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Chapter 3: Physical and Biotic factors The total area of the Sub catchments of Spiti region i.e. 19A to 19H is 587500 Ha. It is observed that these Sub catchments have varied landforms, Forest types, Rainfall patterns, Agroecological zones and Soil types. This chapter gives a brief account of the physiography of the Sub catchments of Spiti region. The detail description of each parameter can be found in the Technical mapping chapter of this report.
2. Forest types
1. Landforms
The forest types those are present in these Subcatchments shows that there are three types of forests viz Dry alpine, Moist alpine and Sub-alpine. The pie diagram depicts that Dry alpine forests cover 56% area of the Sub catchments while Moist alpine and Sub-alpine covers 18% and 26% respectively.
The landforms observed in the Subcatchments shows that there are five types of landforms in its entire area. These landforms are Glaciers, Steep to very steep high hills of greater Himalayas, Steep to very steep high hills of lesser Himalayas, glacio-fluvial valley and Fluvial valleys. The maximum area i.e. 51% area has Steep to very steep high hills of greater Himalayas.
3. Precipitation The entire area falling under these Sub catchments receives precipitation in the form of snow. Now the rainfall has started and observed in these Sub catchments is <700 mm.
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4. Agro-ecological zones
5. Soil types
The pie diagram represents the distribution of Agro-ecological zones in the Sub catchments. It is observed that these Sub catchments have four types of Agro-ecological zones. The Agroecological zone described as Warm, dry, sub-humid, greater Himalayas with 120-180 days LGP covers 48% area while Warm, sub-humid, moist, lesser Himalayas with 180-270 days LGP covers 14%, Cold, arid, greater himalayas with <60 days LGP covers 12% and Cold to warm semi-arid, semi-dry, greater Himalayas with 60-120 days LGP covers 26% .
The Sub catchments have heterogeneous soil with 16 different soil types. The diagram shows the distribution of different soil types in these Sub-catchments. The Soil types 6 and 3 are dominant in the Sub catchments and cover 22% and 16% area respectively out of the total area. The remaining area is reported to have soil types 1, 5, 7, 8, 9, 10, 12, 16, 18, 20, 21, 22, 24 and 25 in varying proportions.
Note: The name of each soil types being very descriptive, we have denoted them as Soil types units. This nomenclature is used in the above diagram and also in the further explanation. The description of the soil types is presented in the table A given below.
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Table A: Soil type description Soil Description Rock outcrops covered with glaciers: associated with: Shallow, excessively drained, sandy skeletal soils with sandy surface, severe erosion and strong stoniness. Shallow, excessively drained, loamy skeletal, calcareous soils on very steep loamy surface lopes with sandy surface, severe erosiox and moderate stoniness, associated with Rock outcrops. Mountain & valley glaciers & rock outcrops; associated with; medium deep, excessively drained, sandy-skeletal soil on very steep slopes with sandy surface, severe erosion & moderate stoniness. Rock outcropes, associated with medium deep, excessively drained, loamy-skeletal calcareous soils on very steep slopes with loamy surface, severe erosion and moderate stoniness. Rock outcropes associated with shallow excessively drained, loamy skeletal soils onvery steep slopes with loamy surface, severe erosion and moderate stoniness. Rock outcropes associated with medium deep excessively drained, loamy-skeletal soils on very steep slopes with loamy surface, severg, wrosion and moderate stoniness. Rock outcropes associated with deep well drained, loamy-skeletal soils on very steep slopes with loamy surface, severe erosion and strong stoniness. Rock outcropes associated with shallow somewhat excessively drained, coarse-loamy, calcareous soils on very steep slopes with loamyg, surface, severe erosion and strong stoniness. Deep excessively drained, mesic, loamy-skeletal soils on steep slopes with loamy surface, severe erosion and moderate stoniness associated with Deep, excessively drained, coarse - loamy soils with loamy surface, severe erosion and moderate stoniness. Rock outcrops associated with deep, excessively drained, sandy- skeletal soils with loamy surface, very severe erosion and moderate stoniness. Deep somewhat excessively drained, coarse loamy, calcareous soils on gentale terraces on very steep slopes with loamy surface, severe erosion and moderate atoniness associated with medium deep well drained, loamy skeletal calcareous soils with loamy surface Rock Outcrops, associated with medium deep, somewhat excessively drained, loamy-skeletal soils on moderately steep slopes with loamyg, surface, severe erosion and moderate stoniness. Deep excessively drained, fine loamy, calcareous soils on gentle slopes with loamy surface, severe erosion and moderate stoniness associated with shallow somewhat excessively drained, loamy-skeletal, calcareous soils with loamy surface, severe erosion Medium deep excessively drained, sandy-skeletal soils on moderately steep slopes with sandy surface, severe erosion and strong stoniness associated with, deep excessively drained, loamy skeletal soils with loamy surface, severe erosion and moderate stoniness Deep moderately well drained, loamy skeletal soils on gentle slopes with loamy surface, moderate erosion and slight stoniness associated with Deep moderately well drained, calcareous coarse-loamy soils with loamy surface and slight erosion. Madium deep. well drained, mesic, coarse-loamy over loamy skeletal soils on gentle slopes with loamy surface and moderate erosion, associated with deep, somewhat excessively drained, sandy soils with loamy surface, slight erosion and moderate stoniness.
Comprehensive CAT Plan of Satluj River Basin
Soil Type Unit Soil Type 1 Soil Type 3 Soil Type 5 Soil Type 6 Soil Type 7 Soil Type 8 Soil Type 9 Soil Type 10 Soil Type 12 Soil Type 16
Soil Type 18 Soil Type 20 Soil Type 21 Soil Type 22 Soil Type 24
Soil Type 25