introduction: preferential flow is one of the major processes influencing the rapid movement of pollutants to ground water.  macropores created by plant roots provide pathways for rapid transport of pollutants in a soil profile. the growth of plant roots into soil causes creation of big pores that improve water movement and solute transport through soil profile. field soils or undisturbed soils...

[1] The estimation of catchment-averaged aquifer hydraulic conductivity values is usually performed through a base flow recession analysis. Relationships between the first time derivatives of the base flow and the base flow values themselves, derived for small and large values of time, are used for this purpose. However, in the derivation of the short-time equations, an initially fully saturate...

Subsurface heterogeneity in hydraulic properties and processes is a fundamental challenge in hydrogeology. We have developed an improved method of borehole dilution testing for hydrostratigraphic characterization, in which distributed temperature sensing (DTS) is used to monitor advective heat movement. DTS offers many advantages over conventional technologies including response times in the or...

The flow through a unit of a drinking water treatment plant is one of the most important parameters in terms of a unit’s effectiveness. In the present paper, a new EPAnet library is presented with the typical hydraulic elements for drinking water treatment processes well abstraction, rapid sand filtration and cascade and tower aeration. Using this treatment step library, a hydraulic model was s...

The analysis of bubble clustering in air-water flows may provide some measure of the bubble-turbulence interactions. A cluster of bubbles is as a group of two or more bubbles, with a distinct separation from other bubbles. This paper compares the results of a clustering study in a dropshaft and in a hydraulic jump to point out differences/similarities between those complex turbulent flows. The ...

Hydraulic fracturing is one of the most common methods of well stimulation for reservoirs with low permeability. Hydraulic fracturing increases the flow capacity, alters flow geometry, bypasses damage and improves recovery factor. The pressure of most of Iranian oil reservoirs is declined and consequently the production is reduced. It is necessary to improve the production by using new stimulat...

the hydraulic characteristic of an up-flow anaerobic sludge blanket fixed film (uasb-ff) were studied by changing two important hydraulic factors that can impact significantly on the hydraulic regime of the uasb-ff bioreactor: the up-flow velocity (vup) and biogas production rate (qg). the analysis of the reactor hydraulic performance was performed by studying hydraulic residence time distribut...

Local scouring in the downstream of hydraulic structures is one of the important issues in river and hydraulic engineering, which involves a lot of costs every year, so the prediction of the rate of scour is important in hydraulic design. Side weirs are the most important of hydraulic structures that are used in passing flow. This study investigate the scouring due to falling jet from side weir...

abstract rockfill dams are usually used for affecting the flood and reducing the peak discharge. the materials used in these dams will usually make the flow turbulent, therefore darcy's law can not be used for this kind of dams and the equations based on the non-darcy flow must be applied. non-darcy flow equations are showed in two general ways including: and .one of the main parameters for flo...

where P represents the pressure gradient between the pulmonary artery and the pulmonary vein, F, the blood flow per unit time, and R. the vascular resistance. For a given pressure gradient and flow rate, R will be determined, among other things, by the physical dimensions of the chaniiels that the blood traverses. In a rigid hydraulic system this formula applies over a wide range of flow and pr...