Assessing the Effects of Different Cropping Patterns on Drainage Capability of the Southern Riverine Basin

摘要

Compared with natural watersheds, only a few studies have been conducted to take the specific characteristics of farmed watersheds into account in hydrological modeling. The purpose of this paper is to develop a conceptual rainfall-runoff model with which both the impact of human activities, especially the existence of drainage practices and ditch network, on flood e-vents and the effects of different cropping patterns on drainage capability of the southern riverine basin could be assessed. The model uses the monolayer soil-structure Tank model with surface water layer and the QualHYMO model to calculate the runoff of paddy fields and dry lands respectively. The Saint-Venant equations are used for flow routing through the main drainage system, and the special technique is employed to simulate the discharges of sluices and pumps. Applications of the model are demonstrated for Luoshan drainage basin, which is located in Hubei province. To analyze the role of cropping patterns, six hypothetical scenarios are discussed. Results show that the drainage system of Luoshan drainage basin can dispose of the excess water from 3-day rainfall totals with return periods of 6. 9 years in five days and with the area of paddy fields being increased, the drainage capability would be strengthened.