Affiliations: National Institute of Hydrology, Belgaum - 590001,
India | Cochin University of Science & Technology, Kochi -
16, India | National Institute of Technology, Tiruchirapalli - 620
015, India
Abstract: Kerala, the southern-most State of India, is characterized by its
unique physiographic setup and 44 small rivers flowing across its narrow width.
Based on 15 years (1986-87 to 2000-01) of daily sediment concentration and
discharge data of 16 rivers, annual, seasonal, monthly, and daily variation in
the suspended sediment yield of the State was analyzed and its controlling
factors are discussed herein. There is a marked variability in sediment yield characteristics from
north to south and from year to year. Sediment concentration in the rivers
varies between 167 mg/l and 2944 mg/l. Chaliyar River transported the highest
annual average sediment load of about 0.40 × 10^6 t,
whereas Meenachil River supplied the lowest of 0.04 ×
10^6 t. Sediment yield varied between 40 and 250
t/km^2/year, with northern rivers showing larger yields. The
central Kerala region, which is drained by major rivers and geologically
stable, yielded lower values. Narrow land strips of northern and southern
regions, characterized by steep slopes, were highly prone to erosion. Due to
the variability in distribution of rainfall, the northern rivers transported
major share of sediment during Southwest (SW) monsoon (75 to 95%), whereas
there was a substantial amount of sediment transport (20-55%) during Northeast
(NE) monsoon through the rivers from the southern region.
Keywords: Sediment load, SW monsoon, NE monsoon, Kerala
