Tuesday, September 25, 2007

Sensing Corruption Remotely

Part 5 of the six part series on Pune city pollution and environment. Updated every Tuesday.

In this blog I integrate geology and high-resolution images with GIS, to showcase some example of poor urban planning and cases of violation of the urban development plan in Pune. The list of violations of building codes in Indian cities will be quite long. In recent months controversies over whether to build on the hills, and flooding of premises built too close to streams and rivers have caught the public attention. I have highlighted these types of violations since they require some geological knowledge and image interpretation skills to spot. At the end I will discuss some limitations of this approach.

Hill Top Hill Slopes:
Hills are measured in terms of gradient, which is merely the rise of the hill over the run. If you're going up 2 feet for every 100 feet you travel, you're on a 2% hill. For the purposes of urban zoning, the Pune Municipal Corporation Development Plan defines any hill slope with a gradient of 20% i.e. 11 deg or more as falling within a Hill Slope/Hill Top zone (HS/HT). According to the development control rules, owners of plots in HS/HT zones can have a built up area up to 4% of the plot area. Recently, all HS/HT were given protected status and all construction halted.

Construction on steep hill slopes can occur under a number of circumstances.

1) The slope was constructed upon at a time when the area fell outside the limits of the development control rules, i.e. outside PMC limits. This is a common situation in the fringe villages which only recently came under PMC jurisdiction.

2) The slope falls under HS/HT zone and has been encroached upon by slums. This situation is common for HS/HT zones under government ownership.

3) The slope falls under HS/HT zone and constructions have come up as per the development restrictions defined for HS/HT.

4) The slope is reclassified as not falling under HS/HT. Constructions on such misclassified slopes follow normal development control rules. This is a particularly insidious form of corruption of the urban development plan, since the "reclassification" allows plot owners to bypass the 4% rule and construct mansions on hills. Image below depicts this situation.

Source: Google Earth ; Image Copyright: 2007 Digitalglobe ; 2007 Europa Technologies; 2005 Google

The green line is the gentler slope. The yellow line is the steep rocky slope (HS/HT). The orange dotted lines outline a layer of black basalt rock. This layer can be traced from the upper left of the photo where it lies in the HS/HT reserved forest of Vetal Tekdi, along the entire length of the base of Chaturshringi hill. Since the basalt outcrop is horizontal the upper and lower dotted lines are analogous to contour lines. The gradient between them is the same along its entire length and should fall under the HS/HT zone along its entire length. On the lower right however one can observe massive constructions intersecting the basalt layer. The gradient at the site of these construction has been "reclassified" to residential to allow owners to maximize FSI (floor space index).

Encroachments of river banks:
During the recent monsoons, Ram Nadi, a tributary of the Mula river flooded its banks. Water entered the premises of several constructions built close to the banks. Residents, city government and the media suddenly woke up to the fact that these houses were built with scant regard to urban development rules, which mandate a no construction zone of 30 metres near water bodies. Below is an example of a clear violation of that rule. Image shows a section of the Mutha river near the bridge connecting Karvenagar and Sinhagad road.

Source: Google Earth ; Image Copyright: 2007 Digitalglobe ; 2007 Europa Technologies; 2005 Google

I have built a 30 metre buffer along the river banks (green band). River banks are the blue lines. Flow is from right to left. On the south bank (top of image) one can clearly see big apartment complexes falling within the 30 metre buffer. Red arrows outline the unnatural right angle the river bank takes, which means that the river bed has been encroached upon by dumping massive amounts of debris.

Blockage of natural drainage:
Hill slopes have natural drainage made up of small streams. A proper urban development plan should take into account such drainage and not allow constructions to block these streams. However, natural drainage everywhere in Pune has been built upon, simply by filling up these streams. Since during monsoons, water does not find a natural drain, this results in sheet flow of water onto the roads. The erosive power of this water is quite significant, resulting in the famous pot-holes of Pune. Below is an example of natural drainage which has been blocked by several constructions.
Source: Google Earth ; Image Copyright: 2007 Digitalglobe ; 2007 Europa Technologies; 2005 Google

Flow of streams is from left to the right of the image. If one follows the red arrows, you can make out the curvilinear outlines of a small stream which at places abruptly terminates against buildings. This stream joins another stream outlined with blue arrows and forms a bigger drain at the purple arrow. This then flows into the Mutha river. Such blocked streams have only recently caught the attention of the city government, which has promised to amend building rules to allow natural passage of this drainage.

Some technologies such as Google earth allows citizens to locate violations of the urban plan. One can use the distance tools to measure and also draw outlines of objects and save them in a geographic format. These files can be shared with other Google earth users. In this way, citizens can participate in discussions and debates on urban planning without needing expensive GIS software. They can also register complaints with the Municipal Corporation online. But the images are not really a monitoring tool. The images are 6 months to 3 years old. The city government however can use remote sensing as a monitoring tool, if they decide on purchasing high-resolution images every 3 months or so. A one meter resolution image covering Pune municipal limits should cost about Rs. 3-4 lacs. So a purchase budget of Rs. 12-15 lacs a year will give the municipality a powerful urban planning tool not just for spotting violations but also for other urban planning purposes. This off course has to be accompanied by a dedicated GIS staff, in which the city government has shown little inclination and interest.

Part1. Idling and Pollution
Part2. PMT buses and Pollution
Part3. Rickshaws and Pollution
Part 4. Urban Forests and Clean Air

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