Resource characterization of foothill riverbed lands of north-western Himalayan region

Abstract

Conducive edaphoclimatic conditions are principal bases for the success of desired vegetation. However, in riverbed lands of north-western Himalayan region, the high gravel content (48.26% by volume) is the major constraint. The profile study indicated that there were high variability not only in. soil : stone ratio but also in layers. Average workable top soil depth mixed with some gravels was less than even 24.45 cm. Among mechanical fractions, the silt and clay contents were very low and coarse sand alone was more than 50 percent, thereby the infiltration rate was very high (2.92 cm hr-1) and water holding capacity was medium. The soil reaction was almost netural. Overall, fertility status of the soil was medium poor, particularly in lower horizons. The water table was shallow (2.5-3 m) during monsoon and deep during summer (6-7 m). Though, there was no definite pattern in genesis of riverbed land development but it was noticed that these lands are formed as a result of lateral migration or shifting course of torrents (seasonal river) and layered deposition of gravels/soils eroded from the adjoining hills. These torrents are originated from the hills and widen as they enter in the foothill plains. The heavy sediment load generated by the increasing erosive processes due to unscientific cultivation on the steep slopes, deforestation, open cast mining, uncontrolled grazing, construction of toads and houses on erosion prone sites etc. is carried out by the torrents and deposited in the valley lands, forming a large area unfit for crop cultivation. The area comes under humid subtropical climate receiving sufficient precipitation (1691 mm yr-'). The maximum and minimum temperature ranges from 19 to 37°C and 3.6 to 24°C, respectively. The wind velocity was always observed below the erosive limit. Sunshine hour and solar radiation were moderate type. Evaporation was also not high. Overall weather is conducive to support variety of vegetation if site constratints are managed properly.