Regionalization of Daily Soil Moisture Dynamics Using Wavelet-Based Multiscale Entropy and Principal Component Analysis.

Yuqing Sun,Jun Niu

doi:10.3390/e21060548

Abstract

Hydrological regionalization is a useful step in hydrological modeling and prediction. The regionalization is not always straightforward, however, due to the lack of long-term hydrological data and the complex multi-scale variability features embedded in the data. This study examines the multiscale soil moisture variability for the simulated data on a grid cell base obtained from a large-scale hydrological model, and clusters the grid-cell based soil moisture data using wavelet-based multiscale entropy and principal component analysis, over the Xijiang River basin in South China, for the period of 2002–2010. The effective regionalization, for 169 grid cells with the special resolution of 0.5° × 0.5°, produced homogeneous groups based on the pattern of wavelet-based entropy information. Four distinct modes explain 80.14% of the total embedded variability of the transformed wavelet power across different timescales. Moreover, the possible implications of the regionalization results for local hydrological applications, such as parameter estimation for an ungagged catchment and designing a uniform prediction strategy for a sub-area in a large-scale basin, are discussed.

Highlights

The Xijiang River basin (Figure 1) is the largest tributary of the Pearl River basin in South China, with a total basin area of 0.35 million km2 [1,2,3]
The present study examines the multi-scale variability of top 1-m grid-based soil moisture data [25] for the Xijiang River in South
Study proposed a framework, mainly including long-term effective hydrological modeling, multi-scale wavelet entropy analysis, and cluster analysis. It demonstrates the hydrological regionalization in terms of the variability and disorder features of soil water dynamics, with a 0.5◦ × 0.5◦

Summary

Introduction

The Xijiang River basin (Figure 1) is the largest tributary of the Pearl River basin in South China, with a total basin area of 0.35 million km2 [1,2,3]. With high-speed social and economic development in the Pearl River Delta, large water demands are required from the new modern cities, such as Shenzhen and Zhuhai. The water amount from the Dongjiang River and Beijiang River basins (the other two major tributaries in the Pearl River) may be not able to meet the various kinds of water demands in the region, especially in the dry years. One large water diversion project, which has already been proposed and approved, aims to divert water from the downstream Xijiang River to the big cities. The variability in the amount of water over the Xijiang River basin is extremely important for the regional water transfer, water allocation, and other water-related management issues. A series of hydrological simulations and predictions under the changing environment are prerequisite to the water resource management in the basin

Results

Discussion

Conclusion