Spatial and temporal variation of hydraulic conductivity and vegetation growth in green infrastructures using infiltrometer and visual technique

Abstract

68Hydraulic conductivity of a vegetated soil (i.e., mixed grass cover) is an important parameter 69 governing the hydrological performance of green infrastructure (GI). This paper focuses on 70 GI with mixed grass cover in the presence of trees. Due to shading effects (interception of 71 radiant energy) of tree canopy, mixed grass cover in the vicinity of trees may not receive 72 direct photosynthetically active radiation (PAR). This can hinder the growth rates resulting in 73 the low grass cover (i.e., in density). The hydraulic conductivity and the performance of GI 74 can be further affected. Several field studies were conducted to investigate hydraulic 75 conductivity in different types of vegetated covers. However, any variation in growth and 76 hydraulic conductivity of mixed grass cover in the vicinity of trees was rarely investigated. 77The objective of this study is to quantify spatial and temporal variation of vegetation growth 78 and hydraulic conductivity in a mixed grass cover in the vicinity of a tree. Field monitoring 79 of a mixed grass cover in the vicinity of a tree in a GI was conducted for about six months. 80Hydraulic conductivity tests were carried out using mini disk infiltrometer (MDI) at 149 81 locations in a selected site once every month. Vegetation density was quantified using image 82 analysis and the images were captured by a DJI Phantom drone. The growth of mixed grass 83 cover around tree vicinity (within 5 m radial distance) was found to be more uniform during 84 months characterized by high rainfall depth. Spatial heterogeneity in both vegetation density 85 and hydraulic conductivity is found to be more significant during a dry period than wet 86 period. Variation of hydraulic conductivity with respect to the change in vegetation density is 87 found to be significant in a wet period than dry period. It is also found that hydraulic 88 conductivity is higher at the portions where shredded leaves are present. The obtained 89 dynamic spatio-temporal relationship of soil, vegetation and atmospheric parameters can 90 support the design of green infrastructures and contribute to a better understanding of the 91 maintenance practices. 92 4

Application of Bio-pore Infiltration Hole as an Urban Runoff Management

“…For the effect of soil compaction, this confirmed with the previous study by Gregory et al Compaction affects the physical properties of the soil while reducing the porosity and pore distribution in the soil [11]. As for the influence of vegetation cover, this was confirmed by Gadi et al that higher vegetation density in the soil results in higher hydraulic conductivity value [18].…”

“…The soil conditioning that has the highest runoff reduction is found in the vegetated soil (plots K1 and L1), then followed by unconditioning soil (plots K3 and L3), soils with variations in combinations of compaction and vegetation (plot K2 and L2), and only compacted land (plots K4 and L4). This is related to the ability of recharge by the BIH of each land condition, where land whose soil is compacted tends to reduce the absorption of water [11] and land that has vegetation cover tends to increase water absorption [18]. For the effect of soil compaction, this confirmed with the previous study by Gregory et al Compaction affects the physical properties of the soil while reducing the porosity and pore distribution in the soil [11].…”

Temporal and spatial variation of infiltration in urban green infrastructure

“…The presence of vegetation does not automatically mean infiltration will be enhanced. There are soil and agricultural sciences studies that show increases and decreases in hydraulic conductivity due to vegetation growth (Gadi et al, ). Coarse root structure and characteristics (e.g., root area index and root depth) may maintain or increase infiltration rates, but fine roots do not necessarily increase infiltration rates especially if they form thick matting in the soil surface layer (Archer, Quinton, & Hess, ).…”

Detailed Assessment of the Spatial Distribution of Urban Parks According to Day and Travel Mode Based on Web Mapping API: A Case Study of Main Parks in Wuhan

“…As an important component of the ecosystem of urban greenspaces, urban parks play an important role in public health, urban environment [1,2], and biological diversity [3]. Moreover, it can enhance social ties, create a sense of community, and improve living standards of urban residents [4,5], and it is considered to exert a great influence on the urban economy and real estate market [6,7].…”