", aimed at *constrain complexity* aforementioned as shown in **Figure 2a** and **e**, it is 367 m in total with average depth of 2.94 m from bed rock to 0.3 m above the ground surface. It is only completed partly because of seeking for a better engineering method for the limited working space.

built up to observe rainfall over trees, rainfall under trees (i.e., throughfall), and stem flow to determine the temporal and spatial redistribution of rainfall, and to estimate the canopy interception. To observe rainfall over trees, four tipping bucket rain gauges were mounted on towers located on the four directions and center of the catchment (**Figure 4b**). To observe throughfall, 8 tipping bucket rain gauges, 80 micro rain gauges under trees, and 94 standard rain gauges under trees were installed under trees (**Figure 4a** and **c**). Stem flow was collected in 14 trees from two dominant tree species (*Q. acutissima* Carruth and *B. papyrifera*) using stem

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To accurately determine the ratios of throughfall, stem flow and canopy interception to gross rainfall, a large quadrat with an area of 25 × 25 m (**Figure 4f**) and a rainfall station under trees with an area of 8.45 × 4.05 m (**Figure 4g**) were constructed in the Nandadish. In this rainfall

**Figure 4.** Instrumentation for precipitation measurement in the Nandadish: (a) locations of stainless troughs and rain gauges; (b) four tipping-bucket rain gauges were mounted on towers; (c) micro rain gauges and standard rain gauges under trees; (d) stem flow measurement using collection collars and tipping-bucket flow meters; (e) the inner construe of the tipping bucket flow meter; (f) photograph of a large quadrat with an area of 20 × 20 m (1-the collection collar collecting stem flow, 2-a tipping-bucket flow meter with 500-mL buckets used to determine the stem flow process; 3-a 100-L water container used to measure the total amount of stem flow); (g) a rainfall station under trees with an area of 8.45 × 4.05 m (1-the collection collar collecting stem flow, 2-a 150-L water container used to buffer the throughfall flow so that the following tipping-bucket flow meter is capable of measuring the flow when strong rain occurs, 3-a tipping-

bucket flow meter with 2.0-L buckets).

flow collection collars and tipping bucket flow meters (**Figure 4d** and **e**).

The coverage during the watershed's construction in 1979 was natural grasses with small shrubs and a few Masson pines aged 5–6 years (**Figure 2b** and **f**). Since then, coverage has shifted to a dense forest with canopy height ca 12 m. There are two dominant tree species (*Q. acutissima Carruth* and *B. papyrifera*) accounting for ~90 and 10%, respectively. The new version of that forest watershed is shown in **Figure 3**.

It follows that a hydrological change is happened, which is summarized in **Figure 2f**, compared with the total runoff 134.57 mm of July 1989 with monthly rainfall of 233.4 mm, the total runoff and all runoff components including surface runoff and subsurface runoff of July 2009 are zero all and even having less monthly rainfall of 186.1 mm. So, the setting of troughs during the renovation of CHL is considered and will be described in the following paragraphs.

#### **2.2. The instrumentation of Nandadish**

#### *2.2.1. Precipitation*

The redistribution of rainfall intensity by the canopy is one of the main research topics in Chuzhou Hydrology Laboratory. Rainfall observation system (**Figure 4a**) in Nandadish was

**Figure 3.** The bird's eye view of the forested Nandadish watershed taken at May 2018. 1-trench with layered troughs; 2-block divider; 3-house for discharge measuring structures.

built up to observe rainfall over trees, rainfall under trees (i.e., throughfall), and stem flow to determine the temporal and spatial redistribution of rainfall, and to estimate the canopy interception. To observe rainfall over trees, four tipping bucket rain gauges were mounted on towers located on the four directions and center of the catchment (**Figure 4b**). To observe throughfall, 8 tipping bucket rain gauges, 80 micro rain gauges under trees, and 94 standard rain gauges under trees were installed under trees (**Figure 4a** and **c**). Stem flow was collected in 14 trees from two dominant tree species (*Q. acutissima* Carruth and *B. papyrifera*) using stem flow collection collars and tipping bucket flow meters (**Figure 4d** and **e**).

To accurately determine the ratios of throughfall, stem flow and canopy interception to gross rainfall, a large quadrat with an area of 25 × 25 m (**Figure 4f**) and a rainfall station under trees with an area of 8.45 × 4.05 m (**Figure 4g**) were constructed in the Nandadish. In this rainfall

**Figure 4.** Instrumentation for precipitation measurement in the Nandadish: (a) locations of stainless troughs and rain gauges; (b) four tipping-bucket rain gauges were mounted on towers; (c) micro rain gauges and standard rain gauges under trees; (d) stem flow measurement using collection collars and tipping-bucket flow meters; (e) the inner construe of the tipping bucket flow meter; (f) photograph of a large quadrat with an area of 20 × 20 m (1-the collection collar collecting stem flow, 2-a tipping-bucket flow meter with 500-mL buckets used to determine the stem flow process; 3-a 100-L water container used to measure the total amount of stem flow); (g) a rainfall station under trees with an area of 8.45 × 4.05 m (1-the collection collar collecting stem flow, 2-a 150-L water container used to buffer the throughfall flow so that the following tipping-bucket flow meter is capable of measuring the flow when strong rain occurs, 3-a tippingbucket flow meter with 2.0-L buckets).

**Figure 3.** The bird's eye view of the forested Nandadish watershed taken at May 2018. 1-trench with layered troughs;

troughs aimed at collecting different runoff components for direct monitoring and sampling as well. From the natural surficial topography, a main trench and a branch trench are set up both with four layered troughs with locations shown in **Figure 2a**, the general view is shown in **Figure 2b** and **c**; (2) These troughs are led to discharge measuring structures separately within an underground building, the original view of four measuring structures under construction corresponding to troughs, respectively is shown in **Figure 2d**; (3) For setting of a *controlled-natural* entity, it needs to close all the underground surroundings until bedrock, the "block divider", aimed at *constrain complexity* aforementioned as shown in **Figure 2a** and **e**, it is 367 m in total with average depth of 2.94 m from bed rock to 0.3 m above the ground surface. It is only completed partly because of seeking for a better engineering method for the limited working space. The coverage during the watershed's construction in 1979 was natural grasses with small shrubs and a few Masson pines aged 5–6 years (**Figure 2b** and **f**). Since then, coverage has shifted to a dense forest with canopy height ca 12 m. There are two dominant tree species (*Q. acutissima Carruth* and *B. papyrifera*) accounting for ~90 and 10%, respectively. The new

It follows that a hydrological change is happened, which is summarized in **Figure 2f**, compared with the total runoff 134.57 mm of July 1989 with monthly rainfall of 233.4 mm, the total runoff and all runoff components including surface runoff and subsurface runoff of July 2009 are zero all and even having less monthly rainfall of 186.1 mm. So, the setting of troughs during the renovation of CHL is considered and will be described in the following paragraphs.

The redistribution of rainfall intensity by the canopy is one of the main research topics in Chuzhou Hydrology Laboratory. Rainfall observation system (**Figure 4a**) in Nandadish was

2-block divider; 3-house for discharge measuring structures.

version of that forest watershed is shown in **Figure 3**.

**2.2. The instrumentation of Nandadish**

256 Hydrology of Artificial and Controlled Experiments

*2.2.1. Precipitation*

*2.2.2. Runoff*

in **Figure 5f**.

*2.2.3. Soil moisture*

*2.2.4. Groundwater*

shown in **Figure 6d**.

*2.2.5. Sap flow*

The surface and subsurface runoff are monitored directly via four layers of troughs fixed in a trench with a gradient of 6.7% (**Figure 5a**). These troughs are stacked on top of each other to capture rainfall, surface, and subsurface flows (**Figure 5b** and **c**): the uppermost trough captures rain; the next lower trough captures surface runoff (SR); and the two lower troughs capture subsurface flow from soil layers spanning the depths of 0–50, and 50–100 cm, inferred as SSR50 and SSR100 troughs. SSR50 and SSR100 troughs have 20-cm stainless lips that extend horizontally into the soil layer to prevent leakage between layers (**Figure 5c**). Waters captured in troughs are routed into a gauging room and measured by 90° V-notch and rectangle weirs (**Figure 5d** and **e**). For SR and SSR50, 90° V-notch and rectangle weirs are combined to measure discharge: when the large discharge occurs (correspondingly the water head above the rectangle weir is higher than 5.0 cm), the V-notch weir fails to measure discharge and the rectangle weir performs better; when the water head above the rectangle weir is lower than 5.0 cm, the discharge is measured more accurately by the V-notch weir than the rectangle weir. For rainfall and SSR100, only V-notch weir is used due to their less discharge compared with that of SR and SSR50. The trough SSR50 previously is located at 30 cm below the ground surface, this depth was extended to 50 cm during renovation due to the big changes happened to the growing of plants together with the deeper extension of their root system as described

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A network of 34 profile soil moisture sensors (SM-1, ADCON, same as those installed in Hydrohill, see latter) were installed in the different depths of soil. The number of profile soil moisture sensors with a depth at 90, 120, and 150 cm below the ground surface are 9, 10, and 15 (**Figure 6a**). The previous network of 34 access tubes (1982–1994) for neutron moisture gauge from UK Institute of Hydrology is shown in **Figure 6c**, the construction of access tube is shown in **Figure 6e**, while the standards of soil moisture for the calibration of neutron

For groundwater monitoring, there are 34 galvanized tube wells intersecting through the soil till the bedrock (**Figure 6b**). Water table measurement is performed with 30 level sensors (LEV1, ADCON, see later in Hydrohill). The previous network of wells for groundwater monitoring and sampling (1982–1994) is shown in **Figure 6c**, while the construction of well is

Sap flow is measured by Granier-type thermal dissipation probes (TDP) (Yugen, Beijing, China) that were installed in the sapwood of sample trees. A set of TDP includes a heated needle above and a reference needle below (**Figure 7a**). The sap flow velocity is calculated based on the temperature difference between the two needles. After the corky bark within a rectangular with a wide of 4 cm and tall of 10 cm was shaved off, the two probe needles

moisture gauge in a special laboratory are shown in **Figure 6f**.

**Figure 5.** Instrumentation for runoff measurement in Nandadish: (a) Main trench with troughs (not shown), (b) the branch trench with four troughs (previously **Figure 13c**), (c) schematic figure illustrating various troughs, (d) discharge measurement structures for different runoff components from troughs 1 for rainfall; 2 and 3 for surface runoff; 4 and 5 for interflow (50 cm below the soil surface); 6 for interflow and groundwater flow (down to bedrock); 7 and 8 for total runoff (weirs are shown (f)and (g)). 1, 3, 5, 6, and 8 are 90° V-notch weir; 2, 4 and 7 are the full width rectangular weirs; 9 is the probe-type water level gauge; 10 is a video for monitoring the runoff processed, (e) combination of a 90° V-notch weir and a full width rectangular weir for SR, SSR50, and the total runoff, (f) the full width rectangular weir for total runoff, (g) the 90° V-notch weir for total runoff.

station, three trees of about 20 years were included, and three tipping bucket flow meters (0.4 L per bucket) were installed to measure the stem flow of each tree. A closing apparatus like a roof was explored to collect the total through rain. This apparatus is named as "collecting roof". The collecting roof with a large area will result in a total amount of through rain when strong rainfalls occur, and thus large flow rates appear in the two outlets of the collecting roof. Two larger tipping bucket flow meters (2.0 L per bucket) were installed in the two outlets to measure flow rates. In addition to measure stem flow and through rain, a tipping bucket rain gauge was laid over the trees to record the rainfall inputting the rainfall station. According to water balance, the rainfall over the trees equals to the sum of stem flows, through rain and interception of trees.

#### *2.2.2. Runoff*

The surface and subsurface runoff are monitored directly via four layers of troughs fixed in a trench with a gradient of 6.7% (**Figure 5a**). These troughs are stacked on top of each other to capture rainfall, surface, and subsurface flows (**Figure 5b** and **c**): the uppermost trough captures rain; the next lower trough captures surface runoff (SR); and the two lower troughs capture subsurface flow from soil layers spanning the depths of 0–50, and 50–100 cm, inferred as SSR50 and SSR100 troughs. SSR50 and SSR100 troughs have 20-cm stainless lips that extend horizontally into the soil layer to prevent leakage between layers (**Figure 5c**). Waters captured in troughs are routed into a gauging room and measured by 90° V-notch and rectangle weirs (**Figure 5d** and **e**). For SR and SSR50, 90° V-notch and rectangle weirs are combined to measure discharge: when the large discharge occurs (correspondingly the water head above the rectangle weir is higher than 5.0 cm), the V-notch weir fails to measure discharge and the rectangle weir performs better; when the water head above the rectangle weir is lower than 5.0 cm, the discharge is measured more accurately by the V-notch weir than the rectangle weir. For rainfall and SSR100, only V-notch weir is used due to their less discharge compared with that of SR and SSR50. The trough SSR50 previously is located at 30 cm below the ground surface, this depth was extended to 50 cm during renovation due to the big changes happened to the growing of plants together with the deeper extension of their root system as described in **Figure 5f**.

#### *2.2.3. Soil moisture*

A network of 34 profile soil moisture sensors (SM-1, ADCON, same as those installed in Hydrohill, see latter) were installed in the different depths of soil. The number of profile soil moisture sensors with a depth at 90, 120, and 150 cm below the ground surface are 9, 10, and 15 (**Figure 6a**). The previous network of 34 access tubes (1982–1994) for neutron moisture gauge from UK Institute of Hydrology is shown in **Figure 6c**, the construction of access tube is shown in **Figure 6e**, while the standards of soil moisture for the calibration of neutron moisture gauge in a special laboratory are shown in **Figure 6f**.

#### *2.2.4. Groundwater*

For groundwater monitoring, there are 34 galvanized tube wells intersecting through the soil till the bedrock (**Figure 6b**). Water table measurement is performed with 30 level sensors (LEV1, ADCON, see later in Hydrohill). The previous network of wells for groundwater monitoring and sampling (1982–1994) is shown in **Figure 6c**, while the construction of well is shown in **Figure 6d**.

#### *2.2.5. Sap flow*

station, three trees of about 20 years were included, and three tipping bucket flow meters (0.4 L per bucket) were installed to measure the stem flow of each tree. A closing apparatus like a roof was explored to collect the total through rain. This apparatus is named as "collecting roof". The collecting roof with a large area will result in a total amount of through rain when strong rainfalls occur, and thus large flow rates appear in the two outlets of the collecting roof. Two larger tipping bucket flow meters (2.0 L per bucket) were installed in the two outlets to measure flow rates. In addition to measure stem flow and through rain, a tipping bucket rain gauge was laid over the trees to record the rainfall inputting the rainfall station. According to water balance, the rainfall over the trees equals to the sum of stem flows, through rain and

**Figure 5.** Instrumentation for runoff measurement in Nandadish: (a) Main trench with troughs (not shown), (b) the branch trench with four troughs (previously **Figure 13c**), (c) schematic figure illustrating various troughs, (d) discharge measurement structures for different runoff components from troughs 1 for rainfall; 2 and 3 for surface runoff; 4 and 5 for interflow (50 cm below the soil surface); 6 for interflow and groundwater flow (down to bedrock); 7 and 8 for total runoff (weirs are shown (f)and (g)). 1, 3, 5, 6, and 8 are 90° V-notch weir; 2, 4 and 7 are the full width rectangular weirs; 9 is the probe-type water level gauge; 10 is a video for monitoring the runoff processed, (e) combination of a 90° V-notch weir and a full width rectangular weir for SR, SSR50, and the total runoff, (f) the full width rectangular weir for total

interception of trees.

runoff, (g) the 90° V-notch weir for total runoff.

258 Hydrology of Artificial and Controlled Experiments

Sap flow is measured by Granier-type thermal dissipation probes (TDP) (Yugen, Beijing, China) that were installed in the sapwood of sample trees. A set of TDP includes a heated needle above and a reference needle below (**Figure 7a**). The sap flow velocity is calculated based on the temperature difference between the two needles. After the corky bark within a rectangular with a wide of 4 cm and tall of 10 cm was shaved off, the two probe needles

**Figure 6.** (a) Locations of profile soil moisture sensors with different depths: 90, 120, and 150 cm (since 2012); (b) network of wells for groundwater monitoring and sampling (since 2012); (c) previous network of access tubes for soil moisture monitoring and that of wells for groundwater monitoring (1982–1994); (d) construction of groundwater monitoring well; (e) construction of access tube for neutron moisture gauge (1982–1994); (f) standards of soil moisture with volumetric contents from 100 to 3% in a special laboratory for the calibration of neutron moisture gauge.

**2.3. Water sampling**

entering.

reaches the ponding of the weir.

Water samples from precipitation, runoffs, and plants were collected. Rain water samples were collected via a specially designed rain gauge and a standard rain gauge, which were installed on the roof of the gauging room (**Figure 8a**). The specially designed rain gauge is capable of collecting rain samples at 1-hour interval, while the standard rain gauge collects the mixed sample of each rain event. A batch sampling system is designed and constructed based on the negative pressure to easily and fast collect the water samples of runoff components of SR, SSR50, and SSR100 (**Figure 8b**). Water samples for runoff components are collected also via a stainless steel tube head fixed at the connection trough before the runoff

**Figure 7.** Installation of thermal dissipation probes: (a) a set of TDP includes a heated needle (1) and a reference needle (2); (b) the reflective bubble shield (3) was wrapped around the TDP probe to avoid monitoring errors caused by direct sunlight and rainfall leaching, and a collection collar (4) for stem flow was installed above the TDP to stop stem flow

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was inserted into the sapwood approximately 5 cm apart vertically. The reflective bubble shield was wrapped around the TDP probe to avoid monitoring errors caused by direct sunlight and rainfall leaching (**Figure 7b**). In the Nandadish catchment, totally 24 sets of TDPs were installed for 12 trees from 5 species, including three *Quercus acutissima Carruth*, three *Broussonetia papyrifera, two Populus L.*, two *Celtis L,* and two *Melia azedarach L.*, to match the sapwood width of different tree species with different DBH, three different lengths of the probe (TDP10, TDP20, and TDP30) were adopted. All of the TDPs were installed about 145 cm above ground, and on both of the south and north sides of each sample tree. The temperature difference between the two needles was scanned at 1 min intervals, and the 10 min average value was recorded by a data logger (CR1000, Campbell, USA Scientific Inc., Logan, UT, USA).

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**Figure 7.** Installation of thermal dissipation probes: (a) a set of TDP includes a heated needle (1) and a reference needle (2); (b) the reflective bubble shield (3) was wrapped around the TDP probe to avoid monitoring errors caused by direct sunlight and rainfall leaching, and a collection collar (4) for stem flow was installed above the TDP to stop stem flow entering.

#### **2.3. Water sampling**

was inserted into the sapwood approximately 5 cm apart vertically. The reflective bubble shield was wrapped around the TDP probe to avoid monitoring errors caused by direct sunlight and rainfall leaching (**Figure 7b**). In the Nandadish catchment, totally 24 sets of TDPs were installed for 12 trees from 5 species, including three *Quercus acutissima Carruth*, three *Broussonetia papyrifera, two Populus L.*, two *Celtis L,* and two *Melia azedarach L.*, to match the sapwood width of different tree species with different DBH, three different lengths of the probe (TDP10, TDP20, and TDP30) were adopted. All of the TDPs were installed about 145 cm above ground, and on both of the south and north sides of each sample tree. The temperature difference between the two needles was scanned at 1 min intervals, and the 10 min average value was recorded by a data logger (CR1000, Campbell, USA Scientific Inc.,

**Figure 6.** (a) Locations of profile soil moisture sensors with different depths: 90, 120, and 150 cm (since 2012); (b) network of wells for groundwater monitoring and sampling (since 2012); (c) previous network of access tubes for soil moisture monitoring and that of wells for groundwater monitoring (1982–1994); (d) construction of groundwater monitoring well; (e) construction of access tube for neutron moisture gauge (1982–1994); (f) standards of soil moisture with volumetric contents from 100 to 3% in a special laboratory for the calibration of neutron moisture

Logan, UT, USA).

gauge.

260 Hydrology of Artificial and Controlled Experiments

Water samples from precipitation, runoffs, and plants were collected. Rain water samples were collected via a specially designed rain gauge and a standard rain gauge, which were installed on the roof of the gauging room (**Figure 8a**). The specially designed rain gauge is capable of collecting rain samples at 1-hour interval, while the standard rain gauge collects the mixed sample of each rain event. A batch sampling system is designed and constructed based on the negative pressure to easily and fast collect the water samples of runoff components of SR, SSR50, and SSR100 (**Figure 8b**). Water samples for runoff components are collected also via a stainless steel tube head fixed at the connection trough before the runoff reaches the ponding of the weir.

**Figure 8.** Water sampling in Nandadish: (a) sampling for precipitation, 1-a specially designed rain gauge capable of collecting rain samples at one-hour interval, 2-a standard rain gauge collecting the mixed sample of each rain event, 3-a tube directing rain water into a sampling bottle at the gauging room; (b) sampling for runoff components, 1-a sample bottle for SR, 2-a sample bottle for SSR50, 3-a sample bottle for SSR100, 4-a safeguard bottle.
