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Subsurface drainage systems
Published in Willem F. Vlotman, Lambert K. Smedema, David W. Rycroft, Modern Land Drainage, 2020
Willem F. Vlotman, Lambert K. Smedema, David W. Rycroft
These systems consist of ditches laid out in various patterns. To function as effective groundwater drains, ditches must be rather deep so that they reach well below the depth at which the watertable is to be maintained (water level ~ 1.0–1.5 m below soil surface). The ditches normally have a trapezoidal section with side slopes varying from 1:1 to 1:2, depending on the soil conditions.
Biological Treatment Systems
Published in Paul N. Cheremisinoff, Handbook of Water and Wastewater Treatment Technology, 2019
Ditches may be constructed of various materials, including concrete, gunite, asphalt, or impervious membranes. Concrete is the most common construction material. Ditch loops may be oval or circular in shape. “Ell” and “horseshoe” configurations have been constructed to maximize land usage. Conventional activated-sludge treatment, in contrast to extended aeration, may be practiced. Oxidation ditch systems with depths of 10 ft or more with vertical sidewalls and vertical shaft aerators may also be used.
Ecological Wisdom and Inheritance Thinking of the Traditional Village’s Water Resources Management in Taihang Mountains
Published in Journal of Asian Architecture and Building Engineering, 2023
Zurui Lin, Yuan Liang, Kaiyi Chen, Shuangshuang Li
In addition, the width of traditional streets and alleys is generally narrower, and most alleys, especially sub-alleys, are of the central concave arc type. Drainage is made from low-lying areas in the middle, and open ditches or culverts are selected only when the slope is large or conditions permit (Wei Nan Zhou 2018). Compared with the modern central convex road surface, the central concave arc pavement can save land and avoid erosion of the wall foundation without affecting traffic (Figure 14). What’s more, the street pavement is mostly made of local materials such as green stone slabs and sandstone, which are porous and have good water absorption and permeability, combined with drainage and permeability after splicing with the inverted trapezoidal practice (Han 2020).
Production of sediment from the running surface of unpaved legacy roads in southeast Ohio, USA
Published in International Journal of Forest Engineering, 2019
Benjamin A. Silliman, Elizabeth Myers Toman
An interesting finding in this study is that segment A had the lowest sediment production rate (18.3 g/m2). This lower production rate might be attributed to a more consistent road shape, as evident by having only 30 m of rutting (one tire track) and therefore a shorter flowpath on the road surface, and the presence of a functional and vegetated roadside ditch. Unbound aggregate roads with rutting have been shown to produce more sediment than those that held their shape in cross section (Foltz and Burroughs 1990; Toman and Skaugset 2011). A consistent inslope or outslope road shape directs runoff from the road surface to the less compacted edges of the road prism where it may infiltrate. A vegetated ditch increases the roughness of the flow pathway thereby reducing flow velocity and allowing for sediments to fall out of suspension. Although this study did not separate road runoff by ditch flow or road surface flow, segment A was the only road segment to have ditch flow during rainfall simulations. As the ditch for this segment was vegetated, the ditch itself was not a likely a source of sediment but could have been a location of sediment deposition.
Conjunctive use of groundwater and surface water to reduce soil salinization in the Yinchuan Plain, North-West China
Published in International Journal of Water Resources Development, 2018
Peiyue Li, Hui Qian, Jianhua Wu
As high groundwater level is the key factor affecting soil salinization in the Yinchuan Plain, lowering the groundwater to reduce evaporation of groundwater should always be given top priority. It is necessary to improve the drainage systems and dredge the drainage ditches regularly. Most importantly, the combination of canal irrigation and well irrigation, as suggested in this study, should be implemented as soon as possible. In terms of the low-lying areas where groundwater-level depth is shallow and soil salinization is very severe, targeted drainage measures should also be implemented in addition to general measures for the entire plain. For example, fish ponds and lacustrine wetlands should be properly protected to reduce their impacts on the surrounding farmland. Reducing lateral water seepage from ponds and lakes to farmland is an effective measure for this issue.