ISSUES AND CHALLENGES IN RIVER MANAGEMENT DUE TO EXCESSIVE SAND MINING Seminar Report Submitted in partial fulfillment of the requirements for the degree of MASTER OF TECHNOLOGY in WATER RESOURCES ENGINEERING & MANAGEMENT By SUJAY RAGHAVENDRA N (12WR10F) Under the guidance of Dr. S.G. MAYYA DEPARTMENT OF APPLIED MECHANICS & HYDRAULICS NATIONAL INSTITUTE OF TECHNOLOGY KARNATAKA SURATHKAL, MANGALORE - 575 025 April 2013 CERTIFICATE This is to certify that the P.G. Seminar Report entitled “ISSUES AND CHALLENGES IN RIVER MANAGEMENT DUE TO EXCESSIVE SAND MINING” submitted by SUJAY RAGHAVENDRA. N (Register Number: 12WR10F) as the record of the work carriedout by her is accepted as the P.G. Seminar Report submission in partial fulfillment of the requirements for the award of degree of Master of Technology in Water Resources Engineering & Management in the Department of Applied Mechanics & Hydraulics Dr. S.G. MAYYA. Professor Department of Applied Mechanics & Hydraulics NITK, Surathkal Head of the Department Department of Applied Mechanics & Hydraulics NITK, Surathkal ACKNOWLEDGEMENT I would like to express my deep sense of gratitude to my project guide Dr.S.G Mayya., Professor, Department of Applied Mechanics & Hydraulics, NITK, Surathkal for his valuable suggestions and guidance, which played a definite role in bringing this report to good shape and extending all facilities to carry out this seminar. I also extend my sincere thanks to each and every faculty who had helped directly or indirectly, and my friends for the preparation of this seminar report. Above all, I thank my parents who gave me the firm platform for the successful completion of this seminar report. NITK SURATHKAL SUJAY RAGHAVENDRA N. Date: 15.04.2013 ABSTRACT In the past few decades, the demand for construction grade sand is increasing in many parts of the world due to rapid economic development and subsequent growth of building activities. Rapid urbanization, the major cause for sand demand is responsible for unsustainable extraction of sand from dried river paths. The layers of sand deposits are exploited almost up to the bottom. This in turn, has increased initial and premature failure of irrigation wells in riparian areas. This, in many of the occasions, has resulted in indiscriminate mining of sand from instream and floodplain areas leading to severe damages to the river basin environment. Moreover, lack of adequate information on the environmental impact of river sand mining is a major lacuna challenging regulatory efforts in many, developing countries. TABLE OF CONTENTS 1 INTRODUCTION. 1. 2 SAND MININING. 1. 2.1 DEFINITION. 1. 2.2 SOURCES OF SAND/GRAVEL. 2. 2.3 SAND DREDGING. 5. 3 SAND MINING IN INDIA. 6. 3.1 SAND MINING IN COASTAL REGULATION ZONE. 6. 4 IMPACTS OF SAND/GRAVEL MINING. 9. 4.1 IMPACTS ON RIVER MORPHOLOGY. 10. 5 ENVIRONMENTAL EFFECTS OF SAND/GRAVEL MINING. 12. 5.1 ENVIRONMENTAL ISSUES OF SAND MINING. 12. 5.2 CURRENT RULES AND POLICIES IN OPERATION. 14. 6 SCIENTIFIC MINING OF SAND/GRAVEL. 15. 7 MANAGEMENT PLANS. 18. 7.1 IN-STREAM MINING RECOMMENDATIONS. 18. 7.2 OFF-CHANNEL/ FLOODPLAIN EXTRACTION RECOMMENDATIONS. 20. 7.3 RECLAMATION PLANS. 21. 8 APPROPRIATE EXTRACTION METHODS. 22. 9 SUMMARY AND RECOMMENDATIONS. 25. 10 REFERENCES. 26. LIST OF FIGURES 2.1 Aggregate extraction can take place in a number of in-stream or near-stream environments (Langer, 2003)……………………………………………………...……..........3 2.2 Distribution of sediment and extraction zones in Reservoir …...…………………..….....4 2.3 Dredger tailings, Mississippi Bar, American River, California.………...……………......4 3.1 Integrated Coastal Zone Management Plan……………………………………………….8 4.1 Extensive Modification to Stream Channel caused by gravel Extraction……...……......11 8.1 Aggregate being “skimmed” off the surface of a bar (Langer, 2003)………......……….22 8.2 Wet-pit channel mining………...……………….……………………..………………...23 8.3 Bar Excavation…………...…………………………...…………………………………24 8.4 Idealized gravel trap (Source: Bates 1987)…...………...……………………………….24 SAND MINING 2013 1. INTRODUCTION. Rivers are the most important life supporting systems of nature. For centuries, humans have been enjoying the natural benefits provided by rivers without understanding much on how the river ecosystem functions and maintains its vitality. Man has changed the nature of many of the world’s rivers by controlling their floods, constructing large impoundments, overexploitation of living and non-living resources and using rivers for disposal of wastes. Among these, indiscriminate extraction of non-living resources like sand and gravel from riverbed is the most disastrous as this activity threatens the very existence of the river ecosystem. A review of literature reveals that indiscriminate extraction of river sand and gravel manifolds higher than natural replenishments and can impart serious offsite and onsite impacts. This ultimately leads to changes in channel form, physical habitats, food webs and engineering structures associated with river channels and inland sediment supply to coastal and nearshore environments. As these adverse effects become increasingly recognised and understood, instream sand mining/aggregate extraction has recognised increasing scientific scrutiny. Although more focussed researches leading to restoration of river environments are progressing in many developed countries, much attention has not been made in the rest of the world. In-stream sand mining can damage private and public properties as well as aquatic habitats. Excessive removal of sand may significantly distort the natural equilibrium of a stream channel. By removing sediment from the active channel bed, in-stream mines interrupt the continuity of sediment transport through the river system, disrupting the sediment mass balance in the river downstream and inducing channel adjustments (usually incision) extending considerable distances (commonly 1 km or more) beyond the extraction site itself. The magnitude of the impact basically depends on the magnitudes of the extraction relative to bed load sediment supply and transport through the reach (Kondolf et al., 2001). In view of the severity of environmental degradation caused by indiscriminate river sand mining and also considering its potential impacts on the developmental initiatives of the area, a study has to be undertaken to assess the environmental impact of sand mining in the rivers. 2. SAND MINING 2.1. DEFINITION Sand Mining is a coastal activity referring to the process of the actual removal of sand from the foreshore including rivers, streams and lakes. Sand is mined from beaches and inland dunes and dredged from ocean beds and river beds. Besides resource extraction, ultimate objectives of riverbed sand mining should be:- i. Protection and restoration of the ecological system, ii. To prevent damages to the river regime, iii. To work out the sediment influx/ replenishment capacity of the river, iv. To restore the riverine configuration (landforms and fluvial geomorphology such as bank erosion, change of river course gradient, flow regime, etc.), v. To prevent contamination of ground water regime, 1 SAND MINING 2013 vi. To prevent depletion of ground water reserves due to excessive draining out of groundwater. vii. To restore the riparian rights and instream habitats. 2.2. SOURCES OF SAND/GRAVEL. The sources of sand are classified as marine and terrestrial deposits. The two most common marine sources are the deposits on the shore and offshore. The most common terrestrial sources are the river channel deposits, floodplain alluvial deposits, and residual soil deposits. There are extensive deposits of sand on the shores of the island, occurring in the intertidal zone, where sand grains are deposited by littoral drift. The beaches vary from narrow strips parallel to the coastline to broad inland deposits of more than a kilometre in width. Although these deposits were extensively mined in the past, the extraction of sand from the maritime zone is prohibited. Some large sand deposits occur in the back beach zone. These are usually found as sand dunes and series of consecutive ancient beaches. Although it is possible to extract a portion of the dune without eliminating the coastal protection, the determination of the extraction area and the buffer zone is difficult without detailed geologic studies. The most common places from which sand is mined include: i. Dredging river channels. ii. Dredging the river floodplains. iii. Extraction of inland residual sandy soils. iv. Dredging submerged deposits. v. Extraction from coastal dunes. vi. Exploiting renewable beaches. Fluvial Gravels as Sources of Construction Aggregate Sand and gravel deposited by fluvial processes are used as construction aggregate for roads and highways (base material and asphalt), pipelines (bedding), septic systems (drain rock in leach fields), and concrete (aggregate mix) for highways and buildings. In many areas, aggregate is derived primarily from alluvial deposits, either from pits in river floodplains and terraces, or by in-channel (instream) mining, removing sand and gravel directly from river beds with heavy equipment. Fluvial and Glacial Outwash Deposits Sand and gravel that have been subject to prolonged transport in water (such as active channel deposits) are particularly desirable sources of aggregate because weak materials are eliminated by abrasion and attrition, leaving durable, rounded, well sorted gravels (Dunne et al. 1981, Barksdale 1991). Sand and gravel are commercially mined from the active channel (instream mining) and from floodplain and terrace pits (Figure 11). Instream gravels thus require less processing than many other sources, are easily worked by heavy equipment, and suitable channel deposits are commonly located near the markets for the product or on transportation routes, reducing transportation costs (which are the largest costs in the industry). Moreover, instream gravels are commonly of sufficiently high quality to be 2 SAND MINING 2013 classified as "PCC-grade" aggregate, suitable for use in production of Portland cement concrete (Barksdale 1991). Figure 2.1. Aggregate extraction can take place in a number of in-stream or near- stream environments (Langer, 2003) River channels and floodplains are important sources of aggregate in many settings by virtue of the durability of river-worked gravels and their sorting by fluvial processes. The relative importance of alluvial aggregates is a function of the quality, location, and processing requirements of alluvial aggregates, and the availability of alternative sources in a given region. Other Potential Aggregate Sources: i. Reservoir Deltas: Reservoir sediments are a largely exploited source of building materials. In general, reservoirs deposits will be attractive sources of aggregates to the extent that they are sorted by size. The depositional pattern within a reservoir of gravel, sand, silt and clay depends on reservoir size and configuration, and the reservoir stage during floods. Small diversion dams may have a low trap efficiency for suspended sediments and trap primarily sand and gravel, while larger reservoirs will have mostly finer-grained sand, silt, and clay (deposited from suspension) throughout most of the reservoir, with coarse sediment typically concentrated in deltas at the upstream end of the reservoir. These coarse deposits will extend farther if the reservoir is drawn down to a low level when the sediment- laden water enters. In many reservoirs, sand and gravel occur at the upstream end, silts and clays at the downstream end, and a mixed zone of interbedded coarse and fine sediments in the middle.(Figure 2) ii. Dredger Tailings: Dredger tailings are long linear deposits left by historical gold mining operations. The tailings are stratified: sand and silt are overlain by mounds of clean gravel and cobble, which hold no interstitial water and thus support little vegetation. These inert ridges of gravel and cobble cover large areas of floodplains of rivers in former gold- mining areas.(figure 3) 3 SAND MINING 2013 Figure 2.2. Distribution of sediment and extraction zones in Reservoir. Figure 2.3. Dredger tailings, Mississippi Bar, American River, California 4 SAND MINING 2013 2.3. SAND DREDGING Sand Dredging is an excavation activity or operation usually carried out at least partly underwater, in shallow seas or fresh water areas with the purpose of gathering up bottom sediments and disposing of them at a different location. This technique is often used to keep waterways navigable. ADVANTAGES DISADVANTAGES It opens up our water ways for easy A release of toxic chemicals (including access and movement for local heavy metals and PCB) from bottom fishermen. sediments into the water column. If done in advance and through a Secondary effects from water column modern method the water way could be contamination of uptake of heavy metals, open for large vessels to pass through it DDT and other persistent organic toxins, bringing a lot of people into the via food chain uptake and subsequent community. concentrations of these toxins in higher It provides employment especially for organisms including humans. the ‘ready to work’ and vibrant youths Secondary impacts to aquatic and benthic of the town. organisms' metabolism and mortality The dredging provides a good and Possible contamination of dredge spoils natural habitat for fishes, which makes sites. them have an increasing population. 5 SAND MINING 2013 3. SAND MINING IN INDIA Sand Mining in India is adversely affecting the rivers, sea, forests & environment. Illegal mining of Sand and the lack of governance, in a big way is causing land degradation and threatened its rivers with extinction. Mining of sand, for instance, is depleting the waters of the rivers. Weak governance and rampant corruption are facilitating uncontrolled and illegal mining of sand and gravel in the rivers, threatening their very existence. This unrestrained and unregulated activity is posing threats of widespread depletion of water resources which may lead to unavoidable food shortages and hardships for the people. In M.P. the major rivers like Narmada, Chambal, Betwa or Wainganga or numerous rivulets and streams all are being ravaged for their sands. The state government has wittingly lent a helping hand by exempting the grant of Environmental Clearance to be taken for mining of sand and gravel, neutralising the provisions made in several central legislations on conservation of environment and mineral resources. A social activist has approached the state high court for quashing of the unconstitutional exemptions so that indiscriminate mining of sand could be put a stop to. Similarly River Bharathapuzha in Kerala has become a victim of indiscriminate sand mining. Despite numerous prohibitions and regulations, sand mining continues rapidly on the riverbed of the Bharathapuzha. Water tables have dropped dramatically and a land once known for its plentiful rice harvest now faces scarcity of water. In the villages and towns around the river, groundwater levels have fallen drastically and wells are almost perennially dry. Study conducted at Neyyar basin Kerela, India reported that channel bank failed due to over deepening of the channel, with standing coconut palm trees uprooted and lost in large number. This led to estimated loss of nearly one million rupees annually. The malaise is pretty widespread as many other states, like Gujarat, Karnataka, Tamilnadu, etc are also victims of unchecked illegal sand-mining the consequences of which are very serious. Rivers of India are already seriously sick. Polluted by industrial and urban effluents, they are also victims of deforestation in their catchments, sequential damming and degradation because of unchecked sand-mining on their banks and beds. Besides, erratic monsoons, induced by changing climate is taking its toll, adversely impacting their capacity to sustain the current levels of economic activities, especially agricultural productivity. 3.1. SAND MINING IN COASTAL REGULATION ZONE The Central Government hereby declares the following areas as CRZ and imposes the following restrictions on the setting up and expansion of industries, operations or processes and the like in the CRZ,- i. The land area from High Tide Line (hereinafter referred to as the HTL) to 500mts on the landward side along the sea front. ii. CRZ shall apply to the land area between HTL to 100 mts or width of the creek whichever is less on the landward side along the tidal influenced water bodies that are connected to the sea and the distance upto which development along such tidal influenced water bodies is to be regulated shall be governed by the distance upto 6 SAND MINING 2013 which the tidal effects are experienced which shall be determined based on salinity concentration of 5 parts per thousand (ppt) measured during the driest period of the year and distance upto which tidal effects are experienced shall be clearly identified and demarcated accordingly in the Coastal Zone Management Plans (hereinafter referred to as the CZMPs). iii. The land area falling between the hazard line and 500mts from HTL on the landward side, in case of seafront and between the hazard line and 100mts line in case of tidal influenced water body. The word ‘hazard line’ denotes the line demarcated by Ministry of Environment and Forests (hereinafter referred to as the MoEF) through the Survey of India (hereinafter referred to as the SOI) taking into account tides, waves, sea level rise and shoreline changes. iv. Land area between HTL and Low Tide Line (hereinafter referred to as the LTL) which will be termed as the intertidal zone. v. The water and the bed area between the LTL to the territorial water limit (12 Nm) in case of sea and the water and the bed area between LTL at the bank to the LTL on the opposite side of the bank, of tidal influenced water bodies. Mining of off shore sand became a topic of interest recently because of the increasing demand and spiralling cost of river sand for construction purposes. Often proposed as an alternative to beach mining, is offshore sand mining. Extensive (and expensive) studies must be conducted before any offshore mining can be attempted. Offshore sand banks, coral reefs and sea-grass beds diffuse the energy of storm waves; if large quantities of sand are removed from offshore sand banks in locations where replenishment would not occur, serious coastal damage would result in the event of a major storm. A complex relationship exists between sand banks, coral reefs, marine biota, current circulation, waves and swells patterns. Sand mining in coastal regions is subject to different regulations throughout the world. While a minimum water depth is commonly used as a restrictive criterion for providing mining licenses in numerous countries. 7 SAND MINING 2013 Figure 3.1. Integrated Coastal Zone Management Plan 8 SAND MINING 2013 4. IMPACTS OF SAND/GRAVEL MINING Mining from, within or near a riverbed has a direct impact on the stream’s physical characteristics, such as channel geometry, bed elevation, substratum composition and stability, instream roughness of the bed, flow velocity, discharge capacity, sediment transportation capacity, turbidity, temperature, etc. Alteration or modification of the above attributes may cause hazardous impact on ecological equilibrium of riverine regime. This may also cause adverse impact on instream biota and riparian habitats. This disturbance may also cause changes in channel configuration and flow-paths. The major hazards caused due to mining of sand/gravel include the following: i. Instream habitat: The impact of mining may result in increase in river gradient, suspended load, sediment transport, sediment deposition, turbidity, change in temperature, etc. Excessive sediment deposition for replenishment/ refilling of the pits affect turbidity, prevent the penetration of the light required for photosynthesis of micro and macro flora which in turn reduces food availability for aquatic fauna. Increase in river gradient may cause excessive erosion causing adverse effect on the instream habitats. ii. Riparian habitat: This includes vegetative cover on and adjacent to the river banks, which controls erosion, provide nutrient inputs into the stream and prevents intrusion of pollutant in the stream through runoff. Bank erosion and change of morphology of the river can destroy the riparian vegetative cover. iii. Degradation of Land: Mining pits are responsible for river channel shifting as well as degradation of land, causing loss of properties and degradation of landscape. iv. Lowering of groundwater table in the floodplain area: Mining may cause lowering of riverbed level as well as river water level resulting in lowering of groundwater table due to excessive extraction and draining out of groundwater from the adjacent areas. This may cause shortage of water for the vegetation and human settlements in the vicinity. v. Depletion of groundwater: Excessive pumping out of groundwater during sand mining especially in abandoned channels generally result in depletion of groundwater resources causing severe scarcity and affecting irrigation and potable water availability. In extreme cases it may also result in creation of ground fissures and land subsidence in adjacent areas. vi. Polluting groundwater: In case the river is recharging the groundwater, excessive mining will reduce the thickness of the natural filter materials (sediments), infiltration through which the ground water is recharged. The pollutants due to mining, such as washing of mining materials, wastes disposal, diesel and vehicular oil lubricants and other human activities may pollute the ground water. vii. Choking of filter materials for ingress of ground water from river: Dumping of finer material, compaction of filter zone due to movement heavy machineries and vehicles for mining purposes may reduce the permeability and porosity of the filter 9 SAND MINING 2013 material through which the groundwater is recharging, thus resulting in steady decrease of ground water resources. viii. Acid Mine Drainage- Threat to water resources: The potential for acid mine drainage is a key question. The answer will determine whether a proposed mining project is environmentally acceptable. When mined materials (such as the walls of open pits and underground mines, tailings, waste rock, and heap and dump leach materials) are excavated and exposed to oxygen and water, acid can form if iron sulfide minerals (especially pyrite, or ‘fools gold’) are abundant and there is an insufficient amount of neutralizing material to counteract the acid formation. 4.1. IMPACTS ON RIVER MORPHOLOGY. Some sections of a stream are more conducive to aggregate extraction than others. Most stream erosion takes place during high-flow events. Constant variations in the flow of the river make the channel floor and riverbanks a dynamic interface where some materials are being eroded while others are being deposited. The net balance of this activity, on a short term basis, is referred to as scour or fill. On a long-term basis, continued scour results in erosion (degradation), while continued fill results in deposition (aggradations). Removal of gravel from some aggrading sections of a river may be preferable to removing it from eroding sections. A general indicator of the stability of a stream relates to the amount of vegetation present. Gravel bars that are vegetated, or where the gravel is tightly packed, generally indicate streams where the gravel supply is in balance. Streams with excessive gravel generally have gravel bars with little or no vegetation, and are surfaced with loosely packed gravel. Even if a stream reach is eroding, aggregate mining may take place without causing environmental damage if the channel floor is, or becomes, armoured by particles that are too large to be picked up by the moving water. For example, some sections of rivers underlain with large gravel layers deposited under higher flow rates than those prevailing at the current time may support gravel extraction with no serious environmental impacts. The impacts from stream avulsion and pit capture can be avoided by constructing a levee along the stream. The levee is designed with armoured spillways that control where the levee will be “breached” by the stream during flooding. The spillway allows water to leave the channel and temporarily flow over the floodplain but keeps stream from creating a new channel and keeps the bed load in the stream. Over-extraction of gravel can destabilise channels and banks, and/or affect the ecologic functioning of rivers particularly if undertaken at the wrong time, or in the wrong place, or in a way that damages the river bed or margins. 10 SAND MINING 2013 Figure 4.1. Extensive Modification to Stream Channel Caused by Gravel Extraction (Langer, 2003) 11 SAND MINING 2013 5. ENVIRONMENTAL EFFECTS OF SAND/GRAVEL MINING i. Sand and gravel extraction can result in a number of physical, chemical, and biological effects on mined streams. Sand and gravel mining can change the geomorphic structure of streams (Sandecki 1989; Kondolf 1994), often resulting in channel degradation and erosion from mining operations located either in or adjacent to a stream. ii. Instream mining typically alters channel geometry, including local changes in stream gradient and width-to-depth ratios. Point-bar mining increases gradient by effectively straightening the stream during floods. iii. Thalweg relocation can occur when flooding connects the stream to floodplain mines. iv. Local channel scouring and erosion can occur as a result of increased water velocity and decreased sediment load associated with mined areas. v. Where mining activities are numerous and concentrated an upstream progression of channel degradation and erosion can occur-a process referred to as headcutting. Headcuts induced by sand and gravel mining can cause dramatic changes in a stream bank and channel that may affect instream flow, water chemistry and temperature, bank stability, available cover, and siltation. vi. Channel erosion from headcuts can cause loss of upstream property values; reduce recreational, fishing, and wildlife values; and contribute to the extirpation and extinction of stream fauna (Hartfield 1993). vii. The combined processes of channel incision and headcutting also can undermine bridge piers and other structures. viii. Channel incision caused by instream gravel mining on the San Luis Rey River in California exposed aqueducts, gas pipelines, and footings of highway bridges (Kondolf 1997). Sedimentation and increased turbidity also can accrue from mining activities, wash-water discharge, and storm runoff from active or abandoned mining sites. ix. Turbidity is generally greatest at mining and wash-water discharge points and decreases with distance downstream. Sedimentation and increased turbidity as a result of mining can have varying effects on fishes. x. Mining-induced changes to the geomorphic structure of the stream can significantly affect fish habitat and abundance. Instream mining can reduce the occurrence of coarse, woody debris in a channel, an important habitat for fish and invertebrates. 5.1. ENVIRONMENTAL ISSUES OF SAND MINING In Tamil Nadu, with a view to drawing the attention of the government to the magnitude of the problem and sensitising people about the risks involved, the Campaign for the Protection of Water Resources-Tamil Nadu arranged a State-level "public hearing" on the 12 SAND MINING 2013 impact of sand mining (on river basins, streams, coastal areas and hill regions). After intense studies in different regions and interaction with the affected people, the Campaign for the Protection of Water Resources, Tamil Nadu has identified 15 adverse consequences of sand mining. They include the depletion of groundwater; lesser availability of water for industrial, agricultural and drinking purposes; destruction of agricultural land; loss of employment to farm workers; threat to livelihoods; human rights violations; and damage to roads and bridges. Representatives of victims from 13 of the 28 districts of the State gave evidence on the damage caused to the environment and livelihoods in these districts. The affected river basins included those of the Palar and its tributaries Cheyyar, Araniyar and Kosathalaiyar (Kanchipuram and Thiruvallur districts); the Cauvery (Karur district); the Bhavani (Erode district); the Vellar (Perambalur district); the Vaigai (Madurai and Theni districts); and the Thamiraparani (Tirunelveli district). Victims from the coastal districts of Nagapattinam, Tuticorin, Ramanatha-puram and Kanyakumari. In Kerala, there has been a significant increase in sand mining since the beginning of the 1990s following a boom in the construction industry, and the activity reached alarming proportions in several areas, particularly in the southern and western regions of the State, after court restrictions on sand mining came into effect in neighbouring Kerala in 1994. Similarly River Bharathapuzha in Kerala has become a victim of indiscriminate sand mining. Despite numerous prohibitions and regulations, sand mining continues rapidly on the riverbed of the Bharathapuzha. Water tables have dropped dramatically and a land once known for its plentiful rice harvest now faces scarcity of water. In the villages and towns around the river, groundwater levels have fallen drastically and wells are almost perennially dry. Illegal and excessive sand mining in the riverbed of the Papagani catchment area in Karnataka has led to the depletion of groundwater levels and environmental degradation in the villages on the banks of the river in both Andhra Pradesh and Karnataka. In Karnataka, legal sand mining from the Papagani river catchment area in Kolar district, been going on for six to seven years. Initially, the Karnataka government gave sand mining rights to some contractors, but due to increased illegal and excessive mining, it has led to environmental degradation and problems for the people by the depletion of ground- water levels in the villages situated on the river banks. Moreover, as these villages are situated in the border between Andhra Pradesh and Karnataka, both the states are affected by this problem. In Megalaya, pollution of the water is evident by the colouration of water which in most of the rivers and streams in the mining area varies from brownish to reddish orange. Low pH (between 2-3), high electrical conductivity, high concentration of ions of sulphate and iron and toxic heavy metals, low dissolved oxygen (DO) and high BOD are some of the physico-chemical and biological parameters which characterize the degradation of water quality. Contamination of Acid Mine Drainage (AMD) originating from mines and spoils, leaching of heavy metals, organic enrichment and silting by sand particles are major causes of degradation of water quality in the area. Mining operation, undoubtedly has brought wealth and employment opportunity in the area, but simultaneously has led to extensive environmental degradation and disruption of traditional values in the society. Environmental problems associated with mining have been felt severely because of the region’s fragile ecosystems and rich biological and cultural diversity. Large scale denudation of forest cover, scarcity of water, pollution of air, water and soil and degradation of agricultural lands are some of the conspicuous environmental implications of coal mining (Swer and Singh, 2004). 13 SAND MINING 2013 5.2. CURRENT RULES AND POLICIES IN OPERATION Kerala: Kerala Protection of River Banks and Regulation of Removal of Sand Act, 2001 Key features: To permit sand mining in select areas and each selected area or Kadavu will be managed by a Kadavu Committee which will decide on matters such as quantum of mining to be permitted, and to mobilise local people to oversee these operations and ensure protection of rivers and riverbanks. Key rivers affected: Bharatapuzha, Kuttiyadi river, Achankovil, Pampa and Manimala, Periyar, Bhavani, Siruvani, Thuthapuzha, and Chitturpuzha, rivers in the catchments of Ashtamudi and Vembanad lakes. Tamil Nadu: Policy that ensures that quarrying of sand in Government poramboke lands and private patta lands will only be undertaken by the Government. Mechanised sand mining is prohibited. In 2008, this policy was countermanded by the government and private parties were given permits for mining. Rivers affected: Cauvery, Vaigai, Palar, Cheyyar, Araniyar and Kosathalaiyar, Bhavani, Vellar , Vaigai Thamiraparani, Kollidam. Districts of Nagapattinam, Tuticorin, Ramanatha- puram and Kanyakumari hill, regions of Salem and Erode districts. Karnataka: The Uniform Sand Mining Policy does not allow sand mining in Coastal Regulation Zone (CRZ) area and prohibits the use of machineries to mine sand from river. High Court of Karnataka banned mechanised boats for sand mining in the state from April 2011. From September 2011, according to Karnataka Minor Mineral Concession (Amendment) Rules 2011,the responsibility of oversight of sand mining has been transferred to the Public Works, Ports and Inland Water Transport Department. Rivers affected: Cauvery, Lakshmanateerta, Harangi, Hemavathi, Nethravatai, and Tungabhadra. Andhra Pradesh: In 2006, the government brought in a new policy that allows only manual labour and bullocks to mine sand in riverbeds. Bullock carts, mules and other animals would be exempted from any mining tax. Contractors will be allotted sand through open bidding by a committee headed by district joint collectors. Sand can be sold only if it has a maximum retail price tag, otherwise there will be a penalty. Use of poclaines has been banned entirely, and mining will be disallowed below three metres. Rivers affected: Godavari, Tungabhadra, Vamsadhara, Nagavali, Bahuda and Mahendratanaya. Maharashtra: New policy announced in October, 2010, under which It is compulsory for contractors to obtain permission from the Gramsabha, for sand mining. Ban on use of suction pumps in dredging and sand mining licences can be given only through a bidding process. Also sand mining projects have to obtain environmental clearances. Rivers affected: creeks at Thane, Navi Mumbai, Raigad and Ratnagiri. 14 SAND MINING 2013 6. SCIENTIFIC MINING OF SAND/GRAVEL Following geoscientific considerations are suggested to be taken into account for sand/ gravel mining:- i. Abandoned stream channels on terrace and inactive floodplains may be preferred rather than active channels and their deltas and floodplains. Replenishment of ground water has to be ensured if excessive pumping out of water is required during mining. ii. Stream should not be diverted to form inactive channel. iii. Mining below subterranean water level should be avoided as a safeguard against environmental contamination and over exploitation of resources. iv. Large rivers and streams whose periodic sediment replenishment capacity are larger, may be preferred than smaller rivers. v. Segments of braided river system should be used preferably falling within them lateral migration area of the river regime that enhances the feasibility of sediment replenishment. vi. Mining at the concave side of the river channel should be avoided to prevent bank erosion. Similarly meandering segment of a river should be selected for mining in such a way as to avoid natural eroding banks and to promote mining on naturally building (aggrading) meander components. vii. Scraping of sediment bars above the water flow level in the lean period may be preferred for sustainable mining. viii. It is to be noted that the environmental issues related to mining of minerals including riverbed sand mining should clearly state the size of mine leasehold area, mine lease period, mine plan and mine closure plan, along with mine reclamation and rehabilitation strategies, depth of mining and period of mining operations, particularly in case of river bed mining. ix. The Piedmont Zone (Bhabbar area) particularly in the Himalayan foothills, where riverbed material is mined. This sandy- gravelly track constitutes excellent conduits and holds the greater potential for ground water recharge. Mining in such areas should be preferred in locations selected away from the channel bank stretches. Areas where channel banks are not well defined, particularly in the braided river system, midstream areas should be selected x. for mining of riverbed materials for minimizing adverse effects on flow regime and instream habitat. xi. Mining of gravelly sand from the riverbed should be restricted to a maximum depth of 3m from the surface. For surface mining operations beyond this depth of 3m (10 feet), it is imperative to adopt quarrying in a systematic bench- like disposition, which is generally not feasible in riverbed mining. Hence, for safety and sustainability restriction of mining of riverbed material to maximum depth of 3m.is recommended. 15 SAND MINING 2013 xii. Mining of riverbed material should also take cognizance of the location of the active channel bank. It should be located sufficiently away, preferably more than 3m away (inwards), from such river banks to minimize effects on river bank erosion and avoid consequent channel migration. xiii. Continued riverbed material mining in a given segment of the river will induce seasonal scouring and intensify the erosion activity within the channel. This will have an adverse effect not only within the mining area but also both in upstream and downstream of the river course. Hazardous effects of such scouring and enhanced erosion due to riverbed mining should be evaluated periodically and avoided for sustainable mining activities. xiv. Mineral processing in case of riverbed mining of the sandy gravelly material may consist of simple washing to remove clay and silty area. It may involve crushing, grinding and separation of valueless rock fragments from the desirable material. The volume of such waste material may range from 10 to 90%. Therefore, such huge quantities of mine wastes should be dumped into artificially created/ mined - out pits. Where such tailings / waste materials are very fine grained, they may act as a source of dust when dry. Therefore, such disposal of wastes should be properly stabilized and vegetated to prevent their erosion by winds. xv. Identification of river stretches and their demarcation for mining must be completed prior to mining for sustainable development. xvi. The mined out pits should be backfilled where warranted and area should be suitably landscaped to prevent environmental degradation. xvii. Mining generally has a huge impact on the irrigation and drinking water resources. These attributes should be clearly evaluated for short-term as well as long-term remediation. Ministry of Environment & Forest (MoEF) also stipulates the following recommendations on mining of minor minerals/ construction materials: i. Mining Lease (ML) area should be demarcated on the ground with Pucca Pillars. ii. For river sand mining, area should be clearly specified for mining operations in the region. The area should be properly surveyed and mapped with the help of GPS to assign geo-coordinates and accordingly erect boundary pillars so as to avoid illegal unscientific mining. iii. Within the ML area, if any forest land is existing, it should be distinctly shown on the map along with coordinates. iv. While considering the sanction of ML area, due attention should be paid to the presence of any National Park/Sanctuary/Ecologically Sensitive landscape. In such cases order of the Hon’ble Supreme Court in .W.P (C) No. 337/1995) should be strictly followed. 16 SAND MINING 2013 v. For mining lease within 10 km of the National Park/Sanctuary, recommendation/ permission of National Board of Wild Life (NBWL) have to be obtained as per the Hon’ble Supreme Court order in I.A. No. 460/2004. vi. Site-specific plans with eco-restoration should be considered/ implemented. Therefore, adverse impacts of mining mentioned here should be avoided or minimized. Remedies include restoration of riparian and instream habitats, restoration of river geometry causing degradation in upstream, downstream and in the mining area, depletion and prevention of contamination of ground water etc. 17 SAND MINING 2013 7. MANAGEMENT PLAN. 7.1. In-Stream Mining Recommendations i. Permit Mining Volume Based on Measured Annual Replenishment In the first year following adoption of the management plan, a volume equal to the estimated annual replenishment could be extracted from the reach of channel. Replenishment (up to the elevation of the selected channel configuration) would need to occur before subsequent extraction could take place. The concept of annual replenishment accounts for the episodic nature of sediment transport. For example, during wet periods with high stream flows, and a high contribution of sediment from hillslopes and tributaries, monitoring data would show that sand and gravel bars are replenished quickly. During drought periods with low streamflow, and little sediment supply or transport, monitoring data would likely show that bars were replenished at a slower rate. The use of monitoring data is essential in measuring when actual replenishment occurs. The use of the concept of annual replenishment protects long-term channel stability as well as aquatic and riparian habitat by extracting a volume sustainable by watershed processes. It is important to develop a system to allocate the total estimated annual replenishment between all of the operators. ii. Establish an Absolute Elevation below Which No Extraction May Occur (Minimum Enveloped Level or Redline) The absolute elevation below which no mining could occur or “redline” would be surveyed on a site-specific basis in order to avoid impacts to structures such as bridges and to avoid vegetation impacts associated with downcutting due to excessive removal of sediment An extraction site can be determined after setting the deposition level at 1 m above natural channel thalweg elevation, as determined by the survey approved by DID. iii. Limit In-stream Extraction Methods to Bar Skimming If mining is limited to the downstream end of the bar with a riparian buffer on both the channel and hillslope (or floodplain) side, bar skimming would minimise impacts. Other methods such as excavation of trenches or pools in the low flow channel lower the local base level, and maximise upstream (headcutting and incision) and downstream (widening and braiding) impacts. In addition, direct disturbance of the substrate in the low flow channel should be avoided. Trenching on bars may be beneficial in the future if the river becomes severely aggraded, flat, shallow and braided. Trenching of bars may initially impact a smaller area of riparian habitat than skimming - as a result of excavating deeper rather than shallow skimming of a large area. However, over the long-term, the upstream and downstream effects of a trench on the bar or in the channel may offset any short-term benefit derived from this method. iv. Extract Sand and Gravel from the Downstream Portion of the Bar Retaining the upstream one to two thirds of the bar and riparian vegetation while excavating from the downstream third of the bar is accepted as a method to promote channel stability and protect the narrow width of the low flow channel necessary for fish. Sand and gravel would be redeposited in the excavated downstream one to two thirds of the bar (or downstream of the widest point of the bar) where an eddy would form during sediment transporting flows. In contrast, if excavation occurs on them entire bar after removing 18 SAND MINING 2013 existing riparian vegetation, there is a greater potential for widening and braiding of the low flow channel. v. Concentrate Activities to Minimise Disturbance In-stream extraction activities should be concentrated or localised to a few bars rather than spread out over many bars. This localisation of extraction will minimise the area of disturbance of upstream and downstream effects. Skimming decreases habitat and species diversity - these effects should not be expanded over a large portion of the study area. vi. Review Cumulative Effects of Sand and Gravel Extraction The cumulative impact of all mining proposals should be reviewed on an annual basis to determine if cumulative riverine effects or effects to the estuary are likely and to ensure that permits are distributed in a manner that minimises long-term impacts and inequities in permits between adjacent mining operations. vii. Maintain Flood Capacity Flood capacity in the river should be maintained in areas where there are significant flood hazards to existing structures or infrastructure. viii. Establish a Long-term Monitoring Program Monitoring of changes in bed elevation and channel morphology, and aquatic and riparian habitat upstream and downstream of the extraction would identify any impacts of sand and gravel extraction to biologic resources. Long-term data collected over a period of decades as sand and gravel extraction occurs will provide data to use in determining trends. ix. Minimise Activities That Release Fine Sediment to the River No washing, crushing, screening, stockpiling, or plant operations should occur at or below the streams "average high water elevation," or the dominant discharge. These and similar activities have the potential to release fine sediments into the stream, providing habitat conditions harmful to local fish. x. Retain Vegetation Buffer at Edge of Water and Against River Bank Riparian vegetation performs several functions essential to the proper maintenance of geomorphic and biological processes in rivers. It shields river banks and bars from erosion. Additionally, riparian vegetation, including roots and downed trees, serves as cover for fish, provides food source, works as a filter against sediment inputs, and aids in nutrient cycling. More broadly, the riparian zone is necessary to the integrity of the ecosystem providing habitat for invertebrates, birds and other wildlife. xi. Limit In-stream Operations to the Period between May and September The in-stream mining should only be allowed during the dry season. xii. An Annual Status and Trends Report This report should review permitted extraction quantities in light of results of the monitoring program, or as improved estimates of replenishment become available. The report should document changes in bed elevation, channel morphology, and aquatic and riparian habitat. The report should also include a record of extraction volumes permitted, and excavation location. Finally, recommendations for reclamation, if needed should be documented. 19 SAND MINING 2013 7.2. Off-Channel or Floodplain Extraction Recommendations i. Floodplain Extraction Should Be Set Back from the Main Channel In a dynamic alluvial system, it is not uncommon for meanders to migrate across a floodplain. In areas where sand and gravel occurs on floodplains or terraces, there is a potential for the river channel to migrate toward the pit. If the river erodes through the area left between the excavated pit and the river, there is a potential for "river capture," a situation where the low flow channel is diverted though the pit. In order to avoid river capture, excavation pits should set back from the river to provide a buffer, and should be designed to withstand the 100-year flood (100-year ARI). Adequate buffer widths and reduced pit slope gradients are preferred over engineered structures which require maintenance in perpetuity. Hydraulic, geomorphic, and geotechnical studies should be conducted prior to design and construction of the pit and bund. In addition to river capture, extraction pits create the possibility of stranding fish. To avoid this impact, all off-channel mining should be conducted above the 25-year ARI level. ii. The Maximum Depth of Floodplain Extraction Should Remain above the Channel Thalweg Floodplain pits should not be excavated below the elevation of the thalweg in the adjacent channel. This will minimise the impacts of potential river capture by limiting the potential for headcutting and the potential of the pit to trap sediment. A shallow excavation (above the water table) would provide a depression that would fill with water part of the year, and develop seasonal wetland habitat. An excavation below the water table would provide deep water habitat. iii. Side Slopes of Floodplain Excavation Should Range from 3:1 to 10:1 Side slopes of a floodplain pit should be graded to a slope that ranges from 3:1 to 10:1. This will allow for a range of vegetation from wetland to upland. Steep side slopes excavated in floodplain pits on other systems have not been successfully reclaimed, since it is difficult for vegetation to become stabilised. Terrace pits should be designed with a large percentage of edge habitats with a low gradient which will naturally sustain vegetation at a variety of water levels. iv. Place Stockpiled Topsoil above the 25-year Return Period or ARI Level Stockpiled topsoil can introduce a large supply of fines to the river during a flood event and degrade fish habitat. Storage above the 25-year flood (25-year ARI) inundation level is sufficient to minimise this risk. v. Floodplain Pits Should Be Restored to Wetland Habitat or Reclaimed for Agriculture There are very few examples of successfully restored or reclaimed extraction pits on river systems. The key to successful restoration or reclamation is to conserve or import adequate material to re-fill the pit, while ensuring that pit margins are graded to allow for development of significant wetland and emergent vegetation. vi. Establish a Long-term Monitoring Program A long-term monitoring program should provide data illustrating any impacts to river stability, groundwater, fisheries, and riparian vegetation. The monitoring program should assess the success of any reclamation or restoration attempted. 20 SAND MINING 2013 vii. An Annual Status and Trends Report The status and trends report described previously should include a section on the hydrologic and biologic components of floodplain pit reclamation. 7.3. Reclamation Plans In-stream reclamation plans should include: i. A baseline survey consisting of existing condition cross-section data. Cross-sections must be surveyed between two monumental endpoints set back from the top of bank, and elevations should be referenced to JUPEM’s bench mark; ii. The proposed mining cross-section data should be plotted over the baseline data to illustrate the vertical extent of the proposed excavation; iii. The cross-section of the replenished bar should be the same as the baseline data. This illustrates that the bar elevation after the bar is replenished will be the same as the bar before extraction; iv. A planimetric map showing the aerial extent of the excavation and extent of the riparian buffers; v. A planting plan developed by a plant ecologist familiar with the flora of the river for any areas such as roads that need to be restored; vi. A monitoring plan. 21 SAND MINING 2013 8. APPROPRIATE EXTRACTION METHODS i. Bar scalping or skimming. Bar scalping or skimming is extraction of sand and gravel from the surface of bars. Historical scalping commonly removed most of the bar above the low flow water level, leaving an irregular topography. Present method generally requires that surface irregularities be smoothed out and that the extracted material be limited to what could be taken above an imaginary line sloping upwards and away from the water from a specified level above the river's water surface at the time of extraction (typically 0.3 - 0.6 m (1-2 ft)). Bar scalping is commonly repeated year after year. To maintain the hydraulic control provided to upstream by the riffle head, the preferred method of bar scalping is now generally to leave the top one-third (approximately) of the bar undisturbed, mining only from the downstream two-thirds. Figure 8.1. Aggregate being “skimmed” off the surface of a bar (Langer, 2003) ii. Dry-Pit Channel Mining Dry-pit channel mines are pits excavated within the active channel on dry intermittent or ephemeral stream beds with conventional bulldozers, scrapers and loaders. Dry pits are often left with abrupt upstream margins, from which headcuts are likely to propagate upstream. 22 SAND MINING 2013 iii. Wet-Pit Channel Mining. Wet-pit mining involves excavation of a pit in the active channel below the surface water in a perennial stream or below the alluvial groundwater table, requiring the use of a dragline or hydraulic excavator to extract sand and gravel from below the water surface. In some areas, such as low terraces, some glaciofluvial deposits, and some ephemeral streambeds, sand and gravel mining may penetrate the water table and may be mined wet or dry. In some geologic settings, wet pits can be made dry by collecting the groundwater in drains in the floor of the pit and pumping the water out of the pit. Figure 8.2. Wet-pit Channel Mining. iv. Bar Excavation A pit is excavated at the downstream end of the bar as a source of aggregate and as a site to trap sand and gravel. Upon completion, the pit may be connected to the channel at its downstream end to provide side channel habitat. On the Russian River, California, recent proposals for bar mining include leaving the bar margins untouched and excavating from the interior of the downstream part of the bar, but above the water surface elevation, a variant intermediate between bar scalping and bar excavation. 23 SAND MINING 2013 Figure 8.3. Bar excavation v. In-stream Gravel Traps Sand or “bed load traps” have been used to reduce sand in downstream channels for habitat enhancement in Michigan. Such traps can also be potential sources of commercial aggregate, provided the amounts so collected are sufficient to be economically exploited. One advantage of the traps as a method for harvesting sand and gravel are the concentration of mining impacts at one site, where heavy equipment can remove sand and gravel without impacting riparian vegetation or natural channel features. Sand and gravel can be removed year after year from the bed load trap. An idealized trap has short dikes to create a constriction downstream and to hold the resultant higher stages. Sand and gravel are removed from the downstream end of the deposit, and a grade control structure at the upstream end of the trap prevents headcutting upstream from the extraction. There is no hydraulic impact upstream due to the extraction, because the engineered constriction is the hydraulic control during high flows. The concentrated flow scours a deep pool immediately downstream from the constriction, which may be important habitat in aggrading reaches where pool formation is limited by deposition. Figure 8.4. Idealized gravel trap (Source: Bates 1987). vi. Channel-wide In-Stream Mining In rivers with a highly variable flow regime, sand and gravel are commonly extracted across the entire active channel during the dry season. The bed is evened out and uniformly (or nearly so) lowered. 24 SAND MINING 2013 9. SUMMARY AND RECOMMENDATIONS In the past 3–4 decades, rivers in the densely populated areas of the world are subjected to immense pressures due to various kinds of human interventions, among which indiscriminate mining for construction grade sand from alluvial reaches is the most disastrous one. This is mainly because of the fact that uncontrolled scooping of sand aggravates river degradation and threatens its tropic structure. The situation is rather alarming in the small rivers of India, which support the life and greenery of the region. Loss of riparian and instream vegetation, changes in the feeding, breeding and spawning grounds of aquatic organisms including fishes not only impose stress in the river ecology but also create damages in the terrestrial and nearshore marine environments as well. There is very much need for laying down strategies for regulating the mining activities on environment friendly basis and also for creating awareness on the impact of river sand mining on the physical and biological environment of these life support systems. Given below are some of the recommendations suggested to improve the overall environmental quality of the river systems of India, in particular. i. An integrated environmental assessment, management and monitoring program should form part of the sand extraction processes. Also, there is an urgent need for integrating the studies on various disciplines on the human induced degradation of the small catchment rivers of India. ii. Evaluate physical, chemical and biological effects of instream mining on a river basin scale, so that cumulative effects of extraction on the aquatic and riparian resources can be recognised and addressed at various levels for proper remedial measures. iii. Examine and encourage alternatives to river sand for construction purposes. Immediate steps are to be taken to intensify research activities leading to the finding of a suitable, low cost and easily available alternative to river sand. iv. Evaluate control measures such as bank stabilisation, revegetation of buffer strips, influences of connected floodplain pits etc. Restoration efforts should concentrate on techniques that will optimise fish production, promote aquatic diversity and restore biotic integrity. v. Awareness campaign should be conducted at various levels about river sand mining, present state of environment of rivers and immediate need for control measures. 25 SAND MINING 2013 10. REFERENCES Kundolf, G.M., 1997. Hungry Water: Effects of dams and gravel mining on river channels. Environmental management, Vol.21, No.4; pp.533-551. Kondolf G M (1994) Geomorphic and environmental effects of instream gravel mining. Landuse and Urban Planning 28:225–243 M. Naveen Saviour. Environmental Impact of Soil and Sand mining: A Review. International Journal of Science, Environment and Technology, Vol. 1, No 3, 2012, 125 – 134 (2012). Binoy Aliyas Mattamana, Shiney Varghese, Kichu Paul., River Sand Inflow Assessment and Optimal Sand Mining Policy Development. International Journal of Emerging Technology and Advanced Engineering, ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 3, Issue 3, March 2013. CSE (Centre for Science and Environment) (2012), ‘Grains of Despair: Sand mining in India’,[Online] Available: http://www.cseindia.org/node/3878(Accessed 11th Dec, 2012) Coastal Regulation Zone Notification (2011), Ministry of Environment and Forests. The Gazette of India, Extraordinary, Part-II, Section 3, Sub-section (ii) of dated 6th January, 2011) River sand mining management guidelines 2009, Ministry of Natural Resources and Environment. Department of Irrigation and Drainage, Malaysia 26
"ISSUES AND CHALLENGES IN RIVER MANAGEMENT DUE TO EXCESSIVE SAND MINING"