Dianchi Shallow Lake Management

Lake Dianchi in the Chinese province Yunnan is a shallow lake suffering from algae blooms for years due to high pollution. We conducted a thorough survey of the water quality of the northern part of the lake called Caohai. This study was intended as the basis for the system understanding of the shallow lake of Caohai. The study consisted of two steps. First we collected available environmental, hydrological and pollution data from Kunming authorities and other sources. It was possible to parameterise a lake model model based on the preliminary data set. It supported first estimations of management scenarios. But the first and quick answers came with a relevant vagueness. Relevant monitoring data was still missing like P release from lake-internal sediment.Because data uncertainty causes model uncertainty and model uncertainty causes planning and management uncertainties, we recommended and conducted a thorough sediment and river pollution monitoring campaign in 2017. Examination of the sediment phosphorus release and additional measurements of N and P was crucial for the improvement of the shallow lake model of Caohai. In May 2018 we presented and discussed the results of StoLaM shallow lake model of Caohai and the outcomes of a set of management scenarios.The StoLaM shallow lake model for Caohai used in SINOWATER indicates that sediment dredging could contribute to the control of algae by limitation of phosphorus, but sediment management can only produce sustainable effects when the overall nutrient input and especially the phosphorus input from the inflows will be reduced significantly.

Predicting Hydrological Alterations to Quantitative and localized Climate Change in plateau regions: A case study of Lake Dianchi Basin

Climate change has greatly impacted hydrological regimes of lakes in sub-trophic and trophic areas. The uncertainties surrounding conventional future hydrological simulation methods with Coupled Model Intercomparison Project phase (CMIP) climate models have long been debated. However, it is crucial to obtain an accurate assessment result to help with better decision-making. In this study, we used the Lake Dianchi Basin (LDB) as a case study to demonstrate the use of a sub-catchment scale integrated model framework to obtain detailed hydrological simulation results and a comprehensive impact assessment of climate change on hydrological regimes. The results showed that 1) For the sub trophic lake basin LDB, its hydrological regimes are significantly impacted by climate change. Precipitation change impacted greater than air temperature change. 2) The 19 hydrological indicators showed large variations among the 18 climate scenarios. Precipitation impacted much greater than air temperature, and wet season might be impacted more by climate change. Climate change might impact more on 1/3/7-day minimums/maximums than 30/90-day minimums/maximums. 3) Enormous ecological and socio-economic risk for the LDB were indicated as its hydrologic regime is vulnerable to climate change. Among all six sub-catchments, Sub_06, characterized by a hilly landscape, would be impacted the most by climate change. 4) This study showed that, in regions with complex climatic conditions and topography, it is necessary to simulate hydrological states at the sub-catchment scale and differences of responses of each indicator to climate change should be fully considered.