Hydraulic and Sediment Handling Performance Assessment of Rani Jamara Kulariya Irrigation Project (RJKIP) by Conjunctive Use of 1D and 3D Simulation Models Authors: Aashis Sapkota, Hari P. Pandit, Rajesh Shrestha Presentation by: Aashis Sapkota (M.Sc. Water Resources Engineering, B.E.civil Engineering) 3rd Int’l Young Researchers’ Workshop on River Basin Environment & Management Naresuan University, Thailand 21-22 December, 2015

CONTENTS OF THE PRESENTATION Introduction Objective of the study Methodology Results and discussions Conclusion and recommendation

1.INTRODUCTION Nepal: Water Main natural resource supporting economy Agriculture Contributes about 35% of GDP Employment for 74% of the work force Many Glacier fed rivers Young and Fragile Geology - Steep Catchment area Sediment handling Challenge to Irrigation and Hydropower

RANI JAMARA KULARIYA IRRIGATION PROJECT: Permanent side intake at Chisapani, d/s of Karnali bridge Contd..

Capacity 100 m3/s up to Settling basin at 4+950 km Main canal up to 8+875 km with capacity 80 m3/s Free side intake, with no control of river water level

2.OBJECTIVE OF STUDY Objectives Studying Hydraulic and Sediment handling capacity using Numerical models like HEC RAS and SSIIM Study limitations in their use Compare 1D and 3D models Specific objectives Check hydraulic capacity and handling of sediment of RJKIP. Trap efficiency of settling basin. Study velocity vectors/ flow pattern in the settling basin using 3D model.

Introduction to HEC RAS and SSIIM HEC RAS : Hydraulic Engineering Center – River Analysis System modeling system to analyze river flow, sediment, and water quality dynamics in 1D SSIIM : Simulation of Sediment In Intakes with Multi Block Options Navier-Stokes equations in 3D on a general non - orthogonal grid For sediment, diffusion/advection equation and a bed load transport formula.

3.METHODOLOGY 1) System including intake, regulator gate, 4800m of canal, 100m transition , 600m settling basin, 110m flush outlet - all modeled into single file in Geometric editor.

- a part of open channel and barrel in cross-section editor

Settling basin as seen in 3D view of HEC RAS

Sediment Data Sediment concentration of August was used for study purpose as most critical period. Particle Size Distribution (PSD) during corresponding concentration, was used.

2) Hydraulic and Sediment analysis using SSIIM: Input Parameters Geometrical data Sediment concentration and discharge at the inlet and outlet of basin PSD, fall velocity & sp. Gravity, Channel boundary conditions and shields coefficient Grid 796x66x13 WaterFlow-3D was executed with convergence 0.001

4.RESULTS AND DISCUSSION Capacity decrease due to increase in manning’s n and due to undermining of bed level by 50 cm at intake Initial Capacity (m3/s) for bed level 191.95m Decrease Capacity for bed level 191.45m % decrease in capacity 100 87 13 80 70 12.5 water surface elevation(m) discharge for n(0.015/0.016) discharge n(0.020) % decrease in capacity 193.71 80 71 11.25 193.84 100 88 12

Hydraulic study (SSIIM) The velocity vectors were studied:

The horizontal velocity were studied at different locations and compared with that from HEC RAS

Comparison between horizontal velocities found from HEC RAS and SSIIM at different sections of Settling Basin Velocity from SSIIM HEC-RAS Remarks Min Max RS 941 0.2417 1.7513 1.471 End of Barrel RS 923 0.0796 1.2784 1.013 End of 1st transition RS 821 0.0651 1.169 0.442 Start of Basin RS 621 0.164 0.4182 0.382 Center of Basin RS 221 0.1611 0.5093 0.3 End of Basin

Sediment Study (HEC-RAS) The figure shows deposition of sediment in the settling basin portion after 20 Hrs of run.

Simulation was run was for 40 hours to see sediment behavior of whole system for critical sediment concentration. Intermittent flushing (Original design length of 600m) Trap efficiency for 0.125 mm - 100% D50 of particles after basin - 0.030mm Rate of filling - 128.37 m3/hr Time for filling(at this rate) - 9 days and 8 hrs Sediment at intake - 3737 mg/l At the end of Basin - 1038 mg/l

Sediment Study (SSIIM) The same case of intermittent flushing was checked in SSIIM. The same Grain Size distribution was used as for HEC RAS. F 2 RIS was used for Result file of WaterFlow-3D.

Sediment concentration The sediment trap efficiency from SSIIM particle group size(mm) Trap% 1 0.5 100 2 0.4 3 0.3 4 0.2 5 0.15 6 0.1 98.51 7 0.06 82.91 8 0.03 41.45

Comparison between HEC RAS and SSIIM, Sediment result Trap efficiency for 0.125 mm - 100% D50 of particles after basin - 0.030mm Concentration at end - 1038 mg/l SSIIM Trap efficiency for 0.15 mm - 100% Trap efficiency for 0.1mm - 98.51% Trap efficiency for 0.030mm - 41.45% Avg. Concentration at end - 1350mg/l

Continuous flushing of Basin with 20 m3/s Trap efficiency for 0.125 mm - 99.997% D50 of particles after basin - 0.035 mm Rate of filling - 171.88 m3/hr Time for filling(at this rate) - 6 days 23 hrs Sediment at intake - 3737mg/l At the end of Basin - 1135 mg/l

Flushing Basin length 400m (without dividing wall) Complete draw down is required. But still not completely effective, velocity of 1.9 m/s is seen to initiate scouring, which is similar to 1.8m/s in design report.

5. CONCLUSION AND RECOMMENDATION Results from 1D- HEC RAS and 3D- SSIIM were coherent 400m settling Basin; divide wall; wider flush gates for complete drawdown for this project This type of study can be really handy to see performance of designed hydraulic structures under different scenario Sediment concentration data of long term for simulation time series The results can be highly trusted if parameters are optimized and validated for flow depths and sediment depositions

Thank You