Relationship between Concentration and Discharge on Storm Events: Case Study at Cakardipa Catchment, Cisukabirus Subwatershed, Upper Ciliwung Watershed, Bogor, West Java

River nutrient loadings rates are frequently determined from discharge and hydrochemistry relationships usingregression techniques. Unfortunately such methods as a conventional technique are inadequate for dealing withthe problem such as differences in shape and direction of loop forming in individual and seasonal storms. Besidesthe relationships are nonlinear and time-dependent, they also varies from site to site. There is a currently method tostudy hysteresis between discharge and concentration of hydrochemistry. The relationship between discharge andsolute concentration was investigated at Cakardipa catchment, Upper Ciliwung watershed, between the years of2009-2010. The characteristics of the hysteresis loops were used to evaluate the temporal variation of the relativecontribution to stream flow of source waters at Cakardipa Catchment including groundwater (CG), soil water (CSO),and rain water (CR). Chemical water analysis was carried out on 497 water samples on storm event. The chemicalanalysis of storm event of Februari 14, 2010 was carried out for the concentrations of K+, Ca2+, Mg2+, Na+, SiO2, SO42-NO3-, Cl-, and HCO3-. Results of the experiment showed that cconcentrations displayed circular hysteresis loopsduring the events, highlighting the complex relation among solutes and discharge during storm hydrographs. Thesolutes of K, Na, and Ca produced concave curvature, anti-clockwise hysteresis loops, and positive trend, so thatclassified as A2 loops with components ranking were CR> CG> CSO. .The solutes of Mg, SO4, NO3 assumed to comefrom groundwater produced convex curvature, clockwise hysteresis loops, and positive trend, indicating aconcentration component ranking of CG > CR > CSO (C2 model). While Si and Cl produced clockwise hysteresis loops,indicating a concentration component ranking of CG> CSO> CR which was C1 model.