Hydrological Effects of Vegetation Cover Degradation and Environmental Implications in a Semiarid Temperate Steppe, China

Di Fang,Kailun Jin,Lei Sun,Xiaolin Huang,Lu Hao,Lizhe Yang

doi:10.3390/su9020281

Di Fang, Kailun Jin + Show 4 more

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https://doi.org/10.3390/su9020281

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Abstract

Studying the impact of vegetation dynamics on hydrological processes is essential for environmental management to reduce ecological environment risk and develop sustainable water management strategies under global warming. This case study simulated the responses of streamflow to vegetation cover degradation under climate variations in the Xilin River Basin in a semi-arid steppe of northern China. The snowmelt and river ice melting processes in the Soil and Water Assessment Tool (SWAT) were improved to estimate the changes in streamflow under multiple scenarios. Results showed that the improved SWAT simulations matched well to the measured monthly streamflow for both calibration (determination coefficient R2 = 0.75 and Nash–Sutcliffe ENS = 0.67) and validation periods (R2 = 0.74 and ENS = 0.68). Simulations of vegetation change revealed that obvious changes occurred in streamflow through conversion between high and low vegetation covers. The reductions in vegetation cover can elevate streamflow in both rainfall and snowmelt season, but the effects are most pronounced during the rainfall seasons (i.e., the growing seasons) and in drier years. These findings highlight the importance of vegetation degradation on modifying the hydrological partitioning in a semi-arid steppe basin. We conclude that in a particular climate zone, vegetation cover change is one of the important contributing factors to streamflow variations. Increases in streamflow in water-limited regions will likely reduce the effective water content of soil, which in turn leads to further degradation risk in vegetation. Therefore, vegetation cover management is one of the most effective and sustainable methods of improving water resources in water-constrained regions.

Highlights

Terrestrial vegetation plays a crucial role in controlling catchment water balance
The simulation results show that the streamflow is sensitive to both climate variations and vegetation cover changes
This study offers an improved Soil and Water Assessment Tool (SWAT) model to simulate the response of streamflow to vegetation cover change and climate variations under multiple scenarios and aims to understand the ecohydrological responses of a water-limited environment to climate changes and to human activities

Summary

Introduction

Terrestrial vegetation plays a crucial role in controlling catchment water balance. Studying the impact of vegetation cover change on streamflow can help water resource managers to develop sustainable management strategies. The terrestrial water cycle would be much slower because of smaller ET losses and lower precipitation rates. Land regions lose their rainwater input either as ET or as surface and groundwater runoff [1]. Arid and semi-arid regions cover 41% of the Earth's land surface and contain 38% of the human population [2]. These regions are more ecologically vulnerable and sensitive to climate change and human activities. Understanding the connection between vegetation degradation and hydrological processes under global climate change is essential for quantifying the likely consequences of climate change and human activities on grassland ecosystems and achieving long-term grassland ecosystem sustainability in semi-arid watersheds

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