Modeling and Management of the Stormwater of the Old City of

Nablus

Nablus – PalestineMay 2010

INTRODUCTION

Stormwater collection have many impacts on civilization (environmental, economical, social).

Stormwater is of concern for two main issues:

The volume and timing of runoff water (flood control and water supplies)

The potential contaminants that the water is carrying.

INTRODUCTION

This project is concerned with stormwater collection system of the Old City of Nablus.

INTRODUCTION

OBJECTIVES

Hydraulically analyze the Old City stormwater collection system

Determine the causes of major problems, critical section and the minimum rainfall intensity where the problem start to show up.

DESCRIPTION OF THE STUDY AREA

Stormwater collection system is affected by the location of the Old City beneath mount Gerizim and its population.

The inefficiency of the stormwater collection system due to :

Large amount of stormwater

Maintenance and cleaning

DESCRIPTION OF THE STUDY AREA

Old design

Lack of pubic awareness

Data CollectionData Collection

Field WorkField Work

Model DevelopmentModel Development

Evaluation the ResultsEvaluation the Results

Scenarios Scenarios

METHODOLOGY

Data ProcessingData Processing

DATA COLLECTION

Collect Maps

Study area and reconnaissance

Dimensions of the stormwater collection

system elements

FIELD WORK

GPS

Taking pictures

Water flow direction

Interview

Determine the missing data

DATA PROCESSING Identification of water flow direction on maps

and determine catchment areas for each catch basin

Determine IDF curves

MODEL DEVELOPMENT(STORMCAD)

StormCAD was used in this study to develop the hydraulic model.

It can provide comprehensive modeling for the design and analysis of storm sewer system.

The general output of the StormCAD presenting the results including (reports, flex tables, profiles, element annotation and color coding)

MODEL DEVELOPMENT

Define the dimension and the type of the pipes.

Define the catch basin by entering the dimension and its type, then insert elevation of catch basins.

Insert all elements of network on StormCAD software and make it resemble the existing system as close as possible to reality.

RESULTS

The result of the model represent sections and elements that were expected to have problems, and define its type:

RESULTS

Pipe overtopping

RESULTS

Catch basin is flooded

SCENARIOS

We suggested some alternative and interpret it into inputs and select the best alternatives.

#Description

Effectiveness in solving the problems

Working area

Scenario “1” The purpose of this scenario is to prevent the

huge amount of Mount Gerizim stormwater from

entering the Old City, and to convert it to another

network system.

Conduit overtopping (Low)

Catch basin is flooded ( High)

Scenario “2” The main idea of this scenario is to change

specific the pipelines with larger ones in order to

increase its capacity.

Conduit overtopping (High)

Catch basin is flooded (Low)

Scenario “3” This scenario based on a combination between

the first and the second scenarios, to overcome

the existing problem.

Conduit overtopping (High)

Catch basin is flooded (High)

SCENARIOSBefore and after scenario 3

Before

After

THE EXISTING DESIGNBefore and after scenario 3

Before

After

APPLYING A STORM EVENT ON SCENARIO 3

The strongest storm event in 2009-2010 was distributed on 3 days with very high rain intensity.

Data Rain depth (mm)

25\2\2010 63.3

26\2\2010 74.6

27\2\2010 12.7

APPLYING A STORM EVENT ON SCENARIO 3

CONCLUSIONS

The problem that was described starts to show up clearly in some sections of the system at rain intensity of 25 mm/hr, and expands to appear in most parts of the network at rain intensity of 40 mm/hr.

The use of pipelines with diameters of 12 inches is not effective in combined stormwater and sewer collection system.

Time of concentration (tc) and rational coefficients (C) have a significant impact on the drainage of stormwater.

The location of the catch basin affects the efficiency of stormwater collection

RECOMMENDATIONS

Exchange the diameter of the pipes the network that was mentioned in Chapter 6 from 12 inches to 20 inches.

Establish a drainage system at the southern entrance “Al-aqaba stairway” and Adjaj stairway "in order to divert stormwater which come from the mountain before entering the Old City.

Make a full maintenance for all network elements, and change the damaged ones, and determine the times of periodic maintenance, especially before winter.

Impose penalties on those dispose of solid wastes in the catch basins in the Old City.