Characteristic and Attribution of Runoff Variation in the Yanhe River Basin, Loess Plateau, Based on the Budyko Hypothesis

Kun Hou,Xiuru Wang,Jiping Wang

doi:10.3390/w14030495

Abstract

The ecological restoration projects in the Loess Plateau (LP) has significantly altered the underlying surface conditions, coupled with a warming–wetting climate, which has profoundly affected the regional water cycle. Evaluating the response of runoff to external environmental change and quantitatively identifying the contribution of anthropogenic interference and climate change are prerequisites for efficient utilization of water resources in arid/semi-arid regions. Daily recorded data of hydrological and meteorological elements between 1969 and 2019 and the elasticity coefficient method based on Budyko hypothesis were used for attribution analysis of runoff change in the Yanhe River basin. The results show the following: (1) the measured runoff decreased significantly (p < 0.05, –0.2845 mm year−1), and suggested substantial difference before and after 2000; (2) the area of woodland and grassland had a sharp increase from 2000, while the elasticity of runoff to precipitation, potential evapotranspiration (ET0), and vegetation all decreased; (3) the improvement of underlying surface conditions has become the leading factor of runoff reduction with a contribution of 96.78%; (4) the impact of vegetation restoration on runoff reduction is effective within a certain threshold. We consider that more attention should be paid to the afforestation scale and its possible negative eco-hydrological effects in future ecological restoration.

Highlights

A changing environment strongly influenced by climate and anthropogenic interference can directly affect the land surface process [1] and alter the mechanism of runoff generation and concentration [2]
The results showed that vegetation growth was very sensitive to temperature and precipitation, and climate change has a significant impact on vegetation growth [21], especially in arid/semi-arid areas [22], where extreme climate leads to a decrease in vegetation coverage
Based on the result of MK analysis, the study period was divided into a reference period (1969–2000, Pa2r0a0m0–e2t0e0r9n increased fro0m.3010.896 (PI)) and a change period (2001–2019, PII), a double mass curve was performed on the precipitation-runoff (Figure 2b)

Summary

Introduction

A changing environment strongly influenced by climate and anthropogenic interference can directly affect the land surface process [1] and alter the mechanism of runoff generation and concentration [2]. The middle reaches of the Yellow River (YR) in China, which is located in an arid/semi-arid region, have undergone profound declines in runoff, and have gradually become areas of considerable research [4]. The variation of meteorological elements such as precipitation, temperature, wind speed, and radiation change the cycle and distribution of water resources, and affect river runoff [8]. Studies have found that the temperature and precipitation have increased in the past 10–15 years in northwest China, exhibiting a trend of warming–wetting [9,10]. Extreme precipitation events may result in infiltrationexcess runoff production, causing surface scour and destroying vegetation roots

Methods

Results

Discussion

Conclusion