Estimation of Recession Constants for springs in Danda Watershed (Uttrakhand)

Abstract

The three interrelated factors which govern the groundwater flow to the spring: geology (type, distribution, and hydraulic characteristics of geologic formations), topography (landforms and relief), and local climatic conditions (timing and amount of precipitation). The geology, topography and climatic conditions play important role in the occurrence of direct runoff and ground water recharge in an area. The spring discharge hydrograph is the output of all processes, both natural and anthropogenic activities that govern the translation of various water inputs due to precipitation, and other sources such as glacier melt, and seepage from adjoining area in the spring’s drainage area, into single output at the spring. In other words, it can be said that the springs can integrate the signal of geological and hydrological processes over large spatial areas and long periods of time and, thus, they are an indirect source of information. A recession curve analysis provides valuable information concerning storage properties and aquifer characteristics. The study of recession flow analysis particularly estimation of recession constant ( k e ) as an indicator of the extent of base flow, has relevance in water resources planning. A major problem in determining recession constant for a particular spring using a single recession segment is high variability encountered in the recession behaviour of individual segments. To overcome the problem, a master recession curve (MRC) that normally is defined as an envelope of various individual recession curves, could be constructed. In present study, automated objective-based method (adapted matching strip method) for MRC separation has been used to estimate recession constant for the thirty springs in Danda watershed, Uttarakhand (India). Daily time series from July, 1999 to 2 March, 2001 (for the Spring ID 1 to 11) while fortnightly discharge time series from 30 October, 1999 to 2 March, 2001 (for the Spring_ID 12 to 30) and two daily time series from 5, March 2001 to 31, December 2004 (for all the springs) have been used to separate hydrograph into three flow components namely surface runoff, interflow and groundwater flow. The recession flow analysis shows that average k values of MRC for all these springs varies between 0.94 to 0.99 with the value of goodness of fit (R2) between MRC’s and fitted curves ranging from 0.64 to 0.98.