Rainwater management

Rainwater harvesting and use Rainwater harvesting (RWH) is the process of collecting and storing rainwater rather than letting it run off. Rainwater harvesting systems are increasingly becoming an integral part of the sustainable rainwater management "toolkit" and are widely used in homes, home-scale projects, schools and hospitals for a variety of purposes including watering gardens, livestock, irrigation, home use with proper treatment and home heating. For households it is effective in reducing electricity and greenhouse gas emissions and providing domestic water; for urban agriculture, it is effective in reducing rainwater runoff and related issues; and for industry, it provides sustainability of facilities and low financial resource utilization. Rainwater harvested from roof structures or other compact surfaces is discharged through drains into storage tank, processed by treatment systems and then deployed in use facilities to complete the beneficial use of rainwater. Rainwater so treated is mainly used for irrigation, washing, laundry, and in some countries it is also considered as drinking water after the necessary purification. Gray-green infrastructure The use of combined sewer systems to treat excess rainwater runoff is common in older urban areas. The Combined Sewer System (CSS) collects rainwater runoff, domestic sewage and industrial wastewater into a single pipe. Combined sewer overflows (CSOs) occur when untreated wastewater is discharged to surface water beyond its hydraulic capacity, when this occurs, untreated rainwater and wastewater are discharged directly into nearby streams, rivers and other water bodies. Combined sewer overflows (CSOs) contain untreated or partially treated human and industrial waste, toxic materials and debris, and rainwater. Gray-green infrastructure is the key technology to solve this problem and is the core technology of the currently introduced "sponge city". The implementation of gray infrastructure, such as upgrading drainage networks, storage facilities or pumping stations with large diameter pipes, is critical to drain rainwater from urban catchments, while most green infrastructure handles the storage and infiltration of rainwater and drainage of gray infrastructure Building vegetated spaces, such as parks integrated with urban facilities, can increase the amount of pervious area. For new and redevelopment projects, reduce the amount of impervious surfaces, such as buildings, roads, parking lots, and other structures. Low-impact development (LID) Low-impact development (LID) refers to systems and practices that use or mimic natural processes that result in the infiltration, evapotranspiration or use of stormwater in order to protect water quality and associated aquatic habitat. Low-impact development (LID) practices provide more sustainable solutions than traditional piping and storm ponds in rainwater management. The sustainability of LID practices is achieved primarily through the use of porous pavement, bioretention, green roofs, rainwater harvesting, and other rainwater management strategies. Bioretention can effectively retain large amounts of runoff, porous pavement can effectively infiltrate rainwater runoff, and green roofs can retain rainwater under a variety of climatic conditions. These methods create and restore green space and reduce the impact of built-up areas at the site and regional scales, promoting the natural flow of water within an ecosystem or watershed. Applied over a wide range of scales, LID can maintain or restore the hydrologic and ecological functions of a watershed. To enhance irrigation in dry conditions, earthen ridges were constructed to collect and prevent rainwater from flowing down the hillsides and slopes. Even during periods of low rainfall, enough water can be collected for crop growth. Rainwater management can increase the productivity of smallholder farmers in arid environments. Productivity of rainfed agriculture is improved through supplemental irrigation, especially when combined with soil fertility management. Global Rainwater Management Program (GRMP):''' UNCCD platform link A comprehensive and globally scalable framework for integrated water resource management. It combines traditional harvesting techniques with advanced technologies, such as AI and GIS, and is differentiated by its focus on Contamination Reduction through multi-staged filtration and artificial wetlands before directing run-off for controlled Aquifer Recharge. Beyond the technical aspects, the program integrates a robust Financial Model that utilizes metrics like Return on Investment (ROI) and leverages methodologies such as Volumetric Water Benefit Accounting (VWBA) to quantify project benefits, which helps address investment gaps. The framework also extends its mandate to promoting Transboundary Water Security and conflict resolution by stabilizing regional water resources. == Tools ==

Rainwater management as a means of multi-stage control and improvement of rainwater systems needs to go through multiple steps of analysis and design, and in the new era of Low-impact development, rainwater management has become more than just a task for engineers, rainwater management projects have tended to become Integrated project delivery (IPD), designers need to consider rainwater management issues at a much earlier stage to avoid The development and use of software such as Rainwater+ is now helping designers to implement rainwater management at the design stage, its more intuitive GUI and simple workflow ensures that designers with little to no experience in hydrology can use Rainwater+, which will reduce later building construction conflicts to facilitate communication between all parties and improve construction quality. == Terminologies ==

Low impact development (LID) The term Low-impact development is commonly used in North America and New Zealand, and was first used in the United States by Barlow et al. Water sensitive urban design (WSUD) Water sensitive urban design (WSUD) is a concept widely accepted and partially acted on throughout Australia's federal and state governments. Integrated urban water management (IUWM) IUWM derives from the broader term, Integrated Water Management, which involves the integrated management of all parts of the water cycle within a watershed. Sustainable urban drainage systems (SUDS) SUDS established in a similar but separate design manual that includes Scotland and Northern Ireland as well as England and Wales, SUDS consists of a range of techniques and technologies based on the concept of replicating the natural, pre-development drainage of the site as closely as possible, culminating in a management system. == See also ==