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| Last Updated:: 11/06/2024

Water

 

         From the point of view of water resources Kerala is having both abundance and scarecity. The average annual rainfall of the state is 3000mm, the bulk of which (70%) is received during the South-West monsoon which sets in by June and extends upto September. The state also get rains from the North - East monsoon during October to December. However the spatial and temporal distribution pattern is mainly responsible for the frequent floods and droughts in Kerala. The average annual rainfall in the lowland of Kerala ranges from 900mm in the south to 3500mm in the north. In the midland, annual rainfall ranges from 1400mm in the south to about 6000mm in the north. In the highland, annual rainfall varies from 2500mm in the south to about 6000mm in the north. Kerala has got 41 west-flowing and 3 east flowing were originating from the Western Ghats. The total annual yield of all these rivers together is 78.041 Million Cubic Meters (MCM) of which 70,323 MCM is in Kerala. The peculiarity of the rivers flowing across Kerala is short length of the river and the elevational difference between the high and the low land leading to quick flow of water collected from the river basin and quickly discharged into the Lakshsdweep sea, the state has not been able to utilise the river water sources to a major extent. The major portion of the runoff through the rivers takes place during the monsoon seasons. 67.29% of the surface water area of 3.61 lakh hectares is constituted by brackish water lakes, backwaters and estuaries.

 

        On a rough estimate, the source wise dependence by rural households for domestic water supply dependent on traditional ground water systems is 80%, 10-15% use piped water supply systems, and 5% use traditional surface and other systems.

.
  Fresh water availability in Kerala is given here

 

A graphical distribution of the locations of water on Earth

 

 

Surface Water Resources:

 

              Kerala is rich with 44 rivers which together yield 70300Mm³of water annually. However the total utilizable yield is estimated to be 42000Mm³, only 60% of the annual yield. Kerala possess only four medium rivers and 40 minor rivers.

 

                In the all India perspective the rivers of kerala are not so significant than even the largest of them cannot find a place among the major Indian rivers. With respect to the national norm Kerala does not have a single major river and has only four medium rivers. The combined discharge of these four rivers is less than half of that of river Krishna. The remaining fourty rivers are only minor ones, the combined discharge of all of them together is only about one-third of that of Godavari. western ghats from where the river originate is devoid of snow and therefore these river systems do not have the benefit of water supplied during the summer seasons as in the north Indian rivers.


Ground water Resource of Kerala:

 

            Kerala is a tiny strip of land, located in the south-western tip of India between North latitudes 80 18’and 120 48’ and East longitudes 740 52’ and 770 22’, occupying only 1.2 percent of India's land area. Its geographical contours can be described as an elongated strip of land, cushioned between the Western Ghats on the east and the sandy shores of the Arabian Sea on the west. Its land area is 38,863 Sq. Km, stretching 580 Km in length and 30.130 Km in average breadth. In terms of area, though Kerala forms only 1.2% of the total area of India (3,287,263 Sq. Km), 3 percent of country's population inhabits the State. The State is subdivided into 14 districts and 152 blocks for administrative convenience.

 

            The occurrence and availability of ground water vary considerably from place to place within the State depending on the prevailing climatic, geomorphological and hydrogeological conditions. About 88 percent of the total geographical area of the State is underlain by crystalline rocks devoid of any primary porosity, with limited ground water prospects. In the alluvial formations having multiple aquifer systems, quality is sometimes a constraint in the optimal development of available resources. Increasing population, rapid urbanization and industrialization has resulted in increasing use of ground water resources over the last few decades in the State. Judicious and planned development of ground water and its scientific management have become necessary to ensure long-term sustainability of this precious natural resource in Kerala. The dynamic ground water resources of the State are being periodically assessed by the Central Ground Water Board (CGWB), jointly with the State Ground Water Department and other Central Government as well as State Government agencies, according to the methodology recommended by the Groundwater Estimation Committee constituted by Govt. of India from time to time.

 

             Groundwater has been the mainstay for meeting the domestic needs of more than 80% of rural and 50% of urban population besides, fulfilling the irrigation needs of around 50% of irrigated agriculture. The ease and simplicity of its extraction has played an important role in its development. Recent the problems of decline in water table, contamination of groundwater, seawater intrusion etc. are being reported at many places.

  

Hydrogeology:

 

          Kerala State is a narrow stretch of land covering 38863 sq.km area bordering the Lakshadweep Sea on the western side and Tamil Nadu Karnataka Station the eastern side. The length of the State from north to south is 560km and the average width is 70km with a maximum of 125km it lies between North latitudes 08 0 18' and 12 0 48' and east longitudes 740 52' and 770 22'. The occurrence and movement of groundwater in various litho-units underlying the State are mainly controlled by the physiography, geological setting and structural features.  

 

(i) Physiography:

 

              The State can be sub-divided into three major units based on their Physiographic characteristics viz. the coastal plains/Lowlands, the midlands and the hill ranges/Highlands. The coastal plains have an elevation of less than 7.6m above mean sea level (a.m.s.l). The elevation of the midland region ranges from 7.6 to 76 m amsl and that of the hill ranges is more than 76 m above mean sea level. Along the hill ranges two distinct plateau regions are seen, the important being the Wayanad plateau, covering major part of Wayanad district, with elevations above 700 m.amsl and the Munnar plateau, located along the northern part of Idukki district with a general elevation of about 1000 m.amsl are the prominent plateaus in the hilly region of the state.

 

(ii) Rain Fall: 

 

                Kerala receives normal annual rainfall of 2807 mm (2022-23), received mainly during the Southwest Monsoon period, extending from May to October, followed by the Northeast Monsoon in the months of November and December. The period between May and October accounts for about 77 percent of the annual rainfall. This period has been considered as monsoon season for computation of monsoon rainfall recharge. The amount of rainfall received shows a gradual decrease from North to South. The spatial distribution of normal annual rainfall in the State is shown below:


 

(iii) Geology:

 

                As much as 88% of the State is underlain by crystalline rocks of Archaean age comprising schistose formations, Charnockites, Khondalites and gneisses. All these formations are intruded by dykes of younger age. The sedimentary formations of the Tertiary age occurring along the western parts of the State comprise four distinct beds viz. Alleppey, Vaikom, Quilon and Warkali. The crystalline and the Tertiary formations are lateralized along the midland area. Alluvial deposits of recent origin are seen along the coastal plains. The general stratigraphic sequence is given below:

 

Stratigraphic Succession of Geological Formations in Kerala

Age

Formation

Lithology

Recent

Alluvium

Sand, clay, riverine alluvium etc

Sub-recent

Laterite

Derived from crystalline and sedimentaries

Warkali

Sandstone, clays with lignite

Quilon

Limestone, marl and clay

Tertiary

Vaikom

Sandstone with pebbles, clay and lignite

Alleppey

Carbonaceous clay and fine sand

Undated

Intrusives

Dolerite, Gabbro, Granites, Quartzo - feldspathic Veins.

Archaean

Wayanad group

Granitic gneiss, Schists etc.

Charnockites

Charnockites and associated rocks

Khondalites

Khondalites suite of rocks and its associates



Occurrence of Ground water:

 

              In hard rock terrain, comprising weathered crystallines and laterites, ground water occurs under phreatic conditions in the weathered residuum and the shallow fractures hydraulically connected to it; below this semi-confined to confined conditions prevails in the deep fracture zones. In the alluvial terrain, ground water in the shallow systems is in phreatic condition. Granular zones in the Tertiary sedimentary formations at deeper levels and forms potential confined to semiconfined aquifers. The shallow aquifers of the crystalline rocks are made up of the highly decomposed weathered zone or partly weathered and fractured rocks. The depth to water level in this aquifer varies from 2 to 16 mbgl and the yield of the well ranged between 2 to 10 m3 per day. Exploratory drilling carried out by Central Ground Water Board in the state in the crystalline formations has indicated that the fractures are encountered at depths ranging between 30 to 175 m.bgl with yield varying from less than 1 to as much as 35 litres per second (lps). In Charnockites, more than 40% of the wells have yielded more than 10 lps or above indicating that in Kerala, Charnockite suite of rocks are better aquifers compared to Khondalite group.

 

                      Laterites are the most widely distributed lithological unit in the state and the thickness of this formation varies from a few meters to about 30 m. Laterite forms potential aquifers along topographic lows and valleys. The depth to water level in this formation ranges from 2 to 25 mbgl and the yield ranges from 0.5 to 30 m3 per day. The alluvial deposits form potential aquifer along the coastal plains and groundwater occurs under phreatic and semi-confined conditions in this aquifer. The thickness of this formation varies from few meters to above 100 m and the depth to water level ranges from less than a meter to 6 mbgl. Filter point wells are feasible wherever the saturated thickness exceeds 5m. This potential aquifer is extensively developed by dug wells and filter point wells throughout the state and the yield ranges from 5 to 35 m3 per day.  


Groundwater Availability of Kerala:

 

Total Annual Ground Water Recharge: The Total Annual Ground Water Availability in Kerala State as on 2023, has been computed as 5.53 Billion Cubic Metre (BCM). Rainfall recharge accounts for about 81.91 percent of the annual recharge, and the rest contributed from other sources. The contribution of districts to the total annual recharge of the State is shown below:

 

Contribution of districts to the Total Ground Water Recharge in Kerala

 

Annual Extractable Ground Water Recharge:  The Annual Extractable Ground Water Recharge for the entire State is 5.01 billion cubic metre (BCM). The district-wise availability in the State ranges from 188.57 MCM in Idukki district to 567.68 MCM in Palakkad district. The spatial distribution of Annual Extractable Ground Water Recharge in Kerala as on 2023 in depth units (m) is shown below:

 

 

Ground Water Extraction: The Ground water Extraction in Kerala is mainly for domestic uses and for irrigation. The Groundwater Extraction of Domestic use is estimated to be 1.59 BCM and the Groundwater Extraction of Irrigation use is estimated to be 1.12 BCM. The Extraction for Industrial uses is very less when compared to Domestic and Irrigation use, and has been estimated using unit draft and consumptive use pattern method, in which assessment unit wise number of wells, industrial units & type and season wise unit draft of each type of well collected by the State Ground Water Dept., Government of Kerala and extraction computed to be 0.01BCM. The Annual Ground Water Extraction for all uses in the State is of the order of 2.73 BCM and ranges from 56.38 MCM in Wayanad district to 346.53 MCM in Malappuram district.

 

 

Annual Ground water Allocation for Domestic Use as on 2025: The Annual Extractable Ground Water Resources are to be apportioned between domestic, industrial and irrigation uses. Among these, as per the National Water Policy, requirement for domestic water supply is to be accorded priority. The estimate of allocation for domestic water requirement has been computed to be 2.195 BCM as per GEC-2015 norms.

 

Net Ground Water Availability for Future use: The water available for future use is obtained by deducting the allocation for domestic use and current extraction for Irrigation and Industrial uses from the Annual Extractable Ground Water Recharge. The resulting ground water potential is termed as the net annual ground water availability for future use and is computed to be 2.016 BCM. The district-wise net ground water availability ranges from 55.29 MCM in Kasaragod district to 228.99 MCM in Kottayam district. District-wise status of Annual Extractable Ground Water Recharge and Ground Water Extraction for all uses is shown below:

 

 

 

Stage of Ground Water Extraction and its Validation: The stage of Ground water extraction for the Kerala State is 54.55 %. The Stage of Ground Water Extraction is the highest in Kasaragod district (72.75%) and the lowest in Wayanad district (27.67%).  

 

Categorization of Blocks

  

              The Assessment units have been categorized as “Over-exploited”, “Critical”, “Semicritical” and “Safe” based on Stage of Ground Water Extraction and the long term decline of average ground water levels in the observation wells in the assessment unit, as per the criteria suggested in GEC-2015 methodology. Out of 152 assessed units in the State, 3 blocks (Chittur & Malampuzha blocks of Palakkad district and Kasaragod block of Kasaragod district) have been categorized as “Critical”; 30 blocks are “Semi-critical” and 119 blocks are in “Safe” category. The spatial distribution of different categories of assessment units are shown below:

  

Categorization of Blocks (Kerala as in March 2023)

(Source: Ground Water Resources of Kerala 2023)

  

District-wise Ground Water Resource Scenario

 

1. Alappuzha: The Annual Extractable Ground Water Recharge of the district is 360.44 MCM and existing Gross Ground Water Extraction is of the order of 141.77 MCM. The Stage of Ground Water Extraction is 39.33 %. All the blocks in the district are Safe from the point of view of ground water extraction.

 

2. Ernakulam: The Annual Extractable Ground Water Recharge of the district is 462.48 MCM and existing Gross Ground Water Extraction is of the order of 229.51 MCM. The Stage of Ground Water Extraction is 49.63%. All the blocks in the district are Safe from the point of view of ground water extraction.

 

3. Idukki: The Annual Extractable Ground Water Recharge of the district is 188.57 MCM and existing Gross Ground Water Extraction is of the order of 102.21 MCM. The Stage of Ground Water Extraction is 54.21%. Out of 8 blocks in the district, 2 have been categorized as ‘Semi-critical’ (Kattappana and Nedumkandam) and 6 blocks as ‘Safe’.

                 

4. Kannur: The Annual Extractable Ground Water Recharge of the district is 398.53 MCM and existing Gross Ground Water Extraction is of the order of 198.25 MCM. The Stage of Ground Water Extraction is 49.75 %. Out of 11 blocks in the district, 3 have been categorized as ‘Semi-critical’ viz; Kannur, Thalassery and Panur and 8 blocks as ‘Safe’.

 

5. Kasaragod: The Annual Extractable Ground Water Recharge of the district is 314.18 MCM and existing Gross Ground Water Extraction is of the order of 228.57 MCM. The Stage of Ground Water Extraction is 72.75%. Out of 6 blocks in the district, 1 has been categorized as ‘Critical’ viz. Kasaragod; 1 as ‘Semi-critical’ viz. Manjeshwar block and 4 blocks as ‘Safe’.

 

6. Kollam: The Annual Extractable Ground Water Recharge of the district is 323.35 MCM and existing Gross Ground Water Extraction is of the order of 167.93 MCM. The Stage of Ground Water Extraction is 51.93%. Out of 11 blocks in the district, 2 blocks (Mukhathala and Sasthamkotta) is ‘Semicritical’ and 9 blocks are ‘Safe’.

 

7. Kottayam: The Annual Extractable Ground Water Recharge of the district is 370.31 MCM and existing Gross Ground Water Extraction is of the order of 137.44 MCM. The Stage of Ground Water Extraction is 37.11%. All the blocks in the district are in ‘Safe’ category.

 

8. Kozhikode: The Annual Extractable Ground Water Recharge of the district is 306.28 MCM and existing Gross Ground Water Extraction is of the order of 188.98 MCM. The Stage of Ground Water Extraction is 61.70%. Out of 12 blocks in the district, 3 are ‘Semi-critical’ (Balussery, Kozhikode and Kunnamangalam) and others are ‘Safe’.

 

9. Malappuram: The Annual Extractable Ground Water Recharge of the district is 484.34 MCM and existing Gross Ground Water Extraction is of the order of 346.53 MCM. The Stage of Ground Water Extraction is 71.55 %. Out of 15 blocks in the district, 8 are ‘Semi-critical’ (Kondotty, Kuttipuram, Malappuram, Mankada, Thanur, Thirurangadi, Tirur & Vengara) and remaining blocks are ‘Safe’.

 

10. Palakkad: The Annual Extractable Ground Water Recharge of the district is 567.68 MCM and existing Gross Ground Water Extraction is of the order of 339.21 MCM. The Stage of Ground Water Extraction is 59.75%. Out of 13 blocks in the district, 2 are ‘Critical’ (Chittur & Malampuzha), 2 blocks are ‘Semicritical’(Pattambi and Thrithala) and 9 blocks are ‘Safe’.

 

11. Pathanamthitta: The Annual Extractable Ground Water Recharge of the district is 208.70 MCM and existing Gross Ground Water Extraction is of the order of 78.53 MCM. The Stage of Ground Water Extraction is 37.63%. All the 8 blocks of the district have been categorized as ‘Safe’.

 

12. Thiruvananthapuram: The Annual Extractable Ground Water Recharge of the district is 257.82 MCM and existing Gross Ground Water Extraction is of the order of 174.62 MCM. The Stage of Ground Water Extraction is 67.73 %. Out of 11 blocks, 6 are ‘Semi critical’ (Athiyannur, Chirayinkil, Nedumangad, Parassala, Pothencode and Varkala) and 5 are ‘Safe’.

 

13. Thrissur: The Annual Extractable Ground Water Recharge of the district is 558.81 MCM and existing Gross Ground Water Extraction is of the order of 340.55 MCM. The Stage of Ground Water Extraction is 60.94%. Out of 16 blocks in the district, 3 are ‘Semi-critical’ (Chowannur, Mathilakam and Thalikulam). All the other blocks are safe.

 

14. Wayanad: The Annual Extractable Ground Water Recharge of the district is 203.78 MCM and existing Gross Ground Water Extraction is of the order of 56.48 MCM. The Stage of Ground Water Extraction is 27.67 %. All four blocks in the district are ‘Safe’.

 

Groundwater Management

 

                The National Water Policy of the Government of India states that the non conventional method for utilization of water such as through artificial recharge to ground water and traditional water conservation practices like rainwater harvesting need to be practiced to increase the utilizable water resources. The rainwater harvesting can be effected by in-situ-Harvesting and artificial recharge to ground water is the process of diverting the surface water into suitable geological formation. The common structures are percolation tanks, khadins, check dam/Anicut, sub-surface dams and injection wells. The ground water storage is the best method for water harvesting as it not only involves filtration of surface but is also safe from evaporation losses, natural catastrophes etc. Central Ground Water Board has implemented various artificial recharge schemes in Kerala like surface dykes, percolation tanks, and of top rainwater harvesting. Four sub-suface dams were constructed at Palghat district (Anaganadi, Bhabaji Nagar, Alanallur and Ottappalam), one at Ernakulam (Odakali), one at Kottayam (Neezhir) one at Quilon (Sandanadapuram) and two at Trivandrum district (Mampazhakara and Ayiolam). Central Ground Water Board has constructed two percolation tanks, one at Chirakulam of Kottayam district and another one at Kadapallam of Kasaragod district. Roof top rainwater harvesting schemes were implemented at two places viz. Ezhimala and Mayyilcolony of Kannur district. The artificial recharge structures have given satisfactory results and the groundwater condition in the area has improved considerably.

 

            Rainwater harvesting is the viable solution in the monsoon rich state of Kerala. The common structures feasible for Kerala are sub-surface dykes, nala bunds, check dams. The traditional water conservation structures like natural ponds, reservoirs should be desilted and cleaned. Participatory watershed development programmes should be implemented in the State. Mass awareness programme on ground water conservation should be arranged at Panchayat level in all districts.

 

Other Resources:

 

             Apart from rivers and wells sources like tanks, ponds, springs and surangams are also use in Kerala for providing water for drinking as well as irrigation. It is estimated that Kerala has approximately 995tanks and ponds having more than 15000 Mm³ summer storage. Natural springs occurring in the highland regions of Kerala state have the potential to be developed as good sources for drinking water supply and also for limited small scale irrigation, especially in remote and under developed areas. A total of 236 springs have been identified in the state. Kasaragode district in Northern Kerala has 510 special kind of water harvesting structure called Surangams which have >111pm discharge.


Hydrology Information Systems:
 

                 The State has 41 west-flowing and three east-flowing rivers, and has an average annual rainfall of about 3,000mm. However, the extent to which it can retain, store, and use these for agricultural purposes is still inadequate. In order to have a realistic assessment of water resources in the State, the Investigation Design and Research Board of Irrigation department is in the process of modernising the existing hydrology information system with a Real-Time Data Acquisition System. The core activity of the hydrology wing of the Irrigation department is the collection, validation, and collation of hydro-meteorological data from various gauging stations, established across Kerala river basins. The National Hydrology Project, funded by World Bank, also aims at improving the quality and accessibility of water resources information and to strengthen the capacity of water resources management institutions in the State. The objective is to establish an effective hydrologic database and hydrological information system for effective water resources planning and management.

 

                   The consecutive floods of 2018 and 2019 necessitated an early flood warning system for the State. Flood Forecasting and Early Warning System (FFEWS) integrated with reservoir operations for Periyar and Chalakudy basins were initiated during the 13th Five-Year Plan period under the National Hydrology Project. FFEWS acts as an end-to-end system for issuing timely warning against disaster. The accuracy of the forecast depends on the real time hydro-met data received, and the quality of topographical features.

 

Irrigation Status: 

 

                 As per the assessment of the Directorate of Economics and Statistics, the extent of irrigation in the State in 2022-23 had varied considerably when compared to the previous year. As reported, the net area irrigated in the State in 2022-23 increased to 4.18 lakh ha as compared to 2021-22 figure of 4.03 lakh ha, an increase of 3.72 per cent. The percentage of net area irrigated to net area sown had risen from 19.87 (2021-22) to 21.04 (2022- 23). However, a decline is reflected in the Gross Irrigated area with a fall in the area from 5.61 lakh ha (2021-22) to 5.14 lakh ha (2022-23). This decline is also reflected in the percentage of gross irrigated area to gross cropped area which fell from 22.25 per cent (2021-22) to 20.45 per cent in (2022-23).

 

               Among the various sources of irrigation, the net area irrigated through wells (including bore well) leads with 1.77 lakh ha during the review period, whereas the benefitted area was 1.66 lakh ha in 2021-22. The extent of net area irrigated through Government canals also showed an increase from 0.72 lakh ha (2021-22) to 0.81 lakh ha (2022- 23). Details on the net area irrigated (source-wise and District-wise) are given below:

 

Net Area Irrigated (Source wise) (in Ha.)

Sl. No

Source

2020-21

2021-22

2022-23

1

2

3

4

5

1

Government canals

81801.33

72491

81985.68

2

Private canals

694.53

257

292.63

3

Tanks

43434.58

47588

45806.27

4

Wells

114121.37

 

166441

177090.91

5

Other sources

149741.87

 

116458

113412.43

6

Total

389793.68

 

403235

418587.92

7

Gross irrigated area

521478

561314.02

 

514497.96

8

Net area irrigated to net area sown (%)

19.5

19.87

 

21.04

9

Gross irrigated area to gross cropped area (%)

20.3

22.25

 

20.45

10

Irrigated area under paddy to total irrigated area (%)

30.61

27.44

 

29.89

(Source: Directorate of Economics & Statistics, GoK)

 

Net Area Irrigated (District Wise) 2022 - 23 are given here.

 

              Crop-wise, paddy and coconut were the crops most benefitted though irrigation. However, the gross area irrigated under paddy had slightly declined to 1.53 lakh ha (2022-23) from 1.54 lakh ha (2021- 22). But the area irrigated under coconut shows a significant increase to 1.56 lakh ha (2022-23) from 1.52 lakh ha (2021-22). Similarly, during the period, vegetables and banana were also benefitted through irrigation. The irrigated area of vegetables had increased to 0.29 lakh ha (2022-23) from 0.25 lakh ha (2021-22) and so is the benefitted area under banana reaching 0.40 lakh ha (2022- 23) from 0.37 lakh ha (2021-22). Details on gross area irrigated and crops benefitted are given here.

 

Gross Area Irrigated (Crop-wise) (in ha.)

Sl. No

Crops

2020-21

2021-22

2022-23

1

Paddy

159639.54

154045.022

153762.38

2

Vegetables

28844.56

25723.77

29887.42

3

Coconut

158834.38

152188.5

156042.18

4

Areca nut

31902.86

30284.32

33375.52

5

Nutmeg

19861

20422.63

19984.87

6

Clove

121

206.82

76.99

7

Banana

52365.64

37889.13

40479.9

8

Betel leaves

252.43

243.32

190.84

9

Sugarcane

920.73

915.41

930.57

10

Others

68735.86

139395.1

79767.29

  Total

521478

561314.022

514497.96

Source: Directorate of Economics & Statistics

  

Status of Major and Medium Irrigation Projects

 

                    Agriculture is an integral part of the development system and irrigation holds the key to increase agricultural productivity. Major and medium irrigation occupy an important position in the irrigation scenario. The implementation progress of Karapuzha and Banasurasagar irrigation projects during the first two years of the 14th Five Year Plan period is described below:

 

                In the Karapuzha Irrigation project, the entire Left Bank Main Canal (LBMC) up to the tail end (Ch. 16,740 m) is now made functional for irrigating an ayacut of 245.17 ha. Water distribution up to the tail end of LBMC was done on March 15, 2023 on trial basis. Having completed the rectification works of the breach in the Right Bank Main Canal (RBMC) between Ch.7,673m and 7,888m, water distribution up to the tail end (Ch.8,805m) is being done in 2023, thereby irrigating 331 ha. Thus, the water distribution through main canals and Arimunda distributory (60.31 ha), helped in achieving a total ayacut of 636.48 ha. Moreover, water distribution through Kolliyil Branch Canal (up to Ch. 1,540 m) was also done on trial basis on March 08, 2023. Thus in 2022-23, both the main canals (25.545 km) and the Kolliyil Branch Canal (1.540 km) of the Karapuzha project was made functional for the first time.

 

           A major constraint of the Banasurasagar Irrigation Project was the bottleneck from Ch.1130m to 1,500m in the Main Canal. The Department had succeeded in overcoming this constraint and works are in progress in this stretch. In 2023-24, water test was conducted in the aqueduct portion of the Main Canal from Ch.0m to 150m. Completion of 775m of Kappumkunnu distributory, 409m of Venniyode branch canal, completion of detailed survey of Kuppadithara and Kurumbala distributories and completion of soil investigation for the aqueduct portion of various distributaries were few other project related activities during the period.  

 

Potential of Minor Irrigation

 

                Minor irrigation schemes have contributed substantially to augment the irrigation potential in the State. Minor Irrigation has its own importance due to low gestation, less investment and quick benefit. The importance given to Minor Irrigation during the 13th Five Year Plan period is being continued during the 14th Plan period.

 

                   During the XIIIth Five Year Plan period, through various surface water MI schemes, 23,600.81 ha of ayacut was achieved. The net area benefitted through MI schemes (surface water) in 2022-23 was 5,076.09 ha. NABARD has sanctioned 1,631 schemes under various tranche including RIDF XXIX. Of these, 1,358 schemes are completed and 24 are in progress. Remaining schemes are dropped due to non-feasibility reasons. Details of physical achievement of MI schemes (surface water) during 2020-21 to 2022-23 are given below:

 

Physical Achievement of Minor Irrigation (Surface Water)        (Net area in ha.)

Name of Schemes

2020-21

2021-22

2022-23

2023-24

upto 31.08.2023

MI Class I

713.88

923.29

1177.88

613.12

MI Class II

354.84

1133.03

1505.04

884.14

Lift Irrigation works

111.68

799.74

883.90

297

Repairs to MI structure

70.36

625.69

1101.47

400.35

MI Class I - NABARD

1914.05

1084.69

407.80

118

Total

3164.81

4566.44

5076.09

2312.61

Source: Irrigation Department (I&A), GoK

 

Groundwater usage

 

                   As per the Dynamic Groundwater Resource Assessment Report for the year 2022, the total annual groundwater recharge for the entire country is 437.60 billion cubic meters (BCM) and the annual extractable groundwater resources for the entire country is 398.08 BCM. Major source of groundwater recharge is the monsoon rainfall, about 55 per cent of the total annual groundwater recharge. The overall stage of Groundwater extraction in the country is 60.08 per cent.

 

                      In Kerala, the total annual groundwater recharge has been estimated as 5.73 BCM and the annual extractable groundwater resource is 5.19 BCM. The stage of groundwater extraction for the State is 52.56 per cent. As compared to 2020 assessment, total annual groundwater recharge of the State has increased from 5.65 to 5.73 BCM and annual extractable groundwater resources from 5.12 to 5.19 BCM. The stage of ground water extraction has increased from 51.68 per cent to 52.56 per cent. Out of the total 152 assessment units, 3 units have been categorised as ‘Critical’, 27 units as ‘Semi-critical’ and 122 units as ‘Safe’ categories of assessment units. The number of Semi-critical blocks has decreased from 29 to 27. Two Semicritical blocks –Kanhangad and Karadka has improved to ‘Safe’ category mainly due to increase in precipitation, increase in recharge from other sources and increase in surface water supply schemes implemented in the State. Details on the total annual ground water recharge, net annual ground water availability and stages of ground water development in the State are given here.

  

Flood Management:

 

               With the assistance of the Rebuild Kerala Initiative, the Irrigation Department has undertaken various flood-related works, such as post-flood repair and maintenance, enhancement of resilience against the impact of climate change and natural disasters, DPR preparation of ‘Room for the River’, and launch of the Kerala Water Resources Information System. In the context of climate change, the greatest challenge is to forecast hydrologic extremes leading to floods and droughts and salinity intrusion and inundation due to sea-level rise. On this basis, forecasting and flood early warning systems assume importance.

 

              As flood control measures, various infrastructural development works such as strengthening of outer bunds, construction of motor thara (platform), motor shed, pile culvert, box culvert, and desiltation of vachalthodu (common drain) through the paddy fields are executed for the development of padasekharams in Kuttanad, Upper Kuttanad, and Onattukara regions. In 2022-23, 54 works were undertaken of which three have been completed. Physical achievements during the period include bund formation for a length of 8,354 m, desiltation works of thodu (2,190 m) and renovation of the retaining wall (1,461.1 m), thereby benefitting an area of 846.1 ha.

 

 

 

  Source: Dynamic Groundwater Resources of Kerala,  Economic Review 2023