Study On The Space-time Evolution Of The Hydrological Cycle Elements In Huaibei Plain

Water resources is the foundational natural resource and the strategic economical resources.In recent decades, global climate change and frequent human activities have been important influences on the hydrological cycle.Huaibei plain is localted in China’s north and south area, water resources problems have become bottleneck to restrict regional economic and social development due to extremely uneven water resources at space-time distribution,frequent human activities and serious water pollution etc.Therefore, studying the temporal and spatial variation of hydrological cycle elements under the background of the climate change and human activities,it is an important guiding role to deeply understand the formation and evolution of water resources, sustainable development and utilization of water resources and the protection of ecological environment.This thesis makes the variation of the hydrological cycle elements in Huaibei Plain as the main line,analysing the features of meteorological elements of the typical experiment station in Huaibei Plain—Wudaogou Experiment Station. It analyses precipitation, evaporation and analysis of characteristics of runoff for change in Huaibei Plain. We test the randomness, trend and mutation of precipitation, evaporation and runoff time series using some main methods such as Hurst index,Kendall rank correlation test and Mann-Kendall test method,T method and Yamamoto method. Paper displays the changes of precipitation and runoff changes in the image of multiple time scales with Wavelet, It proposes the concept of precipitation in he center of gravity in order to analyze the time distribution of precipitation trends, forming the reason to explain the evaporation paradox with the combination of climate change.Finally, this thesis analyses the time and space distribution of the runoff in Huaibei Plain by the cloud model, and it shows heterogeneity and uncertainty of runoff distribution quantitatively and qualitatively, and does a simple analysis of the impaction on the runoff at Yanglou Experiment.The main results are as follows:(1) The temperature of Wudaogou Experiment Station was decreased and then increased, the overall trend of growth rate is0.3℃/10a since1981.Sunshine hours was decreased, throughout the whole year the rate is-184/10a.Wind speed also showed a decreasing trend, average wind speed dropped0.32m/s every10a.The annual average relative humidity was77%. Water vapor pressure difference of the average of24years was6.3mb. Positive correlation between the meteorological elements, temperature and relative humidity is rising. There was no trend of water vapor pressure difference, no mutations of temperature and water vapor pressure difference.(2) There was a positive correlation between series of the average annual precipitation from1956to2008, which was not significant and no mutations. It analysis the two generating functions using Matlab graphics drawn by precipitation series of wavelet showing that the trend is decreased and then increased.It was found that the change is not particularly strong of the focus changes of precipitation in five different years and the location is in the Town of Suzhou City in southern Lingbi Huigou.(3) Eaporation in many years is positively correlated, downside but no mutations. We can conclude that evaporation is largest in huaibei city according to the isoline, gradually reducing from this center to northwest and southeast area. This paper focuses on analysing the relationship between evaporation in Wudaogou lab and meteorological factors, concluding that daily water evaporation in Wudaogou lab from1986to2009is well correlated with temperatures, vapor pressure difference and ground temperature, a little better relationship with sunshine duration and relative humidity, but the relationship is not obvious with wind speed and precipitation, which explains reasons for "evaporation paradox" theory in Huaibei Plain.(4) It is concluded that runoff series is strong sustainability, its tendency was not obvious but no mutations in Huaibei plain from1956to2008.The tendency was reducing firstly but increasing later by analysing annual runoff in the time scale change using Wavelet analysis method.We can get some conclusions using Cloud model that runoff in non-flood season is most stable on time distribution,whole year runoff second,but runoff in flood season is not most stable. The uncertainty of runoff in flood season and whole year is higher than the non-flood season. Discrete degrees is firstly increased and then decreased in spatial distribution (entropy firstly big then small), stability gradually decreases (super entropy increase), super entropy is bigger in the second period, inhomogeneity stability in the space distribution of runoff is lesser.