Accurate and reliable prediction of runoff generation is necessary for flood control scheduling, water supply planning, and hydropower generation. Support vector machine (SVM), which is at the forefront of current research of regression and classification, was used in this paper to conduct monthly mean streamflow prediction. A novel heuristic optimization named bat algorithm (BA) was introduced to determine the parameters of SVM [penalty parameter (C) and kernel parameter (η)], in which the initial fitness was supposed to be equal to the initial loudness for all bats. In order to evaluate the effectiveness of the proposed approach, monthly mean streamflow from 1952 to 2011 of Yichang station in the middle reaches of the Yangtze River were trained and tested. In the meantime, the given data set was also modeled using artificial neural networks (ANN) and cross validation–based SVM. The comparison results indicate that the proposed model (bat algorithm–based SVM) is more accurate compared with both A...

To analyze the anthropogenic activities on water-environment conditions, sampling campaigns and isotope measurement for precipitation, river water and groundwater were conducted in Jinjiang River System, Chengdu, China for one year. The results show that runoff is the main factor affecting the isotopic composition in natural-state rivers, while in rivers affected by human activities, the isotopic composition varies greatly due to the influence of impermeable surface and municipal pipe networks on water evaporation and mixing. The warm-and-humid moisture source and "heat island" effect lead to high slope and intercept of local meteoric water line (LMWL), and the characteristics of surface water line (SWL) are closely related to land types. Isotope changes along the flow path indicate significant evaporation effect in wet season, while the operation of municipal pipe networks partially conceals the evaporation effect in dry season. The intensity of river evaporation is positively correlated with the urbanization level along the river. Isotope mixing model shows that precipitation and river water are the recharge sources of groundwater in rain and dry seasons, respectively, and the mixing ratios between Jiangan River and Fuhe River shows significant seasonal variation. The combination of isotopic analysis and pollutant data reveals that the seasonal water contribution is the main factor influencing the water quality. Risks for water safety and environmental health in Chengdu and cities along lower Minjiang River were assessed.