Using MODIS-NDVI Time Series to Quantify the Vegetation Responses to River Hydro-Geomorphology in the Wandering River Floodplain in an Arid Region

Xarapat Ablat,Gaohuan Liu,Qingsheng Liu,Chong Huang

doi:10.3390/w13162269

Abstract

Vegetation, hydrology and geomorphology are three major elements of the floodplain ecosystem on Earth. Although the normalized difference vegetation index (NDVI) has been used extensively to characterize floodplain vegetation growth, vigour and biomass, methods for quantifying the various distinct responses of floodplain vegetation to hydro-geomorphological changes in different lateral belts in arid regions are still needed. In this study, the Linhe reach was divided into four lateral belts based on their hydro-geomorphological characteristics, and the Moderate Resolution Imaging Spectroradiometer (MODIS)-NDVI time series statistical indicators were used to characterise the distinct changing the patterns of vegetation growth in different belts. The response of floodplain vegetation to river hydro-geomorphology in each belt was analysed. The result showed that the average maximum NDVI value in the regular inundation area was 0.23 and higher than that in the other lateral belts. The correlation between the water persistence time and peak NDVI value in the regular water inundation area was significant (ρ = 0.84), indicating that in contrast to highly frequent or extremely rare water inundation, regular water inundation provides significant benefits to floodplains. Continuous or highly frequent inundation may cause decreased vegetation productivity. Overall, our results suggest that the vegetation greenness response to the river hydro-geomorphology is different from the river to the edge of the floodplain. Thus, a better understanding of the interactions between the floodplain vegetation and river hydro-morphology and river water resource management in arid-region floodplains.

Highlights

Vegetation, hydrology and geomorphology are the three main controlling elements of floodplain ecosystems on Earth, especially in dry areas [1,2,3,4]
The objective of this study was to quantify the spatial changes of vegetation in responses to river hydrogeomorphology in a floodplain region using normalized difference vegetation index (NDVI)- associated indicators derived from a time-series of daily Moderate Resolution Imaging Spectroradiometer (MODIS)-NDVI images
We found that the responses of floodplain vegetation to hydro-geomorphology in the study area varies among zones of the natural vegetation from the riverbed to the floodplain margins

Summary

Introduction

Vegetation, hydrology and geomorphology are the three main controlling elements of floodplain ecosystems on Earth, especially in dry areas [1,2,3,4]. Investigating the response of vegetation to hydrogeomorphological processes can provide insight into floodplain changes and lead to improved management of floodplain ecosystems [7]. The investigation of the influences of hydro-geomorphology on fluvial vegetation began in the late decades of the 20th century. Some studies revealed that changes in floodplain vegetation can, in turn, influence hydro-geomorphological processes [11,20,21,22,23,24]

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Discussion

Conclusion