Abstract
One of the most important factors in determining the Ecohydrological balance is soil moisture content. Any variation in soil moisture, albeit insignificant, can have a chain effect on the quality of soil structure, soil particles, erosion rate, microbiological activity in soil crust, and infiltration rate. which in turn can affect ecosystem dynamics. Therefore, it is important to use more eco-friendly and less invasive techniques, such as rainwater harvesting structures (RHS), to enrich the current soil moisture content in any ecosystem. The study used an RWH structure, namely the Negarim Microcatchment, to observe its real-time effects on soil moisture variations. The continuous effect of certain treatments was also evaluated. To do this, a small area of approximately 3375 m2 in the Dehbar watershed (36 ° 18’ N, 59° 24’ E) located in Khorasan Razavi Province of Iran was selected based on the map of water harvesting potential in the watershed that was generated by GIS to construct the structures. This study aimed to evaluate the efficiency of a number of variations of RHS in retaining soil moisture its different soil depths. For this purpose, FAO’s standard measurement was used to calculate and construct three different sizes of structures for this research. FAO’s standard measurement included the 1 x 1 area for the infiltration pit which was used as the medium-sized (standard) structure. The other two structures were one time larger and one time smaller, respectively. Each size group consists of 38 Microcatchment with two treatments of natural (N) and plastic covered (P) for the catchment area and a combination of natural cover (N), seedling (S), rock cover (R), no rock cover (F), summer irrigation (W), and no summer irrigation (D) for the infiltration pits. After each significant rainfall, soil moisture measurement was measured by TDR sensors with a repetition of three times at five-day intervals throughout two crop years. The data analysis results showed that the main control factor of the structure performance was soil depth and the catchment area cover type. Comparing the three depths, the depth of 30 cm showed more significance by a margin of 10–20% over the depths of 20 cm and 10 cm. The same could be said about the difference between plastic-covered catchments and natural-covered ones at 5–10%. The infiltration pit treatments showed a moderate 2–3% effect. It can also be concluded that while each treatment showed a significant interrelationship between different inter-factors, no significance was found between individual factors. The results of this study indicated that overall variation in RHS can be significant in RHS's ability to conserve soil moisture. The provided data can be used for long-term usage and data monitoring of such structures.