Soil erosion helped wipe out civilizations thoughout history, but soil conservation has enabled some societies to flourish for centuries. Thus, soil erosion and erosion prevention will always be serious matters as long as we raise crops on earth. Soil erosion occurs as sheet and rill erosion (the most common form of water erosion) gully erosion and wind erosion. Soil erosion can reduce onsite capability of soil to produce healthy and abundant crops and can increase the cost and difficulty of managing a farm. Erosion can cause both short term and permanent damage to the soil. SCS estimates that, under 1982 management conditions, 77 million acres of cropland are eroding at rates that would result in loss of 5 percent or more of their productivity within 100 years. The loss is the equivalent of losing production worth more than $ 13.5 billion at 1989 prices. Soil erosion in the world was estimated to lose 23 billion tons of soil from crop lands in excess of new soil formation. Offsite damages are mainly in two areas: farms or land surfaces receiving deposits of transported soil, and the waterways receiving sediment loadings through surface runoff. The land surface damage could be the loss of crops or plants covered or otherwise injured by the deposited soil, or washed away by the force of runoff reinforced by the weight of soil detached from the upper slopes. The damage through surface runoff to waterways increases the sediment load in all waterways receiving the detached soil, silting up the beds of impacted waterways, reducing the storage capacity of lakes and reservoirs, clogging streams and drain age channels, and thus increasing the likelihood of flooding. It also causes deterioration of aquatic habitats, damages water distribution systems and further reduces the usefulness of waterways for navigation and irrigation purposes. It greatly increases the cost of dredging waterways and clearing ditches. The total estimate d annual offsite damages due to soil erosion in the United States ranged from $ 4.8 to $ 19.5 billion, or a point estimate of $ 9.15 billion, and out of it $ 3.3 billion was damages due to cropland soil erosion in 1989 dollars. Nonpoint source pollution is responsible for as much as 73 percent of the total biochemical oxygen demand loadings, 99 percent of the suspended solids, 83 percent of dissolved solids, 82 percent of nitrogen, 84 percent of phosphorus, and 98 percent of bacteria loads in U.S. waterways. Soil erosion is probably the major cause of such nonpoint source pollution. There is a need for continuous investment in soil conservation to sustain the earth's capacity to support its population, and international technical cooperation and assistance in implementing conservation measures are necessary. It is imperative to make soil and water conservation an ethic in every human culture, to build an environmental data base, and to foster global cooperation and coordination on environmental policies and practices, as well as to develop better analytical tools for all nations.
3,810 再 連(C1U630) 員山鄉 121°40’16’’ 24°43’01’’ 140 2,876 寒 溪(C1U670) 冬山鄉 121°42’30 ’’ 1,810 4,608 南 山(C1U720) 大同鄉 121°22’24’’ 24°26’21’’ 1,260 2,545 思 源(C0U730) 大同鄉
地的種子發芽的機率是非凹地地形的4倍,顯然凹地的微地形有利於木麻黃種子發芽。臺中港區木麻黃天然更新之研究報告指出(林睿思等,2009),該區砂地下層5 cm處的土壤含水量 (約12 cm長,徑10 m寬)輕放於播種穴上;再將竹筒外以砂填滿固定,使竹筒上端露出地面約2~4 cm高度,這方法不僅有效阻隔海砂及枯落物覆蓋,也保護幼苗免遭小型動物危害
、宜呈、羽萱、怡雯、思妤、千筑、麗君)一路上的幫忙與鼓勵,同窗立玟、平原、意修、育盛、士恩、佳翰、信賢、瀚陞、廷碩ヽ志豪學長、銘辰學長、謝技師等在生活上的關心與協助,使我的碩 ,為 81.5%,其次則為 6月份之 81.2%,最小則為 12 月份的 70.6%。再氣壓的部分,夏季比較低,以 8 月 1,005百帕最低,冬季則是1 月及12月1,017
路基流失和崩塌,不僅造成路面寬度變窄,部分裸露邊坡仍有再生崩塌之可能,恐造成交通中斷。 圖11 道路調查流程圖 作為分析之用之雨量資料再以常態型、皮爾遜III型、對數皮爾遜III型及極端值I型等4種機率分佈進行降雨頻率分析,並利用卡方檢定及K-S檢定法,作上述機率分佈之適合度檢定
友-雅慧、文瑄、思潁、維、Nothing、老頭、蕃茄 - 郁婷 - 之滲透係數,接著藉由改變試體裝填方式以獲得雙土層於水平滲流及垂直滲流狀態(水流方向與土層界面之關係)下之等值滲透係數。再者,為了解滲流沖蝕發生過程及破壞情形,將滲透室
。』大三時第一次聽到這句話,只覺得老師很「幽默」;做研究如果這麼的「不科學」,怎麼會有好的研究成果? 再次聽到這句話,已是碩二的準畢業生。這幾年換過了一些題目,摸索過了很多方向 寫作黑夜的細心。最後,還要感謝在我低潮時給予我鼓勵與安慰的人,筱雯學姊、國文學長,以及思敏、品含…等,也謝謝在口試後幫忙許多後續處理的宗敏。 最後的最後,當然要謝謝一路陪我
,再而三產生災害,值得吾人省思。 (四)防治對策 1. 炭寮 33 號坑支流向源侵蝕部份: (1)由於向源侵蝕已造成投 42 公路近 50 公尺深之崩塌,崩塌路寬約近 林為首要,因此於野溪兩側或其他裸露應儘速栽植台灣赤楊、相思木、大葉楠、山鹽菁等以防制土石流再次威脅。 4. 坑溝治理 土石流按發育階段可分為(a)發展期土石流(b)旺
用性,再將暴雨採樣資料及年淤積量檢定驗證泥沙濃度,並以暴雨水質資料模擬水質狀態後,推估全年集水區污染物產量做為提供集水區治理規劃之參考。 結果顯示,NPSM 模式能有效模 = − AGWRC:地下水流之每日退水率 10. EVAPT-模擬蒸發散 首先估計勢能蒸發散,再計算實際蒸發散;由以下五個副程式計算實際蒸發散:
doi:10.6342/NTU201601202 II 摘要 近年來台灣水庫皆面臨嚴重淤積問題,因而水庫淤泥去化與再利用之議題即受到極大之關注。因此,本研究期 元的效益。 綜合上述成果,顯示本研究所開發之綠屋頂模組,已達一定程度的效益,應可提供未來水庫淤泥去化及資源再利用之可行方案。 關鍵字:綠屋頂、水庫淤泥去化、綠屋頂植生基材
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