Water Resources and Farmland Management in the Songhua River Watershed under Interval and Fuzzy Uncertainties

The Songhua River Watershed (SHRW) in Northeastern China has been challenged by water scarcity, water contamination, and soil erosion for decades. These problems will remain or even worsen in the following decades, threatening regional eco-environmental quality and socio-economic development. Mitigation of these problems through integrated water resources and farmland management (WRFM) is desired but is challenged by multiple system complexities, e.g. interrelations of diverse system components. To fill this gap, an interval fuzzy water resources and farmland programming (IFWRFP) approach is developed in this study for eliminating the potential problems in the SHRW, leading to increased reliability of the decision support process. A series of systematic WRFM measures are proposed for enabling harmonious development of ecological environment and social economy in the SHRW. For instance, planting should always be the priority due to the major contribution of agriculture to the regional economy. As the primary commercial crop, rice cultivation should be allocated the most irrigation water, followed by corn, potato and soybean. Potato yield should be increased to compensate for reduced productivity of the other crops since 2019. It is also revealed that economic benefits are proportional to water environmental pollution in the SHRW. Therefore, decision-makers should adopt the most reasonable suggested schemes after fully balancing the trade-off of environment and economy. Most importantly, a variety of supporting policies are required for enabling sufficient implementation of these measures across the SHRW. For instance, individual farmers can be encouraged to follow the overall crop cultivation plan by the alteration of subsidiaries, taxes, and prices on crop-related activities. The modeling solutions show that the IFWRFP approach can systematically optimize allocations of water resources and cultivation patterns and thus potentially eliminate the problems of water scarcity, water contamination, and soil erosion in the SHRW.