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kasaragod groundwater book for references purpose
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Thiruvananthapuram December 2013
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द्वारा By के बालकृष् णन वैज्ञाननक ख K. Balakrishnan Scientist B
iv
Sl No.
i) Geographical area (Sq km) 1992 ii) Administrative Divisions Number of Tehsil / Block Number of Municipalities Number of Panchayat / Villages iii) Population (2011 Census) iv) Average annual rainfall (mm)
Major physiographic units Coastal plains, Mid land region, High land region Major Drainages Chandragiri river, Karingote river, Uppala, Mogral
3. LAND USE (Sq km) a) Forest area 56. b) Net area sown 1353. 4. MAJOR SOIL TYPES Lateritic soil Brown hydromorphic soil Alluvial soil Forest loam 5. AREA UNDER PRINCIPAL CROPS (Hectares) (2009-10)
Paddy – 4394 Coconut – 54224 Arecanut – 15256 Rubber – 30624 Pepper – 4764 Fresh Fruits – 7013 Cashew – 8205 Total Food Crops – 42281 Tapioca – 389 Total Cropped area - 138165
6. AREA IRRIGATED BY DIFFERENT SOURCES (Hectares) (2009 -10) Wells (Dug wells / Bore wells) 25664 Tanks / Ponds 10068 Canals 862 Other Sources 3536 Net Irrigated area (Hectares) 40130
v
No. of Dug wells No. of Piezometers
8 PREDOMINANT GEOLOGICAL FORMATIONS Charnockite, Hornblende biotite gneiss, Laterite Alluvium
9. HYDROGEOLOGY Major Water bearing formation
Depth to water level (Pre-monsoon,April 2011)
Depth to water level (Post-monsoon, November 2011)
Long term water level trend in 10 years(2002 - 2011) in m/yr Falling trend premonsoon postmonsoon Rising trend premonsoon postmonsoon
Weathered and fractured Charnockite and gneisses (crystallines), Laterite and Alluvium (a) Alluvium- 2.93 to 5.63 mbgl (b) Laterites – 5.33 to 24.32 mbgl (c) Crystallines – 3.11 to 11.55 mbgl (a) Alluvium- 1.20 to 3.20 mbgl (b) Laterites – 4.15 to 22.60 mbgl (c) Crystallines – 1.95 to 10.97 mbgl
0.015 to 0.206 m/year 0.010 to 0.059 m/year 0.013 to 0.294 m/year 0.011 to 0.185 m/year
10. GROUND WATER EXPLORATION BY CGWB (As on 31- 03 - 2011 ) No. of wells drilled (EW, OW, PZ, SH, Total) EW - 29, OW - 7, Pz - 25 Depth Range (m) 50.5 to 200. Discharge (litres per second) Up to 11. Storativity(S) Transmissivity (m^2 /day) 0.65 to 161. 11. GROUND WATER QUALITY Good Presence of chemical constituents more than permissible limits(e.g. EC, F, As, Fe)
Concentration of Fe more in many places 12 DYNAMIC GROUNDWATER RESOURCES (200 9 ) – in MCM
The name, Kasargod, is said to be derived from the word ‘Kusirakood’ meaning Nux vomica forests (Kanjirakuttom). Kasargod is the northernmost district of Kerala, bordering Karnataka State. The population is mainly agrarian and the major crops raised are coconut, arecanut, cashew, rubber, paddy, pepper etc. Kasargod district is having cash crops as its main stay compared to food crops. Coconut is the single largest crop in the district. Recently there is considerable change in the land use and cropping pattern. The paddy cultivation has reduced from 5512 hectares in 1994-95 to 2464 hectares in 2009-10 because of the low returns from the crops compared to the investment and huge requirement of water to raise the crop. Traditionally arecanut is being cultivated in the valley portion of the district. Arecanuts are being irrigated by the springs and seepages or shallow dug wells in the valley areas or the water collected from the tunnel wells. Recently the irrigation of coconut and arecanut on the valleys and slopes are increased by pumping of borewells. The bore well culture is prevalent in Kasargod district way back from the sixties and seventies much before this was common in other parts of the state. During and after eighties the growth rate of borewell increased steadily at an alarming rate. Because of the increase of borewells in the slopes and laterite terraces, the water availability in the valley portions and tunnel wells reduced considerably. Hence farmers could not irrigate arecanut in summer which has badly affected the crops. About 75% of the area of the district is covered by laterites. Because of the highly porous nature of the laterite, the dug wells tapping laterite get recharged fast in the initial stages of monsoon showers itself, however this water escapes as sub-surface flow and the water level falls quite fast especially in wells located on topographic high and slopes. Further the delay in monsoon and deficit summer showers badly affect the crops and drinking water availability. Earlier days the development of groundwater for irrigation and drinking purposes were mostly through dug wells. Recently the farmers started growing bananas, vegetables etc. in paddy fields and slopes which necessitated accelerated irrigation. This forced the farmers to deepen the existing dug wells and also for construction of deeper borewells in an indiscriminate manner. In the crystalline formations especially in valleys the fracture zone starts from shallow depths. In many places the pumping of borewells badly affect the water level of the phreatic zone. Moreover, the farmers are constructing the bore wells and dug wells without much technical knowledge, which leads to faulty construction
and failure of borewells. The failure of agriculture coupled with the low price of crops, resulted in dues of loans availed by farmers for various purposes.
1.1 Administration
Kasargod district is divided into two taluks (Kasargod and Hosdurg) and 75 villages. The district has one revenue division, 6 Block Panchayaths (Manjeshwar, Kasargod, Kanhangad, Nileshwar, Karadka and Parappa) and 38 Grama Panchayaths and three Municipalities (Kasargod, Kanhangad and Nileshwar).
1.2 Drainage, Irrigation practices
The district is drained by nine rivers, all minor in nature except Chandragiri and Karingote which are originating from the eastern highland and flowing towards the west to join the Lakshadweep Sea. Most of the rivers have an east to west trend.
Even though the district is drained by 9 rivers which discharges about 4257 MCM of water to the ocean every year as surface run off, there is not a single major irrigation scheme to arrest this water for effective utilization for irrigation. At present out of the total cropped area of 1381.65 sq.km., only 401.30 sq.km. is being irrigated by different sources leaving major cropping as rain fed. Coconut is the principal crop irrigated which covers 60% of the total irrigated area followed by arecanut which accounts for 23%. Paddy cultivation in the district is now reduced to 6% of the total irrigated area.
Among source of irrigation, ground water is the principal source of irrigation accounting for about 64% of the area under irrigation and the rest by lift and other methods of irrigation. The index map showing location of block headquarters, boundary, drainage, location of EW, PZ are shown in Figure 1.
1.3 Works carried out by CGWB
The report on ground water resources of Kasargod district was compiled by Dr. K.Md. Najeeb (1987). Reappraisal survey was carried out by Sh. V. Dhingaran (1989-90), Shri V. Kunhambu and Sh. N.C. Nayak (1996-97) and Sh. K. Balakrishnan (2000-2004, 2007-08) Micro level survey was carried out in Kasargod block by Shri K. Balakrishnan (2002-03). Ground water exploration was carried out in Kasargod Taluk during 1983-85 upto the depth of 100 m. Groundwater exploration to the depth of 200 m was continued during the year 2002-03 and 2004-05 using DTH rig of 200 m capacity. Under hydrology project,
Evaporation
Evaporation is more during summer months of March to May. In general it ranges from 2. to 6.3 mm/day. During south west monsoon season it ranges from 2.2 to 3.7 mm/day.
Sunshine Hours
Sunshine ranges from 3.2 to 10.2 hours/day. Maximum sunshine is during the month of February. The months of June to August record the minimum sunshine due to the cloudy sky. Generally good sunshine hours are recorded in the months of November to May.
Wind
The wind speed ranges from 2.1 to 3.3 km/hour. The wind speed is high during the months of March to June and less during the months of September to December.
Potential Evapotranspiration (PET)
PET values are lower than the monthly rainfall during the month of May to October indicating water surplus for possible recharge into groundwater regime during these months. The monthly PET ranges from 119.3 to 177.0mm.
3.0 GEOMORPHOLOGY AND SOIL TYPES
Physiographically the district can be divided into three district units viz. the coastal plains, the midlands and the eastern highland regions. The coastal plains with an elevation of less than 10m occur as narrow belt of alluvial deposits parallel to the coast. To the east of coastal belt is the midland region with altitude ranging from 10 to 300 m amsl. The midland area is characterised by rugged topography formed by small hillocks separated by deep cut valleys. The midland regions show a general slope towards the western coast. To its east is the high land region. The midland and hill ranges of the district present a rugged and rolling topography with hills and valleys. Along the midlands the hills are mostly laterite and the valley are covered by valley fill deposits. The valley fill deposits are composed of colluvium and alluvium.
There are four major soil types encountered in the district. They are Lateritic Soil, Brown Hydromorphic Soil, Alluvial Soil and Forest Loam. Lateritic soil is the most predominant soil type of the district and it occurs in the midland and hilly areas and it is derived from laterites. Brown hydromorphic soil is confined to the valleys between undulating topography in the midlands and in the low lying areas of the coastal strip. They have been formed as a
result of transportation and sedimentation of materials from adjoining hill slopes. The alluvial soil is seen in the western coastal tract of the district. The coastal plain is characterised by secondary soils which are sandy and sterile with poor water holding capacity. The width of the zone increases towards the southern part of the district. Forest loamy soil is found in the eastern hilly areas of the district and are characterised by a surface layer rich in organic matter.
4.0 GROUND WATER SCENARIO
Groundwater occurs under water table conditions in alluvium, laterites and weathered mantle of the crystallines, where as in the deeper fractured crystallines the groundwater occurs under semi confined to confined conditions. The physiographic set up and geological formations are same for Manjeshwar, Kasargod, Kanhangad and Nileshwar blocks, (the block area starts from
the coast and ends on midland areas. The block area of Karadka and Parappa starts from midland on west and ends as hilly area on the east. Alluvium occurs as narrow strips parallel to the coast and the width increases from the northern part of Kanhangad block to southern part of Nileshwar block and around Trikaripur of Nileshwar block. In Kasargod and Manjeshwar blocks alluvium occur as isolated patches close to the coast and have limited thickness. The crystalline formations having phreatic aquifer is found mostly in Karadka and Parappa blocks.
4.1 Hydrogeology
Four hydrogeological units encountered are Alluvium (including valley fills) laterites weathered crystallines and fractured crystallines. Coastal Alluvium occurs as narrow strips parallel to the coast south of Kasargod. The width of alluvium increases to the south and attains about 5 km. around Trikaripur. North of Kasargod (in Kasargod and Manjeshwar blocks), the alluvium occurs as isolated patches close to the coast and have limited thickness. In the Kanhangad and Nileshwar blocks even though the width of alluvium is more, potential zones are seen in the top portion only followed by Tertiary sediments at deeper levels which does not contain potential granular zones. Valley fills occur in between laterite hills which are composed of colluvium and alluvium. The water level ranges from 2.93 m to 5.63 m bgl in pre-monsoon period and 1.20 to 3.20 m bgl in post monsoon period. The water level fluctuation is in the range of 0.98 to 2.68 m.
purposes. Majority of the medium waters supply schemes in the districts are by bore wells. The yield of borewell in the district ranges from 500 to 72,000 lph. The data collected during reappraisal survey in the year 2007-08 pertaining to the depth to water level in pre-monsoon period, post monsoon period are given in Tables 2(a) & 2 (b). The hydrogeological map of the district is shown in Figure 4
Table 2 (a) DTW Range- Pre monsoon (April) Formations DTW range <5 m 5 to 10 m 10 to 20 m >20 m Alluvium (2 4 wells)
Laterites (1 4 4 wells)
Crystallines ( 17 wells)
Table 2 (b) DTW Range – Post monsoon (November) Formations (^) <5m 5 to 10mDTW range 10 to 20 m >20m Alluvium (24 wells)
Laterites (144 wells)
Crystallines (17 wells)
Long term trend of pre-monsoon and post-monsoon water level of groundwater monitoring wells (NHS) between 2002 and 2011 are analysed. Declining water level in the range of 0.015 to 0.206 m/year in pre-monsoon period is observed in some part in the central and western part of Kasargod, Manjeshwar and Kanhangad blocks. However in majority of the area the water level shows a rising trend in the range of 0.013 to 0.294 in pre-monsoon period and 0.11 to 0.185 in the post monsoon period. In the post-monsoon period the water level showed a decline in a few wells only in the range of 0.010 to 0.059 m/year.
4.2 Ground Water Resources
The ground water assessment was done block wise as per GEC-1997 methodology as on March 2009.
Table 3: Salient Details of Assessment of Dynamic Ground Water Resources of Kasargod District as in 2009.
Sl. No.
Assessment Unit/ Block Total Annual Ground Water Recharge Provision for Natural Discharges
during
non monsoon season Net Annual Ground Water Availability
Existing Gross Ground Water Draft
for All uses Net Ground
Water
Availability for future irrigation^ development Stage of Ground Water Development
(%) Categorisation 1 Kanhangad 9085.59 908.56 8177.03 5434.05 2427.11 66.46 Safe 2 Kasargod 8004.09 800.41 7203.68 6509.75 371.01 90.37 Critical 3 Manjeswar 11271.00 1127.10 10143.90 7306.02 2552.50 72.02 Semicritical 4 Nileswaram 7999.65 799.97 7199.69 4083.67 2870.87 56.72 Safe TOTAL (ha.m) 36360.34 3636.03 32724.30 23333.49 8221.48 71. TOTAL (MCM) 363.60 36.36 327.24 233.33 82.21 71.
As per the categorization of blocks based on 2004 data, Kasargod block was under over exploited category. Manjeshwar and Kanhangad under semicritical and Nileshwar block was safe. As per 2009 data computations, Kasargod block became critical, Manjeshwar under semi critical and other two under safe category (Figure 5). The reason for change in categorisation is mainly due to the difference in draft calculations and also due to improved position due to good rainfall.
4.3 Ground Water Quality
The chemical quality of groundwater is generally good in both phreatic as well as deeper fractured rock aquifers. About 45% of NHS samples showed EC less than 100 μs/cm at 25^0 C and almost all the water samples showed EC less than 250 μs/cm at 25^0 C (Annexure II). Only in areas very near to the coast and tidal zones, the water samples had EC around 1000 μs/cm at 25^0 C. All the water samples had fluoride within the permissible limit. The maximum value shown was 0.18 ppm. In laterite formations, the quality of water is generally excellent, but in some instances higher concentration of iron was reported.
In the bore wells, the quality of water is generally good, mostly the EC is in the range of 50 to 250 μs/cm at 25^0 C. Fluoride value is also within permissible limit.
In general the qualities of water in phreatic and deeper fracture zones are suitable for domestic, industrial and irrigation purposes.
puthur panchayaths of Kasargod block, Udma, Ajanur, Pallikkere and Pullur-Periye panchayaths of Kanhangad block, Nileshwar, East Eleri, Kayyur-Chimeni panchayaths of Nileshwar blocks. The borewells are generally shallower in valley areas, lineaments and shear zones and deeper in the hillocks and slopes and ridges. The depths of borewells are generally deeper in the eastern parts of the blocks. The depth range of borewells is given in Table 4(b).
The yields of bore wells are generally up to 5000 lph. In Manjeshwar block about 70% of the bore wells show discharge up to 5000 lph, and in other blocks it is around 58%. In Kasargod block, about 20% of the bore wells are yielding more than 10,000 lph and out of this about 4.5% yields more than 20,000 lph. Most of these high yielding wells are utilizing for regional water supply. The higher yielding wells are constructed in Bedadka, Chemnad and Mogral-puthur panchayaths of Kasargod block, Kumbla, Badiadka, Manjeshwar panchayaths of Manjeshwar block, Pullur-Periye, Pallikkere panchayaths of Kanhangad block. The failure percentage of borewells is generally less than 10%. The discharge range of bore wells block wise is given in Table-5..
Table 4 (a) Depth Range of Wells (Formation wise) Formation Depth Range <5m 5-10m 10-20m >20m Alluvium (2 4 wells)
Laterite (1 4 4 wells)
Crystallines ( 17 wells)
Table 4 (b) Depth Range of Borewells (Block wise) Name of Block
No. of Borewells
Depth Range <50m 50-70m 70-90m >90m Manjeshwar 575 59 10.3%
Kasargod 494 94 19%
Kanhangad 371 86 23.2%
Nileshwar 109 27 24.8%
Total 1549 266 17.2%
Table 5 Discharge Range of Bore wells (Block wise) Name of Block
No. of Borewells
Discharge Range < lph
lph
lph
lph
lph Manjeshwa r
Kasargod 494 55 11.1%
Kanhangad 371 37 10%
Nileshwar 109 12 11%
Total 1549 169 11%
In the recent years, due to the fall in water level, the dug wells were deepened in laterites and the crystalline areas. The wells are deepened by 1 to 3 metres. Horizontal bores were constructed in crystalline areas to increase the yield. The lifting devices of water are through centrifugal pumps, jet pumps for dug wells and submersible pumps and compressor for borewells. Water is also being lifted by bucket and rope from dug wells for domestic purposes. The stage of groundwater development in the district as on 2009 was 71.30% leaving some scope for future development. Out of the four blocks in the district, one is critical, one semi critical and two are safe. Future development can be possible in Nileshwar block and Kanhangad blocks (safe) and limited developments in Manjeshwar block (semi critical) and Kasargod block (critical).
For drinking water needs in the district, Kerala Water Authority and Grama Panchayats are empowered with supply of protected water for domestic use. Open wells, borewells and rivers are the principal sources of water supply. The Kerala Water Authority has 496 borewells, 731 dug wells, 135 ponds/tanks for water supply. Kasargod town is provided with piped water supply from Chandragiri River. The water supply to Kanhangad town is from infiltration galleries made at Kaniyachira Checkweir in Kikankote Chal (stream). In addition to this, most of the houses have their own wells to meet the domestic requirements. Recently under sector reforms and swajaldhara-2 schemes of district panchayat, drinking water facilities were provided in 17 grama panchayaths. From the 431 rural water supply schemes of these projects, a total of 133275 persons were benefited. The Jalanidhi schemes for drinking water supply is further extended to 5 grama panchayats.
There should be a mode for disseminating the technical knowledge through panchayaths. Farmers should also take support of GWD and reliable NGOs for Geophysical surveys for locating borewell sites.
Additional groundwater abstraction structures can be recommended in the district with a feasibility study only except Kanhangad and Nileshwar blocks. Since the data on actual number of groundwater abstraction structures are not available, the actual draft could not be calculated precisely. Indiscriminate construction of borewells in private sector is common in the district for the last ten years. The census data on the number of groundwater abstraction structures is a must for computation of actual draft.
5.2 Water Conservation and Artificial Recharge
CGWB has implemented artificial recharge and rain water harvesting schemes in Kasargod. They are given in Table 6. Table 6: Artificial Recharge and Rain Water Harvesting Schemes S.No. Location Type of Structure Year 1 Kadappallam Percolation tank 2001 2 Bangalamkulam Recharge pond 2001 3 Collectorate Kasargod Roof top rain water harvesting and recharge to groundwater
4 Aninjha Check dam 2003 5 Govinda Pai Memorial Govt. College, Manjeshwar
Artificial recharge to ground water (Checkdams, Gabion structure, Recharge tank, Contour bunds, Contour trenches etc.
6 Govt. UP School, Kolathur II
Recharge pond, Ferro cement tank 2010 7 Pallippara Desiltation of pond 2010
Kadappallam is located on laterite upland. After the development of the percolation tank it is observed that water level in the dug wells at downstream side of the structure has a rise around 0.6 metres in summer compared to previous years and earlier dry dug wells also became perennial. At Bangalamkulam also there is considerable rise observed in the water levels of dug wells down stream of the structure. At Aninjha after the construction of check dam there is considerable rise in water level of dug well on both sides of the stream and upstream side. By construction of different artificial recharge structures at Govinda Pai Memorial Govt. College, Manjeshwar, there is very much increase in yield of dug wells in downstream area and also find good changes in the flora of the surrounding areas. The
recharge pond constructed at Govt. UP School, Kolathur II of Bedadaka grama panchayat collects rain water many times in a season and the recharge of the same is very well observed in the dug wells of the surrounding areas. The desiltation of pond at Pallippara also has shown positive effect in water level. Recently water conservation and artificial recharge works had been taken by the Kasargod district panchayat. Under sector reforms and Swajaldhara-2 schemes, the district panchayat had constructed 2288 rain water harvesting structures in 17 grama panchayaths having a storage capacity of 266.92 lakhs litres. The schemes were confined in 5 panchayats subsequently. The rain water harvesting structures became a boon for coastal panchayat Valiyaparamba which is surrounded all the sides by saline water. Groundwater development could be coupled with management of rainwater and surface water. More stress should be given for water shed management. The existing water resources and dug wells, tanks/ponds and streams should be cleaned and protected. Along with rain water harvesting, artificial recharge schemes should also be practiced in large scale. The hydrogeological set up of the district very well suits for artificial recharge. Using rain water, bore wells can be recharged especially in the critical and semi critical blocks.
The artificial recharge schemes proposed for all the six blocks are
Vented Cross bar
Desiltation and deepening of pond/tank
Borewell recharge with recharge pit
Recharge pit
1 Manjeshwar 4 3 10 5 3 2 Kasargod 4 3 10 5 5 3 Kanhangad 4 3 10 5 3 4 Nileshwar 3 2 5 - - 5 Karadka 4 2 5 5 - 6 Parappa 3 2 5 - -
