Document Type : Research Paper
Authors
1 Associate Professor, Kermanshah Center for Agricultural and Natural Resources Research and Education, Agricultural Research, Education and Extension Organization (AREEO), Kermanshah, Iran
2 Professor, Professor, Kermanshah Center for Agricultural and Natural Resources Research and Education, Agricultural Research, Education and Extension Organization (AREEO), Kermanshah, Iran
Abstract
Introduction
Climate change and its consequences are among the most important concerns for agriculture and the environmental organizations worldwide. Water scarcity and decline soil moisture are the most significant consequences of this trend in arid and semiarid region. One of the consequences of climate change is the phenomenon of oak forest dieback in western Iran (Quercus persica). This issue can disrupt the balance of land resources in the Zagros region, leading to consequences such as degradation of land resources, increased dust storm, soil erosion, flooding, climate change, and impoverishment of local communities.
Materials and methods
One of the fundamental solutions in this regard is to maintain soil moisture on slopes using rainwater harvesting systems, such as interrupted and crescent-shaped bunds. The key objective of this research is to determine the role of crescent-shaped bund systems in collecting surface runoff to control the phenomenon of oak forest dieback in western Iran. To achieve this goal, the Merek forest watershed in Kermanshah province where dieback of forest species has been observed, was selected as the study site. Subsequently, rainwater harvesting systems, including crescent-shaped bunds, were constructed in this forest area. Additionally, a nearby site with similar conditions was designated as the control site for comparison. After the construction of the bunds by the Department of Natural Resources of the province, data collection from the forest site was carried out over a three-year period (2022–2024), this included monthly monitoring of changes in soil aggregate size, organic matter, organic carbon, and soil pH, along with measurements of soil moisture percentage.
Results and discussion
The results of this study explored that among the four soil moisture measurement points, including the bottom of bund, bund downwards, between the bund and the control (without bund), soil moisture storage in sub layer (15 to 30 cm) were about 20, 17, 14 and 13 percent, respectively, which was significantly higher in the bund bottom compeered with control plot. The results of this study also showed that in the third year, the soil organic carbon storage in the bund treatment and the control treatment was 4.01% and 1.6%, respectively, indicating a statistically significant difference between them. In addition, the bunds significant increase the proportion of large and very large soil aggregates. The combination of these conditions led to improvements in cation exchange capacity, essential nutrient elements, and some micronutrients within the area where the bunds were implemented. Finally, the increase in soil organic matter and the accumulation of runoff in the bunds reduced soil erodibility and stabilized it against erosive factors. As a result, the erodibility index in the bund treatment and the control treatment was approximately 0.19 and 0.32, respectively.
Conclusions
According to the results of this research, the proper and precise construction of these bunds without the use of heavy machinery is a simple, economic and effective measure for rainwater harvesting, In addition to soil moisture storage and enhancement of plant biological indicators, it improves key soil characteristics mainly soil organic matter, coarse soil aggregates proportion and soil nutrients, which ultimately leads to soil sustainable, carbon sequestration, curtailing flooding hazards on the hill-slope, and strengthening subsurface flow.
Keywords
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