Groundwater-surface water interactions, vegetation dependencies and implications for water resources management in the semi-arid Hailiutu River catchment, China – A synthesis

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 temperature methods as well as event hydrograph separation techniques at the sub-catchment scale. The results show that almost 88% of the river discharge consists of groundwater. Vegetation dependencies on groundwater were analyzed 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 (<i>Salix matsudana</i>) and poplar (<i>Populus simonii</i>)), bushes (salix (<i>Salix psammophila</i>)) and agricultural crops (maize (<i>Zea mays</i>)), depend on groundwater as the dominant water 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 water demand for socio-economical development and to prevent desertification, more water use efficient crops such as sorghum, barley and millet should be promoted to reduce the consumptive water use for irrigation. Willow trees should be used as wind-breaks in croplands and along roads, and dry resistant and less water use intensive plants (for instance native bushes) should be used to vegetate sand dunes

Climatic controls on sap flow dynamics and used water sources of Salix psammophila in a semi-arid environment in northwest China

“…Chen et al (2013) found that S. psammophila consumes more water than A. ordosica based on diurnal water table fluctuation. Moreover, Zhou et al (2013) confirmed that S. psammophila consumes more water than Salix matsudana at the Hailiutu river catchment. Therefore, S. psammophila might not be a suitable species for stabilizing sand dunes in water-scarce environments.…”

Simulation of Groundwater-Surface Water Interactions under Different Land Use Scenarios in the Bulang Catchment, Northwest China

“…For semi-arid areas such as our study area, a delicate balance among vegetating sand dunes, agricultural production, and water resources conservation must be maintained [44]. Over-vegetating sand dunes with high water consumption species (such as poplar trees and salix bushes) would reduce net groundwater recharge and diminish stream flows.…”

“…Remote sensing data can be employed for estimating the ET by means of energy balance methods, statistical methods using the difference between surface and air temperature, surface energy balance models, and spatial variability methods at different scales [38]. Remote sensing and the Normalized Difference Vegetation Index (NDVI) have been widely employed for estimating groundwater evapotranspiration [39,40], investigating the relationship between vegetation growth and depth to groundwater table [41][42][43][44], and accessing groundwater recharge fluxes [45]. Many researchers have conducted direct measurements like the sap flow method which uses the stem heat balance technique [46], and scaled these values to the catchment level transpiration [47].…”

Simulation of Water Use Dynamics by Salix Bush in a Semiarid Shallow Groundwater Area of the Chinese Erdos Plateau

“…These reforestation projects have prevented further deterioration of arid regions and have rehabilitated the eco-environment. However, recent research has revealed side effects stemming from the improper selection of plants [5], such as the decay of re-vegetation and a decrease in groundwater levels [6]. In arid areas, water resources are extremely scarce and the environment is very fragile.…”