中国东部不同特征小流域水文对比观测试验分析

为探讨中国东部地区变化环境下水循环演变机制,通过水文站网加密观测、构建不同特征试验流域等方法,揭示了不同土地利用和不同城镇化水平下水文要素分布及响应规律。结果表明:①小流域内场次极端降雨局部差异较大,主要受到微地形和风向的影响。②鄞江镇试验流域水位涨幅和单位雨量水位涨幅均高于天然画龙溪试验流域,主要受到了流域大小和城镇化率等因素的影响。③城镇用地和耕地土壤水消退过程较快,林地退水过程相对较慢;浅层10cm、20cm和40cm土壤含水率对降雨滞后响应时间分别为0~0.25h、0.25~0.75h和0.5~0.75h,而深层(60cm和80cm)土壤含水率由于受到优势流的影响,响应较为复杂,响应时间变动范围较大。④小流域地下水对降雨的响应存在滞后性,响应时间为6.5~12h。

Comparative experimental observations and hydrological response in representative basins of Eastern China

To explore the mechanism of changes in the hydrologic cycle under the changing environment in eastern coastal areas of China,based on intensive observations from the hydrological station network and construction of experimental watersheds,we analyzed the distribution and responses of hydrological elements in areas of different land use and urbanization levels. The research results are as follows:① The spatial distribution of extreme rainfall exhibits differences,reaching 50 mm,and is mainly affected by the micro-topography and wind direction of the basin. ② For the runoff response for two basins with different urbanization levels,the flood response time,water level increase,and water level increase per unit rainfall of the highly urbanized basin are higher than those of the low urbanization basin,which is mainly affected by the size of the watershed and degree of urbanization. ③ Forest land plays a critical role in water conservation,and the decreasing process of soil moisture under forest land is slow,whereas the process in urban and cultivated land is faster;the average soil moisture lag times in 10 cm,20 cm,and 40 cm soil layers are 0-0.25 h,0.25-0.75 h,and 0.5-0.75 h,respectively,while the soil moisture response times for deep soil layers (60 cm and 80 cm) are more complex because of the influence of preferential flow. ④ The peak groundwater occurrence time has a hysteresis relationship with rainfall,and the lag time is 6.5-12 h.