1. State Key Laboratory of Hydraulics and Mountain River Engineering, Sichuan University, Chengdu 610065, P. R. China
2. Changjiang Water Resources Protection Institute, Changjiang Water Resources Commission, Wuhan 430051, P. R. China
3. Department of Resource Management and Geography, the University of Melbourne, Victoria 3010, Australia

The water quality in the Danjiangkou Reservoir has attracted considerable attention from the Chinese public and government since the announcement of the Middle Route of the South to North Water Diversion Project (SNWDP), which commenced transferring water in 2014. Integrated research on the evaluation, prediction, and protection of water quality in the Danjiangkou Reservoir was carried out in this study in order to improve environmental management. Based on 120 water samples, wherein 17 water quality indices were measured at 20 monitoring sites, a single factor evaluation method was used to evaluate the current status of water quality. The results show that the main indices influencing the water quality in the Danjiangkou Reservoir are total phosphorus (TP), permanganate index (CODMn), dissolved oxygen (DO), and five-day biochemical oxygen demand (BOD5), and the concentrations of TP, BOD5, ammonia nitrogen (NH3-N), CODMn, DO, and anionic surfactant (Surfa) do not reach the specified standard levels in the tributaries. Seasonal Mann-Kendall tests indicated that the CODMn concentration shows a highly significant increasing trend, and the TP concentration shows a significant increasing trend in the Danjiangkou Reservoir. The distribution of the main water quality indices in the Danjiangkou Reservoir was predicted using a two-dimensional water quality numerical model, and showed that the sphere of influence from the tributaries can spread across half of the Han Reservoir if the pollutants are not controlled. Cluster analysis (CA) results suggest that the Shending River is heavily polluted, that the Jianghe, Sihe, and Jianhe rivers are moderately polluted, and that they should be the focus of environmental remediation.

This work was supported by the National Natural Science Foundation of China (Grants No. 41101250 and 51309031) and the Chinese 12th Five-Year Science and Technology Support Program (Grant No. 2012BAC06B00).

Bao, L. J., Maruya, K. A., Snyder, S. A., and Zeng, E. Y. 2012. China’s water pollution by persistent organic pollutants. Environmental Pollution, 163, 100-108.
[doi:10.1016/j.envpol.2011.12.022]
Booker, D. J., and Woods, R. A. 2014. Comparing and combining physically-based and empirically-based approaches for establishing the hydrology of ungauged catchments. Journal of Hydrology, 508, 227-239.
[doi:10.1016/j.jhydrol.2013.11.007]
Bouza-Deaño, R., Ternero-Rodríguez, M., and Fernández-Espinosa, A. J. 2008. Trend study and assessment of surface water quality in the Ebro River (Spain). Journal of Hydrology, 361(3-4), 227-239.
[doi:10.1016/j.jhydrol.2008.07.048]
Chang, H. 2008. Spatial analysis of water quality trends in the Han River basin, South Korea. Water Research, 42(13), 3285-3304.
[doi:10.1016/j.watres.2008.04.006]
Crosa, G., Froebrich, J., Nikolayenko, V., Stefani, F., Galli, P., and Calamari, D. 2006. Spatial and seasonal variations in the water quality of the Amu Darya River (Central Asia). Water Research, 40(11), 2237-2245.
[doi:10.1016/j.watres.2006.04.004]
Danish Hydraulic Institute (DHI). 2001. MIKE 21 User Guide and Reference Manual. Horsholm: DHI.
El-Shaarawi, A. H., Esterby, S. R., and Kuntz, K.W. 1983. A statistical evaluation of trends in the water quality of the Niagara River. Journal of Great Lakes Research, 9(2), 234-240.
[doi:10.1016/S0380-1330(83)71892-7]
Gevrey, M., Comte, L., de Zwart, D., and Lek, S. 2010. Modeling the chemical and toxic water status of the Scheldt basin (Belgium), using aquatic invertebrate assemblages and an advanced modeling method. Environmental Pollution, 158(10), 3209-3218.
[doi:10.1016/j.envpol.2010.07.006]
Hirsch, R. M., Slack, J. R., and Smith, R. A. 1982. Nonparametric test for trend in water quality. Water Resources Research, 18, 107-121.
[doi:10.1029/WR020i001p00127]
Hu, Y. N., and Cheng, H. F. 2013. Water pollution during China’s industrial transition. Environmental Development, 8, 57-73.
[doi:10.1016/j.envdev.2013.06.001]
Kundzewicz, Z. W., and Robson, A. J. 2004. Change detection in hydrological records-a review of the methodology. Hydrological Science Journal, 49(1), 7-19.
Lindim, C., Pinho, J. L., and Vieira, J. M. P. 2011. Analysis of spatial and temporal patterns in a large reservoir using water quality and hydrodynamic modeling. Ecological Modelling, 222(14), 2485-2494.
[doi:10.1016/j.ecolmodel.2010.07.019]
Long, J., Ji, H. F., and Huang, Z. Y. 2009. Application of time series analysis in water quality prediction. Chinese Journal of Scientific Instrument, 30(6), 350-352. (in Chinese)
Naddeo, V., Scannapieco, D., Zarra, T., and Belgiorno, V. 2013. River water quality assessment: Implementation of non-parametric tests for sampling frequency optimization. Land Use Polocy, 30(1), 197-205.
[doi:10.1016/j.landusepol.2012.03.013]
Nasiri, F., Maqsood, I., Huang, G., and Fuller, N. 2007. Water quality index: A fuzzy river-pollution decision support expert system. Journal of Water Resources Planning and Management, 133(2), 95-105.
[doi:10.1061/(ASCE)0733-9496(2007)133:2(95)]
Nives, S. G. 1999. Water quality evaluation by index in Dalmatia. Water Research, 33(16), 3423-3440.
[doi:10.1016/S0043-1354(99)00063-9]
Olsen, R. L., Chappell, R. W., and Loftis, J. C. 2012. Water quality sample collection, data treatment and results presentation for principal components analysis-literature review and Illinois River watershed case study. Water Research, 46(9), 3110-3112.
[doi:10.1016/j.watres.2012.03.028]
Ott, W. R. 1978. Water Quality Indices: A Survey of Indices Used in the United States. Washington, D.C.: US Environmental Protection Agency.
Paul, M. J., and Meyer, J. L. 2001. Streams in the urban landscape. Annual Review of Ecology and Systematics, 32, 333-365.
[doi:10.1146/annurev.ecolsys.32.081501.114040]
Seeboonruang, U. 2012. A statistical assessment of the impact of land uses on surface water quality indexes. Journal of Environmental Management, 101, 134-142.
[doi:10.1016/j.jenvman.2011.10.019]
Simeonov, V., Stratis, J. A., Samara, C., Zachariadis, G., Voutsa, D., Anthemidis, A., Sofoniou, M., and Kouimtzis, T. 2003. Assessment of the surface water quality in Northern Greece. Water Research, 37(17), 4119-4124.
[doi:10.1016/S0043-1354(03)00398-1]
Sokolova, E., Pettersson, T. J. R., Bergstedt, O., and Hermansson, M. 2013. Hydrodynamic modeling of the microbial water quality in a drinking water source as input for risk reduction management. Journal of Hydrology, 497, 15-23.
[doi:10.1016/j.jhydrol.2013.05.044]
Vanlandeghem, M. M., Meyer, M. D., Cox, S. B., Sharma, B., and Patiño, R. 2012. Spatial and temporal patterns of surface water quality and ichthyotoxicity in urban and rural river basins in Texas. Water Research, 46(20), 6638-6651.
[doi:10.1016/j.watres.2012.05.002]
Xin, X. K., Yin, W., and Yang, F. 2012, Research on water quality evolution trend of Danjiangkou Reservoir by Kendall Method. Yangtze River, 43(13), 91-94. (in Chinese)
Xu, H. S., Xu, Z. X., Wu, W., and Tang, F. F. 2012. Assessment and spatiotemporal variation analysis of water quality in the Zhangweinan River Basin, China. Procedia Environmental Science, 13, 1641-1652.
[doi:10.1016/j.proenv.2012.01.157]
Xu, Z. X. 2005. Single factor water quality identification index for environmental quality assessment of surface water. Journal of Tongji University (Natural Science), 33(3), 321-325. (in Chinese)
Yenilmez, F., Keskin, F., and Aksoya, A. 2011. Water quality trend analysis in Eymir Lake, Ankara. Physics and Chemistry of the Earth, Parts A/B/C, 36(5-6), 135-140.
[doi:10.1016/j.pce.2010.05.005]
Zhang, S. P., and Xin, X. K. 2013. Application of MIKE 21 Module in waste drainage outlet arrangement for enterprise sewage treatment plant. Water Resources and Power, 31(9), 101-104. (in Chinese)
Zhao, Y., Xia, X. H., Yang, Z. F., and Wang, F. 2012. Assessment of water quality in Baiyangdian Lake using multivariate statistical techniques. Procedia Environmental Sciences, 13, 1213-1226.
[doi:10.1016/j.proenv.2012.01.115]
Zhou, N. Q., Westrich, B., Jiang, S. M., and Wang, Y. 2011. A coupling simulation based on a hydrodynamics and water quality model of the Pearl River Delta, China. Journal of Hydrology, 396(3-4), 267-276.
[doi:10.1016/j.jhydrol.2010.11.019]
Zhu, D. S., Zhang, J. Y., Shi, X. X., and Yin, W. 2011. Modern water resources protection planning technology system. Water Resources Protection, 27(5), 28-31. (in Chinese)