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the design drain spacing (L) can be found from the equation in dependence of the drain depth (Dd) and drain radius (r). Drainage criteria One would not want the water table to be too shallow to avoid crop yield depression nor too deep to avoid drought conditions. This is a subject of drainage research.
EnDrain is software for the calculation of a subsurface drainage system in agricultural land. The EnDrain program computes the water flow discharged by drains, the hydraulic head losses and the distance between drains, also obtaining the curve described by water-table level.
These curves are commonly used in hydrology for flood forecasting and civil engineering for urban drainage design. However, the IDF curves are also analysed in hydrometeorology because of the interest in the time concentration or time-structure of the rainfall , [ 2 ] [ 3 ] but it is also possible to define IDF curves for drought events.
A system can be one of several hydrological or water domains, such as a column of soil, a drainage basin, an irrigation area or a city. The water balance is also referred to as a water budget. Developing water budgets is a fundamental activity in the science of hydrology. According to the US Geological Survey: [4]
Drainage density is a quantity used to describe physical parameters of a drainage basin. First described by Robert E. Horton , drainage density is defined as the total length of channel in a drainage basin divided by the total area, represented by the following equation:
Drainage gradient (DG) is a term in road design, defined as the combined slope due to road surface cross slope (CS) and longitudinal slope (hilliness). Although the term may not be used, the concept is also used in roof design and landscape architecture. If the drainage gradient is too low, rain and melt water drainage will be insufficient.
The runoff curve number is based on the area's hydrologic soil group, land use, treatment and hydrologic condition.References, such as from USDA [1] indicate the runoff curve numbers for characteristic land cover descriptions and a hydrologic soil group.
In the past, these calculations were done by hand using a slide rule and with methods such as Simpson's rule. Earthworks cost is a function of hauled amount x hauled distance. The goal of mass haul planning is to determine these amounts and the goal of mass haul optimization is to minimize either or both. [2]