abstract although lateral drains play the main role in removal of excess water from soil profile in subsurface drainage systems, but it is assumed that perforated collectors can directly remove a part of drainwater from soils. this part of discharge in subsurface drains is not usually taken into consideration in drainage design criteria, due to lack required information and its difficult estima...

Abstract This paper describes a new formulation for estimating the permeability of drainages composed natural sands with no clay content, starting from parameters obtained grain size distribution. The conventional relationships are functions granulometric factors and porosity. However, media typically used as drainage, grading is determinant factor, so porosity dependence can be replaced by fun...

Small vegetated drainage ditches play an important role in water and nutrient removal, but may cause water blocking problems. The aim of this study was to investigate vegetated drainage ditches’ hydraulic and wetland hydraulic characters. Field experiment were carried out, small drainage ditches with Juncus, Zizania latifolia, and Acorus calamus were selected under different water flows, and a ...

In copper heap leaching structures, the ore is leached by an acidic solution. After dissolving the ore mineral, the heap is drained off in the acidic solution using a drainage system (consisting of a network of perforated polyethylene pipes and gravelly drainage layers) and is, then, transferred to the leaching plant for copper extraction where the copper is extracted and the remaining solution...

The runoff coefficient was the primary parameter used in both site-scale and area-wide calibration efforts. This coefficient is directly related to the type of land use and land cover observed within the drainage area. The land use was represented in the model as pervious and impervious surfaces assigned to subcatchment areas within the system. In the 2007 InfoWorks (IW) Model, the runoff coeff...

there is a lack of accurate and correct information about erosion in iran. moreover, there is a big difference between measurements and estimations. sediment is also an important environmental problem which pollutes water physically and chemically and therefore, sediment problem is usually studied as environmental problems. estimation of sediment yield of drainage basins is important for preven...

The difference between average pressures of two immiscible fluids is commonly assumed to be the same as macroscopic capillary pressure, which is considered to be a function of saturation only. However, under transient conditions, a dependence of this pressure difference on the time rate of saturation change has been observed by many researchers. This is commonly referred to as dynamic capillari...