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UTILISATION OF WATER RESOURCES AND IRRIGATION DEVELOPMENT

Irrigation development in INDIAN sub-continent

Irrigation & water management in ancient India from history:

Main water resources in ancient India (from literature & history) are wells, tank, canals and bundhs ( small dams)During the period of Chandragupta irrigation systems were mostly state owned, though private irrigation facilities were also existed.Farmers paid tax for the utilization of irrigation system

The amount of tax depend upon to extend of area irrigated and amount of crop produced.A quotation about prosperous irrigated agriculture in India from Pali works and epics: The khettas of Magadha (the land of bhudha) were intersected by network of canals and ridges.. Watering projects were undertaken by specialists who conducted the water as they pleased. The importance of efficient water management in ancient India in the words of Magasthenes (Greek Ambassador in the court of emporer Chandraguptha in about 300 BC): The whole country was under irrigation and very prosperous because of two crops grown in an year with irrigation facilities .. The district officers measure the land and inspect the sluices by which water is distributed into the branch canals so that every one may get his fair share of the benefit.

The most famous ancient irrigation work one still functioning is The Grand Anicut on the Kaveri at the head of its delta in Tamilnadu.The dam was originally built by Karikala Chola around first century AD. The idea behind constructing dam was divert the river to the delta districts thereby boosting irrigation.The diversion weir was subsequently enlarged in A.D 1880 with the massive irrigation distribution system from the head works an area of 4,00,000 ha is being irrigated for centuries.

LESSONS FROM THE PAST

The birth place of modern irrigation - Punjab (land of five rivers) -(satluj, bes, Ravi, chenab, jhelam) During the first half of the 19th centuary a number of diversion works were constructed across Ravi and satluj rivers.Main innovation during that period was introduction of barrages with mechanically controlled sliding gates.By mid-1940s , the total irrigated area in British India was 20 million ha which was double than that of 1900 AD.With partition 30% of irrigated area on the Indus system went to Pakistan.

Water resources development in Pakistan

Country lies mainly within the catchment area of the Indus system of rivers (one of the largest river basin in the world)Physio graphfic classification of the country: 1. The Himalayan mountain ranges (north western part of the border with India and China) 2. The Hindu kush and the western mountains in the north on the boredr with Afghanistan 3. The potwar plateau south of Islamabad 4. The west Indus plain (largly made upof deep alluvium, deposited by the Indus river and its tributaries) 5. The Baluchistan plateau in the south-west, with an average altitude of about 600m

The total cultivable are of Pakistan was estimated at about 30 million ha, concentrated mainly in the Indus plain.Canal irrigation system - one of the worlds largest continuous canal network in the world.8 principal canals, over 20 river diversion works and dams, the Mangala dam on Jhelum, and the Terhala dam on the Indus. Net irrigated area in 1999 was 17.95 million ha but in 2008 it raised upto 19.9 million haThe run-off is harnessed for irrigation by weirs or temporary diversion structures .Farmers divert the spate flow onto their fields by constructing bunds Flood recession cropping areas utilizes the moisture retained in the crop root zone after the flood subsides.

Irrigation is the mainstay of food security and sustainability in Pakistan with its predominantly semi-arid and arid climates.The major challenges facing sustainability are water logging and salinityThe total water loss have been estimated to be 35% of the water reaching the canal outletWith the introduction of large scale irrigation in Indus basin, ground water level increased, water logging and salinity rendered extensive areas unproductive.Two major surface drainage projects were undertaken, namely sukh-Beas drainage scheme and left bank overfall drainage

WATER RESOURCE DEVELOPMENTIN BENGLADESH

The country is endowed with fertile soil, abundant water resources and a high ratio of cultivators to land.But the agricultural productivity is very lowA greater part of Bangladesh lies within the combined Ganga- Brahmaputra- Meghana river system. The rivers over flow their banks with about 3.2 to 4 million ha getting flooded every year.(total land area 14.4 million ha)The flood protection plan envisages the construction of embankments along the major rivers, development of a network of drainage canals and the improvement of river sections to facilitate flow To prevent tidal salt water intrusion and flood during monsoon coastal embankments(earthen) are constructed. automatic flap gates installed on the outlet structures to prevent salt water intrusion into adjoining land.

Irrigation through major canals covers only 6% of the total irrigated area, remaining through low lift centrifugal pumps drawing water from rivers, creeks and ponds, shallow tube wells and deep tube wells and manually operated water lifts.In Bengladesh the conjunctive use of surface and ground water has the following specific applications: a) inside large scale irrigation schemes, ground water pumping can bring highland areas within the project under ground water irrigation and lower the water table and prevent water logging. b) facilitate ground water recharge from major rivers by lowering ground water levels c) use ground water where it is plentiful to allow the scare surface water to be used in areas with inadequate ground water resources

WATER RESOURCES DEVELOPMENT IN CHINA

The distribution of water resources is temporal and spatial as like in India.About 80% of rivers flow through southern regionMore than 50,000 rivers; 1000 of which have their basin areas exceeding 1000km2 2 types of rivers 1) discharging into the seas , 2) inland rivers - which run into depressions into the interior

China has over 22000 large dams, constituting about 45% of the large dams in the worldAn estimated about 85000 dams of all types are in operation in China, excluding small farm-scale irrigation dams and mini and micro-hydro power units.90 dams of over 60 meters height were under construction in 2000 AD2.3 million water wells have been constructed in north chinaOver 1,77,000 km of dikes have been constructed for flood control and prevention of salt water intrusion.

Classification based on irrigated area: 1)large irrigation districts -cover areas over 20,000 ha 2)medium districts - 20,000ha- 667ha 3)small districts - under 667 ha Large and medium irrigation districts are administered by special government organizationsSurface irrigation method is adopted for irrigate 99% of the total irrigated area1% by sprinkler and micro irrigation methods.

WATER RESOURCES DEVELOPMENT IN BHUTAN

3 major landform features of Bhutan 1)southern foothills 2)the inner Himalayas 3)higher HimalayasBhutan has swiftly flowing rivers and streams passing through its valleysOnly 1 river in the country flows to the north directionIrrigation schemes are classified according to their origin (a) indigenous systems, with little or no government assistance (b)farmer initiated irrigation systems constructed by the beneficiaries with technical and other government assistance (c) government owned irrigation systemsThe bulk of the irrigation is through river and stream diversions

WATER RESOURCES DEVELOPMENT IN NEPAL

Country is located in the Ganges basin has 14.8 million ha of land area.The major physiographic units in Nepal : 1. the high Himalayas in the north (23.4% of the land area) 2. the mid hills in the central region (56.2%) 3. the plains in the south (20.4%)More than 6000 rivers, which drain into Ganga riverThe five main river basins in nepal 1. the Mohakali river basin 2. the Karnali river basin 3. the Gandhaki river basin 4. the Kosi river basin 5. the Southern river basinDeep and shallow aquifers are present in plain regions and siwalik valleys

In ancient times farmers cut canals from banks of rivers for irrigate the land areasFirst well designed irrigation system was on 1924Major irrigation developmental projects was through five year plansNet irrigated area in 1999 was 1.135 million ha

WATER RESOURCES DEVELOPMENT IN SRI LANKA

Rivers are flowing in different directions (radial pattern)103 rivers and streamsMahaveli Ganga - largest and the longest riverPhysiographic units 1)plains 2) midland 3) central high land regionsUneven distribution of rainfallTank irrigation is a common method from ancient times shallow open wells and tube wells for domestic and irrigation purposesFirst dam was constructed in 504 BCLargest multi purpose scheme Mahaveli (irrigation and hydro power generation)

WATER RESOURCES DEVELOPMENT IN MYANMAR

Rich surface water sourcesTopographical regions 1.northern and western mountains 2. the eastern plateau 3. central basin 4. coastal stripMajor river basins 1. Irrawady 2. Chindwin 3. Rangoon riversThe river diversion works and tanks constructed in the period of 11th century AD

WATER RESOURCES DEVELOPMENT IN AFGANISTAN

Main source of water - run-off from snow meltMajor source of irrigation water - surface or ground water (depends upon the temporal and spatial distribution of rain)More than 80% of countries water resources originated from Hindu Kush mountain ranges which act as a natural storage of water in form of iceMajor four river basins 1) Amu Darya Basin 2) Helmand river Basin 3) Indus river basin 4) Western river basinPossesses huge reserves of ground water due to increased irrigation and domestic water supply requirements

Spate irrigation - Spate irrigation is a water resource management system in which flash floodwater is diverted from a temporarily flowing watercourse to irrigated fieldsAfghanistan is a vulnerable country in terms of weather and water related events because weather forecasting had been banned as it was considered to be sorcery. Before 1980, there were about 18 well equipped meteorological and hydrological stations. These stations were the main source of data for the planning & operation of water resource systems. All these stations completely destroyed and presently no information is being collected for the analysis of the present situation.Irrigation systems - a) traditional irrigation systems b) modern irrigation systems

Traditional irrigation systems 1) Small-scale informal surface water systems 2) Large-scale informal surface water systems 3) Shallow wells (Arhad) system 4) Springs 5) Karez (qanat) systemsModern Irrigation Systems 1) Formal surface water systems without storage 2) Formal surface water systems with storage 3) Formal ground water systems

Small-scale informal surface water systems:These are centuries old systems. Water is supplied by stream flow diverted with the help oftemporary brush weirs. They are often located in remote valleys along a stream or river andvary in size (up to 100 ha). These systems are constructed and maintained in a traditionalinformal manner on a communal village basis and water rights are also determined andrecognized in the similar manner.Shallow wells (Arhad) system:Ground water is lifted from shallow wells with the help of Persian wheel (arhad) supplyingirrigation water to the fields of an individual farmerFormal surface water systems without storage:They have a permanent intake structure, which is operated and maintained by the IrrigationDepartment30

Overall efficiency is only about 25 to 30 per cent for both modern and traditional irrigation schemes due to the following reasons: 1) high conveyance losses in traditional schemes with earth canals, 2) high operation losses in modern schemes with lined conveyance canals, 3) high on-farm distribution losses (over-irrigation, poorly levelled land) in both traditional and modern schemes.

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