Groundwater is also affected by municipal, industrial and agricultural pollutants. The pollution control action plan of the Ganges basin was formulated in and has been enforced by the Ganges Project Directorate, under the Central Ganges Authority, to oversee pollution control and the consequent cleaning of the Ganges river. The water quality in the middle stretch of the Ganges river, which had deteriorated to class C and D the worst class is E, the best A , was restored to class B in after the implementation of the action plan.
The GBM rivers create flood problems in their respective basin areas during monsoon months almost every year. Bangladesh, being the lower riparian country, suffers most from such floods which cause enormous loss of life and property Parua, after Climate change may alter the distribution and quality of GBM river basin water resources. Some of the impacts include occurrence of more intense rains, changed spatial and temporal distribution of rainfall, higher runoff generation, low groundwater recharge, melting of glaciers, changes in evaporative demands and water use patterns in agricultural, municipal and industrial sectors, etc.
India-Bangladesh River Water Sharing: Politics over Cooperation
These impacts lead to severe influences on agricultural production and food security, ecology, biodiversity, river flows, floods, and droughts, water security, human and animal health and sea level rise. Bihar is the worst flood hit state in India. Hardly a year passes without severe flood damage. With the onset of the monsoon, rivers come down from the Himalayan hills in Nepal with enormous force, causing rivers like Ghagra, Kamla, Kosi, Bagmati, Gandak, Ganges, Falgu, Karmanasa, Mahanadi to rise above the danger level.
This results in severe floods in North Bihar. About 2. Bangladesh is now widely recognized as one of the countries that is most vulnerable to climate change. Increased variability of temperatures and rainfall and increased occurrence of natural hazards are expected to affect the availability of both surface water and groundwater. Investments are needed to ensure a continuous and sustainable access to water resources. Use of water of the Ganges river for irrigation, either by flooding or by means of gravity canals, has been common since ancient times.
Irrigation was highly developed during the period of Muslim rule from the twelfth century onward, and the Mughal kings later constructed several canals. The canal system was further extended by the British. The cultivated area of the Ganges valley in Uttar Pradesh and Bihar benefits from a system of irrigation canals that has increased the production of cash crops such as sugarcane, cotton and oilseeds.
Higher lands at the northern edge of the plain are difficult to irrigate by canal, and groundwater must be pumped to the surface. Large areas in Uttar Pradesh and Bihar are also irrigated by channels running from hand-dug wells. The Ganges-Kabadak scheme in Bangladesh, largely an irrigation plan, covers parts of the districts of Khulna, Jessore, and Kusthia that lie within the part of the delta where silt and overgrowth choke the slowly flowing rivers.
The system of irrigation is based on both gravity canals and electrically powered lifting devices Ahmad and Lodrick. Total area equipped for irrigation in the GBM river basin is estimated to be around Area actually irrigated is estimated at The equipped areas irrigated by groundwater and by surface water account for 67 and 33 percent respectively. Of the 29 million ha equipped for irrigation in India inside the GBM river basin, 67 percent is irrigated by groundwater and 33 percent by surface water.
The development of sprinkler and localized irrigation in recent years has been considerable, mainly the result of the pressing demand for water from other sectors, a fact that has encouraged government and farmers to find water-saving techniques for agriculture. The Government has offered subsidies to adopt drip systems. Drip-irrigated crops are mainly orchards grapes, bananas, pomegranates and mangoes. Localized irrigation is also used for sugarcane and coconut. Investment in drainage has been widely neglected in India, and where such investment has been made, poor maintenance has caused many drainage systems to become silted up.
On the eastern Ganges plain, investment in surface drainage would probably have a greater productive impact, and at a lower cost, than investment in surface irrigation. Seasonal canals accounted for 58 percent of the area irrigated by surface water, permanent canals for 39 percent, and ponds for 3 percent. In , Most irrigation systems use surface irrigation basin, furrow.
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Some areas in the hills and mountains use sprinkler irrigation, but no figures are available. In Bhutan, which is entirely located in the Brahmaputra river basin, most rivers are deeply incised into the landscape and hence the possibilities for run-of-the-river irrigation are limited. The irrigated areas are called wetland in the local classification. This means that they have been terraced for basin irrigation. In summer, almost all wetland is under rice cultivation. Double cropping of rice is limited to the lowest altitudes where the winter temperatures still allow its cultivation.
Where rice cannot be cultivated, wheat, buckwheat, mustard and potatoes are cropped on wetland areas during the winter season. The wetland areas can be cropped during the winter season, though watering of these winter crops is generally limited to one irrigation at the time of land preparation.
To a limited extent, farmers have started to irrigate horticultural crops, including orchards, using hose pipes and surface irrigation methods. In Bangladesh, though the country has abundant surface water resources, particularly in the monsoon season, its flat deltaic topography and the instability of major rivers make large gravity irrigation systems both technically difficult and costly.
On the other hand, during the dry season irrigation using surface water has become difficult or practically impossible owing to limited availability. Therefore the use of groundwater for irrigation has become increasingly important. In the national irrigation coverage was 5. In , the total area of wetlands throughout the country was 3.
Thus, total water managed area is estimated at 6. Surface irrigation is the only technology used in large irrigation schemes. In , total harvested irrigated cropped area in Bangladesh was estimated at 5. Because of the low-lying topography, each year about 18 percent of Bangladesh is inundated during the monsoon season. During severe floods the affected area may exceed 37 percent of the country and in extreme events like the flood about 66 percent of the country is inundated.
Floods are caused by overspills from main rivers and their distributaries, overspills from tributaries and by direct rainfall.
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Flood control works can reduce floods from the first two, but only drainage can have any effect on the latter two. The basic benefit of drainage is water control — supply as well as removal. The particular benefits can be: i potential increase in cropped area through earlier drainage; ii higher yields from transplanted Aman rice through early planting; iii crop diversification in the wet season through better drainage; and iv more control over crop calendars and patterns through control of the water regime.
In , a master plan was initiated for water resources development. This envisaged the development of 58 flood protection and drainage projects covering about 5. Three types of polders were envisaged: gravity drainage, tidal sluice drainage and pump drainage.
Flood control and drainage projects have accounted for about half of the funds spent on water development projects since Total water withdrawal in the GBM river basin is estimated at Irrigation withdrawal accounts for In Bangladesh, in total water withdrawal within the GBM river basin was estimated at about Approximately 79 percent of the total water withdrawal comes from groundwater and 21 percent, from surface water.
In Nepal, in total water withdrawal was estimated at 9. In Bhutan, in total water withdrawal was estimated at 0.
Groundwater Arsenic Contamination in the Ganga River Basin: A Future Health Danger
This represents a mere 0. About 94 percent of this water withdrawn 0. Total water withdrawal of China inside the GBM river basin has been estimated around 0. In Nepal, total dam capacity is estimated at 85 million m 3 , although potential for at least km 3 exists. Hydroelectricity accounted for more than 96 percent of total electricity generation. The two main diversion barrages are the ones of Kosi and Gandaki reservoirs. In Bhutan, several large dams were constructed for hydroelectric power generation.
The m high Punatsangchu dam on Puna Tsang river downstream of Wangduephodrang town is under construction. With the commissioning of the first two units of the Chhukha hydroprojects in , and the other two units in , the electricity generation capacity has substantially increased and Bhutan became a significant exporter of electricity to India.
The expansion of hydropower production capacity in Bhutan has had an enormous impact as by the end of the Ninth Five-Year Plan , the energy sector contributed to around a quarter of GDP. With a further doubling of capacity envisaged by the end of the Eleventh Five-Year Plan , the energy sector will probably contribute close to half of GDP. The following hydroelectric projects have been identified for future development: Mangdue Chu Hydroelectric Project was planned in the Ninth Five-Year Plan and is expected to be completed in the Tenth Five-Year Plan — The project comprises two dams.