地圖上亂山子村北邊這些巨大的圓圈是什麼?
偶然在谷歌地圖上看到這些圓圈,應該是人工的,這些東西是做什麼用途的?誰負責的?
這個是圓形軸心灌溉區(也稱圓形農場),在缺水地區如西亞的沙特很常見,在北美地區也有很長的歷史了。這種方式主要通過抽取地下水灌溉,以達到節水的目的,通常直徑有800米左右。----------------------------------------------記憶的分割線-----------------------------------------------------知道這個源於高中某次期中(or期末?記不清了)考試的地理題,有一道考得知識點是西亞和北非,當時就用了這個圖,試卷質量真的是差的掉渣,完全看不清,考場上一看西亞就直接選了油田,考完試上網搜才發現是這個。所以記憶很深刻。
在40年前,那裡的蓄水層儲水量約為500立方千米,足以充滿整個伊利湖。但是,在過去數十年中,大約有五分之四的地下水資源已被抽取上來用於農業灌溉。該地區每年平均降水量不足200毫米,根本不足以補充被抽取的地下水水量。沙特政府聲稱,由於地下水供應量的不斷減少以及為抽水所造成的大量能源消耗,到2016年灌溉小麥將絕產。為了保證國內糧食需求,沙特將逐漸向國外尋求農業幫助。
鏈接:http://slide.geo.sina.com.cn/slide_29_16805_19938.html#p=2
再補充一點從NASA官網上摘錄的信息:@郭春龍
Northern Saudi Arabia hosts some of the most extensive sand and gravel deserts in the world, but modern agriculture has changed the face of some of them. This photograph from astronauts on the International Space Station presents an almost surreal view of abundant green fields in the midst of a barren desert.
As recently as 1986, there was little to no agricultural activity in the Wadi As-Sirhan Basin. But over the past 26 years, agricultural fields have been steadily developed, largely as a result of the investment of oil industry revenues by the Saudi government. Crops grown in the area include fruits, vegetables, and wheat.
The fields are irrigated by water pumped from underground aquifers. That water is distributed in rotation about a center point within a circular field—a technique known as center-pivot agriculture. The approach affords certain benefits compared to traditional surface irrigation, such as better control of water and fertilizer use. This so-called 「precision agriculture」 is particularly important in regions subject to high water loss due to evaporation. By better controlling the amount and timing of water application, evaporative losses can be minimized.
For a sense of scale, the agricultural fields in active use (dark green) or fallow (brown to tan), are approximately one kilometer in diameter. While much of the Wadi As-Sirhan Basin shown here is sandy (light tan to brown surfaces) and relatively flat, low hills and rocky outcrops (dark gray) of underlaying sedimentary rocks are visible at image left and right.鏈接:Agricultural Fields, Wadi As-Sirhan Basin, Saudi Arabia : Image of the Day
全球綠化沙漠案例:沙特圓形麥田地下水灌溉
沙漠中的綠洲:沙特圓形麥田排列整齊自動旋轉噴灌 其實在普通的公園裡面就有這樣的,原理差不多。
目前比較合適的方法還是滴灌,直接作用在植物根部,在沙漠地區種莊稼,對於地下水的需求太大,明顯得不償失,種一些抗旱耐風沙的樹會比較好。 (抗旱抗澇的樹裡面竟然有柳樹,當時我就很震驚)
你看google earth中 美國中部地區很多的
就是噴灌的田地由於噴灌機是畫圓的噴灌,所以地都是圓形的這個,你見過灌溉么?噴灌的那種。
可以看一下BBC記錄片<<地球>>,裡面有一集專門講到了水資源利用,就有這個地方,是取地下水用的?
噴灌車繞著一個點旋轉,方便覆蓋每寸土地!
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