Abstract
Abstract. During the last decades, large-scale land use changes took place in the Hailiutu River catchment, a semi-arid area in northwest China. These changes had significant impacts on the water resources in the area. Insights into groundwater and surface water interactions and vegetation-water dependencies help to understand these impacts and formulate sustainable water resources management policies. In this study, groundwater and surface water interactions were identified using the baseflow index at the catchment scale, and hydraulic and water temperature methods as well as event hydrograph separation techniques at the sub-catchment scale. The results show that almost 90% of the river discharge consists of groundwater. Vegetation dependencies on groundwater were analysed from the relationship between the Normalized Difference Vegetation Index (NDVI) and groundwater depth at the catchment scale and along an ecohydrogeological cross-section, and by measuring the sap flow of different plants, soil water contents and groundwater levels at different research sites. The results show that all vegetation types, i.e. trees (willow (Salix matsudana) and poplar (Populus simonii), bushes (salix – Salix psammophila), and agricultural crops (maize – Zea mays)), depend largely on groundwater as the source for transpiration. The comparative analysis indicates that maize crops use the largest amount of water, followed by poplar trees, salix bushes, and willow trees. For sustainable water use with the objective of satisfying the water demand for socio-economical development and to prevent desertification and ecological impacts on streams, more water-use-efficient crops such as sorghum, barley or millet should be promoted to reduce the consumptive water use. Willow trees should be used as wind-breaks in croplands and along roads, and drought-resistant and less water-use intensive plants (for instance native bushes) should be used to vegetate sand dunes.
Highlights
Arid and semi-arid areas occupy around one third of the terrestrial earth surface (Scanlon et al, 2006)
River discharges heavily depend on groundwater in the Hailiutu River catchment
Measurements of hydraulic heads and temperatures as well as isotope investigations at the sub-catchment scale indicate that groundwater discharge is the most important component of river flows
Summary
Arid and semi-arid areas occupy around one third of the terrestrial earth surface (Scanlon et al, 2006). Water resources are extremely scarce and the environment is very fragile. Surface water resources are usually limited beside occasional flood events, and groundwater is the main source of water-sustaining stream flow and vegetation. Sustainable use of groundwater resources is fundamental for the co-existence of human society and nature in arid and semi-arid areas. Achieving sustainable use of groundwater remains a major challenge (Gleeson et al, 2012). The practice of using groundwater based on the “safe yield” policy has led to stream flow reduction and loss of wetlands and riparian ecosystems (Sophocleous, 2000). In a river basin where complex interactions exist between groundwater, surface water and ecosystems, the simplistic safe yield
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.
