李 晶,韓 穎,楊 震,苗 輝,殷守強(qiáng)
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基于溫度植被干旱指數(shù)的兗州煤田煤炭開(kāi)采影響邊界遙感提取
李 晶,韓 穎,楊 震,苗 輝,殷守強(qiáng)
(中國(guó)礦業(yè)大學(xué)(北京)地球科學(xué)與測(cè)繪工程學(xué)院,北京 100083)
為識(shí)別植被覆蓋區(qū)煤炭開(kāi)采的生態(tài)影響邊界,該文以兗州煤田為研究區(qū)域,應(yīng)用溫度植被干旱指數(shù)TVDI (temperature vegetation drought index)反演沉陷積水區(qū)外圍的土壤濕度空間分布特征,利用MATLAB擬合TVDI變化趨勢(shì)并依據(jù)其趨于穩(wěn)定的漸近線,反解煤炭開(kāi)采活動(dòng)對(duì)礦區(qū)生態(tài)的影響邊界,將其與采用MSCS(mining subsidence prediction system,MSCS)軟件預(yù)計(jì)獲得的下沉10 mm沉陷邊界進(jìn)行對(duì)比。結(jié)果表明:不同距離的TVDI中位數(shù)隨距積水區(qū)邊緣距離的變化表現(xiàn)為先增加后趨于平穩(wěn)、呈指數(shù)變化特征;基于TVDI分析得到的煤炭開(kāi)采的非積水影響范圍,僅相當(dāng)于沉陷積水面積的2.07倍,預(yù)計(jì)沉陷非積水面積與預(yù)計(jì)沉陷積水面積之比為4.63倍。通過(guò)模型擬合遙感指數(shù)隨距離的變化特征,能夠獲得煤炭開(kāi)采的影響邊界;兗州煤田基于TVDI獲取的煤炭開(kāi)采影響面積,相對(duì)小于預(yù)計(jì)的開(kāi)采沉陷面積。該研究可為確定煤炭開(kāi)采對(duì)生態(tài)影響的邊界提供參考。
遙感;生態(tài);礦區(qū);煤炭開(kāi)采;沉陷積水區(qū);溫度植被干旱指數(shù);土壤濕度;影響邊界
煤炭是中國(guó)的基礎(chǔ)能源,主要開(kāi)采方式為井工開(kāi) 采[1],開(kāi)采過(guò)程不可避免地導(dǎo)致地表沉陷,并對(duì)土地利用、土壤質(zhì)量、植被生長(zhǎng)等造成影響。煤炭開(kāi)采引起的生態(tài)環(huán)境影響一定程度上具有空間傳遞或空間擴(kuò)散性,一直以來(lái),學(xué)術(shù)研究與規(guī)劃實(shí)踐中一般采用《建筑物、水體、鐵路及主要井巷煤柱留設(shè)與壓煤開(kāi)采規(guī)程》(安監(jiān)總煤 裝〔2017〕66號(hào))(簡(jiǎn)稱《三下采煤規(guī)程》)中地表下沉 10 mm邊界作為采煤對(duì)地表的擾動(dòng)邊界,該邊界是基于對(duì)建筑物的影響劃定的。編制土地復(fù)墾方案時(shí)普遍選取地表水平變形、附加傾斜、下沉深度、沉陷后潛水位埋深以及耕地生產(chǎn)力下降等指標(biāo)對(duì)土地?fù)p毀程度分級(jí)評(píng)定,但土地復(fù)墾范圍仍以預(yù)計(jì)10 mm下沉等值線作為邊界。一方面,機(jī)械地用對(duì)建構(gòu)筑物的影響邊界10 mm下沉等值線作為對(duì)植被覆被區(qū)的土地生態(tài)的影響邊界不適宜,另一方面,大范圍監(jiān)測(cè)開(kāi)采影響范圍或定量評(píng)估煤炭開(kāi)采的生態(tài)累積效應(yīng)時(shí),采用傳統(tǒng)變形監(jiān)測(cè)或沉陷預(yù)計(jì)確定的10 mm下沉邊界并不適用,有必要從典型土壤因子、典型植被因子等角度進(jìn)行研究并提出適用的煤炭開(kāi)采影響邊界界定方法。有關(guān)學(xué)者的試驗(yàn)研究證明:煤炭開(kāi)采對(duì)土壤含水量[2-8]、植被長(zhǎng)勢(shì)[4,9-12]等的影響從沉陷盆地下坡、中坡、上坡至非沉陷區(qū)存在有一定規(guī)律的空間變化特征。因此,選取典型土壤或植被參量進(jìn)行研究,即可能形成適用于植被覆蓋區(qū)的煤炭開(kāi)采的影響邊界界定方法。
近年來(lái),遙感以其大范圍、快速和多譜段周期性觀測(cè)、信息量大等特點(diǎn),在定量反演陸地表面參量及礦區(qū)生態(tài)變化動(dòng)態(tài)監(jiān)測(cè)中的應(yīng)用日益廣泛。除采用野外調(diào)查、試驗(yàn)分析等傳統(tǒng)方法研究煤炭開(kāi)采對(duì)土壤含水量理化特征及空間變化特征的影響[2-8]、采煤沉陷區(qū)與非沉陷區(qū)植被長(zhǎng)勢(shì)空間分異特征[4,9-12]、礦區(qū)耕地?fù)p毀程度評(píng)價(jià)[13-14]等外,相關(guān)學(xué)者在基于時(shí)序遙感方法監(jiān)測(cè)煤炭開(kāi)采對(duì)地表擾動(dòng)影響方面也取得了長(zhǎng)足進(jìn)展[15-17]。在前述研究基礎(chǔ)上,本文以中國(guó)東部高潛水位平原煤礦區(qū)兗州煤田為例,基于土地生態(tài)要素空間異質(zhì)性和距離衰減規(guī)律,通過(guò)分析與土壤濕度滿足線性關(guān)系的溫度植被干旱指數(shù)TVDI(temperature vegetation drought index)的空間分布特征[7,18-19],確定開(kāi)采沉陷對(duì)土壤濕度的影響邊界,并分析其與預(yù)計(jì)地表下沉10 mm邊界的差異,為科學(xué)確定煤炭開(kāi)采的生態(tài)影響邊界提供一種思路。
兗州煤田地處山東省兗州、曲阜、鄒城等三市交界地帶,其地理位置為東經(jīng)116°10¢~117°00¢,北緯35°10¢~35°40¢(如圖1所示),是國(guó)家重點(diǎn)建設(shè)的八大能源基地之一,主要包括南屯、興隆莊、鮑店、東灘、北宿、楊村等礦井,研究區(qū)面積合計(jì)258 km2。兗州煤田煤層厚且煤質(zhì)優(yōu)良,自20世紀(jì)80年代后期逐步進(jìn)入大規(guī)模開(kāi)發(fā)時(shí)期,設(shè)計(jì)總產(chǎn)能2451×104t,研究區(qū)氣候溫和,四季分明,雨熱同期;地下水埋深較淺,平均為3~5 m。采煤沉陷導(dǎo)致礦區(qū)內(nèi)大面積土地沉陷并形成積水區(qū),農(nóng)作物減產(chǎn)甚至絕產(chǎn),對(duì)礦區(qū)內(nèi)生產(chǎn)和生活產(chǎn)生了嚴(yán)重影響。
圖1 研究區(qū)及沉陷積水區(qū)位置圖
選取了2009年8月30日的Landsat TM影像作為遙感數(shù)據(jù)源(http://www.gscloud.cn/),其中熱紅外波段空間分辨率已被重采樣至30 m。影像條帶號(hào)122、行編號(hào)35,空間分辨率30 m,含云量3.66%。開(kāi)采計(jì)劃、沉陷預(yù)計(jì)參數(shù)、地下水位觀測(cè)數(shù)據(jù)通過(guò)實(shí)地調(diào)查獲取,采用開(kāi)采沉陷預(yù)計(jì)系統(tǒng)(mining subsidence prediction system,MSCS)并結(jié)合地下水位觀測(cè)數(shù)據(jù),得到10 mm下沉等值線邊界和預(yù)計(jì)沉陷積水區(qū)。根據(jù)獲取的TM影像數(shù)據(jù)并結(jié)合Google Earth影像,目視解譯得到影像獲取時(shí)間的沉陷積水區(qū),如圖1b所示。
高潛水位平原礦區(qū)煤炭開(kāi)采影響區(qū)域的地表形態(tài)多形成下沉盆地,在沉陷盆地底部形成常年積水區(qū),向外至盆地邊緣依次為季節(jié)性積水區(qū)和非積水坡地區(qū),積水區(qū)通過(guò)遙感影像易于識(shí)別,難點(diǎn)在于非積水影響區(qū)尤其是外圍邊界的識(shí)別。
本文為識(shí)別高潛水位煤田區(qū)煤炭開(kāi)采對(duì)礦區(qū)土地生態(tài)影響范圍邊界,以溫度植被干旱指數(shù)TVDI為例,以每一沉陷積水區(qū)邊緣為起點(diǎn),自積水區(qū)邊緣向外以30 m為間隔劃分不同的空間梯度距離,分析不同距離像元溫度植被干旱指數(shù)TVDI的中位數(shù)隨距積水區(qū)距離的變化,并通過(guò)指數(shù)擬合變化趨勢(shì),依據(jù)TVDI趨于穩(wěn)定的漸近線反解出煤炭開(kāi)采活動(dòng)對(duì)礦區(qū)生態(tài)影響的范圍邊界,將其與沉陷預(yù)計(jì)下沉10 mm邊界進(jìn)行對(duì)比分析兩者差異。技術(shù)流程見(jiàn)圖2。
本文對(duì)遙感影像所做的預(yù)處理包括影像的輻射校正、幾何校正、波段合成、影像裁剪等。
根據(jù)開(kāi)采計(jì)劃進(jìn)行了開(kāi)采沉陷預(yù)計(jì)[20]。將開(kāi)采沉陷數(shù)據(jù)等進(jìn)行格式轉(zhuǎn)換,應(yīng)用6個(gè)礦井采掘工程平面圖、相關(guān)地下水位觀測(cè)數(shù)據(jù)等資料并結(jié)合下沉系數(shù)()、水平移動(dòng)系數(shù)()、主要影響角正切(tan)、拐點(diǎn)偏移距()、開(kāi)采影響傳播角()等地表移動(dòng)預(yù)計(jì)參數(shù),采用概率積分法,利用開(kāi)采沉陷預(yù)計(jì)系統(tǒng)(MSCS)獲得預(yù)計(jì)地表下沉10 mm等值線以及預(yù)計(jì)地表沉陷積水區(qū)范圍。
2.2.1 溫度植被指數(shù)
研究表明,土壤水分與地表溫度有關(guān),且土壤水分與地表植被存在一種脅迫關(guān)系。研究區(qū)內(nèi)像元對(duì)應(yīng)的植被指數(shù)和地表溫度構(gòu)成的散點(diǎn)圖呈三角/梯形空間,在三角/梯形空間中,地表溫度與植被指數(shù)存在明顯的負(fù)相關(guān)關(guān)系,TVDI可以由地表溫度與植被指數(shù)的關(guān)系斜率來(lái)表示[21-25],能從很大程度上反映土壤濕度的狀況。最大地表溫度在干邊上與植被覆蓋度成線性關(guān)系,其原理見(jiàn)圖3所示。
圖2 煤炭開(kāi)采影響邊界識(shí)別研究技術(shù)流程圖
圖3 地表溫度與NDVI特征空間原理圖
TVDI計(jì)算見(jiàn)式(1)。
式中T表示任意像元的地表溫度;Tmin表示相同NDVI值的最小地表溫度,對(duì)應(yīng)T-NDVI特征空間的濕邊;Tmax表示相同NDVI值的最大地表溫度,對(duì)應(yīng)T-NDVI特征空間的干邊。其中,在T-NDVI特征空間中對(duì)濕邊和干邊進(jìn)行模擬分別見(jiàn)式(2)和(3):
式中1、1、2和2分別是濕邊和干邊擬合方程的系數(shù)。TVDI取值范圍為0~1,TVDI越大,表明越接近干邊,對(duì)應(yīng)的土壤水分越低。
2.2.2 NDVI和地表溫度的反演
1)歸一化植被指數(shù)NDVI的反演
NDVI是反映地表植被覆蓋及其生長(zhǎng)狀態(tài)的重要指標(biāo),通常用紅外波段與紅光波段反射率差與和之間的比值表示,NDVI在植被檢測(cè)方面具有靈敏度高的優(yōu)勢(shì),在礦區(qū)土地利用/土地覆蓋變化LUCC(land use and land cover change)檢測(cè)中也得到了極為廣泛的應(yīng)用[17,26],其計(jì)算方法見(jiàn)式(4):
式中NIR為近紅外波段的反射率,為紅光波段的反射率。
2)地表溫度的反演
本研究使用輻射傳輸方程算法,在大氣參數(shù)已知的情況下根據(jù)普朗克方程來(lái)反演地表溫度,該方法反演精度較高,結(jié)果也比較可靠[27-30]。溫度為T的黑體在熱紅外波段的輻射亮度(T),見(jiàn)式(5):
式中為地表比輻射率,T為地表真實(shí)溫度(K),(T)為普朗克定律推到得到的黑體熱輻射亮度,為大氣在熱紅外波段的透過(guò)率,↑為大氣向上輻射亮度,↓為大氣向下輻射亮度。式中大氣在熱紅外波段的透過(guò)率()、大氣向上輻射亮度(↑)、大氣向下輻射亮度(↓)可從NASA官網(wǎng)(http://atmcorr.gsfc.nasa.gov/)查詢。
通過(guò)式(5)以及大氣輔助參數(shù)計(jì)算得到黑體熱輻射亮度(T),地表真實(shí)溫度(T)計(jì)算方法見(jiàn)式(6):
式中1,2均為常量,對(duì)于TM影像數(shù)據(jù),1=607.76 W/(m2·sr·m),2=1260.56 K。反演得到的Landsat TM數(shù)據(jù)各像元對(duì)應(yīng)的地表溫度數(shù)據(jù),主要集中在20~30 ℃之間,地表溫度的低溫區(qū)所占比例大。
2.2.3 溫度植被干旱指數(shù)反演
在MATLAB中以0.005為步長(zhǎng),提取像元NDVI值域內(nèi)對(duì)應(yīng)相同位置像元地表溫度最大值和最小值,并繪制相應(yīng)的散點(diǎn)圖(圖4)?!案蛇叀笨傏厔?shì)不是一條直線,其散點(diǎn)可分為3段-0.14 (8) 從線性擬合的效果來(lái)看,干邊線性擬合的效果更好。利用式(1)和相應(yīng)的干濕邊方程式(7)及式(8),計(jì)算得到TVDI空間分布數(shù)據(jù)集[31],如圖5所示。研究區(qū)內(nèi)TVDI集中分布在0.2~0.4、0.4~0.6之間,土壤濕度主要集中在“正常”和“微旱”2個(gè)等級(jí),“正?!蓖寥罎穸鹊燃?jí)比重最大,占研究區(qū)面積的45.17%,其次“微旱”土壤濕度等級(jí)占研究區(qū)面積的40.09%,適宜植被生長(zhǎng);且NDVI集中分布在0.2~0.8之間,均值為0.6,在指數(shù)函數(shù)擬合的時(shí)候不會(huì)出現(xiàn)較大的誤差項(xiàng)。 煤礦區(qū)及周邊,理論上存在地表生態(tài)受采煤“擾動(dòng)”與“非擾動(dòng)”、“有影響”與“無(wú)影響”的邊界,從不同角度或不同目的,邊界的劃分方法不同。本研究?jī)H考慮采煤沉陷對(duì)地表生態(tài)的直接影響(不考慮對(duì)地下水、煤炭運(yùn)輸、物質(zhì)遷移等引起的間接影響),將反映土壤濕度狀況的溫度植被干旱指數(shù)(TVDI)作為生態(tài)影響的一項(xiàng)直接檢測(cè)指標(biāo)。檢測(cè)指標(biāo)從積水區(qū)邊緣向外變化到接近“周邊正常值”、趨于穩(wěn)定的臨界距離定義為采煤對(duì)地表生態(tài)的影響邊界。兗州煤田是中國(guó)典型的高潛水位煤礦區(qū),煤炭開(kāi)采造成的地表沉陷積水區(qū)相對(duì)容易識(shí)別,而難點(diǎn)則在于確定非積水區(qū)開(kāi)采沉陷直接影響的“邊界”。 圖5 研究區(qū)TVDI空間分布 在ArcGIS中提取沉陷積水區(qū)邊緣TVDI像元中心點(diǎn),從沉陷積水區(qū)邊緣向外,以像元分辨率30 m為距離間隔,由近及遠(yuǎn)劃分不同的空間距離梯度。分析不同距離的TVDI中位數(shù)隨距積水區(qū)邊緣距離的變化規(guī)律,并求出TVDI趨于穩(wěn)定的值,見(jiàn)式(9): 式中代表擬合值;代表擬合初始值(沉陷積水區(qū)邊緣向外第一個(gè)像元距離的TVDI中位數(shù));¢代表變化速度,代表漸近線(即TVDI趨于穩(wěn)定的值),代表距沉陷積水區(qū)邊緣的距離。 根據(jù)漸近線(TVDI的穩(wěn)定值),確定對(duì)地表生態(tài)影響邊界。將擬合模型引入誤差項(xiàng),TVDI的變化范圍很小,取0.005倍的穩(wěn)定值(即0.005)作為誤差項(xiàng),對(duì)隨積水區(qū)往外TVDI達(dá)到穩(wěn)定的距離()進(jìn)行估計(jì),見(jiàn)式(10): 式(10)取“=”時(shí),得到采煤沉陷對(duì)土壤濕度的影響邊界。 研究區(qū)內(nèi)TVDI不僅受到采煤沉陷的影響,也受到建設(shè)活動(dòng)、土地利用差異等其他因素的影響,為了減少其他因素影響:1)自然水體、建設(shè)用地光譜特征與植被覆蓋區(qū)域差異大,且?guī)缀畏植继卣鞑煌菀鬃R(shí)別。剔除積水區(qū)邊緣的自然水體、建設(shè)用地、未利用地像元,利用純凈的有植被像元點(diǎn)的TVDI研究采煤沉陷積水區(qū)對(duì)土壤濕度空間特征分布的影響;2)空間交互受到距離衰減效應(yīng)的影響,空間上相近的區(qū)域具有更高的屬性相似性和交互強(qiáng)度[32],為減小空間交互作用的影響,剔除沉陷積水區(qū)邊緣以外300 m范圍內(nèi)其他小范圍積水區(qū)的像元點(diǎn)。東灘礦區(qū)的沉陷積水區(qū)之間最小距離60 m,空間交互作用顯著,將其作為一個(gè)整體從其外緣向外進(jìn)行分析;3)位于研究區(qū)邊界的沉陷積水區(qū),同一沉陷單元僅部分位于研究區(qū)內(nèi),故不做分析(如圖1中的沉陷積水區(qū)E,距離研究區(qū)邊界最近距離為220 m)。通過(guò)式(9)擬合不同距離的TVDI中位數(shù)隨距積水區(qū)邊緣距離的變化規(guī)律,如圖6所示。以沉陷積水區(qū)A為例,越靠近沉陷積水區(qū)邊緣TVDI值越低,在其向外90 m范圍內(nèi),TVDI變化幅度最明顯,周邊土壤濕度所受影響最大,在120 m范圍外,TVDI值在0.395左右小幅度上下波動(dòng)。其他沉陷積水區(qū)也有相同的變化規(guī)律,隨著距積水區(qū)邊緣距離增加,TVDI均呈現(xiàn)先增加后趨于穩(wěn)定的趨勢(shì)。 圖6 TVDI隨距積水區(qū)邊緣距離的變化特征 根據(jù)不同距離TVDI中值變化確定井工煤炭開(kāi)采對(duì)地表生態(tài)的擾動(dòng)邊界,式(9)擬合的結(jié)果較好,各積水區(qū)向外TVDI趨于穩(wěn)定的穩(wěn)定值在0.38~0.43之間,相關(guān)系數(shù)均達(dá)到0.6以上,且最高達(dá)到0.95,均方根誤差均小于0.02。受煤層及賦存特征、開(kāi)采規(guī)模與方法、最大下沉深度、地下水位變化、沉陷積水區(qū)范圍等因素影響,各沉陷積水區(qū)邊緣向外TVDI趨于穩(wěn)定的穩(wěn)定值()與距離()均有差異。根據(jù)圖6知,截止2009年底煤炭產(chǎn)量最多的東灘礦區(qū),其破碎且不規(guī)則的沉陷積水區(qū)H,空間交互作用明顯,影響范圍最大,距積水區(qū)邊緣達(dá)到了781 m;積水區(qū)D面積最小,影響范圍也最小,為53 m。其他沉陷積水區(qū)A、B、C、F、G的影響范圍分別為143、501、386、119、181 m。 2009年的預(yù)計(jì)沉陷積水區(qū)和預(yù)計(jì)地表沉陷邊界圖,與兗州煤田煤炭開(kāi)采沉陷積水對(duì)土壤濕度的影響邊界圖疊加,如圖7所示。統(tǒng)計(jì)兗州煤田實(shí)際沉陷積水面積、提取的煤炭開(kāi)采非積水影響范圍、預(yù)計(jì)沉陷積水面積與預(yù)計(jì)沉陷非積水面積,見(jiàn)表1所示。2009年實(shí)際沉陷積水總面積為14.91 km2,基于TVDI提取的兗州煤田煤炭開(kāi)采非積水影響面積為30.91 km2;預(yù)計(jì)沉陷積水面積為4.69 km2,預(yù)計(jì)沉陷非積水面積為21.72 km2。預(yù)計(jì)的沉陷積水面積普遍小于實(shí)際沉陷積水面積,這是由于預(yù)計(jì)的沉陷積水區(qū)是根據(jù)當(dāng)?shù)氐叵聺撍粶y(cè)算的,且實(shí)際開(kāi)采情況相比于最初的開(kāi)采計(jì)劃發(fā)生了變化,在這樣的情況下進(jìn)行2種方法得到的開(kāi)采影響面積絕對(duì)值比較的意義不大。 圖7 2009年兗州煤田影響邊界空間分布 表1 提取結(jié)果與沉陷預(yù)計(jì)結(jié)果比較 上述數(shù)據(jù)相對(duì)比較分析仍能發(fā)現(xiàn):采用10 mm下沉等值線作為開(kāi)采影響邊界,預(yù)計(jì)沉陷非積水面積是預(yù)計(jì)沉陷積水面積的4.63倍,而基于TVDI分析得到的煤炭開(kāi)采非積水影響范圍,僅相當(dāng)于實(shí)際沉陷積水面積的2.07倍。由此推測(cè),煤炭開(kāi)采對(duì)以地表土壤濕度等生態(tài)因子的影響面積要小于以地表下沉10 mm作為影響邊界的范圍。需要說(shuō)明的,采用本文提出的方法與采用10 mm下沉等值線確定煤炭開(kāi)采影響邊界,兩者不存在優(yōu)劣的差異,只是兩者適用條件不同,前者更適用于采煤對(duì)建構(gòu)筑物影響邊界的界定,后者更適用于確定植被覆蓋區(qū)煤炭開(kāi)采對(duì)地表生態(tài)的影響邊界,尤其是針對(duì)大范圍的煤炭開(kāi)采影響范圍或累積效應(yīng)界定時(shí)將更為適宜。 本文以東部高潛水位平原區(qū)兗州煤田為研究區(qū),分析了沉陷積水區(qū)邊緣向外600 m范圍內(nèi)像元中心的TVDI中位數(shù)隨距離的變化特征,提取了典型區(qū)地下開(kāi)采對(duì)地表生態(tài)的影響邊界,將之與開(kāi)采沉陷預(yù)計(jì)下沉10 mm邊界進(jìn)行了對(duì)比分析。結(jié)論如下: 1)從沉陷積水區(qū)邊緣向外,以像元分辨率30 m為距離間隔,由近及遠(yuǎn)TVDI中位數(shù)隨距積水區(qū)邊緣距離的增加呈現(xiàn)先增加后趨于穩(wěn)定的趨勢(shì),TVDI值在某一值附近小幅度上下波動(dòng)并趨于平穩(wěn)。指數(shù)模型擬合表明,相關(guān)系數(shù)均達(dá)到0.6以上,且最高達(dá)到0.95,均方根誤差均小于0.02。 2)采用10 mm下沉等值線作為預(yù)計(jì)開(kāi)采沉陷邊界,預(yù)計(jì)沉陷非積水面積是預(yù)計(jì)沉陷積水面積的4.63倍,而基于TVDI分析得到的煤炭開(kāi)采的非積水影響范圍,則僅相當(dāng)于實(shí)際沉陷積水面積的2.07倍。兩者比較說(shuō)明,以地表土壤濕度等生態(tài)因子測(cè)算的煤炭開(kāi)采影響面積要小于以地表下沉10 mm作為影響邊界的范圍。 煤炭開(kāi)采對(duì)地表生態(tài)影響是多維的,涉及地形、土壤、植被、動(dòng)物、地表及地下水環(huán)境、大氣等,本研究在傳統(tǒng)的僅依據(jù)地表下沉值等確定開(kāi)采影響范圍的基礎(chǔ)上,提出了基于遙感指數(shù)隨距離變化的趨勢(shì)擬合和變化趨于穩(wěn)定的漸近線來(lái)反解開(kāi)采沉陷對(duì)地表生態(tài)的影響邊界的方法。雖然不能全面、綜合、系統(tǒng)地揭示煤炭開(kāi)采的影響范圍,但是從一個(gè)新的視角——遙感生態(tài)指數(shù)空間變化趨于穩(wěn)定的理論邊界來(lái)進(jìn)行研究,有助于改進(jìn)僅應(yīng)用10 mm下沉等值線確定煤炭開(kāi)采生態(tài)影響邊界過(guò)于“機(jī)械”和不適用于植被覆蓋區(qū)的弊端,且可以應(yīng)用于大范圍、長(zhǎng)時(shí)序的研究,有助于定量研究煤炭開(kāi)采影響范圍及其時(shí)空生態(tài)累積效應(yīng)。 [1] 張發(fā)旺,侯新偉,韓占濤,等. 采煤塌陷對(duì)土壤質(zhì)量的影響效應(yīng)及保護(hù)技術(shù)[J]. 地理與地理信息科學(xué),2003,19(3):67-70. 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[32] 劉瑜,龔俐,童慶禧. 空間交互作用中的距離影響及定量分析[J]. 北京大學(xué)學(xué)報(bào),2014,50(3):526-534. Liu Yu, Gong Li, Tong Qingxi. Quantifying the distance effect in spatial interactions[J]. Acta Scientiarum Universitatis Pekinensis, 2014, 50(3): 526-534. (in Chinese with English abstract) Identification of boundary about coal-mining influence on ecology by remote sensing in Yanzhou Coalfield based on temperature vegetation drought index Li Jing, Han Ying, Yang Zhen, Miao Hui, Yin Shouqiang (100083,) How to determine the ecological impact boundary of coal mining is one of the difficulties in the research field of land ecology in mining areas. For a long time, surface subsidence depth of 10 mm is generally used as the coal mining disturbance boundary not only to the developed land but also to the vegetation-covered land in the academic research and planning practice. Land reclamation is still bounded by the subsidence contour with the expected surface subsidence depth of 10 mm as the boundary. In fact, many scholars and other professionals have realized that 10 mm sinking is not adaptable as the boundary of mining influence on land ecology. Our research goal was to find a remote sensing method to identify mining impact boundary, which could be used to evaluate ecological accumulating effect of coal mining on vegetated area. Yanzhou coal field, a typical coal mine area with high groundwater level in the eastern China, was taken as the study area, where the coal mining has caused a lot of impounded water areas, and the spatial distribution characteristics of the temperature vegetation drought index (TVDI), which is linear with soil moisture, were analyzed. Then the influence boundary of mining subsidence on soil moisture was determined, and the difference between the influence boundary using TVDI spatial changing tendency and the expected surface subsidence of 10 mm was analyzed. Firstly, the authors calculated TVDI and found it was mainly concentrated in the range of 0.2-0.6, which meant soil moisture levels were mainly “normal” and “slight drought”. The areas belonging to “normal” level and “slight drought” accounted for 45.17% and 40.09% of the whole study area respectively. Secondly, the authors tried to obtain the influence boundary of soil moisture and analyzed the spatial distribution characteristics of TVDI from the edge of the impounded water area by mining subsidence. The impounded water areas i.e. A, B, C, D, F, G and H were taken as the research objects and the different distance ranges from the edge of the impounded water area were divided. With the increase of the distance from the edge of the impounded water area, the median TVDI value increased and then tended to be stable. Due to the differences in coal seam, mining methods and processes, the influence range of coal mining on soil moisture varied in different subsided areas. The authors proposed an exponential model to identify the mining influence boundary, in which the value of asymptotic line was defined as the disturbed boundary. Study results showed that TVDI stable value in each impounded water area is between 0.38 and 0.43. Fitting TVDI value with exponential function, it could be found that the correlation coefficients are greater than 0.60,and the mean square root errors are less than 0.02. The impounded water area H is fragmented, irregular and has strong internal spatial interaction, which has the largest influence distance reaching 781 m. Finally, the ecological disturbance range of coal mining based on TVDI extraction method was expected to be smaller than subsidence depth boundary, namely 10 mm. The paper¢s innovation is to propose a new method to identify the mining influence boundary, which is the theoretical boundary is the asymptotic line of ecological index changing from the edge of impounded water area to the unmined area by increased disturbance range. remote sensing; ecosystems; mining water area; coal mining; impounded area by mining subsidence; temperature vegetation drought index; soil moisture; influence boundary by mining 10.11975/j.issn.1002-6819.2018.19.033 F205;X171.4 A 1002-6819(2018)-19-0258-08 2018-04-20 2018-09-06 國(guó)家自然科學(xué)基金資助項(xiàng)目(41501564) 李 晶,女(漢族),吉林農(nóng)安人,教授,博士,博士生導(dǎo)師,主要研究方向?yàn)橥恋乩门c土地復(fù)墾、生態(tài)遙感、3S應(yīng)用。Email:lijing@cumtb.edu.cn 李 晶,韓 穎,楊 震,苗 輝,殷守強(qiáng). 基于溫度植被干旱指數(shù)的兗州煤田煤炭開(kāi)采影響邊界遙感提取[J]. 農(nóng)業(yè)工程學(xué)報(bào),2018,34(19):258-265. doi:10.11975/j.issn.1002-6819.2018.19.033 http://www.tcsae.org Li Jing, Han Ying, Yang Zhen, Miao Hui, Yin Shouqiang. Identification of boundary about coal-mining influence on ecology by remote sensing in Yanzhou Coalfield based on temperature vegetation drought index[J]. Transactions of the Chinese Society of Agricultural Engineering (Transactions of the CSAE), 2018, 34(19): 258-265. (in Chinese with English abstract) doi:10.11975/j.issn.1002-6819.2018.19.033 http://www.tcsae.org2.3 煤炭開(kāi)采影響邊界提取方法
3 結(jié)果與分析
3.1 煤炭開(kāi)采影響邊界提取
3.2 預(yù)計(jì)邊界與提取邊界的對(duì)比分析
4 結(jié)論與討論