农业工程学报
農業工程學報
농업공정학보
2013年
14期
210-219
,共10页
植被%风%速度%归一化植被指数%宁蒙河段
植被%風%速度%歸一化植被指數%寧矇河段
식피%풍%속도%귀일화식피지수%저몽하단
vegetation%wind%velocity%Normalized Different Vegetation Index(NDVI)%Ningxia-Inner Mongolia Reach
黄河上游宁夏-内蒙古段穿越河东沙地、乌兰布和沙漠和库布奇沙漠,大量风沙被吹入黄河,因此,迫切需要揭示宁夏-内蒙古河段沙粒起动风速的空间分布规律,从而为该区域的风沙防治工作提供理论依据。首先,应用归一化植被指数(normalized different vegetation index,NDVI)数据集计算该河段地表植被盖度、植被迎风面积指数与粗糙度。而后,通过植被迎风面积指数计算摩阻起动风速的影响函数,研究河段摩阻起动风速的空间分布。利用实测数据检验摩阻起动风速的计算方法,表明摩阻起动风速的计算方法误差较小。研究表明,研究区内风速廓线均呈对数函数的分布规律,并利用风速廓线方程计算了研究区不同下垫面(10 m高度)处的起动风速,进而得到跃移沙粒起动风速的空间分布。结果显示研究区风蚀风险最大的几个区域大多临近黄河。最后,根据当年最大NDVI值与下一年风季(3月至5月)NDVI平均值之间的关系,提出利用当年最大NDVI值对下一年风季起动风速的预测方法,该研究为黄河宁夏-内蒙古段的风蚀预报提供理论支撑。
黃河上遊寧夏-內矇古段穿越河東沙地、烏蘭佈和沙漠和庫佈奇沙漠,大量風沙被吹入黃河,因此,迫切需要揭示寧夏-內矇古河段沙粒起動風速的空間分佈規律,從而為該區域的風沙防治工作提供理論依據。首先,應用歸一化植被指數(normalized different vegetation index,NDVI)數據集計算該河段地錶植被蓋度、植被迎風麵積指數與粗糙度。而後,通過植被迎風麵積指數計算摩阻起動風速的影響函數,研究河段摩阻起動風速的空間分佈。利用實測數據檢驗摩阻起動風速的計算方法,錶明摩阻起動風速的計算方法誤差較小。研究錶明,研究區內風速廓線均呈對數函數的分佈規律,併利用風速廓線方程計算瞭研究區不同下墊麵(10 m高度)處的起動風速,進而得到躍移沙粒起動風速的空間分佈。結果顯示研究區風蝕風險最大的幾箇區域大多臨近黃河。最後,根據噹年最大NDVI值與下一年風季(3月至5月)NDVI平均值之間的關繫,提齣利用噹年最大NDVI值對下一年風季起動風速的預測方法,該研究為黃河寧夏-內矇古段的風蝕預報提供理論支撐。
황하상유저하-내몽고단천월하동사지、오란포화사막화고포기사막,대량풍사피취입황하,인차,박절수요게시저하-내몽고하단사립기동풍속적공간분포규률,종이위해구역적풍사방치공작제공이론의거。수선,응용귀일화식피지수(normalized different vegetation index,NDVI)수거집계산해하단지표식피개도、식피영풍면적지수여조조도。이후,통과식피영풍면적지수계산마조기동풍속적영향함수,연구하단마조기동풍속적공간분포。이용실측수거검험마조기동풍속적계산방법,표명마조기동풍속적계산방법오차교소。연구표명,연구구내풍속곽선균정대수함수적분포규률,병이용풍속곽선방정계산료연구구불동하점면(10 m고도)처적기동풍속,진이득도약이사립기동풍속적공간분포。결과현시연구구풍식풍험최대적궤개구역대다림근황하。최후,근거당년최대NDVI치여하일년풍계(3월지5월)NDVI평균치지간적관계,제출이용당년최대NDVI치대하일년풍계기동풍속적예측방법,해연구위황하저하-내몽고단적풍식예보제공이론지탱。
Through the Hedong Sandy Land, the Ulanbuh Desert, and the Kubuqi Desert, Ningxia-Inner Mongolia Reach of the Yellow River suffered from serious blown sand hazard. A mass of aeolian sediment deposited in the Yellow River and brought a serious siltation in the Yellow River. It is in urgent need to develop a warning system to reveal the spatial distribution of threshold wind velocity for wind erosion in the watershed of the Ningxia-Inner Mongolia Reach of the Yellow River. The aim of this research is to provide theoretical guidance to prevent the blown sand hazard in this region. In this research, integrated Normalized Difference Vegetation Index (NDVI) data set and the observations in the study area, the threshold wind velocities of different surfaces were calculated, and spatial distribution of threshold wind velocity for wind erosion in the study area was revealed. Firstly, using a map of NDVI, we calculated the vegetation coverage, frontal area, and roughness length in the study area. Then, the frontal area was used to calculate the threshold friction velocity by the vegetation influence function. With tested calculation method of threshold friction velocity using the observed sand flux data, we found the simulated errors were all small. Based on the truth that the wind profiles above the study area all obeyed logarithmical functions, we estimated the spatial distribution of threshold wind velocity for wind erosion in the watershed of Ningxia-Inner Mongolia Reach of the Yellow River. We found that most of the regions that with wind erosion risk were near the Yellow River. At last, this paper proposed a method that using the maximum NDVI in this year to predict the threshold wind velocity based on the relationship between NDIV in the next windy season and maximum that in this year. We hope this research would provide some theoretical advises for predicting the wind erosion hazard in the watershed of the Ningxia-Inner Mongolia Reach of the Yellow River.