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Zhou Y.,UNSCO IHE Institute for Water Education | Yang Z.,UNSCO IHE Institute for Water Education | Yang Z.,China University of Geosciences | Zhang D.,Hohai University | And 2 more authors.
Hydrological Sciences Journal | Year: 2015

Abstract: Two river catchments, the Huangfuchuan and the Hailiutu, located in the same climate zone in the Erdos Plateau, China, have distinctly different flow regimes. This study systematically compared differences between the flow regimes of these two catchments using several statistical methods, and analysed the possible causes. The variations in yearly, monthly and daily mean discharges were found to be much greater in the Huangfuchuan catchment than in the Hailiutu catchment. Preliminary analysis indicated that these differences are not caused by changes in climate, but are instead attributable to differences in geology, geomorphology, hydrological processes and human interventions. In the Hailiutu catchment, the dominant groundwater contribution maintains stationary daily and monthly river discharges, while shifts in yearly mean discharges were closely associated with the expansion or reduction of crop area. In the Huangfuchuan catchment, the dominant direct rainfall–runoff process generates flashier daily and monthly river discharges, while the decrease of yearly mean discharges is caused mainly by the construction of check dams. These findings have significant implications for water resource management and the implementation of proper soil and water conservation measures in the middle reach of the Yellow River Basin of China. Editor Z.W. Kundzewicz; Associate editor Y. Gyasi-Agyei © 2015, IAHS.

Zhou Y.,UNSCO IHE Institute for Water Education | Wenninger J.,UNSCO IHE Institute for Water Education | Wenninger J.,Technical University of Delft | Yang Z.,UNSCO IHE Institute for Water Education | And 8 more authors.
Hydrology and Earth System Sciences | Year: 2013

During the last decades, large-scale land use changes took place in the Hailiutu River catchment, a semiarid area in northwest China. These changes had significant impacts on the water resources in the area. Insights into groundwater and surface water interactions and vegetationwater 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. © Author(s) 2013.

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