22-27 September 2019
Trade Fairs and Congress Center (FYCMA)
Europe/Madrid timezone

Numerical assessment on the impact of water table decline on phreatophytes in arid regions

27 Sep 2019, 11:15
15m
Conference room 1.A ()

Conference room 1.A

Oral Topic 6 - Groundwater, wetlands and natural heritage Parallel

Speaker

Prof. Lihe Yin (Xi'an Center of Geological Survey, China Geological Survey)

Description

Water demands have been increasing for the recent decades, leading to a continuous decline of water table in many parts of the world. As a result, phreatophytes (groundwater-dependent plants) in these regions are threaten by the increase of water table depth induced by groundwater abstractions. Quantitative assessment of the impacts of groundwater level decline on phreatophytes in hyper-arid and arid regions is key to sustainable groundwater management. Although relationships between the responses of phreatophytes to water table decline were developed by previous studies, these relations are site-specific. A general model describing the response of phreatophytes to falling water table across (hyper-) arid regions is not available. In this study, we aims to develop a general model that enables to predict such response across arid regions. A variable saturated flow model, HYDRUS-1D, was used to numerically assess the controls of depth to water table (DWT) and mean annual precipitation (MAP) on transpiration of groundwater-dependent vegetation in (hyper-) arid regions of northwest China where MAP ranging from 15 mm to 198 mm. An exponential decrease is found for the normalized transpiration (a ratio of transpiration at a certain DWT to transpiration at 1 m depth, Ta) with increasing DWT, while a positive linear relationship is found between Ta and MAP. The sensitivity analysis show that the model is insensitive to parameters, such as saturated soil hydraulic conductivity, water stress parameters and rooting depth, indicated by an insignificant variation (less than 20% in most cases) under ± 50% changes of these parameters. Based on these two relationships, a general model was developed to forecast the response of phreatophyte transpiration to groundwater drawdown for (hyper-) arid regions using MAP only. The Ta* estimated from the model was reasonable comparing to the published measured values.

Primary author

Prof. Lihe Yin (Xi'an Center of Geological Survey, China Geological Survey)

Presentation Materials

There are no materials yet.
Your browser is out of date!

Update your browser to view this website correctly. Update my browser now

×