基于河链结构和LUCC的分布式流域水文模型及径流响应

Runoff Response with Distributed Hydrological Model Based on River Structure and LUCC

为了定量评估土地利用/覆被变化的水文水资源效应,并考虑流域水文效应的空间差异,提出考虑土地利用/覆被变化的分布式流域水文模型。该模型基于Shreve河链概念对流域河网进行单元划分,基于中国科学院土地资源分类系统的一级类型,将流域划分为6种不同土地利用及覆被变化类型;在每一类土地利用及覆被变化面积上,分别考虑蒸发和下渗的差异,并利用蓄满-超渗耦合产流模型计算该面积上的地表径流量和地面以下径流量;利用地貌汇流模型和线性水库模型将每类面积上的地表径流量和地面以下径流量演算至流域出口断面,从而得到流域的水文过程。模型参数包括流域地貌特征参数、产流参数和汇流参数,前者可以根据地理信息系统技术和遥感技术获得,而后者则需要根据流域的水文资料通过最优化方法求得。利用大理河流域1981—1990年的逐日降雨、蒸发及流量资料对该模型进行了参数率定和检验,率定期1981—1987年的水量平衡系数为0.993,年径流深合格率为100.0%;检验期1988—1990年的水量平衡系数为1.230,径流深合格率为66.667%,计算结果表明该模型在大理河流域具有良好的适应性。并以2000年大理河流域的土地利用/覆被状况为基准,计算得到流域的基准径流深为30.36 mm,并对大理河流域未来土地利用情况进行情景分析,为充分发挥小流域(或单元)水土保持措施带来的各种效益提供参考依据。

In order to evaluate quantitatively the hydrology and water resources effects of land use and land cover change（LUCC）,a distributed watershed hydrological model considering land use and land cover change（ZWHM- LUCC） is developed.In ZWHM- LUCC,divided basin into the units based on Shreve river chain concept,and based on the first-order type of land resources classifying system of Chinese Academy of Sciences,a basin is divided into six different types of LUCC.On the area of each type of LUCC,considering the difference of evaporation and infiltration respectively,the surface runoff and the runoff below surface are calculated by using runoff yield model coupling of excess infiltration and excess storage.The surface runoff discharge and the runoff below surface discharge of each area are routed to the outlet section of basin by using geomorphology concentration model and linear reservoir model,thus the basin hydrology discharge process is obtained.The model parameters include watershed geomorphologic characteristic parameters,runoff yield parameters and concentration parameters.The former can be obtained by geography information system technology and remote sensing technology,but the latter need to be derived by the optimization method according to watershed hydrological data.According to the daily rainfall,evaporation and discharge data of Dali River Basin during 1980—2000,the parameters of the model were calibrated and verified.The coefficient of water balance（R） is 0.993 and the qualified rate of annual runoff depth（DR） is 100% during calibration period 1986—2000,and the R is 1.230 and the DR is 66.67% during calibration verification 1980—1985.The calculated results indicate that this model has good adaptability in Dali River Basin.Based on the land use / cover situation of Dali river basin,calculated the benchmark runoff depth was 30.36 mm,and divided the scenarios about for future land utilization in Dali river basin,to the benefit of exert kinds of benefits on the unit（or small basin） water and soil conservation planning and water resources planning.