Whole process phosphorus management strategy construction with phosphorus load characteristics, driver and efficiency from the material flow perspective

End-of-pipe treatment is the main measure to control phosphorus pollution in lake watershed. Although a large number of lake watersheds have taken this measure, the lake environment has not improved significantly. Therefore, from the perspective of material flow, this study aims to put forward the whole-process lake watershed phosphorus management strategy system, including phosphorus flows characteristics, drivers analysis and phosphorus utilization efficiency from phosphorus input and discharge to entering into the lake, which is also an important way to control phosphorus pollution in lakes. Take Erhai Lake as an example, the results indicated that the phosphorus flows have stage characteristics, with the phosphorus reduction efficiency in society remained stable around 95% before 2012 then declined to 86% in 2017, the phosphorus self-purification efficiency in nature fluctuation rise from 53% to 84% before 2012, then declined to 80%. Besides, the net anthropogenic phosphorus input slowly increased before 2012, while declined 2.4-fold during 2012–2017 mainly form fertilizer and food/feed. The phosphorus discharge related to rural production and life, accounting for over 83%, mainly from the livestock and poultry farming wastewater. Phosphorus from overflow entering into the lake account for around 32% and the phosphorus from internal release of sediment keep rising to 13% from 2000 to 2012. Fertilizer application was the main driver across the phosphorus transport process, except of per capital gross domestic product. Therefore, the P management strategy optimization in Erhai lake should pay more attention on P utilization efficiency, waste management and its way into the lake, especially in the field of agriculture production and life. The constructed whole-process watershed management strategy could support the lake watershed comprehensive treatment for improving P utilization efficiency and has universality.