Abstract
Soil hydraulic conductivity has a direct influence on infiltration rate, which is of great importance for modelling and design of surface runoff and stormwater control measures. In this study, three measuring techniques for determination of soil hydraulic conductivity were compared in an urban catchment in Ljubljana, Slovenia. Double ring (DRI) and dual head infiltrometer (DHI) were applied to measure saturated hydraulic conductivity (Ks) and mini disk infiltrometer (MDI) was applied to measure unsaturated hydraulic conductivity (K), which was recalculated in Ks in order to compare the results. Results showed significant differences between investigated techniques, namely DHI showed 6.8 times higher values of Ks in comparison to DRI. On the other hand, Ks values obtained by MDI and DRI exhibited the lowest difference. MDI measurements in 12 locations of the small plot pointed to the spatial variability of K ranging between 73%–89% as well as to temporal variability within a single location of 27%–99%. Additionally, a reduction of K caused by the effect of drought-induced water repellency was observed. Moreover, results indicate that hydrological models could be enhanced using different scenarios by employing a range of K values based on soil conditions.
Highlights
One of the crucial information points for effective and comprehensive management of urban waters is soil infiltration rate, as it determines the portion of the infiltrated water and runoff
A distance map of mini disk infiltrometer (MDI) measurement results was formed (Figure 7), where dark blue colour presents the largest differences in distances between locations and white colour the smallest differences or a match
The results demonstrate that dual head infiltrometer (DHI) measured the highest average Ks (8.2 ± 5.9 × 10−3 cm/s), followed by MDI (2.6 ± 0.5 × 10−3 cm/s) and the lowest Ks was measured by Double ring infiltrometer (DRI) (1.0 ± 1.1 × 10−3 cm/s)
Summary
One of the crucial information points for effective and comprehensive management of urban waters is soil infiltration rate, as it determines the portion of the infiltrated water and runoff. Once the soil is fully saturated, infiltration rate becomes constant (i.e., quasi-steady state) and equal to saturated soil hydraulic conductivity (Ks ). Infiltration contributes to continuous precipitation losses and is one of the governing factors that define water balance for urban catchments, especially in case of large open spaces [1]. Ks is used for modelling and dimensioning of (i) urban drainage systems and (ii) stormwater control measures (SCMs). Modelling of urban drainage systems employing hydrological-hydraulic (HH) models is being used to better understand their response to precipitation and identify critical areas within the systems [2]. One of the most widely used HH models for modelling urban drainage systems is Storm water management model (SWMM) developed by United States
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