Abstract
In the flat lowland agricultural areas of subtropical climate zones, the runoff process has a great influence on the regional water quantity and quality. In this study, field data about rainfall, evapotranspiration, soil moisture, groundwater table, and surface water dynamics were collected in two different experimental sites in the Taihu Basin, China. Results showed that densely distributed ditches contributed to shallow groundwater depths and persistent near-saturation soil. A correlation analysis was conducted to improve the understandings of runoff generation in humid lowland areas of the Taihu Basin. It was found that a Dunne overland flow was the dominant mechanism responsible for the rapid runoff generation. The total rainfall and runoff expressed a good linear relationship with an R2 of 0.95 in the Hongqiwei test site. The initial groundwater depth was considered as the indicator of the antecedent soil moisture estimation for the close relationship. The depression storage was suggested in a range from 4.72 to 8.03 mm for an estimation based on the water balance analysis for each rainfall event, which proves that the depression storage should not be neglected when calculating the runoff generation process in humid lowlands.
Highlights
IntroductionWhich can be characterized by a flat terrain, shallow water table, and extensive river networks [2]
About 30% of the Taihu Basin, a typically humid lowland region in China, are lowland polders [1]which can be characterized by a flat terrain, shallow water table, and extensive river networks [2].These water-rich areas have dense populations [3,4] and intensive agricultural activities [5,6] which are vulnerable to flooding and are polluted [7,8,9]
This study aims to explore the runoff generation process in humid lowland areas in the Taihu Basin, China
Summary
Which can be characterized by a flat terrain, shallow water table, and extensive river networks [2] These water-rich areas have dense populations [3,4] and intensive agricultural activities [5,6] which are vulnerable to flooding and are polluted [7,8,9]. It was highlighted that ephemeral water storage in depressions [22,23] contributes to higher variability in low-gradient terrain than upland watersheds [24,25]. Human activities such as artificial drainage building, land development, Water 2020, 12, 1216; doi:10.3390/w12041216 www.mdpi.com/journal/water
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