Storm Water Management - Assignment Example

Before urban development, the water used to get soaked in water and was recycled easily by the atmosphere. Moreover, it contributed to land enrichment. In addition to causing pollution, stormwater can cause stream erosions and increased flooding.

            Moreover increased flooding conditions cause property damage due to the chemicals and pollutants that get dissolved in the water runoff. Thus it is becoming a source of public health risk. Even though safety measures are being taken, but still there a high risk of public safety getting compromised.

            Stormwater can also become a source of pollution after heavy rainfalls. In many countries such as USA and UK, some regulations have been set to prevent such cases. Water runoff is a serious problem in Asian countries like Pakistan, India, and Bangladesh where there is an unusually great amount of rainfall during the monsoon period. The conditions of the drainage system in the above-mentioned countries are below average. A design for stormwater management in these countries is yet to be produced. The new constructions are also making the situation worst due to the fact that new roads designed are not given the proper slopes to get rid of the stormwater runoff problems.

            The contributing drainage region establishes the boundary restrictions for the flow of runoff - from the highest elevation to the lowest point of elevation. Some of the impacts of the development on the hydrological cycle include increased peak discharges of runoff compared to pre-development levels, Increased volume of runoff formed by each storm in comparison to the pre-development situation, decreased time in which runoff reaches the stream, chiefly if extensive drainage changes are made.

            For the solution to this storm-water management problem that has become a great issue all over the world, many approaches are considered but the two most commonly used approaches are:

1. Conventional approaches
2. Water-sensitive approaches.

            There are limitations in conventional stormwater management system because it only focuses on transportation and reduction of peak flow. The concept of a conventional stormwater drainage system is to transport all water draining off impervious surfaces directly to the nearest water body through a network of drains and pipes. There are no concepts of water quality and harvesting to help the ecosystem be healthy.

            The conventional approach focuses on the removal of stormwater as quickly as possible from a site or area to reduce the possibility of flooding. This goal is achieved by providing curbs, gutters, and pipeline systems that can discharge the water to the nearest surface water source. Although this is an efficient way to remove water quickly and prevent on-site flooding, it has proven to be devastating to downstream waters by increasing the frequency and magnitude of floods, altering stream channel morphology

alignment, cross-section geometry, streambed composition) and reducing groundwater recharge, all of which make less water available for drinking water withdrawal and stream base flows. Therefore, it can cause flooding. It has been shown (Monk & Till) that the conventional system for urban stormwater management is to:

• Vegetation should be removed to a great extent
• Resistant surfaces should be used for building large areas
• Install pipes and constructed / hydraulically efficient channels that drain water away from an area as quickly as possible, by directly discharging stormwater into receiving water bodies.

            Water-sensitive urban design (WSUD) is a land planning and engineering design approach which describes the urban water cycle, as well as stormwater, groundwater, and water supply, into urban design to minimize environmental degradation and advance the aesthetic and recreational appeal. The use of water-efficient appliances to reduce potable water use;

• Grey water reclaims as an alternate resource of water to conserve potable supplies.
• Detention, instead of rapid conveyance, of stormwater;
• Recycle, storage and infiltration of stormwater, instead of drainage system augmentation;
• Use of vegetation for stormwater filtering use.
• Water resourceful landscaping to reduce potable water consumption;
• Protection of water-related environmental, recreational, and cultural values by minimizing the ecological footprint of a project associated with providing supply, wastewater, and stormwater services;
• Localizedwastewater treatment and reuse systems to reduce potable water consumption and minimize environmentally harmful wastewater discharges;
• Provision of stormwater or other recycled urban waters (in all cases subject to appropriate controls) to provide environmental water requirements for modified watercourses;
• Flexible institutional arrangements to cope with increased uncertainty and variability in climate;
• A focus on longer-term planning; and
• A diverse portfolio of water sources, supported by both centralized and decentralized water infrastructure.

            In conclusion, Stormwater is an excellent alternative to non-portable use, it is easy to capture, manage and store on-site. Conventional urban stormwater management has focused on providing highly efficient drainage systems to rapidly collect and remove stormwater runoff. However, the system does not consider quality and harvesting management related to the aquatic ecosystem. Water-sensitive urban design (WSUD) can substitute the conventional method to maintain stormwater efficiently and also can help to improve ecological habitats. I believe that the water-sensitive system should be a priority when governments and companies deal with urban design.