Hydraulic geometry of streams introduction of elevation as the new stream classifying parameter
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HYDRAULIC GEOMETRY OF STREAMS & INTRODUCTION OF ELEVATION AS THE NEW STREAM CLASSIFYING PARAMETER. RAJAN JHA, EIT, VIRGINIA TECH ADVISOR : Dr PANOS DIPLAS. Outline . Hydraulic Geometry of streams - An Overview Stream classification system- An Overview

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Hydraulic geometry of streams introduction of elevation as the new stream classifying parameter

HYDRAULIC GEOMETRY OF STREAMS & INTRODUCTION OF ELEVATION AS THE NEW STREAM CLASSIFYING PARAMETER

RAJAN JHA, EIT, VIRGINIA TECH

ADVISOR : Dr PANOS DIPLAS


Outline
Outline THE NEW STREAM CLASSIFYING PARAMETER

  • Hydraulic Geometry of streams - An Overview

  • Stream classification system- An Overview

  • Compilation of hydraulic geometric field data- UK, US & Canada streams

  • Grain size (D50) based statistical analysis of the field data

  • Elevation based statistical analysis of the field data

  • Overall conclusion of this study


Hydraulic geometry of streams an overview
Hydraulic geometry of streams THE NEW STREAM CLASSIFYING PARAMETER– An overview

  • Hydraulic geometric equations describe the quantitative variations of stream properties with changing discharge. [Ferguson, 1986]

  • Leopold and Maddock (1953) established following hydraulic geometric relations in power form:

    w = aQ.5 d = cQ.33 v = kQ.17

  • Hydraulic geometric variables considered in this study : Aspect ratio, channel slope & Sinuosity (All dimensionless)


Defining the hydraulic geometric terms
Defining the hydraulic geometric terms THE NEW STREAM CLASSIFYING PARAMETER

  • Aspect Ratio (Ar)– For any channel or stream, it is defined as the ratio of bankfull width to bankfull depth


Defining the hydraulic geometric terms1
Defining the hydraulic geometric terms THE NEW STREAM CLASSIFYING PARAMETER

  • Channel gradient (Sc) – For any channel or stream, it is defined as the ratio of drop in the elevation per unit horizontal length


Defining the hydraulic geometric terms2
Defining the hydraulic geometric terms THE NEW STREAM CLASSIFYING PARAMETER

  • Sinuosity (P) – For any stream reach, it is defined as the ratio of actual sinuous length (channel length) to the shortest straight line distance (valley length).


Compilation of hydraulic geometric field data
Compilation of hydraulic geometric field data THE NEW STREAM CLASSIFYING PARAMETER


Stream classification system an overview
Stream classification system –An overview THE NEW STREAM CLASSIFYING PARAMETER

  • More than 20 different stream classification systems have been proposed till date

  • Streams have been classified on the basis of bed material, patterns, age, sediment inputs, orders etc

  • Rosgen (1994, 1996) developed a new approach to channel classification system where he divided the channels into four hierarchical levels

  • Even with the existence of so many available classification systems, none of them have been accepted universally till date


Research objectives
Research Objectives THE NEW STREAM CLASSIFYING PARAMETER

  • Calculating most probable values of Ar, Sc & P occurring together in nature for each stream type : sandy, gravel and cobble

  • Introducing “elevation above mean sea level” as the new parameter for stream classification system

  • Identifying trends existing in the behavior of stream variables (Ar, Sc & P) while moving upstream


Median grain size d 50 based analysis of hydraulic geometry of streams
Median grain size (D THE NEW STREAM CLASSIFYING PARAMETER50) based analysis of hydraulic geometry of streams

Brief Outline:

  • Dividing field data into sandy, gravel & cobble groups

  • Application of joint probability distribution on Ar, Sc, P of each group

  • Finding MPVs of the hydraulic variables for each group occurring together

  • Analyzing 3-Dimensional plots


D 50 based distribution of cumulative data
D THE NEW STREAM CLASSIFYING PARAMETER50 based distribution of cumulative data


Sandy gravel cobble streams
Sandy, Gravel & Cobble streams THE NEW STREAM CLASSIFYING PARAMETER

Sandy streams

Cobble streams


Modal values of ar sc p for each stream type
Modal values of THE NEW STREAM CLASSIFYING PARAMETERAr, Sc & P for each stream type

  • Probability density functions of hydraulic geometric variables were estimated for each stream type and modal values were calculated


Joint probability distribution of ar sc p
Joint probability distribution of THE NEW STREAM CLASSIFYING PARAMETERAr, Sc & P

  • Using kernel density estimation and smoothing on a fine grid in statistical software R, joint probability plots in 3 dimensional forms were also obtained for each stream type

  • The peak in the plots represent the most probable values (MPVs) of the three variables [Ar, Sc, P] occurring together in the nature for each stream type


Joint probability 3 d plots for sandy streams
Joint probability 3-D plots for sandy streams THE NEW STREAM CLASSIFYING PARAMETER


Joint probability 3 d plots for gravel streams
Joint probability 3-D plots for gravel streams THE NEW STREAM CLASSIFYING PARAMETER


Joint probability 3 d plots for cobble streams
Joint probability 3-D plots for cobble streams THE NEW STREAM CLASSIFYING PARAMETER


Most probable values of ar sc p occurring together
Most probable values of THE NEW STREAM CLASSIFYING PARAMETERAr, Sc & P occurring together


Elevation based analysis of hydraulic geometry and establishing it as the new stream classifying parameter

Brief Outline:

  • Dividing complete field data into 14 fine elevation ranges

  • Calculation of Modal values of Ar, Sc & P for each range

  • Formation of final fine elevation zones and calculating MPVs for each zone

  • Classifying sandy, gravel and cobble streams on the basis of the 5 elevation zones


Grouping of data into 14 fine elevation zones
Grouping of data into 14 fine elevation zones establishing it as the new stream classifying


Modal values calculated for 14 elevation ranges
Modal values calculated for 14 elevation ranges establishing it as the new stream classifying


Formation of final 5 elevation zones
Formation of final 5 elevation zones establishing it as the new stream classifying


Mpvs calculated for each of the 5 zones
MPVs calculated for each of the 5 zones establishing it as the new stream classifying


3 dimensional probability density plots
3 Dimensional Probability density plots establishing it as the new stream classifying

  • Presented for highest elevation zone : 5000 ft & above

  • Rest all zones followed similar distribution behavior



Summary conclusion
Summary & Conclusion streams

  • Statistical analysis is a strong tool in understanding the co-relation and interdependency existing amongst the stream variables

  • Elevation provides a consistent framework for grouping streams on the basis of its hydraulic characteristics. Thus elevation based classification can be considered as the new morphology based stream classification system.


Summary conclusion1
Summary & Conclusion streams

  • Elevation based classification provides a logical progressive expression of trends occurring in channel characteristics .

  • MPVs can be very useful for engineers while designing canals, channels and obtaining representative dimensions for laboratory and numerical modeling


Acknowledgement
Acknowledgement streams

  • Dr Panayiotis Diplas- Professor & Department Chair, Civil & Environmental Engineering, Lehigh University , (Previously at Virginia Tech)

  • Dr Shrey K. Shahi- Stanford University

  • NCHRP – National Cooperative Highway Research Program (Funding Agency)


Dedicated
Dedicated streams

  • Dedicated to those who lost their lives in the tragic incident called “Himalayan Tsunami”, June 2013, India.

  • More than 5700 people died and many still missing


Questions streams


Thank you streams


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