![]() During the dry season, the average monthly rainfall is 37 mm with several months without rain. Between October and December, there are short rains with 100 mm average monthly rainfall. For the long rainy season between April and July, the average monthly rainfall is 134 mm. Annual precipitation is 1024 mm (data from 1984 to 2013 by the Kenya Meteorological Department). The city experiences a tropical climate, which is hot and humid throughout the year with a mean daily minimum and maximum temperature of 22 ☌ and 30 ☌, respectively. Depending on the need and data availability, WEAP simulates several aspects such as sectoral water demands, water allocation rights and priorities, ground and surface water flows, reservoir operations, and the assessment of vulnerability and cost-benefit analysis, amongst others. The water resources system in WEAP is represented by demand sites, supply sites, catchments, withdrawal points, transmission links, wastewater treatment, environmental needs, and the generation of pollution. The model uses scenarios to promote stakeholder involvement in the entire water resources planning and decision making process. WEAP follows the principle of the “scenario-based gaming approach” that has been developed to reduce water demand-supply conflicts within the area of interest. Demand and supply sites are considered concurrently. It is both a model for simulating water systems in an integrated manner (natural and manmade components/infrastructures) and a policy oriented decision-support system (DSS). WEAP (Water Evaluation and Planning System), developed by the Stockholm Environment Institute (SEI, Stockholm, Sweden), is a planning tool extensively used in integrated water resources management. The rooftop area is a crucial input for the incorporation of RRWH systems into water resource system models, which can be applied for the quantitative planning of water resources and the development of water policies. Due to first flush diversion, the quantitative yield of RRWH systems is reduced. First flush diverters need to be incorporated into the system in order to protect the water quality in the collection tank from contamination. It describes the amount of initial rainfall, which is needed after a dry period to remove contaminants such as particles, dirt, bird droppings, and insect bodies from the roof and the gutter. The “first flush” is a criteria often used for the design of RRWH systems. Furthermore, the slope of the roof has considerable influence on the roof runoff. A study by showed that galvanized steel yielded the best quality rainwater that met the WHO (World Health Organization) drinking water guidelines for chemical, physical, and biological parameters. Hard surfaces like iron, concrete, and tiles produce the highest amount of collected water because they have high runoff coefficients. The quantity and quality of the harvested rainwater greatly depend on the type of roofing material used. In Sub-Saharan Africa, the reliability of RRWH systems for domestic water supply can be improved by the consideration of rainfall characteristics, e.g., the number of events above a certain threshold, wet spells, etc., and improved technical design. ![]() RRWH can be one aspect of the adaptation of water supply systems to climate change. This is particularly important in developing countries where women and children have to walk over long distances to fetch water. ![]() ![]() The authors of observed that the most important feature of RRWH at a domestic level is its ability to deliver water to households “without walking”. RRWH can support the water supply in almost any place either as a sole source or by reducing stress on other sources through water savings. ![]() The level of expertise required is low and ownership can be at a household level, making it easily acceptable to many people. Rooftop rainwater harvesting (RRWH) refers to the collection and storage of water from rooftops. The authors of describe rainwater harvesting to be a dominant contributor for sufficing urban water demand. Rainwater harvesting is a technique used to collect and store rainwater e.g., from buildings, rock catchments, and land or road surfaces. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |