Pune lies on the western margin of the Deccan plateau, on the leeward side of the Sahyadri mountain range. The city is blessed with Mula and Mutha Rivers that originate in the Sahyadri ranges and traverse across Pune. The two rivers further meet and upon their confluence Mula-Mutha river is formed which further drains itself into the Bhima River. The total length of these three rivers traversing through Pune Municipal Corporation is 44km approximately. Out of this, 22.2km is Mula River, 10.4km is Mutha River and 11.8km is Mula Mutha River.
Fig 1. Map showing Pune and its Rivers
Both Mula and Mutha Rivers are dammed in their upstream. Mutha River has three dams- Khadakwasla, Warasgaon and Temghar while Mula River has Mulshi Dam that controls the release of water in the rivers. The rainfall only in the catchment area below the dams finds its way into the rivers. The rainfall in the
upstream reaches the reservoirs of the various dams from which it is released into the rivers in a controlled manner. The map below shows the catchment areas and the flood discharge for Pune's Rivers-
Fig 2. Map showing Catchment Area and Flood Discharge
Pune's Rivers have been degraded over time. This is due to a number of factors:
Urbanization along river - Heavy urbanization in PMC and PCMC areas over the past few decades has led to haphazard urban development along the river. At some locations, the development extends right up to the edge of the river.
Construction of Dams - The Mutha and Mula Rivers in Pune have dams in their upstream, controlling the discharge of water into them. Presently, the dams have stopped the flow of water into the rivers, keeping them dry.
Release of untreated sewage - Significant Number of Nallas and piped outfalls discharge untreated sewage directly into the rivers, converting the river into a polluted 'drain'.
Lack of Access - Pune's rivers are not easily accessible. In the areas that are already developed there are very few points where one can approach the Rivers. While along most of its length, the banks are lined by private properties making the River inaccessible for citizens.
Poor connectivity across the banks - results in the river becoming a barrier that divides the city.
All of the above, have over the period of time transformed a beautiful river into a polluted drain that the city has turned its back to.
Fig 3. Images highlighting the key issues of Pune's Rivers
There is no hard and fast boundary that separates a river channel from the land that surrounds it and therefore it is not possible to define the 'natural' width of any river. Think of the lines on your palm when holding it at an incline. Rivers are essentially irregular inclined channels with land on either side sloping towards the channel.
The width of a river, or its extent, therefore, has to be artificially demarcated. Two departments of the state government normally concerned with designating the extent of the river are:
i. Irrigation Department, which designates the width of the river with reference to flooding
ii. Revenue Department, which designates the extent of the river based on land ownership information
The Irrigation Department demarcates the extent of a river as the area that is likely to be inundated when the river floods.
To do this, technical specialists such as geographers and hydraulic engineers first simulate the level of water that can be expected at all points along the center line of the river channel during a flood. They mark the area on either side that is likely to be inundated on topographic maps. This 'area of inundation' is demarcated as the extent of the river.
When demarcated in this way, the extent (or width) of the River depends on two factors:
1) Natural geography of the river and the surrounding terrain- ridges, valleys, slope, nature of bank, soil, etc.
2) Level of flood passing through the River
The Irrigation Department of the Government of Maharashtra have used a 'blue line' to demarcated the area along Pune's Rivers that is likely be inundated for the highest flood that can be expected during any 25-year period. Furthermore, they have used a 'red line' to demarcate the area that will be inundated for the highest flood expected during any 100-year period.
The 'blue-line' and 'red-line' demarcations are artificial constructs they are widely but wrongly considered to be the 'natural' extent of Pune's rivers.
This is because while calculating the level of water along center (line) of Pune's Rivers, disturbances such as unevenness in natural terrain, various obstructions to the flow of water caused by manmade structures like bridges, causeways, weirs and check dams have also been considered. These man-made disturbances result in raising the high flood level and further spreading of the area of inundation. If these disturbances were to be removed and river flow improved, the high flood levels will decrease, and the blue and red lines on either side of the river will have to be redrawn closer to each other.
The Revenue Department defines the River's extent based on land ownership information. They distinguish between plots of land and riverbed land using cadastral records. Cadastral records comprise of: 1) cadastral maps which show shape and location of plots and, 2) ownership cadasters which records plot size and the name of the owner.
Information for cadastral maps was originally collated by surveying the extent of plots as defined by boundary wall, fences, etc. on the ground. At the time when such surveys were carried out, land within a river channel that was not customarily 'owned' by anyone (say, because it was prone to periodic flooding or was unclaimed for other reasons) and was designated as being riverbed land. The extent of the river according to Revenue Department maps is based on this customary understanding of what constituted the riverbed at that time when the original survey was undertaken. Therefore, where revision surveys have not been conducted, Revenue maps reflect a historic situation.
Cadastral maps were originally created for collecting agricultural revenue. Mapping technology was primitive at that time. As a consequence Revenue Maps are cartographically inaccurate. Information for ownership cadasters is usually more up to date.
Since Revenue Department's cadastral maps are the basis for legally determining ownership of land, they exert much legal force, even though the extent of plots and riverbed land as demarcated in them are cartographically inaccurate.
Thus, despite the River extent demarcated in Revenue maps carries much legal force there is nothing 'natural' about the demarcation.
The Irrigation Department has delineated the red and blue lines on a topographic survey of the Pune region. This map indicates the administrative boundaries of Pune Municipal Corporation, but, it neither has cadastral information nor does it show the extent of development in the Pune region. As a result it is not possible to unequivocally answer the above question based on the official maps of the Irrigation Department.
However, it is possible to overlay the 'red' and 'blue' lines, the administrative boundaries of the PMC and some cadastral information, on a satellite map. Since the satellite picture also shows the extent of development it is possible to give a fairly accurate answers to the above question. The findings from the overlay exercise that has been undertaken for the Pune Riverfront Project shows that there is a significant amount of land within red line and blue line as shown in figure No. 4. However it will be accurately calculated on the basis of latest cadastral map to be prepared for this project.
Based on the cadastral information that has been plotted on the satellite map up to now, it is not possible to distinguish between publicly and privately owned plots.
No, the land included within red and blue lines inundation areas are not free of development. Approximately 46% of the total land designated as plots is developed, while the rest remains vacant.
Build Embankments for flood protection
The project proposes to protect low-lying areas along the River from flooding by building a variety of well-modulated embankments along the banks of Pune's Rivers. In sparsely developed areas, further away from the city center, 'rural riparian embankments' will be built. In moderately developed areas ‘urban riparian embankments will be built. In intensely developed area with high banks, more engineered embankments will be built. The embankments on either side of the river will be designed to contain floods between them bringing the red and blue lines within the riverbed as defined in Revenue maps.Reduce the impact of man-made obstructions to the flow of water in the river
The Pune Riverfront Development Project's first concern is to address the threat of flooding in city. It recognizes that a considerable portion of the area within the red and blue lines – area that can get inundated – is already developed. The project first proposes to reduce the impact of indiscriminately built obstructions such as bridges, causeways, weirs, check dams etc. on flow of water in Pune's rivers by removing, streamlining, remodeling, or rebuilding them. The effect of such interventions will be to reduce the high flood level. This in turn will reduce the extent of area likely to get flooded by a 25 or 100 year flood. Another way of saying this is that the effect of these measures will help to redraw the red and blue lines closer together.Create public realm along the river
Building the embankments will also enable the creation of a continuous public realm along both banks of Pune's rivers. Having such a continuous public realm will ensure that unlike today, people will be able to move along the length of the river.Curb Pollution by Drainage and Sewage Treatment Works
The project also proposes to curb the sewage flowing directly into the Pune Rivers by laying an interceptor sewer which will curb and divert the sewage to the nearest STP. As this project will span for longer time duration, thus, it becomes essential to plan for infrastructure services well in advance. The embankment so designed will house the interceptor sewer line curbing the sewage falling directly into the river.Enhance connectivity
At present there is limited connectivity along and across the Pune's Rivers. There are far too few connections and there are long stretches where the river lacks connectivity across to the other side. The project thus proposes to strengthen the existing street network by introducing bridges and access roads that will further enhance the connectivity to the river. Pedestrian and cycling routes will also be planned along the promenades of the riverfront.Integrate River in the life of the city
Another objective of this project is to create a network of gardens, open spaces, public promenades that will preserve the natural environment and turn the Pune Rivers into an important asset for the city. Also, existing open spaces like gardens and parks, heritage structures along the river, ghats etc. will also be integrated with the riverfront development.
Fig 6. View showing a rural riparian embankment for sparsely developed areas
Fig 7. View showing a urban riparian embankment for moderately developed areas
Fig 8. View showing an engineered embankment for intensely developed areas
Various ruling of Courts and the National Green Tribunal have prohibited all construction in the area between the blue lines and restricted development in the area between the red lines. Thus the development within the red and blue line exists in an area where development is not allowed and hence faces the risks related to the same. Also as explained in the points above, all the plots lying within the red and blue lined areas are vulnerable to the highest flood expected during any 100-year period, based on the current ground conditions.
Fig 5. Section showing the existing situation and the scenario during floods
The Pune Riverfront Development Project proposes to make a comprehensive plan of works, the implementation of which will have the effect of modifying the red and blue lines to be within the proposed works. By proposing works in this sensitive manner (as shown in the diagram below), that fully respect the spirit and intentions of the court ruling the PMC is confident that its works will receive approvals not only from the courts but also from environmentalists interested in reversing the environmental degradation of Pune's rivers.
Fig 9. Section showing the condition during floods at present and the scenario with proposed flood protection embankment
The Pune Municipal Corporation is interested in creating awareness and sensitivity about Pune Riverfront Development Project in Pune city. It has created an official webpage for this project which will ensure periodic information dissipation to citizens, thus, ensuring people participation since the very beginning of the project.
The PMC also intends to consult Pune's citizens and maintain transparency in what it intends to do. By taking such an approach it intends to also build popular support for the project.