People collect and store rainwater in buckets, tanks, ponds and wells. This is commonly referred to as rainwater harvesting and has been practised

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2 People collect and store rainwater in buckets, tanks, ponds and wells. This is commonly referred to as rainwater harvesting and has been practised for centuries. Rainwater can be used for multiple purposes ranging from watering for livestock, irrigating crops to domestic use in washing, cooking and drinking. Rainwater harvesting is a simple low-cost technique that requires minimum specific expertise or knowledge and offers many benefits.

3 Collected rainwater can supplement other water sources when they become scarce or are of low quality like brackish groundwater or polluted surface water in the rainy season. It also provides a good alternative and replacement in times of drought or when the water table drops and wells go dry. The collected rainwater is a valuable supplement that would otherwise be lost by surface run-off or evaporation

4 Due to pollution of both groundwater and surface waters, and the overall increased demand for water resources due to population growth, many communities all over the world are approaching the limits of their traditional water resources. Utilization of rainwater is now an option along with more conventional water supply technologies, particularly in rural areas

5 Increasing water needs/demands Lower ground water tables and Depleted reservoirs Variations in water availability Water from sources such as lakes, rivers and shallow groundwater can fluctuate strongly Advantage of collection and storage near the place of use Collecting and storing water close to households improves the accessibility and convenience of water supplies and has a positive impact on health. Quality of water supplies Rainwater is generally of good quality

6 Catchment Surfaces The catchment of a water harvesting system is the surface that receives rainfall directly and drains the water to the system. Any roofing material is acceptable for collecting water. However, water to be used for drinking should not be collected from thatched roofs or roofs covered with asphalt. Lead should not be used in these systems. Galvanized, corrugated iron sheets, corrugated plastic and tiles make good roof catchment surfaces. Flat cement or felt-covered roof can also be used provided they are clean

7 The rooftop catchment usually consists of gutters hanging from the sides of the roof sloping towards a downpipe and tank. This delivery system or guttering is used to transport the rainwater from the roof to the storage reservoir. For the effective operation of a rainwater harvesting system, a well-designed and carefully constructed gutter system is crucial because the guttering is often the weakest link in a rainwater harvesting system.

8 Vessels used for small-scale water storage Storage reservoirs for large quantities of water (from 1 m3 to 30 m3 for domestic system at the household level)

9 Large Scale rain water storage Option Schematic of a Storage Tank Reservoir

10 Four types of user regimes can be discerned: Occasional - Water is stored for only a few days in a small container. This is suitable when there is a uniform rainfall pattern and very few days without rain and there is a reliable alternative water source nearby. Intermittent There is one long rainy season when all water demands are met by rainwater, however, during the dry season water is collected from non-rainwater sources. RWH can then be used to bridge the dry period with the stored water when other sources are dry. Partial - Rainwater is used throughout the year but the harvest is not sufficient for all domestic demands. For instance, rainwater is used for drinking and cooking, while for other domestic uses (e.g. bathing and laundry) water from other sources is used. Full Only rainwater is used throughout the year for all domestic purposes. In such cases, there is usually no alternative water source other than rainwater, and the available water should be well managed, with enough storage capacity to bridge the dry period.

11 Water needs: - Domestic Use - Drinking, cooking and cleaning - Crop Production - Irrigating ( Using in drip irrigation technology) - Livestock Production - Irrigating and cleaning.

12 Know your location and have an Idea of is average rainfall Decide upon roof catchment its type and area. Know your water demand and reservoir storage size. Courtesy of Hydro-meteorological Service, Ministry of Agriculture - Guyana

13 Courtesy of Hydro-meteorological Service, Ministry of Agriculture - Guyana

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15 In the month of February 2016, Lethem recorded the lowest value of evapotranspiration. The this value 2.1 mm was recorded on the 13 th of February 2016.

16 Location: Latitude: Longitude: Roof size: Roof Type: Lethem, Guyana degrees degrees square meters Metal Runoff Coefficient: 0.9 Water demand: 480 litres per day Rainfall The average rainfall at this location varies between 26.4 mm in the driest month (February) and mm in the wettest month (June). The total annual rainfall in an average year is 1609 mm.

17 Water availability: A metal roof has a runoff coefficient of 0.9, which means that 90% of the rain can be harvested. Based on this runoff coefficient and a roof area of square meters a volume of liters (74.1 mm x m² x 0.9) of water can be collected in the driest month (October) and liters (404.6 mm x 30 m² x 0.9) in the wettest month (June). The total yearly amount of water that can be collected from the roof is liters (835m³) in an average year.

18 Water demand: The water demand for 40 persons is 800 liters per day, which equals to about liters per month. The total water demand is liters (292 m³) per year. During every month the amount of water that can be collected from the roof is larger than the water demand.

19 Required storage Since the amount of water that can be collected from this roof is enough to fulfil the demand, even in the driest months, no large storage reservoir is required. A small storage volume to bridge a number of days without rain should be enough to provide an adequate water supply throughout the year.

20 Water Needs for Sheep range from 2 litres to 12 Litres per day.

21 Location: Guyana Upper Takutu-Upper Essequibo Latitude: degrees Longitude: degrees Roof Size: 300 Square meters Roof Type: Metal Runoff coefficient: 0.9 Water demand: 600 litres per day Water demand Summary of the Results: During an average year there is no need to construct a large storage reservoir, but during a dry year a storage reservoir of litres (38.4 m3) is required to have enough water during the dry season. The water demand is 600 liters per day, which equals to about liters per month. The total water demand is liters (219 m³) per year. During every month the amount of water that can be collected from the roof is larger than the water demand.

22 1. Surface Irrigation Running or impounding water over the surface and allowing it to saturate the soil to some depth. 2. Sprinkle irrigation Spraying water into the air and allowing it to fall on to the plants and soil as simulated rainfall 3. Drip Irrigation Dripping water on a fraction of the ground surface so as to infiltrate into the root zone 4. Subsurface extruders Introducing the water directly into the root zone 5. Sub-irrigation Raising the water-table from below (in places where the groundwater is shallow and controllable) so as to moisten the root zone by capillary action.

23 Drip irrigation The principle of a drip irrigation system is to provide a plant with a direct and accurate dose of water, hence to the roots. Drip irrigation is very popular for irrigating vegetables, herbs, fruit crops and newly planted trees. The crop gets ample water; not too much nor too little, and will grow well. Very little is lost through evaporation, surface run off or by weed uptake. Sprinkler irrigation Sprinkler irrigation is a method of applying irrigation water which is similar to natural rainfall. Water is distributed through a system of pipes usually by pumping. It is then sprayed into the air through sprinklers so that it breaks up into small water drops which fall to the ground. The pump supply system, sprinklers and operating conditions must be designed to enable a uniform application of water. There is a higher loss of water through surface run off and evaporation.

24 Manual cleaning of Debris For both Drip Irrigation and Sprinkle Irrigation it is important that the water be clean and free from sediment as these can create blockages in nozzles. It is important to install filters to reduce the amount of debris in the water collected. First flush removal of Debris Catchment - Roof First flush removal of Debris

25 Filter Main line This model of rain water harvesting and drip irrigation takes gravity flow as a advantage. As system of valves can also control the flow of water to the lower levels. In areas that are flat, water can be pumped upwards to tanks on trestles. The flow of gravity will allow the water through the tubes to the plants.

26 Add Mulch to reduce evaporation A layer of Mulch can be added this layer helps to reduce the drying out of the top layer of the soil. In the drip irrigation system, the water is applied in small amounts directly at the root of the plants. The water penetrates into the soil directly in the root zone area to be utilized by the plant. However one must remember that mulch should be kept back slightly from the stems of the plants.

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