Sensitivity of hydrological connectivity in a semiarid basin with a high-density reservoir network

Abstract

Water reservoirs, in general, have been considered to be the major cause of reduction of downstream hydrological connectivity in channels. Therefore, this study analyzed the sensitivity of hydrological connectivity in the Orós Reservoir hydrographic basin by using the ResNet model, designed to simulate the processes involved in fluvial hydrological connectivity in environments with a high density of reservoirs. The analysis of hydrological connectivity was performed with the model ResNetM, which simulated hydrological processes and considered hydrological connectivity between the reservoirs, according to the criteria established in this research. To identify the main elements that affect hydrological connectivity, sensitivity analysis (SI) was performed of some input parameters of the model. The sensitivity analysis indicated that the modification of the topology of the reservoir network was the variable that presented the highest sensitivity to hydrological connectivity, with a sensitivity value of 1.07, followed by the runoff coefficient, which obtained a sensitivity of 0.8. The modification of the rainfall and of the reservoir storage capacity, showed an intermediate sensitivity, with values of 0.46 and 0.45, respectively. On the other hand, the parameters of potential evaporation and transmission loss showed the lowest sensitivity, obtaining values of 0.19 and 0.01, respectively. In conclusion, the runoff coefficient and the reservoir network (change in the reservoir number of the network) were the parameters evaluated with the highest sensitivity of hydrological connectivity. Thus, the alteration of the landscape by man provides significant changes in river navigation between the reservoirs in the basin.