- 5 1 tich phan hai ve (3.3) ta dupc:
3-He so loan luu KM
He sd loan luu la mdt dai lupng bien ddi theo chieu cao vi vay trong tinh toan ta thudng quan tam tdi gia tri cua nd tai dp cao Im va ky hieu la Ki.
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Trong md hinh Buduko, he so loan luu tang tuyen tinh theo do cao trong gidi han ldp KQSD:
K = ^ m u:,c z • (3.39) Khi -L - Im ta cd Ki = m.u* «£,
Cac gia tri tinh ki dupe trinh bay tren hinh 3.9 cho thay: gia tri cua nd bien doi trong khoang tii 0.05 m^/s den
2
0.3 m /s phy thupc vao m va u*, do dd nd ciing dat gia tri eye dai vao budi trua.
0,4 •
0.1 -
iO 13 16 19
Hinh 3.9: Gia tri he sd loan luu ki tinh theo md hinh Buduko
De tien tinh toan trong thyc te, ngoai ki, Buduko cdn dua ra dai lupng khac dac trung cho mile dp xao trpn loan lyu, dd la dd dan loan luu. GiUa dp dan loan luu cua mdt ldp nao dd cd be day Z2 - zi va he so K cd mdi lien he sau:
1 D(Zl,Z2) = Z2 dz (3.40) K Zl
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nhiet, ddng am thang dilng qua hieu gia tri nhiet do, do am rieng d hai mUe bat ky. That vay, neu bd qua sy khac biet giiia he so loan luu K vdi he so dan nhiet do loan luu va he sd khuech tan am loan luu ta cd:
39 H = -Cp9K (3.41) H = -Cp9K (3.41) 3z E = -9K 3q 3z (3.42)
Bo qua sy khac biet rat nho giiia vi phan va dao ham,