Abstract
River nutrient loadings rates are frequently determined from discharge and hydrochemistry relationships using regression techniques. Unfortunately such methods as a conventional technique are inadequate for dealing with the problem such as differences in shape and direction of loop forming in individual and seasonal storms. Besides the relationships are nonlinear and time-dependent, they also varies from site to site. There is a currently method to study hysteresis between discharge and concentration of hydrochemistry. The relationship between discharge and solute concentration was investigated at Cakardipa catchment, Upper Ciliwung watershed, between the years of 2009-2010. The characteristics of the hysteresis loops were used to evaluate the temporal variation of the relative contribution 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 chemical analysis 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 concentrations displayed circular hysteresis loops during the events, highlighting the complex relation among solutes and discharge during storm hydrographs. The solutes of K, Na, and Ca produced concave curvature, anti-clockwise hysteresis loops, and positive trend, so that classified as A2 loops with components ranking were CR> CG> CSO. .The solutes of Mg, SO4, NO3 assumed to come from groundwater produced convex curvature, clockwise hysteresis loops, and positive trend, indicating a concentration 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.
Highlights
There is a dynamic relationship between discharge and solute concentration during a storm event in a catchment area (Evans et al 1998)
The solutes of K, Na, and Ca produced concave curvature, anti-clockwise hysteresis loops, and positive trend, so that classified as A2 loops with components ranking were CR> Catchment including groundwater (CG)> CSO. .The solutes of Mg, SO4, NO3 assumed to come from groundwater produced convex curvature, clockwise hysteresis loops, and positive trend, indicating a concentration component ranking of CG > CR > CSO (C2 model)
The solutes of Mg, SO4, and NO3 which were assumed coming from groundwater produced concave curvature, clockwise hysteresis loops, and positive trend, indicating a concentration component ranking was CG > CR > CSO (C2 model)
Summary
There is a dynamic relationship between discharge and solute concentration during a storm event in a catchment area (Evans et al 1998). This relationship may be represented in a circular pattern that is called a C/Q hysteresis loop. More studies have shown that C/Q hysteresis analysis is rarely linear, and that it tends to produce a circular pattern from the differing concentrations on the rising and falling limbs (Walling and Webb 1986). The pattern of the relationship between discharge and concentration is circular because the total concentration levels of solutes vary during different periods of a storm. The variation in concentration is the product of dilution and “end-member mixing (the mixing of the different components of discharge, which are quantities of water from multiple sources).
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