降水特征頻率的研究對指導(dǎo)區(qū)域農(nóng)業(yè)規(guī)劃、水利工程設(shè)計和抗旱防洪具有重要意義。渭北旱塬北部常發(fā)生旱澇災(zāi)害,影響了該地區(qū)冬小麥的正常生長和最終產(chǎn)量。尤其是偶發(fā)的暴雨性降水造成的澇災(zāi)是僅次于干旱的農(nóng)業(yè)災(zāi)害。本文選取渭北旱塬29個氣象站點,從1981～2012年的日降水資料,采用皮爾遜Ⅲ型曲線,分析了5%、50%、95%三個不同頻率的年降水量分布特征,在此基礎(chǔ)上,計算和確定了5%、10%、20%三個頻率下,相對于冬小麥全生育期需水量和7個生育階段需水量的降水超出量和缺水量。研究結(jié)果表明,渭北旱塬地區(qū)由東北向西南,年降水量逐漸增加。寶雞地區(qū)年降水量最高,渭北旱塬西北地區(qū)最低。在小麥生長全生育期,5%的頻率下,整個七個生長階段的雨量過剩只發(fā)生在長武,過剩值25至60mm,而在頻率10%和20%,各縣區(qū)的冬小麥生長都發(fā)生缺水;此外,冬小麥的7個生育期的降水量與需水量相比,降水過多主要發(fā)生在第一階段(播種至分蘗)、第二階段(分蘗至越冬)和第七階段(開花至成熟)。尤其在第七階段,長武、彬縣、千陽、鳳翔、寶雞區(qū)、寶雞縣等地都出現(xiàn)了可造成澇災(zāi)的大量的特大降水。而在低頻率極端降水發(fā)生的條件下,缺水仍頻頻發(fā)生在第三...

【文章頁數(shù)】：71 頁

【學(xué)位級別】：碩士

【文章目錄】：
摘要
ABSTRACT
ABBREVIATIONS
CHAPTER1 INTRODUCTION
    1.1 Research background and significance
    1.2 Research objective
    1.3 Research scheme and Framework
    1.4 Scope and limitation of the study
    1.5 Research Contents
CHAPTER2 LITERATURE REVIEWS
    2.1 Ordinary Kriging interpolation
    2.2 Curve fitting method
    2.3 Review on Water needs of Winter wheat crop
    2.4 Review on relation between precipitation and agriculture
CHAPTER3 MATERIALS AND METHODS
    3.1 Study area
    3.2 Data collection
        3.2.1 Precipitation data
        3.2.2 Crop water needs of winter wheat
    3.3 Methodology
        3.3.1 Curve fitting method
        3.3.2 Empirical frequency computation of sample series
        3.3.3 Ordinary kriging interpolation method
CHAPTER4 COUPLING CHARACTERISTIC OF EXTREME RAINFALL WITH CROP WATER NEEDS IN FULL GROWING PERIOD OF WINTER WHEAT IN NORTHERN WEIHE LOESS PLATEAU
    4.1 Distribution characteristics of annual precipitation of different frequencies at5%,50%,and95%
    4.2 Excess and shortage rainfall of full growing period
    4.3 Discussion
CHAPTER5 COUPLING CHARACTERISTICS OF EXTREME RAINFALLWITH CROP WATER NEEDS IN DIFFERENT GROWING STAGES OF WINTER WHEAT IN NORTHERN WEIHE LOESS PLATEAU
    5.1 Excess and shortage rainfall of Sowing to Tillering stage
    5.2 Excess and shortage rainfall of Tillering to Wintering stage
    5.3 Excess and shortage rainfall of Wintering to Greening stage
    5.4 Excess and shortage rainfall of Greening to Jointing stage
    5.5 Excess and shortage rainfall of Jointing to Heading stage
    5.6 Excess and shortage rainfall of Heading to Flowering stage
    5.7 Excess and shortage rainfall of Flowering to Ripening stage
    5.8 Discussion
CHAPTER6 CONCLUSIONS AND RECOMMENDATIONS
    6.1 Conclusions
    6.2 Recommendation
REFERENCES
APPENDICES
ACKNOWLEDGMENTS
AUTHOR BIOGRAPHY



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