Surface Runoff and the Stormwater Management Cycle Assignment

Assignment Task

Introduction

Water can be differentiated into multiple classifications on the basis of accumulation, storage etc. Storm water is the water that is accumulated from surface runoff of either rainwater or melted ice. The quality and flow of this runoff depends upon geographical characteristics and infrastructure facilities available in the area. Geographical characteristics like slope, natural drainage pattern decides the flow of the storm water in particular area. Rainfall quantity, catchment area influences the total quantum of storm water to be generated in particular area. Improper planning of infrastructure or hampering the natural drainage flow of storm water can result into situations like water logging, flooding etc. Many urban areas are facing these issues now a days, which has developed the need of storm water management.

Storm water management deals with reducing the quantity of stormwater by means of multiple techniques. The practice of storm water management has evolved significantly over the last twenty years and it is focused primarily on flood and erosion control. Total elimination or control of floods is neither practically possible nor economically viable as Flash floods is natural phenomenon. Hence, flood management aims at providing a reasonable degree of protection against flood damage at economic costs and preserves the environment. The uneven distribution of rain fall coupled with Mindless urbanization, encroaching upon and filling up natural drainage channels and urban lakes to use the high-value urban land for buildings are the cause of urban flooding. Over densification and modification of undeveloped land is also resulting increased flow with increased pollution. Irrespective of the city, most of our city’s face will be fractured, if a heavy storm with high run off is hit, due to improper drainage facilities. Sustainable storm water management is also an important component of integrated water management, and can contribute to multiple benefits such as enhancing livability.

Structural management measures include storage reservoirs, drainage channels, anti-erosion works, flood embankments, channel improvement works, retention and detention basins and non-structural measures include flood forecasting, flood plain zoning, disaster preparedness, flood proofing etc. this study will look into analyzing problem in the city and propose sustainable measurement with help of GIS. 

Need of the study

Pimpari chinchwad is the most developed industrial area in Maharashtra State. It is situated in the north western side of Pune. City is known for its industrial development. It has multiple IT, Manufacturing industries. It is located at 530 m above the mean sea level. It is located between north latitudes 18° 37' and east longitudes 73° 48'. It is surrounded by bordering limits of Pune Municipal Corporation in the South and Sourtheast, Chakan in North, Talegaon dabhade in west. Pimpari chinchwad area has three rivers, Indrayani in north, in south it is bounded by pavana river which further meets to Mula river near dapodi. At city has catchment area of three rivers it becomes crucial to study the storm water management in PCMC area. In historic period main grounds of flooding used to be the excessive rainfall. But now a days, as the cities increasing and growing rapidly, paved areas are also increasing which is resulting into lesser infiltration and increased runoff and causing the urban flooding and water logging. Urban flooding is the situation when water overflows from the designed storm water drains and flows on roads, into houses. This has been witnessed multiple times in Pimpari chinchwad. It clearly shows the need to increase the size and maintenance of the provided drainage system as well as practicing an innovative way to dispose of the sudden water. In this paper we shall find out the proper need of such a method.

Aim of study

Study the storm water management techniques for study area and propose innovative strategies for storm water management.

Objectives of the study

• To understand different reasons behind urban flooding and different storm water management practices.
• To identify the study area in Pimpari chinchwad city.
• To study existing storm water management system and identify its constraints using GIS.
• To propose SWM techniques to improve existing situation in study area.

Scope of study

The study is not focused on conventional stormwater management practices but on alternative approaches which will be cost effective and universally applicable.

Limitations of study

Due to the limitation of time study of whole city was not possible so, one of the basins is selected for study.

Probable outcomes

Propose techniques for improvement of stormwater management.

Methodology

• Identification of problem: Severe water logging and flooding problem is witnessed in the pimpri chinchwad City through observation.
• Study of existing situation & selection of study area: For analyzing the exact problematic areas primary survey was conducted. Due to time limitation small area is selected for detail study purpose.
• Literature review: literature review for understanding storm water management, Urban flooding and practices for sustainable SWM.
• Data collection: Data is collected regarding elevation, sewage line, land cover changes, rainfall in city, drainage basins etc.

Stormwater

Water in habitable area exist in different forms from natural drinking water to grey water. Major typologies are natural drinking water, artificial drinking water, storm water, waste water and grey water. Availability of these depends upon natural resources available in and around city, population of city, artificial or manmade water resources in the city.

Storm water is the water that originate from precipitation contributed from either heavy rains or melted hails or ice. Storm water further transforms into three types; storm water becomes on ground water after getting soaked into water, strom water contributes to storage of artificial or natural water and third is surface runoff which further merges into river, sea etc. In all way storm water contributes to major water demand of any geographic area. Distribution of storm water in above mentioned types depends upon multiple factors like availability of natural water resources, type of drainage and sewer system in city, extent of built-up area and permeability of built-up area etc. In the view of understanding storm water management, it is necessary to understand the different factors affecting storm water.

Urban floods in Delhi

Delhi has five drainage basins of Yamuna River. Delhi has experienced multiple floods in last century. In last 60 years, around 7 times Yamuna River has crossed danger level and inundated many areas causing live loss and property loss. There are multiple reasons for severity of floods in recent years. In case of Sahibi Nadi, earlier flow merging from Sahibi Nadi was very low due to interception at JahajGarh but after the increasing the built-up area in drainage basin Haryana flow is increased. Due to this increased flow in 1977, 1995 it has created worst impacts. Also, in recent floods of like 2021 many areas were inundated due to lack of proper drainage system and flood mitigation strategies. In case of Yamuna River, huge development in river basin along with the resultant loss of soft landscape have led to high surface water runoff rates. This results in floods in the low lying areas even after moderate precipitation. Another factor adding to this effect is that of River Yamuna because the river is normally flowing at a higher level within its embankments during such periods. Thus, the water gets logged in the city areas and it takes several days to mechanically pump it out and bring the situation under control. Similarly, during the past few years, flooding due to the city’s 18 major drains has also become a common phenomenon. Already under the pressure of the city’s effluent discharge, these drains experience reverse flow from the Yamuna, which is in spate, and as a result they tip their banks, flooding the neighboring colonies.

Efforts for flood mitigation

Master plan of Bhopal 2005 has proposed some strategies for flood mitigation as follows;

• Bhopal Master plan has suggested some structural changes like land use regulation, building byelaws zoning regulations, widening of culverts, clearing of drains re-densification of affected areas by concerned agencies etc.
• Nonstructural measures suggested by Bhopal Master plan are flood prepared measures, local social structure strengthening, action plans for emergency response measures like communication and public information management, search and rescue co-ordination, shelter management, and distribution of food and supplies, contacting and requesting
• additional support, debris management, financial management, volunteers coordination and donations management in coordination with government, semi government and concerned agencies with people’s participation.

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