Present research has been executed in Chaharmahal va Bakhtiary Province in order to investigation

of rainwater harvesting techniques for runoff generation optimizing. Towards this attempt, nine rainwater

harvesting systems having three different treatments(isolated surface, removed surface and natural vegetation

cover) with three replicates were made on a slope of 20 percent. At the end of each system, a reservoir has

been installed to collect runoff coming from the plot. Rainfall amounts are estimated using a rain-gauge

nearby and runoff volume was measured in the reservoir. Compare of the mean of treatments indicated that

the system with isolated surface has generated the maximum runoff volume. The runoff volume generated

by isolated surface was five equal of removed surface and 17.5 equal of natural vegetation cover. Analysis

of 21 rainfall events led to runoff generation showed that the mean runoff coefficient derived from the

system with isolated surface was 64.3 percent. Statistical analyses using SAS software, proves that there

is a significant difference in the system with isolated surface(p<0.01). So utilization of isolated surfaces

can be recommended in supplying water for hillside orchards in watersheds using rainwater harvesting

systems