The development of land use planning scenarios based on land suitability and its influences on eco-hydrological responses in the upstream of the Huaihe River basin

Abstract Agricultural activities are one of the leading causes of influencing deforestation and land degradation, which desperately needs reasonable land use planningschemes. Land use planningis a beforehand task that needs to estimate the possible eco-hydrological consequences of land usechanges at the watershed scale. The method based on combination of land usescenarios and hydrological model simulations usually provides guidance suggestions for land use planningand land management. However, the setting of land usescenarios often ignores the objective natural conditions in local region. In this paper, a suitability evaluation method was developed, which synthetically considered the topographic, soil, meteorological and water supply conditions on the agriculture land, to obtain land use planningscenarios in the upstream of the Huaihe River basin. Subsequently, the Soiland Water Assessment Tool( SWAT) modelwas employed to evaluate the influences of land usescenarios on eco-hydrological responses. Model calibration and validation were performed based on the land usestatus in 2000, after which the validated simulations were conducted based on the planning scenarios. Suitability evaluation results demonstrated that 40.83% of the existing agriculture land in 2000 was considered to be unsuitable, especially in the northern part of the studied area, where plantations of grass and forest were implemented to derive the short-term and long-term land planning scenarios, respectively. The SWAT modelwith daily time step was set up for the studied area. It simulated reasonably the relationship between rainfall and runoff with the Nash–Sutcliffe efficiency ( NSE ) values of 0.72 and 0.66 for the calibration and the validation periods. Relative changes of eco-hydrological components simulated by the validated SWAT modelwere analyzed both temporally and spatially. The simulation results counted at multiple temporal scales showed that both short-term and long-term land use planningoperations reduced the maximum runoff and total water yield as well as the total sediment loads, meanwhile, increased the evapotranspiration. For runoff components, the decreasing surface runoffand the increasing groundwater were much more significant than the increasing lateral flow. Sub-basin analyses revealed that the simulated changes in eco-hydrological responses varied spatially, whereas the decreases in total water yield and the surface runoffand the increase in evapotranspiration were closely related to the percentages of de-farming in sub-basins. Overall the eco-hydrological responses to long-term land use planningwere more profound than that to short-term land use planning. This study provides a synthetic suitability evaluation method for creating land use planningscenario, which overcomes the shortcoming of traditional way of assigning land usescenario that being lack of objectivity.