| In recent years,under the influence of global warming and human activities,the climate of Loess Plateau has changed significantly.At the same time,the vegetation coverage of Loess Plateau has improved quickly due to the implementation of the“Grain for Green”project.The change of climate and land use will affect the regional hydrological cycle,which will have a significant impact on the development of national economy and sustainable evolution of ecology.The He-Long Region produce the most runoff and the sediment of Loess Plateau.And the“Grain for Green”project influenced this region significantly.The evaluation of the rain water resources is very important to the water resource management and the evaluation of sustainable vegetation restoration.This paper analyzed the changes of climate and land use of current situation and future firstly.And then we construct distributed hydrological model which is suitable to He-Long Region and can be used to calculated the rainwater harvesting potential(RWHP).and influence of climate on the RWHP was stripped from the influence of the land use by comparing the different scene.Finally,the future weather data was used to driving the distributed hydrological model,analyzing the temporal-spatial characteristics of the RWHP of future.The main conclusions of this paper are as follows:(1)The changes of the climate and the land use are significant of He-Long Region.The average annual precipitation increased in the current situation(1980-2015),and the average annual temperature increased significantly,and the mutation occurred in the 1990s.In the future two climate scenarios(2021-2050),annual precipitation and annual average temperature are both rising,and the average annual average is higher than the current situation.Under the RCP2.6 scenario,the trend of temperature in some areas is decreased.And the trend of temperature under the RCP8.5 scenario is increased in the whole region.In terms of annual precipitation,both climate scenarios show an overall regional trend.Under the RCP2.6 scenario,the annual precipitation trend in the south was more significant than that in the north,while the situation of RCP8.5 was the opposite.The land use transfer matrix found that the total area of land use changed slightly,but the land use pattern changed greatly.(2)We constructs a distributed hydrological model in this region to evaluate the RWHP.The study area was divided into 232 sub-basins with an average area of 483km2.The correlation coefficient and the Nash efficiency coefficient of the model are greater than 0.5,which meets the verification requirements.The simulation results of monthly scale runoff are better than that of daily scale runoff.(3)During the period from 1980 to 2015,the annual average surface runoff,soil water increment and rainwater resource potential of the study area showed an upward trend.In the study area,the average rainwater resource potential was 347.19 billion m3,of which the surface runoff was 33.06 billion m3,accounting for 9.52%of the total,and the increase of soil water was 314.13 billion m3,accounting for 90.48%of the total.The potential of rainwater resources in the study area is increasing,and the rising trend is significant in the central region.Climate change is the leading factor and positive influence on the potential of rainwater resources,and the contribution rate is 63.4%.The change of land use was a secondary factor and negative effect,contributing 36.6%.(4)The study found that the trend of the change of rainwater resources in the future two climate scenarios did not pass the significance test.The spatial distribution of rainwater resources in two climate scenarios is similar,and the distribution pattern is low in the south and the north.Compared with the two scenarios,the potential of rainwater resources in RCP8.5scenario is generally higher than that in RCP2.6 scenario.Under the RCP2.6 scenario,the RWHP is 35.15 billion m~3,and the RWHP under the RCP8.5 scenario is 36.77 billion m~3,which is higher than current situation. |
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