Numerical Simulation On Hydrodynamics And Water Environment In Strongly Disturbed Region

Water resource shortage and water environment deterioration have become major challenges for comprehensive basin management.This study took the highly disturbed Huai River Basin with serious contradiction between social economic and water ecological environment as the study area,and was supported by National Grand Science and Technology Special of Water Pollution Control and Improvement(2014ZX07204-006).This study analyzed the spatio-temporal distribution of water quantity and water quality within the study area with statistical analysis methods.In addition,the evolution of water quantity and water quality in the key sub-region was further analyzed by one-dimension hydrodynamic and water environmen-tal mathematical models,which could provide scientific support for intergated water quantity and quality management.The main work and achievements include:(1)Based on the standardized precipitation index(SPI),three evaluation indexes,including drought frequency,drought station proportion and drought intensity,were used to analyze and evaluate the spatio-temporal distribution of drought in the Huai River Basin.The results indicated that Anhui and Henan provinces had relatively higher frequency of drought than other areas.Annual drought intensity and drought station proportion showed a weak decreasing trend.Overall,it was generally characterized by mild drought.(2)The comprehensive water quality identification index,spatial cluster analysis and seasonal Mann-Kendall method were adopted to assess spatio-temporal evolution of water quality in Shaying River.The results indicated that water quality in the Beiru,Sha and Li tributaries was generally good,while the Jialu and Xiaoying Rivers were contaminated seriously.The water quality stations on Shaying River could be classified into four groups in both flood and non-flood seasons.The improvement trend of water quality in the Jialu River was obvious,and there was an opposite trend in the Sha River.In Xiaoying River,water quality had deteriorated significantly in the middle-upper reaches while was improved in the lower reaches.Meanwhile,the water quality in downtream reaches within Anhui province showed an improving trend.Specifically,total phosphorus concentration increased obviously across the Shaying River basin.(3)The variation characteristics of hydrodynamic factors in the highly regulated Zhoukou-Mohekou River reach was simulated with MIKE11 HD Model and hydrodynamic simulation model based on Pressimann Four-point eccentric implicit format and interaction with SQL SERVER database.The simulated river was divided into five simulation units,and the roughness coefficient of each simulation unit was calibrated.For the MIKE 11 HD Model,the deterministic coefficients of runoff simulation and water level simulation reached to 0.80 and 0.90 respectively in calibration period and reached to 0.74 and.0.88 respectively in verification period.For the one-dimensional hydrodynamic model,the two deterministic coefficients were 0.82 and 0.97 in calibration period,and 0.74 and 0.88 in verification period.(4)Instream ammonia nitrogen in Huaidian-Genglou River reach was simulated with MIKE11 HD Model and Jieshou was set as the calibration section.The results showed that the maximum and average errors were 33.79%and 15.37%in calibration period,and 16.52%and 12.88%in verification period,the simulation model could effectively reflect the evolution of river ammonia nitrogen in highly disturbed condition.