River Sand

RIVERS: LET US GIVE ANOTHER CHANCE. Dr.Thrivikramji.K.P. [email protected] Introduction In what follows I will try to establish a case and need for doing away with the use of river sand as a finer aggregate in the construction sector. When India became independent our population was nearly half of what it is today. Though, we were economically backward, the demand for finished goods and services certainly were very low. The environmental concern was not in the governmental agenda. The new govt. had concertedly invested in the successive development plans huge sums of money for investment in the agricultural, industrial and service sectors. This had required great demands on the natural resources identified in the various members of the physical system of the country. Steady exploitation of these without much concern for the response of the natural system ensued. This led to scores of problems, which had affected the environment in general. Alongside there was the explosion of population, which to day stands at one billion. The greater demand for all sorts of natural materials led to greater environmental degradation and the rivers and river basins were no exception. The degradation is profound that the government had to come up with new legislations to protect the various natural systems including the rivers. EARLY DAYS The rivers had to face the attack by humans on two fronts. Firstly, the channels became the choicest dumping ground for any sort of refuse - agricultural, human including dead ones and of late industrial. Further, the water resource of the river was diverted for agricultural, drinking, industrial and power generation purposes, which drastically and sharply reduced the through flow in the system. The combination of these two types of river use or rather exploitation led to the demise of the original river system. On reflection I strongly feel that as humans and specialists we never understood or cared to understand the system of the river in its entirety or enormity. For a certain kind of specialist, the river is only the water it carries and the wastes it delivers into the oceanic sink. For another, the sand carried by the river and accumulating in the riverbed, for one thing is nature-made fine aggregate lying there to be just removed by us, the humans. Yet another person may think that the fisheries potential is the only attraction the river has. Perhaps, the geologist may be the only exception, as he has understood the river in its entirety, for the fact that the river is a system in which the channel, sediment and water it carries down stream (and the aquatic life) are all important and each one of these have functional relation with the rest. The proportion of the former group grew exceptionally high in the post- independence era leading to the death of the rivers. Like many of the countries of the world India too is endowed with a very large number of small and large rivers. Some of the Indian River basins had been the playpens for several of the advanced but ancient civilizations known to human kind. The rivers are also one of the most important sources of the life sustaining freshwater without which the fruits of industrial development would not have become a reality. The rivers also perform a very important geological function, in that they are the chief conduits of transport of land-based detritus to the temporary or permanent sinks viz., adjacent seas and oceans. In fact the history of many a civilization is intimately intertwined with the history of the rivers. The rise and fall of many such are attributed to the changes in course of rivers due to phenomena like faulting, landslides or volcanic debris blocking the route, climatic change and diversion of the flow. The early history of humanity was ruled and rather dictated by river and vagaries of river flow.

HARMONIUS EXISTENCE The New York State Barge Canal, now only a heritage site and tourist attraction, is a living example of the ingenuity of man to harness the use of water way in transport of goods and raw materials at a very cheap cost by barges pulled by horses on the tracks alongside the barge canal. Well, for one thing, horses and horsemen worked on shifts in this route. The unevenness of topography along the canal route is over come by a system of locks in the canal. Plus the adventurous individuals came across the Beaver dams in the interior of forests, where this animal (a cousin of common otter) diligently and skillfully uprooted trees like lodge pole pines and then had cut couple of foot and short-round logs to float them down the mountain streams to be stranded by a natural obstacle and hence to partially block the through flow. The smaller reservoirs thus created pools of water that would support aquatic life on which the beaver and family fed on and survived and sustained themselves. In some of the NW states of the US, some spring season s floods are triggered by breakage of beaver dams and its domino effect in the beaver dams in the down stream. With the dawn of the last century, humans learned the tools and tricks to over come the river flow and rather manage the river flow by building pervious and impervious barriers to control and regulate the through flow in the river. In fact, with the introduction of steam engine heralding the industrial revolution, also considerably enhanced the pace of flow regulation with larger and efficient barriers across the rivers. The harnessing of energy of the flowing water or storing the water for later use became a default option in the minds of intelligent humans. This inaugurated the construction of dams across river channels. The Ganges to the north Indians is the Ganga Maiyya or Ganga ma or mother Ganga. This connotation is very apt if we reflected ourselves just for a while. Bearing the burden of children from the 1st and rearing them till the last day is what a mother pleasingly does. The legend has it that Ganga R. also does the same thing. The dead body is finally burned or cremated on the sand bars of the riverbed and/or floated down the river toward the ocean. Unequivocally the chief uses of a river are very simple and straightforward. Firstly. it is the principal source of water for every day use. Secondly, it is a local dumping site of waste. The modern man has invented several new uses, like for e.g., an enviable source of granular sand as well as floodplain mud chiefly consumed by the construction industry. As long as the extraction was not intense, the river system did not react or respond. As a consequence, several large and small towns came into being alongside the river courses due to the proximity to water, construction material and an easy out let for the waste generated by the community. Boundaries and ground rules were not exceeded. Day to day waste, chiefly biodegradable, logically got disposed into the flowing water in the streams. If through flow exists in a segment of the river, that water must be clean was the axiom of those days. HUMANS VS. RIVERS How ever increased manufacturing contributed newer types of wastes different from what the smaller and larger communities generated in the past, which very logically got disposed off into the stream channels. In addition, parallel to this there was abstraction of water from the streams, not only for use in the manufacturing process to cool off the plant and machinery but also for domestic use to the towners who gathered around the industrial hubs. All the human activities pitching humans vs. nature or natural systems in one sense or other were driven by insight or intuition. As long as the limits set by nature were not exceeded, there was not any irreparable damage done to the natural system. This was very true when the population as well as the degree of industrialization were much lower or less. But the picture changed significantly with population explosion as well as higher degree of industrialization. Then environment as well as the physical system of the rivers was intensely stressed mainly due to

release of (solid, liquid and gaseous) waste into the system. With the introduction of Portland cement, the river bed was the most sought after source of fine aggregate or the common construction sand that goes into making of cement mortar and cement concrete. Generally speaking, the rivers in other parts of India probably are in a different situation unlike the Kerala Rivers. A word about the size of rivers in Kerala will be in order. Rao (1975) basing the aerial extent of the river basins classified them into large (>20,000 Km 2), medium (2000 20,000 Km 2) and small (<2000 Km2). Under this scheme, there is not even a single large river in Kerala. Out of 41 west-flowing rivers only 11 fall in the category of medium rivers. With the population of 3 cores, and channel length of about 2000 Km. per capita entitlement of river channel stands at 6.66 cm.- an appallingly low figure. Further, if we examine the size of the side of the support square of Keralite, a measure of assessing the pressure on land, for a population of 31.8 million (Census, 2001) and a land area of 38,863 Km2, it stands only at 36 meters. This figure is several orders of magnitude larger for Europeans and Americans. What it means from the point of view of the river? Basically it means that the degree and rate of exploitation of river is intense. The dependency of population on river for its intrinsic resources is stupendous. Both water and streambed sediment are equally intensively exploited. The utilization of river channel as a dumping site for solid and liquid residues generated by cities and small towns along the river course is also considerable. Demand driven Dilemma Let us stop for a moment to reflect on the process of formation of natural sand, which is nearly pure quartz sand. Quartz (Silicon dioxide), a mineral very durable during weathering of rocks and hence naturally remains as stable entity in river and in beach sands. Quartz content in the crystalline rocks (common building stone around here) is only 30% and remainder is nearly all feldspar and some minor accessories like coloured minerals and opaques The chemical weathering (i.e., chemical break down of minerals other than opaques and quartz) taking place on the surface conditions of the earth that converts rock into soil, needs at least a few hundred thousand years for completing this process to generate soil. The immediate source of sand is the soil and soil erosion is the process that propels the sand in the soil into the river net. Obviously, the process of sand supply to the rivers is perhaps one of the many slowest processes in nature, which is the hallmark of the earth system and hardly understood by humans. Certainly our demand for sand outpaces the ability of the earth to supply it. A point ordinary human s and some scientists have not bothered to understand. In all the Indian states like in many developing nations, riverbed sand is the cheapest and readily available aggregate, though it may not be the most desirable. In regions where river courses are far away from the construction site, fine aggregate (a.k.a. crusher sand) comes as a by- product of a mill producing coarser aggregate. Now I will examine the consequences of sand borrowing out of river beds for various purposes, which in Kerala is chiefly as a fine aggregate in cement concrete and cement mortar. But in our state, the demand for fine aggregate is so strong that almost all the river channels have been scrapped for the last particle of sand up to the bed rock foundation . What rules the price of sand in the sand commodity market is the demand. The demand has naturally driven the unit price of sand skyward. Another consequence of this sheer demand is the sand mafia turning towards the ancient river alluvium stored in the valley (especially in the ML and CL segments) and exposed in the channel walls. Clandestinely, such walls are forced to collapse, uprooting the standing long-term crops like coconut trees, hutments and finally little precious land owned by poor marginal agricultural laborers. This is a delicate operation. The crew legally entitled to gather channel sand, chips away at the submerged sand bearing channel walls to gather more sand, and thus increase the free

board from the bed to bank top of the channel , forcing a disequllibrium to set in, between the channel floor and channel wall. Now it is only a matter of time before the collapse and sliding down of the channel wall along with a small or large portion of river shore land. The landowner with small landholding suffers most. In my own estimate (carried out in 1986 in the Neyyar basin), of loss incurred by land owners with standing crops including coconut trees as a result of bank collapse, stood at a million rupees. This included the economic loss due to lost wages by harvesters also. The sand gathering in the channel, in the late last century is by diving into the river armed with a specially made large sized metallic spoon, to dig at the sand bed. This scheme stirs up the bottom sediment and water triggering the finer particles to stay in suspension in the water column. The continuation of sand gathering on a commercial scale, led to an unprecedented increase in the suspended sediment content and finer sediment at the bed, which adversely affected the river ecology. Addition of extra dose of the finer sediment to the substrate sediment in the channel, and hence the modified bed sediment texture, a large number of species of aquatic animals (e.g. many fresh water species characteristic of rivers) have become extinct due to loss of spawning ground. The increase in the suspended sediment in the river water column also affected the depth to the photic zone, and hence the depth to which the energy providing sunlight can penetrate. Obvious consequence is the fall in the density of primary producers in the water column. Naturally it will affect and in fact had affected the diversity of the riverine aquatic life. No wonder that these days we don t even see the larger sized fish, our ancestors angled and brought home for the entire family to relish. Yet another indirect consequence of sand removal is what very young and old persons face in their daily life. In the past, during the days of less or no harm to the river in terms of sand removal, these people could go across the river by wading through the water, with out fear of drowning in the deep holes created by excessive removal of sand. In the past, only sites to be watched out at the time of wading were the river bends where the river floor stood unusually deep. These same spots also were the abodes of larger sized fish population and hence promising fishing grounds. The longer-term damages done to the physical system of the river due to sand removal are the loss of natural scenic or esthetic value or looks of the channel during base flow stage. What usually appeared as a channel with free flow of water over a sand bed through pools and riffles disappeared forever? The pools are the segments of the riverbed, where it is relatively deeper in comparison with the adjoining riffle where the bed is very shallow and covered with relatively coarser sediment. The river shores were lined with certain species of trees and plants very much characteristic of the riverine environment. Not only that the ever present sand bar also vanished, along with it also gone are the crystal clear chirping flow of water (typically in the mid land and highland tracts), and the diverse aquatic life. Another kill is the elevation of the channel bed. Stability and hence safety of several road and some rail bridges have become questionable due to fall in river bed elevation. Masonary or concrete foundations of many bridge piles, are now exposed in the bed due to lack of sand (cover) in the channels. This is yet another smoking pistol of over-exploitation of the river channel sand. Due to steady removal of sand in excess of nature s quota and fall in river floor elevation,, affected the ground water regimen of the river valley. This logically led to a steep fall in water table at least locally. In other words, the water level in domestic wells (and irrigation wells also), stood deeper. This had several consequences. For one thing, in pumped wells, the pump needed to be repositioned at a lower level and at a price, and threatening the continuous supply of water for

domestic and/or agricultural needs. Many perennial wells changed to ephemeral ones or supply became insufficient for which the well was constructed in the first place. Obviously, this called for additional capital investment for deepening and reconstructing the well or starting a new well in a different location. In summary, the affected well owners had incurred a huge loss of capital for which as per the existing law no one can be held responsible. In fact, the sand mining from the riverbed is a practice that affects the river system itself and affects the lower forms of life and humans alike. But then we need to continue the development activities. The engineer s code never specifically recommended river sand as a finer aggregate. On the other hand, river sand - one of the easily available natural materials - very well qualifies. This started off the threat to the river system and despite the rules and regulations it continues unabatedly. PROSPECT All over the world concrete is most preferred construction material and calls for use of finer aggregate or sand. Unlike in Kerala, several Indian states have identified sources of sand grade material from natural as well as industrial byproducts. For example crusher sand is an excellent substitute for river sand. Quarried rock is crushed with suitable machines to manufacture artificial sand the crusher sand. With the right machinery in place, the often-heard complaints of noise and dust pollution can be nearly eliminated. For e.g., in New Delhi, the national capital, with perhaps very huge construction projects sources the finer aggregate by crushing what a geologist would call as Delhi quartzite. In most of Maharashtra, the sand is sourced from the crushers utilizing quarried Deccan Basalt as the input. I strongly believe that the Keralite will have to turn to the crusher sand to meet the construction needs. It is high time that we learned to leave the river sand where it belongs. This will offer the river and the riverine ecosystem a second chance to spring back to its old self to make not only you and me, but also the posterity cheerful. -----