东江源寻乌水流域径流变化特征及其原因分析

东江源水资源安全影响着珠三角社会经济发展和香港繁荣稳定,径流是水资源安全评价的重要水文要素.该文收集东江源区干流寻乌水1980-2016年逐日水文气象数据、6期土地利用及土地耕作属性等数据,采用IHACRES水文模型和统计分析等方法,分析寻乌水径流变化特征及其影响因素.结果表明:在模型基准期(1980-1992)和变化期(2009-2016)中,径流年际变化模拟效果评价指标R²、N_S和P_BIAS的值分别为0.99、0.99、0.37和0.8

The Variation Characteristics of Runoff and Its Driving Factors in the Xunwu River Basin of the Source Area of Dongjiang River

The safety of water resources in the source area of Dongjiang River affects the social and economic development of the Pearl River Delta and the prosperity and stability of Hongkong.Runoff is an important hydrological factor for water resources security evaluation.The data include hydro-meteorological data and land use data,such as daily values of runoff,rainfall,temperature during 1980-2016,and land use maps and land tillage data of six phases,which is the main stream of the source area of Dongjiang River.The IHACRES model and statistical analysis methods are adopted to analyze the characteristics of runoff change and its driving factors in the Xunwu River.Some conclusions can be drawn as follows.The two stages of 1980-1992 and 2009-2016 are selected as the datum period and change period of the IHACRES model,respectively.The three evaluation criteria values(R²,N_S and P_BIAS)of annual runoff simulation in both datum period and change period are 0.99,0.99,0.37 and 0.82,0.82,0.04,respectively,which indicates that IHACRES model is suitable for runoff simulation in the Xunwu River Basin.The effect of seasonal simulation is also acceptable(0.72≤R²≤0.92,0.71≤N_S≤0.75,1.72≤P_BIAS≤2.33)except autumn.The R²,N_S and P_BIAS values of the model in autumn are 0.53,0.39 and -9.61,respectively.These indicate that the climatic factors are the main causes of the interannual variation of runoff in the source area of Dongjiang River.Human activities induce the decrease of runoff in the source area of Dongjiang River in autumn.By analyzing the characteristics of land use change of the study area,the area of orchard increases by about 40% and the area of woodland decreases by about 40% in recent years.The orchards need sufficient water in the autumn mature period and increase water intake from river, which results in the reduction of the measured runoff in autumn.