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Drainage water management is a growing concern worldwide, especially due to the recent floods that are associated with climate change.

Drainage water management is a growing concern worldwide, especially due to the recent floods that are associated with climate change.

The effective control of runoff which pertains to water from rain or snowmelt, and subsurface waters aims to reduce potential risks on lives and properties. Less visible yet equally important are the concerns of agricultural managers who need to ensure that nutrient pollutants are conveyed safely away from downstream water to maintain the latter’s quality. Several areas relevant to this are discussed including (a) Drainage system design, (b) controlled drainage, (c) drainage ditch management, (d) wetlands, (e) buffers and vegetative filter strips, (f) side-inlet controls, (g) reactive barriers, and (h) agronomic management.1 This short essay touches on some of these.

Site selection for a drainage management system is determined by the proximity of critical sources of pollutant, usually facilitated by “simple site assessment tools (Phosphorus Index, Nitrogen Leaching Index).”2 Managers keen in this regard aim to install “remedial practices to areas where a pollutant source and a process to mobilize that pollutant overlap.”3 Once the sites are picked, the particular drainage could be one or combinations of several including the controlled type. This type allows one to adjust the water table to any level between ground surface and the drainage depth.4 Managers may also opt to go for vegetative buffers-practically grass that “reduce the velocity of runoff water”5 in order to increase “water infiltration and deposition of suspended solids.”6 A more advanced option is to put up reactive barriers which “intercept drainage water with materials that remove chemical contaminants”7, say to “decrease nitrogen loads entering ditches.”8 Also known as a bioreactor, this permeable barrier demands little maintenance and requires minimal crop land to be taken out of production.

Water drainages for urbanized settings are akin to those in agricultural settings, and so also require consideration of several factors. In particular, the planning and design of storm water drains depend on information about the place where they are to be installed. An urban center with its buildings and pavements allows lesser movement of water through pores in the soil and permeable rocks as compared to agricultural lands. Consequently the runoff rate and volume increase with urbanization and flood occurs in the floodplain.10 Therefore numbers and graphs of the following are crucial: runoff details, precipitation data, infiltration indices, concentration time, and intensity of rainfall.11 The article cited here refers to these as it discusses the design of a drainage system based on the runoff estimate. By using this estimate in what is known as the Rational method, sizes of drainages are arrived at which are more responsive to the prevalent weather of the place.

In conclusion, this essay provides an overview of the multi-faceted field of water drainage system. In urbanized settings, the improvement and maintenance of these systems is highly demanded owing to the direct impact of excess runoff on pedestrians and vehicular traffic flow. Drainages bear upon the quality of life for city dwellers. In the agriculture sector, the implementation of techniques other than the use of open ditches is almost stymied due to their high initial and maintenance costs. Moreover the return on investment is minimal, and so the pursuit of environmental-friendly options is driven predominantly by altruism.

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