Study on Waterlogging Reduction Effect of LID Facilities in Collapsible Loess Area Based on Coupled 1D and 2D Hydrodynamic Model

Abstract

The accurate evaluation method of LID toward the attenuation of urban flood is still a hot issue. This paper focuses on a coupled 1D and 2D hydrodynamic model, investigating the model parameters set in a collapsible loess area, and the changes in the surface runoff, waterlogged area, and drainage network indicators under different rainfall patterns. The results show that the coupled model can effectively simulate the effect of LID facilities under unaltered and retrofitted conditions. It is found that the infiltration parameters in a collapsible loess area are higher than in other eastern cities by calibration and validation. After implementing the LID facilities, the total runoff, peak flood flow, waterlogged area, runoff coefficient, and drainage pressure under different rainfall patterns have all been reduced. With the increases in the rainfall return period, the waterlogging reduction effect of LID facilities would gradually weaken. The rainfall return period has a great impact on the indicators of surface runoff, waterlogged area, and drainage capacity. The coefficient of rainfall peak has a relatively big impact on indicators of pipelines, such as the proportion of overflow nodes, the proportion of fully loaded pipelines, and the average full-load duration. The rainfall duration has a major impact on the total runoff quantity, runoff coefficient, and average full-load duration.

Potential of Decentral Nature-Based Solutions for Mitigation of Pluvial Floods in Urban Areas—A Simulation Study Based on 1D/2D Coupled Modeling

“…With R2E, the effectiveness of the systems Type 5 a declines significantly. It is widely known in the literature that the effectiveness of NBSs for flood mitigation decreases with more intense rain events [15,16,27]. However, infiltration systems of Type 100 a can still effectively reduce flooding and achieve almost three times the flood reduction compared to systems such as Type 5 a.…”

“…To assess the performance of NBSs in flood reduction, mainly models are used due to the lack of data from actual field measurements or other data [13]. The Storm Water Management Model (SWMM) [14] is widely used for the representation of NBSs with their LID elements [15,16]. Numerous studies have utilized the observed data from experimental NBSs to validate and calibrate the LID model approach in SWMM [17][18][19].…”

“…The primary model approaches in urban drainage are 1D, 2D, or 1D/2D coupled models. However, 1D models cannot simulate the flooding on the 2D surface [16], whereas 2D models do not consider the drainage systems. Dual-drainage concepts as 1D/2D coupled models provide the most detailed representation of an urban catchment with its topography, path-modifying elements (buildings, curbs), and sewer system [20,21].…”

“…Several modeling studies have investigated the effect of NBSs on flood reduction [16,[22][23][24][25][26][27][28]. The study areas varied in scale (regional, city, or catchment), topography, drainage system capacity, and infiltration characteristics of the soil.…”

“…In many studies, researchers simulated only one scenario with different combinations of NBS types and compared them to the base model without an NBS [16,[22][23][24]. This approach makes it impossible to quantify the effect of individual NBS types on flood reduction.…”