Investigating effects of rainwater catchment systems on soil moisture for establishment of dryland gardens in steep lands

The present research was carried out at a research station in Qarehchryan, located in north-west of Zanjan City, Iran. Rainwater catchment systems had dimensions of 5×8 m, with five treatments of control (withness)(A), without vegetation and gravel with gravelly filter (B),without gravelly filter (C), impervious  a part of the system with gravelly filter (D) and without gravelly filter (E) in a randomized complete block design with three replications. There were nine daily rainfall events from April until late August 2013, with two times irrigation with an interval of 60 days, 45 liter for every seedling and 33 times of measurement of moisture at depths of 20 and 50 cm. Results showed that spring rainfall had not been able to produce runoff in the control treatments and had no effect on soil moisture. Soil moisture influence has been increased by daily rainfall in both B and C treatments compared to control treatments.. Soil moisture influence from daily precipitation has been increased up to 30 percent in D and E treatments due to insulating surface of existing systems and impervious surface of rainwater catchments. Timeline  of the average moisture at the depths of 20 and 50 cm is almost similar in all treatments. This situation indicates that the distribution of moisture in depth of 20 to 50 cm is similar with no significant difference, but, the moisture at the depth of 20 cm is more than 50 cm.