钱塘江河口仓前段盐度变化特征及取水保证率分析

Analysis of salinity variation characteristics and water intake guarantee rate in Cangqian reach of Qiantang River Estuary

盐水入侵是钱塘江河口水资源利用最大的制约因素,杭州钱塘新区大江东片从钱塘江仓前段取水主要受制于盐度指标。基于仓前水文站2000—2016年的逐日氯度观测资料,分析仓前河段氯度的时间变化特征,以农田灌溉标准规定氯度0.35 g/L为控制标准,统计不同保证率的可取水天数。结果表明:仓前段年际、年内、月内、日内氯度变化均较大,其年际、年内变化主要由径流变化所致,月内、日内变化主要由潮汐大小变化所致。保证率为50%的年份,可取水天数达297 d;保证率为80%的年份,可取水天数计237 d;其中上半年取水条件较好,下半年取水条件较差,10月份最差。

Saltwater intrusion is the the biggest constraint on water resources utilization in the Qiantang River Estuary.Water intake from the Cangqian reach of Qiantang River Estuary in the Dajiangdong section in Hangzhou Qiantang New District is mainly restricted to salinity.Based on the daily chlorinity observation data of Cangqian Hydrological Station from 2000 to 2016,the temporal variation characteristics of the chlorinity were analyzed.Taking the chlorinity of 0.35 g/L specified in the farmland irrigation standard as the control standard,the available water intake days with different guarantee rates were counted.The results show that the inter-annual,intra-annual,intra-month and intra-day variations of chlorinity in the Cangqian reach are large.The inter-annual and intra-annual variations are mainly caused by runoff changes,and the intra-month and intra-day variations are mainly caused by tidal changes.In the year with 50%guarantee rate,the water intake days are 297 d,and in the year with 80%guarantee rate,the water intake days are 237 d.The water intake conditions are good in the first half of the year,poor in the second half,and the worst in October.