[Insert Figure 5 here]

3.3 Spatial distribution of lake level changing rates during 2016-2018

Our results of lake level changing rate are shown in Fig. 6 and Table 3. Obviously, most lakes experienced a significant increase during the period 2016-2018. To be specific, except the lake level of Nam Co remained relatively stable with little fluctuations, the water level time series of other lakes revealed the rising tendency with the mean rate of 0.74 m/a. The three lakes in the northwestern TP, Jieze Caka, LumajangdongCo, and Heishibei Lake showed significantly difference in water level rising rates, and the level for Heishibei Lake rose fastest, reaching 1.39 m/a. The northern part of the TP is located in the Hoh Xil region, known for complex and harsh geographical environment. A large number of endorheic lakes are distributed in this region. As listed in Table 3, most of the lakes were expanding with an average level increase of larger than 0.82 m/a. The level for XijingUlan Lake increased at the greatest rate of 1.52 m/a. Ayakkum, the largest lake in this region, also exhibited a significant increase of 0.83 m/a. The average increasing rate was 0.66 m/a in the central part of the TP. The lake levels for Dagze Co and Zhari NamCo experienced the rapid rising, exceeding 1 m/a. In Qinghai Province, the level for Qinghai Lake maintained a steady increasing trend of 0.47 m/a. Overall, most lakes in the northern Tibetan Plateau experienced a relatively faster rates of water level rise, compared to those in the NETP and eastern CTP.