KN-12
Transcription
KN-12
Conservation and Restoration of Lakes and wetlands K.K.Vass Central Inland Fisheries Research Institute, Barrackpore, Kolkatta , India. Structure ¾General status ¾Concerns ¾Why conserve ¾Restoration Lakes and wetlands Lakes and wetlands are ecosystems whose formation, processes and characteristics are determined by water These ecosystems are diverse, both in terms of physico-chemical, biological, and socio-economic characteristics as well as geographical distribution Floodplains, marshes, deltas, swamps, peat lands, bogs, reservoirs, rivers and lakes are all types of wetlands Lake A lake (from Latin ligacus) is a body of water of considerable size contained on a body of land. Relatively large body of slow-moving or standing water that occupies an inland basin. Inland body of standing water occupying a hollow in the earth's surface. Wetlands definition According to Ramsar Convention (Article 1.1), wetlands are defined as “areas of marsh, fen, peat land or water, whether natural or artificial, permanent or temporary, with water that is static or flowing, fresh, brackish or salt, including areas of marine water, the depth of which at low tide does not exceeds six meters”. In addition, the Ramsar Convention (Article 2.1) provides that wetlands “may incorporate riparian and coastal zones adjacent to the wetlands, and islands or bodies of marine water not deeper than six meters at low tide lying within wetlands”. Classification of wetland types (Ramsar Convention) 1) Lacustrine wetlands (wetlands associated with lakes) 2) Riverine or floodplain wetlands (wetlands along river or streams), 3) Palustrine (marshes, swamps, and bogs) 4) Marine (coastal wetlands, including rocky shores and coral reefs) 5) Estuarine (including deltas, tidal marshes and mangroves) 6) Artificial water bodies (fish ponds, reservoirs and artificial lakes). It is generally understood that wetlands occupy the transitional zone between permanently wet and generally dry environments. MAIN FEATURES ¾ Lakes/Wetlands of all sizes and morphometric characters ¾ Both Open and Closed ¾ Formed through natural and manmade processes ¾ Most of these have heavy component of macrophytes ¾ Have both onsite and offsite benefits ¾ Have multi-user operations ¾ Large human settlements around them ¾ Urban and Peri-Urban settings Distribution of lakes and wetlands over the world . Colour code is the percentage coverage by a pixel height of 1 degree, i.e. 1 nm2 or 3.43 km2. (Darras et al. 1998) Fresh water covers approximately 8% of terrestrial surface Only 10% of world’s lakes are located in the tropics Global view on water and fish production frozen ground lakes saline soil moisture rivers atmosphere World's water resources Inland water 2% frozen 88 % Inland water ground 12 % saline 0.31 % Fish species Capture Aquaculture Total production atmosphere 0.04 % rivers 0.004 % Other 1% lakes 0.38 % Oceans 98 % Oceans 60 % 80 % 5% 85 % soil moisture 0.20 % Inland waters 40 % 9% 6% 15 % Tropical lakes 0.04 % Size and depth distribution of tropical lakes • • • • Natural lakes in the tropics are rare except for Africa (Rift Valley) Asia and South America possess few natural lakes but have many reservoirs Based on water surface alone Africa seems to have large potential for enhancements Swamps, floodplains, shallow lakes and reservoirs = 57% of the total water surface area Lakes vs. reservoirs Characteristics Lakes Qualitative (absolute) difference Nature natural Geological age old Aging slow Formed by depressions Shape regular Shore development ratio low Maximum depth near centre Bottom sediments autochthonous Gradients wind-driven Outlet surface/none Quantitative (relative) difference Ratio watershed/lake area low Retention time high Coupling with watershed less Morphometry U-shaped Level fluctuations less Hydrodynamics more regular Cause of pulses natural Reservoirs man-made young rapid (first few years) river valleys dendritic high extreme (at the dam) allochthonous flow-driven deep high low great V-shaped great highly variable man-made drawdowns Major wetland/lake resources in India Assam West Bengal Bihar Uttar Pradesh Uttarakhand Himachal Jammu & Kashmir North East States Coastal States The biological base for productivity Food webs are often shorter in the tropics: Tropical lakes Temperate lakes Fish B A Phytoplankton A = Crustacea B = Rotifera and Protozoa Bacteria Detritus Fish B A Phytoplankton Bacteria Detritus WATER RESOURCES RIVERS WETLANDS & FLOODPLAINS LAKES/LAGOONS ESTUARIES RESERVOIRS Area estimates of wetlands in India excluding rivers and canals (in million ha) Area under paddy cultivation 40.9 Area suitable for fish culture 3.6 Area under capture fisheries (brackish and freshwater) 2.9 Mangroves 0.4 Estuaries 3.9 Backwater 3.5 Man-made impoundments 3.0 Rivers, including main tributaries (28,000 km) Canals and irrigation channels (113,000 km) Total Area of Wetlands (Excluding Rivers) 58.2 mill. ha (Source: Directory of Asian Wetlands, IUCN, 1989). Trophic classification Measured parameter Oligotrophic Mesotrophic Eutrophic Total Phosphorus (mg/m3) 3 - 18 10 - 95 16 – 386 Chlorophyll a (mg/m3) 0.3 - 5 3 – 11 3 – 78 Secchi Disk Depth (m) 5 - 28 2–8 0.8 – 7 Data from Wetzel, 1983 Above classification is important tool in Management strategy. CONCERNS Rapidly deteriorating Since 1900, more than half of the world such water bodies have disappeared About 50,000 ha area of wetlands / lakes is degraded every year in Asia There are many stakeholders whose diverse interest lay claim on the ecosystem function Agricultural producers drain and convert them to agricultural land Water abstraction for drinking, irrigation, industries and human settlements. Soil acidification, erosion, nutrient loss Hydrological changes Loss of biodiversity and ecosystem functions. Concerns contd… Majority Neglected ecosystems with very little or no management inputs Common Property Resources, for everyone to use but none to pay for services and take care. Reclaimed and transformed into unplanned urban, agricultural or aqua culture production sites causing huge economic and ecological damage and loss in the long-term 70-80% of the wetlands in the Ganga basin have been lost in the last 50 years Rate of wetland loss in India is at 2 to 3% of area every year Mangrove wetlands have reduced from 700,000 ha. to 453,000 ha. in India Lack of co-ordination and complicity and contradictory objectives of policies have led to unwise, unsustainable and destructive exploitation of wetlands Destructive Fishing & De-silting a lake Causes for loss About 12% of wetland loss is through hunting and associated disturbances About 22% were lost to human settlements 19% to fishing and associated disturbances 25% through drainage for agriculture Soil erosion and siltation contribute to over 12 % of wetland loss Nearly 10 % due to pollution from industries Pollution Load from Domestic & Industrial Sources 25000 (63%) Domestic 20000 Industrial 15000 (37%) (68%) 10000 (32%) 5000 (66%) (34%) 0 Wastewater(MLD) BOD(t/d) BOD reduction(t/d) Metal Contamination in Different Components Metal Levels (μg g-1) Components Hg Zn Cu Pb Cd Water 0.01 – 0.37 14 – 363 1 – 26.3 12.4 – 63.1 3.3 – 5.6 Macrophytes (different types) 1.65 – 3.04 68 – 310 NE NE NE Fishes (mainly carps) 0.075 – 0.370 11.5 – 37 NE NE NE Sediment metals in Indian rivers (ppb) Zn 120 Cu 100 80 • Metals levels in water and sediments are moderate, except near pollution zones. • Concentration of some organochlorine pesticides in water are above permissible limits • Metals and pesticides in fish flesh are within the safe levels. • Some pesticides and metals get biomagnified in food-chain to high levels 60 40 20 0 Ganga Mahanadi Godavari Krishna Cauvery Narmada River Total residue (ppt) Permissible limit exceeded by Ganga river system 17 - 80 4,4’-DDT aldrin dieldrin Biomagnification of DDT in aquatic food chain (ppb) Organochlorine pesticides in fish of river Ganga 120 Bivalve 950 100 Plankton 150 Fish 450 Gastropod 220 R e s id u e c o n c . in p p b Water 0.06 Sediment 70 80 60 40 20 0 L. dero L. dero C. mrigala R. rita Rishikesh Hardwar Farukhabad Kanauj Residue (ppb) 17 23 45 74 R. rita C. garua R. rita Kanpur Varanasi Patna 33 100 26 A. aor R. rita A. gagora Farakka Barrackpore Haldia 74 90 16 Sectors contributing to modification of lakes/wetlands Anthropogenic Activities Industrial Domestic Agriculture Urbanization Discharges to Wetlands √ √ √ √ Non-point Source Pollution √ √ √ √ Air pollutants √ X X √ Toxic chemicals √ √ √ X Deposition of fills √ √ √ √ Construction X √ √ √ Crop production X X √ X Siltation √ √ √ √ Changing nutrient levels √ √ √ X Tourism/ recreational X X X √ Physical modification √ √ √ √ WHY CONSERVE THESE WATERS ? These critical resources are important for : Providing ecosystem services, livelihoods & cultural services Through the provision of regulating services and products which generate socio-economic benefits they are vital to the livelihood strategies of local communities These different services vary from site to site, especially with the type of wetland REGULATING SERVICES >Water storage >Groundwater recharge & discharge >Flood control & river regulation >Water purification >Sediment retention >Climate regulation LIVELIHOOD SERVICES >Water supply - domestic & animals >Agriculture resources >Fisheries >Forage resources >Craft materials >Medicinal plants CULTURAL SERVICES >Biodiversity >Cultural sites >Tourism >Human settlement Stakeholders Goods & Services ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ Fishers Agriculture Farmers Water Managers Local Community Recreation Transport Eco-Tourism Jute Industry Economic value of wetlands When wetlands are drained or degraded, there is a financial cost incurred by society to replace the ecological goods and services provided by these ecosystems, such as > Increased water treatment costs > Increased illness and health care costs ¾ Shortage in irrigation water ¾ Water hauling and making deeper wells > Increased insurance costs due to flood damages > Decreased property value due to degraded aesthetic qualities > Decreased swimming/fishing opportunities > Decreased revenues from tourism activities associated with healthy ecosystems Cultivation of Makhana in wetlands, a gainful employment in parts of Bihar and UP. Lotus seeds from wetlands; means of livelihood from weed choked wetlands in Bihar. Lotus rhizome used as vegetable in Kashmir lakes- good trade. Harvesting Trapa from a wetland in Bihar; additional livelihood for fishers Gastropods form a sizeable portion of the benthic fauna in wetlands. Species like Pila/Belamya harvested from wetlands being consumed by local people. Lakes / Wetlands being used as channels for transportation often causing environmental disturbance Fishing & Fishery in Lakes / Wetlands Subsistence fishing support livelihoods of hundreds of people living around lakes/ wetlands, especially women and children Fishing with plunging net, a common sight In wetlands of Assam, in the northeast India A variety of fishing methods are being used to fish from wetlands Fishing in a wetland for Indian major carps using drag net Indian major carps are being regularly stocked and fished when they reach harvestable size (>200g) in wetlands, which are managed by cooperative societies in West Bengal and Assam Wild - Fishing and Pollution Fish Marketing Man made floating islands, made of aquatic vegetation, in Loktak lake, Manipur. A local contraption for aggregating and capturing fishes. Several people live in huts built on these floating islands Majority of the lakes/ wetlands in the country are weed infested, affecting their productivity. Paddy cultivation along the marginal areas of wetlands in Bihar, West Bengal cause encroachment and reduction in water spread. Jute retting, a cause for degrading water quality in several wetlands in West Bengal. Jute cultivation bring additional income and firewood/thatching material for fishers’ housing Major Fishes of food value Catla catla Cirrhinus mrigala Three Indian major carps being stocked in wetlands under culture based fishery management Labeo rohita Minor Fishes of food value Channa punctatus Channa marulis Anabas testudineus Badis badis Ornamental fishes Colisa lalia Colisa sota Devario devario Chanda nama Ornamental fishes Puntius conchonius Rasbora daniconius Tetradon cutcutia Rasbora rasbora Production (000 t) State Area (ha) Existing Potential West Bengal 42.5 9.56 53.15 Bihar 40 4.80 30.00 Assam 100 12.00 95.00 Uttar Pradesh 152 22.80 114.00 Other NE states Total 19.2 353.7 1.49 50.65 % Projected Gap increase Increase 43.59 455.96 4.6 fold 25.20 525.00 5.3 fold 83.00 691.67 6.9 fold 91.20 400.00 4 fold 15.78 14.29 307.93 257.28 959.06 507.96 9.6 fold 5 fold Production enhancement methods Environmental impact Production potential per unit area versus spatial scale of production units of the various methods used in lakes and reservoirs. Arrow indicates the perceived increased environmental impacts moving from natural harvest to intensive culture. (Ranges of production are tentative) Sustainable Fishery Development System Analysis ¾ ¾ ¾ Production Function Estimates Biodiversity Assessment Identification of Interventions Fishery Enhancement ¾ ¾ Stock Manipulation Pen-culture & Cage-culture Awareness & Participation Network Formation Economic Value of the Muthurajawela Wetland (3068ha), Sri Lanka Annual economic value (converted to 2003 US$) Flood attenuation 5,033,800 Industrial wastewater treatment 1,682,841 Agricultural production 314,049 Support to downstream fisheries 207,361 Firewood 82,530 Fishing 64,904 Leisure and recreation 54,743 Domestic sewage treatment 44,790 Freshwater supplies for local populations 39,191 Carbon appropriation TOTAL ECONOMIC VALUE The Economic Value of the World’s Wetlands: WWF 8,087 7,532,297 RESTORATION Dal Lake Wular lake Harike lake Jheels in the vicinity of Haidergarh Dahar and Souj jheel Southern gulf of Kutch Gulf of Khambhat Dipor(deepar) beel Loktak lake Salt lake swamp The Sundarbans Chilka Lake Kolleru lake Estuaries of Karnataka Coast Kaliveli Tank and Yedayanthittu Estuary The Cochin backwater Wet lands in the Andaman and Nicobar Island Conservation Conservation is management of resources to maximize efficiency of use, minimize wastage and preservation for future. Resources such as lakes/wetlands vary over time and space, their conservation requires reserves that can be maintained and managed so as to ensure the supply of their goods and services for future and do not reduce options or impoverish future generations. Restoration The act of correcting an error or a fault or an evil. This is the action to be taken to correct, to the possible extend, the aberrations happened. Regulation, Policy & Integration ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ ¾ Most Complex & Difficult to implement technologies at field level Water a State Subject, Centre Advisory Role Departmental Ownership & Control Privately Owned only a Few Multiple Users/Beneficiaries Policy Support Varies, State to State Regulation, for declared protected sites only For others Fragmentary in Nature Cooperatives for Fishery, only in a few Integration/Network with Water as Focus ? Success story of Chilka restoration largest lagoon along the east coast of India and a Ramsar site Shelters a number of endangered species listed in the IUCN red list of threatened species Livelihood of more than 0.15 million fisher folk Water quality deteriorated Fish production declined Salinity dropped Sand bar blocked the connecting channel to the sea Placed in the Montreux record in the year 1993 by Ramsar bureau due to change in its ecological characters Restoration Desiltation of the lead channel and an artificial mouth was opened on 23rd September 2000, which reduced the length of the outflow channel by 18 km Sand bar formation along the mouth of Chilka lagoon Monitoring results indicated that there is a marked improvement in the lagoon ecosystem Opening a new mouth was a hard strategy, which restored Chilka environment Improvement Fishers’ annual income increased by more than Rs. 50,000 per family Improvement in fish landing in Chilka Chilka is removed from the Montreux record in 2003 2005-06 2004-05 2003-04 2002-03 2001-02 1999-00 After 1998-99 1997-97 Before 2000-01 16000 14000 12000 10000 8000 6000 4000 2000 0 1996-97 Fish+Prawn+Crab landinf (M. T) The fish landing improved substantially OTHER LAKES UNDER GOI NATIONAL LAKE CONSERVATION PLAN MAASIVE EFFORTS HAVE BEEN MADE FOR OTHER LAKES ALSO. SOME ARE : DAL LAKE – MANY INITIATIVES TAKEN STILL IMPACT IS NOT VISIBLE BHOPAL LAKE – AFTER INTERVENTION SOME IMPROVEMENT IS REPORTED. NAINITAL LAKE – ACTION PLAN UNDER IMPLEMENTATION HYPOLIMNION AREATION BEING TESTED. LOKTAK LAKE – MASSIVE EFFORT IMPROVEMENT TO BE ON SUSTAINABLE BASIS. Massive growth of Macrophytes Dal Lake before and after dredging operations Removal of illegal "Radhs" (Floating Gardens) from Dal Lake Mechanical and traditional method of deweeding Dumping & transportation of weeds in progress Save Lakes / wetlands water for food – water for life.