Characteristics and Controlling Factors of the Drought Runoff Coefficient

Rei Itsukushima

doi:10.3390/w13091259

Abstract

Increasing water demand due to population growth, economic development, and changes in rainfall patterns due to climate change are likely to alter the duration and magnitude of droughts. Understanding the relationship between low-flow conditions and controlling factors relative to the magnitude of a drought is important for establishing sustainable water resource management based on changes in future drought risk. This study demonstrates the relationship between low-flow and controlling factors under different severities of drought. I calculated the drought runoff coefficient for six types of occurrence probability, using past observation data of annual total discharge and precipitation in the Japanese archipelago, where multiple climate zones exist. Furthermore, I investigated the pattern of change in the drought runoff coefficient in accordance with the probability of occurrence of drought, and relationships among the coefficient and geological, land use, and topographical factors. The drought runoff coefficient for multiple drought magnitudes exhibited three behaviors, corresponding to the pattern of precipitation. Results from a generalized linear model (GLM) revealed that the controlling factors differed depending on the magnitude of the drought. During high-frequency droughts, the drought runoff coefficient was influenced by geological and vegetation factors, whereas land use and topographical factors influenced the drought runoff coefficient during low-frequency droughts. These differences were caused by differences in runoff, which dominated stream discharge, depending on the magnitude of the drought. Therefore, for effective water resource management, estimation of the volume of drought runoff needs to consider the pattern of precipitation, geology, land use, and topography.

Highlights

The causes of droughts and adaptations to natural disasters have been studied from the perspectives of hydrology, environmental science, geology, meteorology, and agronomy [1]
In addition to the impacts of natural factors, intensification of drought is expected to occur because of growing water demand associated with population growth, economic development [9,10,11], and changes in the hydrological cycle associated with anthropogenic impacts, such as land-use-change [12,13,14]
The results for annual precipitation, volume of drought runoff, and drought water volume per unit drainage area for each occurrence probability are presented in Tables 1 and 2

Summary

Introduction

The causes of droughts and adaptations to natural disasters have been studied from the perspectives of hydrology, environmental science, geology, meteorology, and agronomy [1]. A shortage of surface or subsurface water in relation to water utilization, as determined by established water resource management, is defined as hydrological drought [17,18]. Agricultural drought indicates declining soil moisture, regardless of surface water resources, causing crop failure [20,21]. Socioeconomic drought occurs in cases of defectiveness and incompatibility of the water resource system in relation to water demand [22,23]

Methods

Results

Discussion

Conclusion