Water from Small Dams

It is difficult to estimate the water requirement for irrigation because it depends on thetype of irrigation method used, the soil type, climate, crop type and its growingperiod. For example, bucket irrigation of vegetables requires about double the volumeof water required for drip irrigation. Table 3 illustrates the water requirement fortomato/kale production using drip irrigation on a 1/4 acre.Table 3. Example of water requirements for drip irrigationType of Type of crop Daily Water Total waterirrigationrequirementfor 90 dayson a ¼ acre(approx. 1000 m 2 )requirementDrip irrigation Tomatoes/kale 1,000 x 90 = 90,000 litresTotal requirements for drip irrigation of 1/4 acre is 90,000 litresSource: Drip Irrigation Project, Kenya Agricultural Research Institute (KARI).2.4.4 Total water requirementA reasonable estimate of the water demand that a pond or small earth dam may beexpected to meet can now be worked out by simply adding together the total waterrequirements for domestic, livestock and irrigation in tables 1, 2 and 3.Table 4. Example of total water requirement for domestic, livestock andirrigationDomestic water for a household for 180 days20, 160 litresWatering 35 animals for 180 days90,000 litresDrip irrigation of 1/4 acre for one growing season90,000 litresTotal water requirement200,160 litresThe total water requirement is estimated as 200,160 litres which can be converted intocubic metres by dividing the figure by 1,000 as follows; 200,160 litres / 1,000 =200.16 cubic metres, say 200 m 3 .2.5 Total water storage requirement9