Prioritization of sub-watersheds in Tuirial river basin through geo-environment integration and morphometric parameters

Abstract

Watersheds are the basic planning units. Topography is one of the predominant controlling factors which augment erosion. Tuirial watershed in Mizoram is one such area witnessing severe soil erosion due to rugged sedimentary terrain with heavy precipitation which needs immediate action to prioritize at the sub-watershed level. Analytical hierarchy process (AHP) and compound value methods were utilized to compute through erosional parameters of morphometry, average annual soil loss (AALS), sediment transport index (STI), and sediment production rate (SPR). The compound index value below 7.5 in sw1, sw2, sw4, and sw6 which contribute 25.88% of the total area were given the highest priority. The values between 7.55 and 8.5 of sw3, sw5, sw10, and sw14 are under moderate priority zones which comprise 29.36% of the total basin. Similarly, the compound index values above 8.5 of sw7, sw8, sw9, sw11, sw12, and sw13 with 44.74% of the total area are under the least priority zone. The weightage of erosional parameters for prioritization of sub-watershed was judged by a multi-criteria decision analysis (MCDA)-based analytical hierarchy process (AHP). This study revealed that the combination of morphometric features and geo-environment parameters ranking of the compound value (Cv) and analytical hierarchy process (AHP) to determine highly influencing factors of soil loss risks are the most suited methods to the prioritize at the sub-watershed level.