Abstract
Conceptual rainfall–runoff models have become a basic tool for evaluating effects of land use/cover changes on the hydrologic processes in small-scale as well as large watersheds. The runoff-producing mechanism is influenced by land use/cover changes. In this study, we analysed the effect of land use change on hydrological model parameters by calibrating the model parameters of different time periods with different land use via a linearized calibration method. The parameter calibration of a conceptual model usually involves the construction of objective function and optimization methods for good performance of observed data. However, the objective function of the minimum-sum-squared error will introduce an unrelated optimum solution for the parameter calibration problem of a conceptual model, which belongs to a highly complex nonlinear system. Thus, a linearized parameter calibration method, which searches for the optimal value on a parameter surface, is presented, based on the analysis of the problems of the objective function of the minimum-sum-squared error. Firstly, an ideal model is shown that illustrates the efficiency and applicability of this method. Secondly, the novel method is demonstrated for solving the Xinanjiang daily model parameter calibration. Finally, 50 years of data are divided into 4 different periods for parameter comparison, through which the effects of land use/cover changes on runoff in Dapoling watershed are evaluated. The results show that the linearized parameter calibration method is convergent, reasonable and effective. For example, the model parameter of evapotranspiration coefficient KC varied considerably, from 0.658 to 0.922, in response to land use/cover change within the watershed. Keywords: land use/cover change; parameter calibration; linearized; upper Huaihe River Basin
Highlights
Conceptual rainfall–runoff models have been widely used for quantification of the effect of land use and land cover change on runoff dynamics (Burns et al, 2005; Jiang et al, 2004, Wan and Yang, 2004; Wang et al, 2007; Yuan and Shi, 2001; Zhang et al, 2004)
It was developed to solve the theoretical problem of unrelated local optima produced in the nonlinear model parameter calibration by using the objective function based on error sum of squares
Streamflow at the outlet is the comprehensive response of the whole basin system to the input, precipitation, and invariably, to the change of underlying surface in the basin. In appreciation of this fact, a number of studies have focused on using conceptual rainfall–runoff models to quantify the effect of land use and land cover change on runoff dynamics
Summary
Conceptual rainfall–runoff models have been widely used for quantification of the effect of land use and land cover change on runoff dynamics (Burns et al, 2005; Jiang et al, 2004, Wan and Yang, 2004; Wang et al, 2007; Yuan and Shi, 2001; Zhang et al, 2004). The runoff-producing mechanism and hydrological response will be influenced by land use/cover changes, and this influence can be reflected by the calibrated parameter values of different time periods (Tao et al, 2015; Zhang et al, 2016; Zhong-Bo et al, 2014). Minimum-sum-squared error (MSSE) has been widely used as an objective function (Bárdossy and Singh, 2008; Bao, 1991; Bao et al, 2004; Rusli et al, 2015; Zádor et al, 2006) This objective function has been shown to work well in linear parameter calibration, which has been proved to attain the unique optimal value. An ideal model was used to verify the efficiency and applicability of this method The change of land use and the impact on hydrological response processes are analysed by the model parameters at different stages
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