Water Management

 The meaning of water management is optimization of watering a crop as per it's requirement.In coming years we are going to face water stress in many parts of the world where as  to feed the growing population, cultivable land needs to be  increased along with water requirement for Agriculture. Therefore we are to control water while irrigating a crop. We should not allow water for deep percolation and drainage rather supply water up to root zone depth of a crop. We are to harvest each drop of rain water & prohibit it to drain to river & ocean.

For example Rice consumes about 4,000 - 5,000 litres of water per kg of grain produced & It takes about 1500 litres of water to produce 1 kilogram of wheat. Rice is not a aquatic crop: it has great ability to tolerate submergence. By keeping two  inch standing  water in Rice field, we control weeds but cut off sunlight and aeration to the ground. An innovative method called the System of Rice Intensification (SRI) has been developed by a Jesuit priest Henri de Laulani, about 20 years back in the African country Madagascar .Norman Uphoff ,scientist from the Cornell Institute for Food, Agriculture and Development, USA,bought this method into limelight. SRI is now being practised in more than 20 countries, including India. It has four components: soil fertility management, planting method, weed control, and water (irrigation) management.The key ones are: soil nutrient management through adequate farmyard manure application, transplanting young seedlings (8 to 12 days old), transplanting with soil clump (along with seed) and regular weeding and protective irrigation to keep soil wet without flooding. Rice grown this way has larger root system and yields are almost double that of the conventional crops. The secret is that rice plants do best when a young plant is transplanted carefully in an area 25 cm long and 25 cm wide. This area is larger than that conventionally allocated to rice plants, but it ensures rice roots grow larger on soil kept well aerated with abundant and diverse soil micro-organisms.But what about standing water requirements? Standing water only arrests weed growth; it has no other beneficial impact on rice plants. But sri encourages weeds to grow in the spaces between plants. Meticulous weeding ensures pests do not intrude in to the plant area. In fact the rice plant sucks away nutrients from the weeds. This alternate Wetting and Drying method adopted in SRI  requires 30 to 60 per cent less water  compared to conventional cultivation methods. It is observed in many cases a higher annual yields of 8 tonnes per hectare (ha)  as against the average yield of 3.5 tonnes/ha in conventional method. The cost of cultivation has also reduced. Seed requirement is only 2 kg per 0.5 ha , much less than 20 kg per ha in conventional method.

From table-1 below, we conclude that Rajasthan being a desert & in the western part of India receives the lowest annual average monsoon rainfall i.e. 313mm.But due to the longest Indira Gandhi LAHAR(Canal) in the Thar desert, Rajasthan's irrigation potential is 39.49%. The longest canal of India starts from the Harike Barrage at Harike, a few kilometers below the confluence of the Satluj and Beas rivers in the Indian state of Punjab and terminates in irrigation facilities in the Thar Desert in the north west of Rajasthan state. Previously known as the Rajasthan Canal, it was renamed the Indira Gandhi Canal on 2 November 1984 following the assassination of Prime Minister Indira Gandhi.  The canal traverses seven districts of Rajasthan: Barmer, Bikaner, Churu, Hanumangarh, Jaisalmer, Jodhpur, and Sriganganagar.The main canal is 445 km long . From 1458 RD, one branch starts, known as Sagar mal gopa branch or the SMGS. Sagar mal gopa branch is 96 km long. From the end point of SMGS, another subbranch starts, which is the last subbranch of this canal named as Baba Ramdev sub-branch and it is 92 km long. It ends near Gunjangarh village in Jaisalmer district.

Though Haryana,Punjab receives less rain i.e. 617mm & 649mm respectively, both the states have achieved irrigation potential 87% & 99% respectively.Maharastra similarly receives less rain i.e. 900mm & being the richest state has also very low % of irrigation i.e.16.80%.Maharastra has highest numbers of dams in the country.In Marathwada alone the rain shade area has 11 major projects with storage capacity of 5143 MCM,75 medium projects having storage capacity of 934.57 MCM but as rain is erratic, the reservoirs adjacent to the dams hardly filled up with water.The no of  major, medium & minor projects including barrages on Godavari & Manjra are 843 with projected storage capacity of 7968 MCM.The Marathwada region comprising districts Parbhani,Nanded,Beed, Latur & Osmanabad receives annual average rainfall of 779mm.These area of Maharashtra is a rain shade area where one can not expect or predict assured rainfall.Due to water stress, highest nos of farmers suicide in the country is in this area of Maharashtra. 

Another curious fact is though there is water stress in the state, farmers go for Sugarcane, the cash crop which is a water guzzling plant.No of Sugar factories, breweries,sugar cooperatives are highest in Maharashtra.The sugar lobby controls the politics in Maharashtra.DESPITE various farmer welfare schemes, including a loan waiver in 2017, Maharashtra recorded 3,927 farmers' suicide in 2019 — the highest in the country, which registered a total of 10,281 suicides in the farm sector last year, according to data released by NCRB whereas in Odisha, 38 farmers have committed suicide in the last three financial years upto March 2019 but none of the cases was linked to crop loss or loan burden. “Not a single farmer in the state has committed suicide for reasons related to farming as reported by Odisha Government.

The 3rd table below tells that ground water irrigation in all states are more than canal irrigation.The 4th slide below tells that due to heavy exploitation of ground water for cultivation in Punjab & Haryana, the water table in Indus basin is declining & this aquifer is at a danger label.Between 2005 to 2013, average ground water table drop by 25 feet in Haryana & 32 go 36 feet in Punjab & Rajasthan.

Twenty-one of the world’s 37 largest aquifers — in locations from India and China to the United States and France — have passed their sustainability tipping points, meaning more water was removed than replaced during the decade-long study period.Underground aquifers supply 35 percent of the water used by humans worldwide. Demand is even greater in times of drought. Rain-starved California is currently tapping aquifers for 60 percent of its water use as its rivers and above-ground reservoirs dry up, a steep increase from the usual 40 percent.

Thirteen aquifers declined at rates that put them into the most troubled category. The researchers said this indicated a long-term problem that’s likely to worsen as reliance on aquifers grows.

Scientists had long suspected that humans were taxing the world’s underground water supply, but the NASA data was the first detailed assessment to demonstrate that major aquifers were indeed struggling to keep pace with demands from agriculture, growing populations, and industries such as mining.

Researchers found that 13 of the planet's 37 largest aquifers studied between 2003 and 2013 were being depleted while receiving little to no recharge. ..Groundwater aquifers can be truly huge. The world's largest aquifer is the Great Artesian Basin in Australia. It covers 1.7 million square kilometres, equivalent to about a quarter of the entire country and 7 times the area of the UK. The Great Artesian Basin is also the deepest aquifer in the world.The Northwest India Aquifer (NWIA) has been shown to have the highest groundwater depletion (GWD) rate globally, threatening crop production and sustainability of groundwater resources.

Brazil has highest freshwater resources in the world which accounts for approximately 12% of the world's freshwater resources. It is just because Amazon region this country contains 70% of the total freshwater. Russia has second largest freshwater reserve which is approximately 1/5 of freshwater in the world.20-Sept-2018.

The stage of ground water extraction is very high in Delhi, Haryana, Punjab and Rajasthan, where it is more than 100 per cent, which implies that in these states, the annual ground water consumption is more than annual extractable ground water resources. In the states of Himachal Pradesh, Tamil Nadu, Uttar Pradesh and UTs of Chandigarh and Puducherry, the stage of ground water Extraction is between 70-100 per cent. In the rest of the states / UTs, the stage of ground water development is below 70 per cent.

5 states — Uttar Pradesh, Rajasthan, Bihar, Madhya Pradesh, and Kerala — account for 49 per cent of the overall extraction of groundwater in the entire country.These top five states withdraw about 24.37 billion cubic metres (BCM),” the data from the Ministry of Jal Shakti showed adding, between year 2004 and 2020, groundwater drawl has increased from 18.09 BCM to 27.31 BCM implying an average annual increase of 576 million cubic metres.

As per the 2017 assessment of Dynamic Ground water resources, the total annual ground water recharge for the entire country has been assessed as 432 BCM and total natural discharges worked out to be 39 BCM, making the annual extractable ground water resources for the entire country to be at 393 BCM. The total annual ground water extraction of the entire country for the year 2017 has been estimated as 248.69 BCM with the agriculture sector being the predominant consumer of groundwater resources. About 89 per cent of total annual ground water extraction i.e. 221.46 BCM is for irrigation use. Only 27.24 BCM is for domestic & industrial usage, which is about 11 per cent of the total extraction