The spatial distribution of farmland shelterbelts in desert oasis areas under water resource constraints: A study based on the SWAT model and scenario analysis

Farmland shelterbelts play a crucial role in reconciling water resource constraints with eco-agricultural development in arid regions. By mitigating aeolian erosion and improving farmland microclimates, they serve as protective barriers, enhancing ecological stability and agricultural productivity. However, increasing water stress and degradation risks have emerged due to water scarcity and reduced lateral seepage recharge under evolving irrigation practices. Existing research remains limited in integrating water balance and habitat suitability into spatial planning for afforestation. To bridge this gap, this study develops a multi-constraint spatial layout framework for afforestation in arid regions. Under two irrigation scenarios (border irrigation and low-pressure pipe irrigation), the SWAT model was coupled with an ecological water requirements model to assess the afforestation potential of Populus alba var. pyramidalis in arid areas from 2009 to 2020. Results show that evapotranspiration, surface runoff, and lateral flow account for 75.6%, 21.3%, and 4.1% of the total water consumption, respectively. The afforestation potential of Populus alba var. pyramidalis decreases gradually from the central irrigation zones toward the peripheries. Under traditional border irrigation, agricultural intensification zones can support higher tree density, ranging from 3730 to 14,474 trees/km², whereas under the low-pressure pipe irrigation scenario, the suitable range is 4021–13,855 trees/km². These findings provide a scientific basis for balancing water use between agriculture and forestry, optimizing the spatial configuration of farmland shelterbelts, and promoting sustainable ecological and agricultural development in arid regions.