Flood Analysis Study of Incheon-Gyo Catchment with SOBEK Model TEAM BLUE Adviser : Shie – Yui Liong (NUS) Leader : He Shan (NUS) Members : Lee Seung Woo (UI) Lee So Young (UI)

Contents INTRODUCTION BLUE TEAM INTRODUCTION WATERSHED DATA INFORMATION PRE – PROCESSING WITH GIS INTRODUCTION SOBEK MODEL SOBEK MODEL SET UP FUTURE WORK PLAN

INTRODUCTION BLUE TEAM

Adviser : Shie – Yui Liong Nationality : Singapore Position : Head of Education Group, Tropical Marine Science Institude INTRODUCTION BLUE TEAM

Team Leader : He Shan Nationality : Singapore Position : Reserch Engineer, Tropical Marine Science Institude Major : Hydrology

INTRODUCTION BLUE TEAM Members : Lee Seung Woo Nationality : The Republic of Korea Position : Master’s Course (National University of Incheon) Major : Environment Hydrauics

Members : Lee Seung Woo Nationality : The Republic of Korea Position : Master’s Course (National University of Incheon) Major : Environment Hydrauics INTRODUCTION BLUE TEAM

WORK PLAN COLLECTION DATA GIS CONVERSATION SOBEK SIMULATION REPORTS PRESENTATION

INTRODUCTION to STUDY AREA (1) YELLOW SEA  Incheon-Gyo Watershed, Incheon, South of Korea  This Area was a sea and completed to reclamation in 1985

Area : 34 ㎢ Length : 8 ㎞ Mostly urban area Flood records in 1997 to 2001 (except 2000) INTRODUCTION to STUDY AREA (2)

Linked with the sea through two retention pond Complicated drainage network There are 4 main drainage networks A drainage network is linked with the sea directly The other networks are linked with the reservoir INTRODUCTION to STUDY AREA (3)

GIS from Incheon City Hall Contour Ground Level Manhole Sewer Network Recorded Flooding Area Rainfall Data Real precipitation Probability rainfall intensity Formula DATA INFORMATION General Condition CAD file Field Trip Photo Retention Pond Data Tidal Data

PRE – PROCESSING WITH GIS To Make DEM –To make TIN –TIN to Grid (Cell size 50m) –To define the boundary of watershed –To make catchment shape file –7 subcatchments to import SOBEK

SOBEK is a powerful 1D and 2D instrument for flood forecasting, drainage systems, irrigation systems, sewer overflow, ground-water level control, river morphology, salt intrusion and water quality. INTRODUCTION SOBEK MODEL

SOBEK has three basic product lines covering any fresh water management situation in River, Urban and Rural systems alike. Each product line consists of different modules to simulate particular aspects of the water system. These modules can be operated separately or in combination. The data transfer between the modules is fully automatic and modules can be run in sequence or simultaneously to facilitate the physical interaction.

'import network' In this task block the origin of the schematisation must be defined. Schematisations, used in SOBEK, can be either imported from a database or set-up from scratch. If a schematisation is already available in the standard exchange format it can easily be imported from the database to SOBEK. SOBEK MODEL SET UP

Importing Network system data into Sobek SUF_HYD is the Dutch standard exchange file format for data regarding sewer systems. Select the radio button ‘Import Suf-HYD network’

Sub-catchment conceptualization The rainfall-runoff process is conceptualized using the following two network elements in SOBEK: 1.Flow – Manhole with Runoff (called “Manhole” henceforth in this document) 2.Flow – Pipe (called “Pipe” henceforth in this document) The Manhole stores the total runoff (or acts as a collection point for the runoff) and the Pipe conveys the stored runoff to the main channel. Figure 1 shows a sub-catchment with a network of drains, which is replaced by the Manhole & Pipe concept. Sewer network

Task block 'Settings‘ SOBEK-Rural 1DFLOW The SOBEK-Rural 1DFLOW module is a sophisticated module that can be used for the simulation of one-dimensional flow in irrigation and drainage systems. SOBEK-Urban 1DFLOW The SOBEK-Urban 1DFLOW module is a sophisticated module for the simulation of one-dimensional flow in wastewater and storm water systems. It is a tool that can be used to simulate and solve problems in urban drainage systems. The RR (Rainfall-Runoff) module is a module that can be used for the simulation of rainfall-runoff processes. The RR module is frequently used in combination with the SOBEK-Rural 1DFLOW and SOBEK-Urban 1DFLOW modules.

The SOBEK-Urban RR (Rainfall-Runoff) concept The inflow towards the sewer system consists of runoff from rainfall and dry weather flow. The Runoff model of Flow-Manhole and Flow-Pipe, also called NWRW model, describes the dry weather flow and the transformation in time of rainfall into runoff entering the sewer system. The Runoff model is based on the guidelines. The processes included are:moistening and puddle forming;infiltration;runoff delay. It is illustrated that the rainfall-runoff process with netto rainfall is the same as the runoff towards the sewer system and is equal to the rainfall minus evaporation minus infiltration minus the change of storage.

The rainfall-runoff process Different types of surfaces can be distinguished, depending on surface characteristics and slope. The model distinguishes four types of surfaces (closed paved, open paved, roof, unpaved) and three types of slopes (area with a slope, flat, stretched flat), thus twelve different area types. The slope of the surface and the infiltration capacity largely influence the rainfall-runoff process. The infiltration of rainfall takes place in the open paved areas and unpaved areas. The infiltration capacity depends mostly on the type of surface and moisture condition. Other factors may also play an important role. The delay of runoff depends on the average distance to the inflow location in sewer system, the slope and the geometry of the catchment. The formula which describes the runoff to the sewer system is the formula of the rational method.

The rainfall-runoff process The runoff over the sub-catchment surface to the Manhole is described by the following formula (which is the formula of the Rational Method): q = c. h (1) where q is the inflow into the Manhole (in mm/min), c is the runoff factor (min-1) and h is the rainfall (in mm). The flow in the Pipe is described by the Manning formula (assuming the pipe is rectangular in cross-section): Q = (2) where n is the Manning coefficient, b is the width, H is the height and I is the bed slope.

Dynamic wave

Dynamic wave

The rainfall-runoff process is conceptualized using the following two network elements in SOBEK: 1.Flow – Manhole with Runoff 2.Flow – Pipe The Manhole stores the total runoff (or acts as a collection point for the runoff) and the Pipe conveys the stored runoff to the main pipe.

Sub-catchment conceptualization The storage area at the street level is fixed as the area of the sub-catchment.

Sub-catchment conceptualization The storage area at the street level is fixed as the area of the sub-catchment.

Sobek has the option to import Mouse SVK19 files. SVK19 is a Scandinavian Exchange Format which Mouse supports as export format. In the Import Task block, select Suf-Hyd, and then later on select the Mouse TXT files. Optional also HGF runoff files can be included. 1) NUMBER CIRCULAR MANHOLES FORM KG NODE X-COOR Y-COOR BOTTL TOPL SHP DIAM MRout

2) NUMBER CONDUITS (PIPES) FORM L NODE-U NODE-D M A BL-U BL-D A FLOW GW-LE A DIAM E13506 D D66173 MRout A18675 L L L K A A K ) // Runoff Catchment Description [MOUSE_Catchments] SYNTAX_VERSION = 3 UNIT_TYPE = 1 LineHeader = 'LOCATION', 'CATCHMENTID', 'TYPENO', 'INHAB', 'CAREA', Line = '1194', '59024', 1, 0, 0.84,, , Line = '2652', '69499', 1, 0, 0.89,, , Line = '3313', '63857', 1, 0, 0.62,, , Line = '3497', '72455', 1, 0, 0.02,, ,

Future Plan 1 Apply the water gate and pump station data into boundary condition 2 Analyze the heavy precipitation intensity 3 with the runoff result, think how to solve the flood problem