This study aims at assessment the water quality condition in the rivers of Lake Chaohu Basin (LCB), and exploring the crucial parameters affecting its water quality. Four sampling activities were conducted seasonally from April to December in 2018 at 83 sites covering main rivers of LCB. We measured 15 physicochemical parameters, such as turbidity (tur), dissolved oxygen (DO), ammonium (NH₄-N), nitrate (NO₃-N), and permanganate index (COD_Mn). There were significant differences of the 15 environmental parameters (except T) on spatial level, and three significant groups (i.e., Group I, II, and III) were divided according to cluster analysis. Water quality was evaluated by a water quality index (WQI) based on these parameters, which are commonly used in WQI calculation. Generally, the water quality state was classified as “moderate” in LCB (mean value of 69.1). Meanwhile, the state varied obviously among the three groups, with “good” in Group I and “moderate” in Group II and III. Seasonally, WQI in autumn was highest, which was significantly different from that in the other seasons. The distribution of water quality was consistent with other studies regardless of some typical rivers and the whole basin. Moreover, a minimum water quality index (WQI_min) consisted of 5 crucial parameters (i.e., tur, DO, NH₄-N, NO₃-N, and COD_Mn) was not significantly different with the WQI based on all the 15 parameters, and its percentage error was relatively low (6.02%). With the excellent application in Lake Taihu Basin (LTB) nearby LCB, this WQI_min was robust and potentially universal in determining river water quality assessment in both basins. This finding is probably beneficial to low-cost and quick water quality evaluation in adjacent basins. In addition, TN maybe not suitable for WQI_min development in rivers, especially in the area with relatively high concentration, which probably resulted in an underestimation of water quality condition.

本研究旨在评估巢湖流域（LCB）河流水质状况，并探索影响其水质的关键参数。2018年4月至12月，在LCB主要河流的83个站点上按季节进行了四次采样活动。我们测量了15个物理化学参数，例如浊度（tur），溶解氧（DO），铵（NH ₄ -N），硝酸盐（NO ₃ -N）和高锰酸盐指数（COD _Mn））。在空间水平上，这15个环境参数（T除外）存在显着差异，并且根据聚类分析将三个重要的组（即I，II和III组）划分为多个。基于这些参数，通过水质指数（WQI）评估水质，这些参数通常用于WQI计算中。通常，水质状态在LCB中被归类为“中度”（平均值为69.1）。同时，三组之间的状态明显不同，第一组为“好”，第二组和第三组为“中等”。从季节上看，秋季的WQI最高，与其他季节明显不同。无论某些典型的河流和整个流域如何，水质的分布都与其他研究一致。此外，最低水质指数（WQI _min）由5个关键参数（即tur，DO，NH ₄ -N，NO ₃ -N和COD _Mn）组成，基于所有15个参数与WQI均无显着差异，并且其百分比误差相对较低（6.02 ％）。凭借在LCB附近的太湖流域（LTB）中的出色应用，该WQI _min在确定两个流域的河流水质评估中非常强大，并且可能具有普遍性。这一发现可能对相邻盆地的低成本和快速水质评估有利。此外，TN可能不适用于河流中的WQI _min开发，尤其是在浓度相对较高的地区，这可能导致水质状况被低估了。