Simulation of soil water movement and water utilization of shrub community in a gravel desert of arid northwestern China during twelve years

Abstract

Study region: A gravel desert in the middle reaches of the Heihe River Basin, northwestern China. Study focus: Lack of long-term monitoring of soil water and groundwater level (GL) limited accurately quantifying the interactions between soil water, groundwater, and the shrubs in the desert ecosystems. This study focused on clarifying the water movement in the groundwater-soil-plant-atmosphere continuum in the desert ecosystems. Hydrological processes of a shrub community were simulated by developing the HYDRUS-1D model based on the twelve-years monitoring in a gravel desert. New hydrological insights for the region: Evapotranspiration of the shrub community was properly partitioned by the Penman-Monteith equation with the dual crop coefficient approach. Reaumuria songarica and Nitraria sphaerocarpa community relied on shallow soil water. Actual transpiration and evapotranspiration ranged from 33 mm and 80 mm in a dry year to 65 mm and 171 mm in a wet year, respectively. Only 39 % of evapotranspiration was used for shrub growth, and growing-season rainfall was more efficiently used in a dry year. Water rising from lower layers was dominant in the 0–10 m layer. The capillary fringe varied from 102 cm to 267 cm, averaging 205 cm above GL during the growing seasons. The rising groundwater is unavailable but promising for the shrubs’ utilization. The results of this study are valuable for developing sustainable management strategies for the similar gravel desert ecosystems.

Keywords

• Desert ecosystem
• Hydrological processes
• Soil water movement
• Groundwater-soil-plant-atmosphere continuum