# The effects of spatially distributed rainfall on catchment response: a thesis presented in partial fulfilment of the requirements for the degree of Master of Engineering in Agricultural Engineering in the University of Canterbury [Lincoln College], Christchurch, New Zealand / by D.M. Scott.

##### By: Scott, D.M.

Material type: BookPublisher: Lincoln, N.Z. : The author, 1973Description: 158 pages : illustrations ; 30 cm.Subject(s): RAINFALL | CATCHMENTS | HYDROGRAPHS | MATHEMATICAL MODELS | THESES | NEW ZEALANDHoldings: GRETA POINT: 556.51:551.577 SCO Online resources: Click here to access onlineItem type | Current location | Call number | Copy number | Status | Date due | Barcode |
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BOOK | WELLINGTON BOOKS | 556.51:551.577 SCO | 1 | Available | B019778 |

ACKNOWLEDGEMENTS – SYNOPSIS -- CONTENTS -- LIST OF FIGURES -- LIST OF TABLES – 1. INTRODUCTION -- 1.1 STATEMENT OF OBJECTIVE -- 1.2 SCOPE OF INVESTIGATION -- 1.3 THEORETICAL BACKGROUND 1.3.1 Systems Approach to Unit Hydrograph Theory -- 1.3.2 The Nature of Catchment Response -- 1.3.3 Distributed Catchment Models -- 1.4 METHOD OF INVESTIGATION – 2. THE DISTRIBUTED LINEAR CATCHMENT MODEL -- 2.1 INTRODUCTION -- 2.2 DESCRIPTION OF CATCHMENT MODEL -- 2.2.1 Sub-area Response to Rainfall Input – 2.2.2 Sub-area Response to Upper Channel Input -- 2.3 THE COMPOSITE CATCHMENT MODEL -- 2.3.1 Effect of Number of Sub-areas on Model Response -- 2.3.2 Description of Unit Hydrograph of Composite Catchment Models – 2.2 DESCRIPTION OF INPUT FOR CATCHMENT MODEL -- 3.1 INTRODUCTION – 3.2 THE SPATIAL DISTRIBUTION OF STORM RAINFALL -- 3.3 INPUT FOR CATCHMENT MODEL – 3.3.1 Input for Moving Storms of Constant Intensity -- 3.3.2 Input for Stationary Non-uniformly Distributed Storms – 4. THE IDENTIFICATION PROBLEM -- 4.1 INTRODUCTION -- 4.2 THE EFFECTS OF DATA ERRORS ON THE IDENTIFICATION PROBLEM -- 4.3 THE LUMPED REPRESENTATION OF SPATIALLY DISTRIBUTED RAINFALL -- 4.4 IDENTIFICATION OF UNIT HYDROGRAPHS -- 4.4.1 Black Box Analysis -- 4.4.2 Parametric Systems Synthesis – 5. RESULTS ANID DISCUSSION -- 5.1 INTRODUCTION -- 5.2 MODEL RESPONSE TO SPATIALLY DISTRIBUTED INPUT – 5.2.1 Model Response to Moving Storms -- 5.2.2 Comparison with Equivalent Stationary Storms -- 5.2.3 Model Response to Stationary Storms with Non-uniform Rainfall Distribution -- 5.2.4 Apparent Non-Linearity of Model Response -- 5.3 IDENTIFICATION OF UNIT HYDROGRAPHS -- 5.3.1 Error Determination and Evaluation -- 5.3.2 Unit Hydrograph Errors for Spatially Uniform Input -- 5.3.3 Least Squares Unit Hydrographs -- 5.3.4 Modified Least Squares Analysis -- 5.3.5 Gamma Distribution Unit Hydrographs -- 5.3.6 Effects of Storm Extent, Velocity and Direction -- 5.4 SUMMARY OF IDENTIFICATION RESULTS -- 5.5 APPLICATION OF DERIVED UNIT HYDROGRAPHS -- 6. SUMMARY AND CONCLUSIONS -- 6.1 SUMMARY -- 6.2 CONCLUSIONS -- 6.3 RECOMMENDATIONS FOR FUTURE RESEARCH – REFERENCES -- APPENDIX A. TABLES -- APPENDIX B. COMPUTER PROGRAMMES.

It is commonly assumed in the application of many models of catchment behaviour that catchment rainfall is uniformly distributed over a catchment. This study examines the effects of non-uniform spatially distributed rainfall on the application of the unit hydrograph theory. A simple distributed linear catchment model is used to simulate the response of a catchment to stationary and moving storms and three different unit hydrograph derivation techniques have been applied to the responses obtained. The model responses demonstrate that spatial distribution of rainfall can produce effects which might be mistakenly used as evidence of non-linear catchment behaviour. The unit hydrograph derivation techniques were least successful for slow moving storms and large catchments. Overall the gamma distribution method resulted in the best estimates of the unit hydrographs. However the least squares technique achieved the best results for stationary storms. The spatially distributed rainfall resulted in the derivation of markedly different unit hydrographs for different storms on the same catchment. An examination of the lumped representation of distributed rainfall showed that an alternative to the catchment mean rainfall could allow significant improvements in the application of the unit hydrograph theory for the case of moving storms.

GRETA POINT: 556.51:551.577 SCO

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