*Article* **Study on Ecological Water Demand and Ecological Water Supplement in Wuliangsuhai Lake**

**Fang Wan 1,\*, Fei Zhang <sup>1</sup> , Xiaokang Zheng <sup>2</sup> and Lingfeng Xiao <sup>1</sup>**


**Abstract:** Wuliangsuhai Lake is the largest shore lake in the upper reaches of the Yellow River and has become an important ecological barrier and habitat for birds in northern China. In recent years, pollutants and nutrient loads have been partially reduced, and the water quality in the lake area has been alleviated to a certain extent. However, the overall water treatment of Wuliangsuhai Lake is worrying and needs to be improved urgently. In this paper, according to the current situation of water quality and the goal of ecological environment protection, the ecological water demand of Wuliangsuhai Lake was estimated by using the dynamic viewpoint. The calculation of ecological water demand mainly considered: water of evaporation and leakage in the lake, and water demand of pollutant dilution. The requirements of ecological water demand in Wuliangsuhai Lake were solved in four ways: agricultural wastewater in the irrigation area; strengthening water saving in the main canal; carrying out water-saving system reform; and transporting ecological water use for washing salt to Wuliangsuhai Lake during an irrigation gap period. For Wuliangsuhai Lake in the Mengxin Plateau, which is located in a serious water shortage area, it is of great significance to protect the ecological environment by ensuring the amount of water entering the lake, maintaining the existing water surface of the lake, and giving full play to its water ecological function.

**Keywords:** Wuliangsuhai Lake; ecological water demand; ecological water supplement; ecological function
