73 lines
1.6 KiB
Plaintext
73 lines
1.6 KiB
Plaintext
18. DRYLANDS
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Salting and Interceptor Banks
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9o. militate“ AREA. WA, AUSTRALIA.
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Deforestation. grazing. and wheat cultivation have produced
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Widespread salting, here visible as collapsed soil at seepage lines. The
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bro'wnish barley greas (Hordeum maritimum) is also indicative of soil
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cu apse.
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.4 e:"l""e:v'~
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‘43 "f“ ’g.»{7§’:
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e!-
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w '5 ’v
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a
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R“
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D.
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92. OUAIRADING, WA, AUSTRALIA.
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A farmer develops interceptor banks to run surface water and
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throughflow off fields to a natural valley. thus isolating soil blocks for
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rain leaching and preventing a 'cascade' effect downhill of salty
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overland flow or throughtiow,
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a
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91. NEAR QUAIRADING, WA. AUSTRALIA.
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A closer look at a once—forested marsh in wheatlands, now a saitpan.
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93. QUAIRADING, WA, AUSTRALIA
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A classic interceptor bank, ending on the streamline as marked by the
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distant trees, A bulldozer has rammed subsoil on the downhill wall of
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the bank. Depth = 1.5 m, width 4 m. spacing not more than 100 m
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apart. or (on slopes) 1 m vertical separation. Soil pit below this bank
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shows no throughtlow. no rising salted groundwater.
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94. BEERMULLAH, WA, AUSTRALIA.
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An interceptor has prevented soil collapse by flooding (note rushes on
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upslope side). thus protecting crop below the bank. Spike rush
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(Juncus) is another indicator of imminent soil collapse, surface
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flooding, and anaerobic soils. Subsoils are dry, cemented. or subject
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to groundwater rising.
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95. BEERMULLAH, WA, AUSTRALIA.
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A series of interceptor banks in wheatfields isolate soil blocks from
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overland flow and salting effects.
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