scholarly journals Tracking Sustainable Restoration in Agro-Pastoral Ecotone of Northwest China

2021 ◽  
Vol 13 (24) ◽  
pp. 5031
Author(s):  
Lixiao Yang ◽  
Stéphanie Horion ◽  
Chansheng He ◽  
Rasmus Fensholt
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Ecological Restoration ◽  
Water Resource Management ◽  
Vegetation Index ◽  
Northwest China ◽  
Water Dynamics ◽  
Anthropogenic Activity ◽  
Contribution Rate ◽  
Change Type

Large-scale ecological restoration (ER) projects have been implemented in northwest China in recent decades as a means to prevent desertification and improve ecosystem services. However, previous studies have demonstrated adverse impacts in the form of widespread soil water deficit caused by intensive ER activities. Understanding the role of climate change and ER efforts in vegetation dynamics and soil moisture consumption is essential for sustainable ecosystem management. Here, we used the break for additive season and trend (BFAST) method to analyse spatial patterns in the normalized difference vegetation index (NDVI) variation over the agro-pastoral ecotone of northwest China (APENC) for 2000–2015. From the combined use of generalized additive modelling (GAM) and residual-trend analysis (RESTREND), we distinguished and quantified the effects of climate and human management on vegetation and soil water dynamics. Approximately 78% of the area showed vegetation variations representing a significant change in NDVI, of which more than 68% were categorized as abrupt changes. Large areas of the abrupt change type, interrupted increase and monotonic increase in NDVI were observed before 2006, and small areas of the change type of negative reversals were observed after 2012. Anthropogenic activity was found to be the major driving factor of variation in vegetation (contribution rate of 56%) and soil moisture (contribution rate of 78%). The vegetation expansion, which was mainly related to the large number of ER programs that started in 2000, was found to increase soil moisture depletion. By comparing areas where anthropogenic activities had a high contribution rate to vegetation increase and areas where soil moisture consumption was severely increased, we identify and discuss hotspot areas of soil moisture consumption caused by the ER programs. The current methodological workflow and results represent a novel foundation to inform and support water resource management and ecological-restoration-related policy making.

A laboratory study of the effect of soil-water dynamics on the migration of gases from subsurface sources

2021 ◽  
Author(s):  
Ana M. C. Ilie ◽  
Tissa H. Illangasekare ◽  
Kenichi Soga ◽  
William R. Whalley
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Sandy Soil ◽  
Land Surface ◽  
Soil Gas ◽  
Water Dynamics ◽  
Gas Migration ◽  
Soil Water Dynamics ◽  
Scale Test ◽  
Properties Of Soil

<p>Understanding the soil-gas migration in unsaturated soil is important in a number of problems that include carbon loading to the atmosphere from the bio-geochemical activity and leakage of gases from subsurface sources from carbon storage unconventional energy development. The soil water dynamics in the vadose zone control the soil-gas pathway development and, hence, the gas flux's spatial and temporal distribution at the soil surface. The spatial distribution of soil-water content depends on soil water characteristics. The dynamics are controlled by the water flux at the land surface and water table fluctuations. Physical properties of soil give a better understanding of the soil gas dynamics and migration from greater soil depths. The fundamental process of soil gas migration under dynamic water content was investigated in the laboratory using an intermediate-scale test system under controlled conditions that is not possible in the field. The experiments focus on observing the methane gas migration in relation to the physical properties of soil and the soil moisture patterns. A 2D soil tank with dimensions of 60 cm × 90 cm × 5.6 cm (height × length × width) was used.  The tank was heterogeneously packed with sandy soil along with a distributed network of soil moisture, temperature, and electrical conductivity sensors. The heterogeneous soil configuration was designed using nine uniform silica sands with the effective sieve numbers #16, #70, #8, #40/50, #110, #30/40, #50, and #20/30 (Accusands, Unimin Corp., Ottawa, MN), and a porosity ranging in values from 0.31 to 0.42. Four methane infrared gas sensors and a Flame Ionization detector (HFR400 Fast FID) were used for the soil gas sampling at different depths within the soil profiles and at the land surface.  A complex transient soil moisture distribution and soil gas migration patterns were observed in the 2D tank. These processes were successfully captured by the sensors. These preliminary experiments helped us to understand the mechanism of soil moisture sensor response and methane gas migration into a heterogeneous sandy soil with a view to developing a large-scale test in a 3D tank (4.87 m × 2.44 m × 0.40 m) and finally transition to field deployment.</p>

scholarly journals Relating surface backscatter response from TRMM Precipitation Radar to soil moisture: results over a semi-arid region

2009 ◽  
Vol 6 (5) ◽  
pp. 6425-6454
Author(s):  
H. Stephen ◽  
S. Ahmad ◽  
T. C. Piechota ◽  
C. Tang
Keyword(s):  
Soil Moisture ◽  
Water Content ◽  
Soil Water ◽  
Soil Water Content ◽  
Arid Regions ◽  
Vegetation Index ◽  
Temporal Trends ◽  
Model Parameters ◽  
Precipitation Radar ◽  
Semi Arid

Abstract. The Tropical Rainfall Measuring Mission (TRMM) carries aboard the Precipitation Radar (TRMMPR) that measures the backscatter (σ°) of the surface. σ° is sensitive to surface soil moisture and vegetation conditions. Due to sparse vegetation in arid and semi-arid regions, TRMMPR σ° primarily depends on the soil water content. In this study we relate TRMMPR σ° measurements to soil water content (ms) in Lower Colorado River Basin (LCRB). σ° dependence on ms is studied for different vegetation greenness values determined through Normalized Difference Vegetation Index (NDVI). A new model of σ° that couples incidence angle, ms, and NDVI is used to derive parameters and retrieve soil water content. The calibration and validation of this model are performed using simulated and measured ms data. Simulated ms is estimated using Variable Infiltration Capacity (VIC) model whereas measured ms is acquired from ground measuring stations in Walnut Gulch Experimental Watershed (WGEW). σ° model is calibrated using VIC and WGEW ms data during 1998 and the calibrated model is used to derive ms during later years. The temporal trends of derived ms are consistent with VIC and WGEW ms data with correlation coefficient (R) of 0.89 and 0.74, respectively. Derived ms is also consistent with the measured precipitation data with R=0.76. The gridded VIC data is used to calibrate the model at each grid point in LCRB and spatial maps of the model parameters are prepared. The model parameters are spatially coherent with the general regional topography in LCRB. TRMMPR σ° derived soil moisture maps during May (dry) and August (wet) 1999 are spatially similar to VIC estimates with correlation 0.67 and 0.76, respectively. This research provides new insights into Ku-band σ° dependence on soil water content in the arid regions.

Water source and transmission in Haloxylon ammodendron in the desert margin of the Manas River Basin, China

2021 ◽  
pp. 1-12
Author(s):  
Wanjing Li ◽  
Li Zhao ◽  
Guang Yang ◽  
Ke Yan ◽  
Xinlin He ◽  
...  
Keyword(s):  
Soil Water ◽  
Ecological Restoration ◽  
Moisture Transfer ◽  
Water Source ◽  
Desert Plant ◽  
Contribution Rate ◽  
Haloxylon Ammodendron ◽  
Water Transportation ◽  
Stem Flow ◽  
Average Contribution

Abstract Analysis of water source and moisture transfer characteristics of desert plants is of great significance for ecological restoration in arid areas. In this study, the water source utilized by the desert plant, Haloxylon ammodendron, was analysed using the stable isotope technique, and the water transportation characteristics were obtained based on the proportional heat balance method under different weather conditions. The results showed that (1) before raining, the moisture of H. ammodendron mainly relied on groundwater (the average contribution rate was 34.14%) and on soil water located at a depth of 120–180 cm (the average contribution rate was 29.87%). After the rain, H. ammodendron mainly absorbed soil water from a depth of 60–120 cm (the average contribution rate was 33.19%) and groundwater (the average contribution rate was 30.67%); (2) the stem flow of H. ammodendron showed an obvious diurnal variation, showing a “midday rest” phenomenon. The stem flow showed a peak value, and in sunny days, it was ~2 fold higher than that in cloudy days. (3) The stem flow rate of H. ammodendron varied regularly overtime as follows: August > July > September > June > May, and the meteorological factors affecting its stem flow were solar radiation (0.826) > atmospheric temperature (0.598) > humidity (-0.573). The results provide basic support for the ecological conservation of the desert plant H. ammodendron, while also having important implications for ecological restoration in arid regions.

scholarly journals Parameterization of Soil Hydraulic Parameters for HYDRUS-3D Simulation of Soil Water Dynamics in a Drip-Irrigated Orchard

Water ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 1858 ◽  
Author(s):  
Jesús María Domínguez-Niño ◽  
Gerard Arbat ◽  
Iael Raij-Hoffman ◽  
Isaya Kisekka ◽  
Joan Girona ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Drip Irrigation ◽  
Water Dynamics ◽  
Hydraulic Parameters ◽  
Soil Water Dynamics ◽  
Heterogeneous Distribution ◽  
Neutron Probe ◽  
Soil Hydraulic Parameters ◽  
Soil Hydraulic

Although surface drip irrigation allows an efficient use of water in agriculture, the heterogeneous distribution of soil water complicates its optimal usage. Mathematical models can be used to simulate the dynamics of water in the soil below a dripper and promote: a better understanding, and optimization, of the design of drip irrigation systems, their improved management and their monitoring with soil moisture sensors. The aim of this paper was to find the most appropriate configuration of HYDRUS-3D for simulating the soil water dynamics in a drip-irrigated orchard. Special emphasis was placed on the source of the soil hydraulic parameters. Simulations parameterized using the Rosetta approach were therefore compared with others parameterized using that of HYPROP + WP4C. The simulations were validated on a seasonal scale, against measurements made using a neutron probe, and on the time course of several days, against tensiometers. The results showed that the best agreement with soil moisture measurements was achieved with simulations parameterized from HYPROP + WP4C. It further improved when the shape parameter n was empirically calibrated from a subset of neutron probe measurements. The fit of the simulations with measurements was best at positions near the dripper and worsened at positions outside its wetting pattern and at depths of 80 cm or more.

Water exchange process and water uptake for irrigated maize cropland in a desert-oasis transition area, Northwest China

2020 ◽  
Author(s):  
Yongyong Zhang ◽  
Wenzhi Zhao ◽  
Chun Zhao
Keyword(s):  
Soil Moisture ◽  
Stable Isotope ◽  
Water Potential ◽  
Soil Water ◽  
Water Exchange ◽  
Exchange Process ◽  
Northwest China ◽  
Transition Area ◽  
Desert Oasis ◽  
Water Stable Isotope

<p>Soil water and groundwater convert frequently under cropland in a desert-oasis transition area, Northwest China. Crops variedly utilize soil water and groundwater during different growth periods under the cropland with shallow groundwater. The study of water exchange process under irrigated cropland has important significance for regulating the contradiction between water saving and groundwater recharge in the desert-oasis transition area. Soil moisture and soil matric potential at depths ranging from 0 to 70 cm were measured using HydraProbe II and TEROS-21 soil sensors in maize (Zea mays L.) fields in 2019. Stable isotope (δ<sup>2</sup>H、δ<sup>18</sup>O) in different water sources (precipitation, irrigation water, soil water, crop stem, and groundwater) was also measured. The results showed that the groundwater depth varied between 0.57-1.07 m during the maize growth periods. The groundwater depth increased in summer due to the influence of pumped well, while the depth decreased in autumn resulting from the irrigation return water. In the maize growing season, soil moisture and water potential at depths from 10 cm to 30 cm responded to three irrigation times, while soil moisture and water potential below the depth of 50 cm were greater and kept a steady state, which were affected by upward capillary rise of groundwater. The relationship of soil water stable isotope values ​​was δ<sup>2</sup>H=2.45δ<sup>18</sup>O-31.41, which was lower than the slope of the local atmospheric precipitation line due to the evaporation effect. The soil water stable isotope values at depth of 10 cm varied, while the variation of soil water stable isotope values decreased with the increase of soil depth. The soil water stable isotope values at the depths from 70 to 90cm were close to the groundwater isotope values, which were affected by the groundwater. The stable isotope values in crop stem water were relatively scattered, indicating that the maize used multiple water sources and the water use strategy changed during the growth periods.</p>

scholarly journals Incorporation of Manure into Ridge and Furrow Planting System Boosts Yields of Maize by Optimizing Soil Moisture and Improving Photosynthesis

Agronomy ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 865 ◽  
Author(s):  
Anzhen Qin ◽  
Yanjie Fang ◽  
Dongfeng Ning ◽  
Zhandong Liu ◽  
Ben Zhao ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Soil Water ◽  
Loess Plateau ◽  
Cropping System ◽  
Northwest China ◽  
Chemical Fertilizer ◽  
Arid Areas ◽  
Grain Yields ◽  
Semi Arid ◽  
Planting System

A sustainable management strategy of soil fertility and cropping system is critical to guaranteeing food security. However, little is known about the effects of soil amendment strategies on crop growth via regulating soil moisture and photosynthesis in a ridge and furrow cropping system. Here, field experiments were carried out in 2017 and 2018 in semi-arid areas of Loess Plateau, northwest China to investigate the effects of integrated use of ridge and furrow planting and manure amendment on grain yields of maize. Four treatments were designed: CK (flat planting with 100% chemical fertilizer), RFC (ridge and furrow planting with 100% chemical fertilizer), RFR (ridge and furrow planting with 100% control-released fertilizer), and RFM (ridge and furrow planting with 50% manure fertilizer + 50% N fertilizer). On average, RFM increased photosynthetic rates (Pn) by 74%, followed by RFR by 47%, and RFC by 26%, compared to CK. Also, stomatal conductance (Cd), transpiration rates (Tr), and intercellular CO2 concentration (Ci) were highest with RFM, followed by RFR and RFC. Averaged across the two years, RFM conserved 10% more soil water storage (SWS) than CK did at harvest, followed by RFR with an increment by 8%. However, RFC consumed more soil water than CK did, with its ETc 8% higher than CK. Consequently, spring maize treated with RFM suffered less drought stress, especially in 2017 when precipitation was insufficient. On average, grain yields and water use efficiency of RFM were increased by 18% and 27%, compared to CK. Structural equation modeling analysis showed that there existed significant positive correlation between SWS in top layers and grain yields, while SWS in deep layers had negative effects on grain yields. In conclusion, the incorporation of manure into ridge and furrow planting system can be an efficient agronomic practice to improve plant photosynthesis, optimize soil moisture, and boost grain yields in semi-arid areas of Loess Plateau, northwest China.

Soil water dynamics in forested and irrigated sites in Cyprus 

2021 ◽  
Author(s):  
Marinos Eliades ◽  
Adriana Bruggeman ◽  
Hakan Djuma ◽  
Melpomeni Siakou ◽  
Panagiota Venetsanou ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Water Potential ◽  
Soil Water ◽  
Water Flow ◽  
Water Retention ◽  
Soil Depth ◽  
Soil Water Potential ◽  
Water Dynamics ◽  
Annual Rainfall ◽  
Irrigation Amount

<p>The water storage in soil is a dynamic process that changes with soil, vegetation and climate properties. Water retention curves, that describe the relationship between the soil water content (θ) and the soil water potential (ψ), are used to model soil water flow and root water uptake by the plants. The overall objective of this study is to derive the retention curves of soils at two forested (Agia Marina, Platania) and two irrigated (Galata, Strakka) sites in Cyprus from in-situ soil moisture and soil water potential observations. <br>The long-term (1980 – 2010) average annual rainfall at Strakka olive grove (255 m elevation), Agia Marina P. brutia forest (640 m), Galata peach orchard (784 m) and Platania P. brutia forest (1160 m) is 298, 425, 502 and 839 mm, respectively.  The average soil depth at Agia Marina is 14 cm, while at other sites it is around 1 m. We installed a total of 18 TEROS21 soil water potential sensors, 37 5TM and 19 SMT100 soil moisture sensors, at different soil depths at the four sites. <br>Results from January 2019 to January 2021 show differences in the water retention curves of the four sites due to different soil textures. At the forested sites, θ reached wilting point at the summer period, indicating that trees extend their roots beyond the soil profile, to the bedrock in order to survive. At the irrigated sites, θ exceeds field capacity during irrigation, indicating over-irrigation. We found different water retention relations after rainfall and after irrigation, indicating that irrigation has an uneven spatial distribution. These findings suggest that the irrigation in these fields is not optimal and farmers may need to increase the number of irrigation drippers, while reducing the irrigation amount per dripper. From a monitoring perspective, increasing the number of sensors may give a better representation of the soil moisture conditions. <br>The research has received financial support from the ERANETMED3 program, as part of the ISOMED project (Environmental Isotope Techniques for Water Flow Accounting), funded through the Cyprus Research and Innovation Foundation.</p>

Sign in / Sign up

Export Citation Format

Share Document