Scheduling coefficient helps us to define how much critical dry area shall be left in irrigated area and irrigation duration being necessary for its application to eliminate this area (Zoldoske. 2003). In calculation of SC. it is useful to be benefitted from computer program. Due to limitations in DU approach SC gains value especially in turf and golf industry (Wilson and Zoldoske, 1997). The driest area is usually user defined as 1. 2. or 5 percent of the coverage area. SC generally varies between 1.1 and 1.4. An efficient irrigation system should aim to achieve a scheduling coefficient less than 1.3.
SC = Average catch overall / Average catch in the critical dry area (9)
4.2 Supplemental irrigation methods in landscape irrigation
Drip and micro sprinkler irrigation are used in areas here sprinkler irrigation is not appropriate in landscape irrigation. Drip irrigation system is installed in two different types such as under soil and over soil. Water is transmitted to root region through a pipe network and applied here by a means of drippers. Vaporization, runoff and deep seepage into deeper are prevented due to water’s implication by low flow rate in drip irrigation system. Therefore it is irrigation method of which application performance is the highest (Schwankl & Prichard. 1999). Also, drip irrigation minimizes sickness and insect damages because it makes irrigation without wetting leaves. It has less operating pressure. It applies water at fewer amounts as compared to sprinkler irrigation. Problem of weed occurs less because certain part of area is wetted. Also, drip irrigation performs at high efficiency without runoff on hilly terrain. This method is used in soils where area to be irrigated is narrow and saltiness ratio is problematic and resource for water is limited and soil is highly inclined in landscape irrigation (Dines & Brown. 2001).
Micro Sprinkler can be carried out by placing them singularly under trees in situation that drip irrigation can’t provide adequate wetting area. Throw distance of these heads is highly low. However, flow rates changes between 30-300 l/h. accordingly wetting ratio which is requested is provided in a more economic way. Micro sprinkler is developed by the purpose of linking good sides of sprinkler and drip irrigation system.
5. Planning stages of sprinkler irrigation systems
Steps of sprinkler irrigation project are carried out a number of calculations starting from choice of head and to flow of pump.