Groundwater plays an important role in feeding springs and streams, supporting wetlands and land surface stability. In Finland, most water is held in the soil than the surface systems. Hence, Finland’s water resources depend on groundwater and biogeochemical processes. The study of groundwater in peatland is important for maintaining ecological balance and conservation of water resources. The groundwater level is one of the key indicators of aquifer conditions and groundwater basins. It helps to interpret hydrogeology, groundwater flow, groundwater sustainability and land usability. The study tries to analyze ground water recharge on peatland catchments using hydrograph recession analysis. The equation for the hydrograph recession curve can be utilized to predict groundwater recharge during each recession period. The steps involved during recession curve analysis includes selection of analytical expression, derivation of recession characteristic and optimization of the parameters. While computing groundwater recharge with recession curve, the high variability of each recession segments creates major problem. Each segment shows the outflow process which creates short-term or seasonal influence. The variation in rate of recession which causes problems for derivation of recession characteristics. The computer software such as hydro-office, VBA macro excel and Matlab are used for recession analysis. The results obtained do not consider climatic influences. The results were then confirmed by using water balance model and statistical tests. The e-water toolkit is used for water balance model and statistical tests are performed using R-software. The rainfall-runoff data are used as input to the software used in each method. From the analysis, required output recession parameters are obtained for further calculation. These estimated recession parameters can be used to predict low flows (groundwater contribution to runoff) to understand catchment groundwater resources and as inputs for the rainfall-runoff model analysis. Hence, the objective of this study is to analyze groundwater recharge by studying the recession limb of the runoff hydrograph. The study work compares various recession analysis methods. It also tries to identify the better method by comparing groundwater recharge from different methods with groundwater recharge from unsaturated water balance model.
Table of Contents
1 Introduction
2 Site Description
3 Methods
3.1 Hygrograph recession analysis
3.1.1 Individual Recession Analysis
3.1.2 Master Recession Analysis
3.1.3 Wavelet transformation
3.1.4 Recession constant and recharge from baseflow separation
3.1.5 Recession constant and storage from specific yield
3.2 Unsaturated moisture balance components
4 Calculations
4.1 Hydrograph recession and Specific approach
4.2 Recharge volume from unsaturated water balance
5 Results
6 CONCLUSION
Research Objectives and Focus
The primary objective of this study is to analyze yearly groundwater recharge in two peatland catchments by evaluating and comparing various hydrograph recession analysis methods against an unsaturated water balance model to identify the most efficient approach.
- Comparison of diverse hydrograph recession analysis techniques.
- Evaluation of groundwater recharge in peatland environments.
- Integration of the unsaturated moisture movement model as a benchmark.
- Application of statistical tests to validate recession parameters and recharge volumes.
- Correlation of climatic and geomorphological features with hydrological behavior.
Excerpt from the Book
3.1.1 INDIVIDUAL RECESSION ANALYSIS
The analysis of individual recession curves is carried out using RC 4.0 tool from hydro office software [4]. By using RC tool, an individual recession segments are separated from runoff hydrograph. The runoff data is the major input and rainfall is optional. An individual recession curve is selected for short time period with small numbers of declining runoff values. In an individual analysis there is different flow constant for the slow and fast runoff. It consists of two linear models. One represents fast flow and the other represents slow flow. For each model, recession curve is divided into two portions (upper and lower).The initial flow and constant (k) are given by user. For the calibration of individual recession curve, a tool called single calibration in hydro office software is used. The outputs obtained from the software are initial flow, recession coefficient and recession time days. The output obtained is used to calculate final discharge and groundwater recharge during recession period.
Summary of Chapters
1 Introduction: Discusses the significance of peatlands in the global ecosystem and the role of hydrological studies in understanding surface and subsurface water systems in Finland.
2 Site Description: Details the characteristics and geographical locations of the Marjasuo and Röyvänsuo catchments used for the study.
3 Methods: Describes the various analytical techniques employed, including individual and master recession analysis, wavelet transformation, baseflow separation, and specific yield methods.
4 Calculations: Presents the application of the defined methods to compute recession constants and groundwater recharge for the study catchments.
5 Results: Analyzes the findings through box plots and comparisons to theoretical values to identify the most efficient recession analysis method.
6 CONCLUSION: Summarizes the study's findings, suggesting that the master recession analysis method is the most efficient technique and highlighting the need for further research.
Keywords
Runoff Hydrograph, recession Parameters, Runoff, Groundwater recharge, unsaturated water balance, Statistical tests, Peatland, Hydrology, Finland, Master Recession Analysis, Baseflow separation, Wavelet transformation, Catchment, Specific yield, Water balance model
Frequently Asked Questions
What is the primary focus of this research?
The research focuses on comparing different methods for calculating groundwater recharge and recession constants using hydrograph recession analysis in peatland catchments.
Which catchments are analyzed in this study?
The study analyzes two peatland catchments in northern Finland: Marjasuo and Röyvänsuo, utilizing data collected between 2010 and 2013.
What is the main objective of the study?
The objective is to identify the most efficient hydrograph recession analysis technique by comparing its results with those derived from an unsaturated water balance model.
Which scientific methods are employed for the analysis?
The study employs individual recession analysis, master recession analysis, wavelet transformation, baseflow separation, and specific yield methods.
What is the role of the unsaturated water balance model?
The unsaturated water balance model acts as a precise benchmark to which the results of the various recession analysis methods are compared.
Which keywords characterize this work?
Key terms include Runoff Hydrograph, recession parameters, groundwater recharge, peatland hydrology, and unsaturated water balance.
Why is the wavelet transformation used in this study?
It is used as a relatively new, qualitative method for calculating recession constants from time series runoff data to compare against theoretical values.
What conclusion does the author reach regarding the best method?
The author concludes that the master recession analysis method is the most efficient among the techniques tested for the catchments studied.
- Quote paper
- Rajib Maharjan (Author), 2014, Hydrograph recession analysis methods and its comparison using unsaturated moisture movement model, Munich, GRIN Verlag, https://www.grin.com/document/280795
