Abstract

Abstract. The change pattern and trend of soil moisture (SM) in the Wuding River basin, Loess Plateau, China is explored based on the simulated long-term SM data from 1956 to 2004 using an eco-hydrological process-based model, Vegetation Interface Processes model, VIP. In-situ SM observations together with a remotely sensed SM dataset retrieved by the Vienna University of Technology are used to validate the model. In the VIP model, climate-eco-hydrological (CEH) variables such as precipitation, air temperature and runoff observations and also simulated evapotranspiration (ET), leaf area index (LAI), and vegetation production are used to analyze the soil moisture evolution mechanism. The results show that the model is able to capture seasonal SM variations. The seasonal pattern, multi-year variation, standard deviation and coefficient of variation (CV) of SM at the daily, monthly and annual scale are well explained by CEH variables. The annual and inter-annual variability of SM is the lowest compared with that of other CEH variables. The trend analysis shows that SM is in decreasing tendency at α=0.01 level of significance, confirming the Northern Drying phenomenon. This trend can be well explained by the decreasing tendency of precipitation (α=0.1) and increasing tendency of temperature (α=0.01). The decreasing tendency of runoff has higher significance level (α=0.001). Because of SM's decreasing tendency, soil evaporation (ES) is also decreasing (α=0.05). The tendency of net radiation (Rn), evapotranspiration (ET), transpiration (EC), canopy intercept (EI) is not obvious. Net primary productivity (NPP), of which the significance level is lower than α=0.1, and gross primary productivity (GPP) at α=0.01 are in increasing tendency.

Highlights

  • The Wuding River basin, in the Loess Plateau, China has been suffered severe soil erosion damages

  • The change pattern and trend of soil moisture (SM) in the Wuding River basin, Loess Plateau, China is explored based on the simulated long-term SM data from 1956 to 2004 using an eco-hydrological process-based model, Vegetation Interface Processes model, VIP

  • Besides SM, such Climate-Eco-Hydrological (CEH) variables as observed precipitation, air temperature and runoff and simulated evapotranspiration ET, leaf area index (LAI), and production by the VIP model are used for SM trend analysis

Read more

Summary

Introduction

The Wuding River basin, in the Loess Plateau, China has been suffered severe soil erosion damages. A physically process-based model with detailed information about soil-vegetation-atmosphere water and energy transfer is needed to correctly simulate long term SM time series for trend analysis. One of them is using the iterative procedure proposed by Zhang et al (2000), refined by Wang and Swail (2001) and Zhang and Zwiers (2003) In this method, called Zhang method, the autocorrelation is computed after removing the significant trends from the series. The M-K test for trend is run on the resulted time series and Sen approach (Sen, 1968) is used to compute the slope Another method is Trend Free Pre-whitening procedure proposed by Yue and Pilon (Yue et al, 2002) – called Yue method.

Model introduction
Trend analysis method
The judgement of the significance of serial autocorrelation
Basin description
SM data
Model implementation and analysis
The interannual variation of SM and its variability within each year
Northern drying?
Man-made Northern drying or nature-made
The representative of SM simulation via VIP
Findings
Conclusions
Full Text
Published version (Free)

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 call