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首頁> 外文學(xué)位 >Hydrology, water quality, and channel morphology across an urban-rural land use gradient in western Georgia, United States of America.
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Hydrology, water quality, and channel morphology across an urban-rural land use gradient in western Georgia, United States of America.

機譯：美國佐治亞州西部城鄉(xiāng)土地利用梯度的水文，水質(zhì)和河道形態(tài)。

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The southeastern United States is experiencing rapid urban development. Consequently, Georgia's streams have been threatened by hydrologic alteration, nutrient and bacteriological impairment, and channel morphometry changes from extensive development and from other land use activities such as livestock grazing and silvicultural practices. A study was performed to assess the above activities across an urban to rural land use gradient within 24 west Georgia watersheds ranging in size from 500-2500 ha that were drained by 1st, 2nd, and 3rd order streams. Dominant land covers in the study watersheds included: urban, developing, pasture, managed forest, and unmanaged forest.; Stream hydrology was continuously monitored in 18 watersheds from 29 July 2003 to 23 September 2004 using InSitu pressure transducers. Dependent variables were estimated from the discharge data and placed into four categories, including flow frequency (i.e., the number of times a predetermined discharge threshold is exceeded), flow magnitude (i.e., maximum and minimum flows), flow duration (i.e., the amount of time discharge was above or below a predetermined threshold), and flow predictability and flashiness. Fine resolution data (i.e., 15-min interval) was also compared to daily discharge data to determine if resolution affected how streams were classified hydrologically. Urban watersheds experienced flashy discharges during storm events, whereas pastoral and forested watersheds showed more stable hydrographs. Flow frequency variables were most tightly correlated to land cover. Further, stream hydrology response variables were explained similarly with both the 15-minute and daily data resolutions.; A two-phase study approach was used to investigate differences in stream water nutrient and bacteriological loading across the land use gradient. During phase 1, nutrient and biological data were collected within 18 watersheds, and data were used to generate regression models between land cover and the nutrient/biological parameters. Results from the phase 1 suggested nutrient and fecal coliform concentrations within watersheds having >5% impervious surface often exceeded those levels in nonurban watersheds during both base flow and storm flow. During phase 2 of the study, regression models were tested based on data from 6 new watersheds with representative land use/cover patterns for the area.; To assess sediment movement and channel morphometry, 18 study watersheds were monitored. (Abstract shortened by UMI.)
機譯：美國東南部正在經(jīng)歷快速的城市發(fā)展。因此，格魯吉亞的河流受到水文變化，營養(yǎng)和細菌損害的威脅，并且由于廣泛的發(fā)展和其他土地利用活動（例如放牧和造林活動）而改變了河道的形態(tài)。進行了一項研究，以評估上述喬治亞州西部24個流域內(nèi)城市到農(nóng)村土地利用梯度的上述活動，流域的面積為500-2500公頃，流經(jīng)一階，二階和三階流。研究分水嶺的主要土地覆蓋包括：城市，開發(fā)中的牧場，管理型森林和非管理型森林；從2003年7月29日至2004年9月23日，使用InSitu壓力傳感器對18個流域的溪流水文學(xué)進行了連續(xù)監(jiān)測。從排放數(shù)據(jù)估計因變量，并將其分為四類，包括流量頻率（即超過預(yù)定排放閾值的次數(shù)），流量大?。醋畲罅髁亢妥钚×髁浚髁砍掷m(xù)時間（即流量）放電時間超過或低于預(yù)定閾值），以及流量可預(yù)測性和浮閃性。還將精細分辨率數(shù)據(jù)（即每15分鐘間隔一次）與每日排放數(shù)據(jù)進行比較，以確定分辨率是否會影響流在水文方面的分類方式。城市流域在暴風(fēng)雨期間經(jīng)歷了暴雨排放，而牧區(qū)和森林流域顯示出更穩(wěn)定的水位圖。流量頻率變量與土地覆蓋最緊密相關(guān)。此外，用15分鐘和每天的數(shù)據(jù)分辨率對河流水文響應(yīng)變量進行了類似的解釋。采用了兩階段研究方法來研究整個土地利用梯度中溪流水養(yǎng)分和細菌載量的差異。在第一階段，在18個流域內(nèi)收集了養(yǎng)分和生物學(xué)數(shù)據(jù)，并使用這些數(shù)據(jù)生成了土地覆蓋率和養(yǎng)分/生物參數(shù)之間的回歸模型。第一階段的結(jié)果表明，在基礎(chǔ)流量和暴雨流量期間，具有> 5％防滲表面的流域中的營養(yǎng)物和糞便大腸菌群濃度通常超過非城市流域的水平。在研究的第二階段，根據(jù)來自6個新流域的數(shù)據(jù)測試了回歸模型，該流域具有該地區(qū)的代表性土地利用/覆蓋模式。為了評估沉積物的運動和河道的形態(tài)，對18個研究分水嶺進行了監(jiān)測。 （摘要由UMI縮短。）

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