Abstract
In the Heihe River basin, China, increased salinity and water shortages present serious threats to the sustainability of arid wetlands. It is critical to understand the interactions between soil water and salts (from saline shallow groundwater and the river) and their effects on plant growth under the influence of shallow groundwater and irrigation. In this study, the Hydrus-1D model was used in an arid wetland of the Middle Heihe River to investigate the effects of the dynamics of soil water, soil salinization, and depth to water table (DWT) as well as groundwater salinity on Chinese tamarisk root water uptake. The modeled soil water and electrical conductivity of soil solution (ECsw) are in good agreement with the observations, as indicated by RMSE values (0.031 and 0.046 cm3·cm−3 for soil water content, 0.037 and 0.035 dS·m−1 for ECsw, during the model calibration and validation periods, respectively). The calibrated model was used in scenario analyses considering different DWTs, salinity levels and the introduction of preseason irrigation. The results showed that (I) Chinese tamarisk root distribution was greatly affected by soil water and salt distribution in the soil profile, with about 73.8% of the roots being distributed in the 20–60 cm layer; (II) root water uptake accounted for 91.0% of the potential maximal value when water stress was considered, and for 41.6% when both water and salt stress were considered; (III) root water uptake was very sensitive to fluctuations of the water table, and was greatly reduced when the DWT was either dropped or raised 60% of the 2012 reference depth; (IV) arid wetland vegetation exhibited a high level of groundwater dependence even though shallow groundwater resulted in increased soil salinization and (V) preseason irrigation could effectively increase root water uptake by leaching salts from the root zone. We concluded that a suitable water table and groundwater salinity coupled with proper irrigation are key factors to sustainable development of arid wetlands.
Highlights
In arid and semi-arid wetlands, salinity and water scarcity are two serious and chronic environmental problems threatening the ecosystem [1]
In order to elucidate the impacts of artificial watering on soil water, salt dynamics, and to determine how to alleviate salt stress on the arid wetlands, we evaluated the influence of a preseason irrigation event applied at the initial stages of plant growth starting on 2 May 2012
Validation period resulted in root mean square error (RMSE) = 0.046 cm3·cm−3 and R2 = 0.82 for soil water and RMSE = 0.035 dS·m−1 and R2 = 0.95 for ECsw
Summary
In arid and semi-arid wetlands, salinity and water scarcity are two serious and chronic environmental problems threatening the ecosystem [1]. In the Heihe River basin, China, wetlands are often experiencing extended periods of high soil salinization levels and associated water availability problems due to the impacts of high evaporative conditions, poor surface drainage, human population pressures, and the associated changes in land use [2,3]. Soil salinity limits plant growth [4]. Negatively influences soil quality [5,6], resulting in the change of community structure, density, and growth status. Wetland areas decreased by 42% from 1975 to 2010 within the middle Heihe River basin [7]. Before developing reliable countermeasures, it is important to evaluate the interactions between soil water and salts and their impacts on plant water use, based on factors such as the groundwater quality, the water table, and the plant tolerance to salinity
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
