Friday, September 19, 2014
Heavy rainfalls battered the western Himalayas last week due to a clash between monsoon currents and winds from the Caspian Sea.
Dr. Nitish Priyadarshi
Tuesday, September 16, 2014
Inadequate surface drainage and encroachment in the floodplains has caused the floods of Kashmir.
Dr. Nitish Priyadarshi
For hundreds of million years Kashmir Valley is supposed to have remained under Tethys Sea and the high sedimentary-rock hills seen in the valley now were once under water. Geologists have come to believe that Kashmir Valley was earlier affected by earthquakes. Once there was such a devastating earthquake that it broke open the mountain wall at Baramulla and the water of the Satisar lake flowed out leaving behind latchstring mud on the margins of the mountains known as karewas. Thus came into existence the oval but irregular Valley of Kashmir.
In September 2014, the Kashmir region was hit by heavy floods from torrential monsoon rains. The regions of Jammu and Kashmir in India, as well as Azad Kashmir, Gilgit-Baltistan and Punjab in Pakistan, were affected by these floods.
The cause of the flood is continuous heavy rainfall due to which local rivers broke out into the streets. The areas affected by the flood are mostly districts in south kashmir which include Anantnag, Avantipore and Pulwama.
The main rivers in this region are Ravi, Chenab and Jhelum. These rivers are the tributaries of the Indus. They carry quite substantial discharges during monsoon and also large volume of sediment. They change their course frequently and leave behind vast tract of sandy waste. The major problem is that of inadequate surface drainage which causes inundation and water-logging over vast areas.
The river Jhelum rises from Verinag Spring situated at the foot of the Pir Panjal in the south-eastern part of the valley of Kashmir in India. It flows through Srinagar and the Wular lake before entering Pakistan through a deep narrow gorge.
Floods in Jammu and Kashmir aren’t exactly an uncommon phenomenon, if history and indeed its geography is to be believed. Starting last week, the state has seen an unprecedented amount of rainfall, resulting in its worst floods since 1959. Floods in the state are invariably linked to the Jhelum River and its history of crossing the danger mark, its streams and rivulets overflowing and thereby inundating the “Valley” (south Kashmir) in the process.
In the last 60 years, more than 40 percent of lakes, ponds and wetlands of Srinagar have been encroached upon for constructing buildings and roads. The banks of the Jhelum river have been taken over in a similar manner, vastly reducing the river's drainage capacity.
Jhelum which is a main source of irrigation in the Valley has been marred by extensive siltation in last few decades. In absence of any conservation measures, the river had lost its carrying capacity and led to blockage of its lone outflow channel in Baramulla, posing a risk of floods in the Valley.
There are three reasons why the floods have caused so much damage:
- deforestation in the catchment areas of rivers – especially Jhelum, Chenab and Indus – and of streams;
- unplanned construction of buildings and roads, especially in the floodplains of the rivers and the banks of the lakes;
- rampant and unchecked dumping of garbage in the rivers and lakes;
Taking the factors that exacerbated the floods one by one, deforestation has long been a major problem in the northern half of the Kashmir valley, in adjacent parts of Pakistan-administered Kashmir and in Gilgit-Baltistan.
Coming to the second reason, for decades the elite in the Kashmir valley has been building fancy villas right on the floodplains of rivers and streams, sometimes even on tiny islands in the middle of the river. The process has been repeated and accelerated on the banks of famous lakes like Dal and Nageen in Srinagar, with some hotels and restaurants even being built with their foundations in the lake – a result of the tourism boom.
As the Jhelum River meanders through Srinagar, every neighbourhood adds its untreated household garbage to the river – once again a recipe for choked riverbeds and lakebeds and for the water to overflow whenever it rains heavily.
Overuse of chemical fertilisers, especially in the fruit orchards throughout Kashmir, also exacerbates flooding. The excess fertiliser gets washed into streams and rivers, where it causes eutrophication, and again leads to algae blooms which choke waterways.
Jhelum meanders in a serpentine way from South to North Kashmir and settles in Wullar, Asia’s largest freshwater lake, before pouring into Pakistan administered Kashmir through Baramulla. Experts said the devastating flood in 1959 caused backwater effects to Jhelum due to low outflows from Wullar Lake in north Kashmir which has been nearly chocked by heavy accumulation of silt and narrow outflow channel.
There are number of rivers, tributaries and nullahs which are joining Jehlum River. For proper water resources management, sufficient amounts of hydrological data are required. But sufficient hydrological data on these rivers, tributaries and nullahs are not available. Some of the reasons behind the lack of the data are:
1) The area is mountainous with some of the world’s highest mountains situated in it.
2) The accessibility of many places is very difficult, especially in the winter season.
Observers are bemoaning that Srinagar is looking like a vast lake. Urban planners, environmentalists or anybody with common sense is not surprised. Without immediate corrective action, the calamity is likely to strike again.
Friday, September 5, 2014
The hills of Ranchi are generally small isolated residual hills.
Dr. Nitish Priyadarshi.
Fig.1. A small hill in Pithoria.
The hills of Ranchi are generally small isolated residual hills. In Ranchi hills are generally steepsided made of massive granite-gneiss. We have also found the hills which are not steepsided but a mere irregular pile of huge boulders were found on the hills especially in Pithoria area of Ranchi district. This is the result of highly jointed elements of granite gneiss.
According to climatic geomorphologist like Tricart qualify such hills as inselbergs. They are steepsided residual hills made of massive granite-gneiss. But close by within a few kilometers or a few hundred meters we have residuals which are not steepsided inselbergs but a mere irregular pile of huge boulders.
The rocks disintegrate along these joints under the hydrothermal and atmospheric effects thus leading to the formation of tors or rounded shapes of these ancient granite rocks are the result of cracking and erosion from exposure to sun, wind and rain. The hill slopes are subjected to complex attack by a variety of erosive weapons, water being the most active agent for the removal of waste material from most of the slopes.
A tor commonly appears as a pile of rock slabs or a series of slabs standing on end, according to whether the dominant joint system is horizontal or vertical. Weathering proceeds most actively along joint planes, thus reducing an originally solid mass first to piles of slabs and ultimately to a heap of loose boulders. Tors usually overlie unaltered bedrock and are thought to be formed either by freeze–thaw weathering or by groundwater weathering before exposure. There is often evidence of spheroidal weathering of the squared joint blocks. Tors are seldom more than 15 metres (50 feet) high and often occur as residues at the summits of inselbergs and at the highest points of pediments.
Fig.2. This is a picture of small granite tor near Ranchi city.
Fig.4. Irregular pile of huge boulders on the top of Pithoria hill.
Fig.5.Irregular pile of huge boulders. They are the result of highly jointed elements of granite gneiss.
Fig.6. A balancing rock was also seen on the top of the hill.
A balancing rock, also called balanced rock or precarious boulder, is a naturally occurring geological formation featuring a large rock or boulder, sometimes of substantial size, resting on other rocks, bedrock or on glacial till. Some formations known by this name only appear to be balancing but are in fact firmly connected to a base rock by a pedestal or stem.
Its an erosional remnant rock formation that remains after extensive wind, water and/or chemical erosion. To the untrained eye it may appear to be visually like a glacial erratic, but instead of being transported and deposited it was carved from the local bedrock.