PROCEDURE FOR OBTAINING GROUNDWATER PERMIT FOR INDUSTRIES IN WEST BENGAL

West Bengal has a very good groundwater potential. The reason of such affluence is due to her geographical location, high rainfall, and geological setting. But in recent times groundwater development in some districts in this state has been increased to such an extent that in some areas conditions of near overexploitation has developed. The condition, though not severe yet, has inspired hydro-geologists to think for conservation and sustainable development of groundwater. It has become necessary to assess the state of art and to find ways to augment the resource. Groundwater is not an isolated resource. It is a phenomenon within the hydrological cycle. So depending on the hydro-geological condition, water level condition, and stage of development proper measure for control of groundwater exploitation should be undertaken.

Now groundwater in West Bengal has now become a precious commodity. New industries are coming up in west Bengal, who will also be more dependants on groundwater. So the Act is a very timely intervention of the Government in proper management and conservation of the precious natural resource. It has become a great task of the implementing agency to carry on with it. 

Initially the groundwater Act 2005 was extensive and covered all types of structures that exploit groundwater through mechanical pumping devices. But recent changes have spared the farmers from obtaining permit. So the Act is now being implemented upon industries that are willing to use groundwater for their production or other uses in the industrial areas.

Some significant changes are made to the procedures for obtaining permit, though the main protocols, like submission of application, depositing permit/ application fees, and the authority who will receive the permit have not been changed.

There are two authorities:

1) the District Level Authority or the DLA, where the District Majistrate of the respective district is the chairman and the Geologist in charge of the district level offices of State Water Investigation Directorate (SWID) is the member secretary and the key technical person. The DLA has 10 to 12 maembers from the line departments and the Zilla Parishad who will initially examine the application.

2) The State level authority (SLA) gives the final vetting of the application. The Superintending Geologist of SWID is the member secretary and the Director SWID is the chairman of the SLA. There are other members of the Expert Committee from departments like, PHED, CGWB, Agriculture, Irrigation, Minor Irrigation etc.

The basic procedures for obtaining the permit are:

1.       Apply in plain paper to the DLA and collect requisite number of application forms from the DLA. The format of the form is available at  http://www.howrah.gov.in/Templates/swid/FORM%20I%20-%208%20TO%2010.pdf

2.       Fill up the form (it is a bit complicated) collect all required documents and information and get treasury challan form (TR 7). You can download the form here http://birbhum.gov.in/try2/9TR_Form_No_7.pdf

3.       Fill up the treasury challan and visit the geologist of your district (where the industry will come up). 4 copies of TR form will be required for each application.

4.       The Geologist (the member secretary of the SLA) will sign on your TR form.

5.       You will then have to deposit the application fee (Rs. 500) to the State Bank of India branch of the district. The Bank will return 2 copies of the TR form.

6.       You now come back to the DLA office and submit the Application form along with the TR form and the relevant documents.

7.       The member secretary will examine the form, your water requirement, visit the location of the propose tubewell, prepare a note on the hydrogeological condition of the site, the merit of the application and place it to the DLA meeting.

8.       DLA if satisfied forward the application to the SLA with their recommendation.

9.       Your Case will be discussed in the SLA meeitng and a high power committee will examine your case. If they are satisfied they will vet the case and instruct the DLA to issue the permit.

10.    The DLA will issue a letter of information to the applicant. The applicant will again submit Rs. 1000 as permit fee to the bank. Come back to the geologist and receive the permit.

 The documents required: (not limited to)

1.       The application form duly filled in.

2.       DPR of your Industrial Project + proof of ownership of land

3.       The mouza map of the area showing the location of the proposed tube well.

4.       Your detailed break up of water use.

5.       You detailed plan about how you are going the get the required water, the quantity and source

6.       Your water conservation plan

7.       Your rainwater harvesting plan

8.       Details of water harvesting structures ( no groundwater recharge in industrial area is allowed by the West Bengal Pollution Control Board)

9.       Location of the RWH ponds will have to be shown in the mouza map and also in the proposed layout plan.

10.    A declaration in plain paper that you will maintain the RWH ponds as long as the plant will be there.

11.    You will have to keep the existing ponds in your plant, but if you wish to fill it you will have to take necessary arrangements fos alternative pond excavation and conversion of the pond land.

12.    Your CSR activities related to groundwater conservation and augmentation.

13.    A hydro-geological feasibility report of your proposed plant area (buffer zone) to support your demand.
14.    Impact analysis of the whole operation of groundwater extraction.

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FUNDAMENTALS OF AQUIFER MAPPING

The water Resource Ministry of Government of India has released a notification and a fact sheet on National Aquifer Mapping Programme (NAQUIM). The Central Groundwater board and the State Groundwater Departments will act as the main functionaries in this programme. It is also decided by the government that national level aquifer mapping will progress substantially through the 11^th five year plan period. Considering the fact that those government departments alone cannot accomplish the job it has been decided that stake holders and NGOs would be involved in this endeavor.  This national level programme also has components like nation wise training and human resource development.

But, what is an aquifer map and what it is for?

The concept of aquifer mapping is not new. Many developed countries like Australia and USA have already completed aquifer maps in certain areas like Murray Darling Basin and Texas. They have already published some of the reports and maps. An aquifer map is not a single map, on the other hand it is a group of several maps that would describe the aquifer system and management criteria and options in an area.

In NAQIM programme of India it has been proposed that aquifer maps would include (1) Identification of Aquifer Management Units (AMU) (2) Evaluation of AMU, (3) Data preparation and generation of different categories (4) Prioritization of AMU, (5) Preparation of aquifer management plans and aqifer management and information system, (6)  Participatory groundwater management.

1.      IDENTIFICATION OF AQUIFER MANAGEMENT UNITS:

Aquifer management units are something different from a Hydrogeological unit. In a hydrogeological map generally geological units are described by its hydrogeological characteristics. But an AMU contains much more than that. It includes the 3 dimensional matrix of all information like extent of the aquifer, depth, thickness, geology, hydrology, land use on it, recharge and discharge related information and its political and social boundaries.

2.      EVALUATION OF OF AMU:

This is the most difficult task. Aquifer evaluations are conducted for various purposes including water supply development as well as groundwater contamination and remediation situations. They can range from fairly intense evaluations involving test drilling, geophysical investigations, installation of monitoring or observation wells, test pumping, physical and chemical water quality analyses, analytical and digital modeling to rapid evaluations based on existing data.

3.      DATA PREPARATION AND GENERATION OF DIFFERENT CATEGORIES:

The groundwater departments and states are generating groundwater data on regular basis. But those data are generally categorized on the basis of revenue boundaries and not on the basis of aquifer boundaries. So under NAQIM aguifer related data should be compiled and generated. A suggestive list of required data is given below.

   - Evaluation of existing data

   - Test drilling

   - Installation of monitoring or observations wells

   - Geoprobing and/or hydro probing

   - Geophysical investigations

   - Geophysical borehole logging

   - Groundwater gauging

   - Groundwater sampling and analyses

   - Test pumping

   - Slug testing

   - Analytical and digital groundwater modeling

   - Solute transport modeling

   - Groundwater monitoring

4.      PRIORITISATION OF AMU:

AMUs are basically aquifers subdivided into management units. These units are prioritized according to the demand and usage depending on the evaluated parameters of the aquifer. Before prioritization a management framework is required. The framework may include:

• Establish the baseline groundwater conditions and range of natural variability in the aquifer to facilitate enhanced knowledge and detection of change.

• Provide a consistent approach to understanding potential effects from all development activities on the surrounding environment.

• Facilitate projections of change based on future scenarios, such as expanding development or climate variability and change.

• Support and supplement the current pollution prevention and risk management principles as part of groundwater quality and quantity management.

 Prioritisation index:

Depending on the hydrogeology, quality of water and development status a prioritization index is to be developed by the groundwater authorities.

AMUs are initially ranked according to an index (equation 1) based on normalised current groundwater extraction, the fraction of groundwater allocation currently extracted , the fraction of sustainable yield currently extracted , a potential growth index and an index of the predicted future impact of groundwater extraction on surface water flow.

Apriority evaluation index has been attempted in Murray-Darling Basin Sustainable Yields Project (http://www.clw.csiro.au/publications/waterforahealthycountry/mdbsy/technical/Q-GMU-Prioritisation.pdf) Several other algorithms can be developed to prioritise aquifers in our country. In a GIS platform both raster and vector based analysis may lead to an efficient decision support system.

5.      MANAGEMENT PLAN

This initiative will seek to protect the long term water supply capacity of the aquifer by controlling average annual aquifer use and balancing it with average annual recharge.

                                i.            Aquifer Protection Plan: This initiative will seek to assess the quality of the water in the aquifer and then to protect it by encouraging activities that enhance water quality and by discouraging activities that degrade it.  The key components are

                              ii.            Maintain Status Quo where water level is alarmingly depleted.

                            iii.            Reduce withdrawal of water: Water withdrawal may be reduced by introducing innovative farming, recycling of water and reducing consumption. The management plan will address aquifer specific recommendation.

                            iv.            Enhance Natural Recharge: To enhance natural recharge proper steps should be taken. This may include afforestation, gully plugging, construction of sub surface dykes etc. This initiative will seek to maximize aquifer recharge with good quality water by encouraging beneficial land and water management practices and by investigating the potential to use stream flow.

                              v.            Monitoring plan: This initiative will seek to maintain a current and comprehensive scientific database on the aquifer by collecting, compiling and evaluating data. The current aquifer monitoring activities could be reviewed to coordinate and redesign them, focusing on the comprehensive protection of the Aquifer.

                            vi.            Manage Pollution Risks: Activities carried out in pits and dumping areas within the primary recharge area present a variety of risks to aquifer water quality. The risks associated with these activities could be assessed and, where required, action taken to manage them as part of an aquifer protection plan. Other risks like geogenic contamination like As and Fl should be properly addressed in the management plan to reduce public health hazards.

                                      vii. Reduce Incoming Salt Water: The regional salt water flow to the aquifer could possibly be intercepted by installing a set of management structures or through innovative engineering activities.

6.      AQUIFER EDUCATION PLAN

The potential long term success of this management plan depends on the understanding and cooperation of a diverse group of people.  It is believed that a better informed group makes better decisions.  Only common understanding will engender the cooperation needed to formulate,  implement and maintain a successful long term stewardship plan for the Aquifer. Additional study is required to achieve a better understanding.  Extension education is required to make knowledge gained available to all area residents.

Hydrogeology of Rajarhat New Town

Geology

The project area and its surrounding parts are underlain by huge thickness of quaternary sediments laid down by the southerly flowing Bhagirathi river and its tributaries. The major area is occupied by recent alluvium comprising of gray sticky clay, fine and medium sand mainly. At a depth of 120 metre or more there is a brown clay horizon of sub recent age. Average thickness of the clay layer near to the surface is about 25 metres.

Hydrogeology:

Groundwater occurs in several granular zones deposited by the river system. Sand horizons of different grades textures and colours constitute the main aquifers. In Rajarhat area due to the presence of thick clay at the top the upper aquifer gives a semi confined character. The drilling data available from the tube well drilled at Ecospace, Bengal Ambuja Complex shows that there is a thick gray clay bed upto a depth of 10 metres. From 10 to 42 metres there are several layers of fine sand often mixed with clay. This is the upper low yielding aquifer of the area. Below this there is a dark gray clay bed between 42 metre and 55 metres.  From 55 metres to 84 metres there is a bed of fine sand. Below this medium sand occurs  upto a depth of 100 metres (16m thickness). Below this upto a depth of  135metres there is fine sand.

The litho log and assembly is given in plate I

The zone between 55 metre and 135 metre constitutes a potential aquifer in this area and most of the groundwater is withdrawn from this area.

GROUNDWATER LEVEL

Groundwater level in Rajarhat block is regularly monitored. The post monsoon Groundwater level (2011) of 7 monitoring stations in and around the project area is given in the table1. With the help of the data a depth to water level zonation map is prepared which is shown in plate II.

Table 1. Post Monsoon depth to water level of Rajarhat area. (Source: SWID)

Sl NoMouza	Location	Type of well	Post monsoon DWL mbgl
1              Patharghata	Village centre	Tube well	5.5
2              Chandpur	Panchayet office	Tube well	0.85
3              Gopalpur	Health Centre	Tube well	11.25
4              Rajarhat	Bishnupur Health Adm unit	Tube well	5.53
5              Ghuni	Primary School	Tube well	9.9
6              Jagadishpur	Primary School	Tube well	7.7
7              Sukantanagar Salt Lake	Near Club	Tube well	12.3

It appears that the post monsoon depth to water level of the project area is between 8 to 9 metres below ground level. Water level is also collected from a deep tube well of the Tinkanya project site. The depth to water level of that well on25 January 2012 is 8.29 mbgl. The tube well tapped the aquifer between the depth 80m bgl to 95 m bgl.

PRESENT GROUNDWATER SCENARIO OF WEST BENGAL

Introduction
Introduction
Groundwater is prime natural resources in the earth .Not only it supported almost all types of life form to evolve, but also helped in growth of human civilization. It quenches thirst and meets the household demands. Used in the fields for production of food grains .Lastly the industries catering to the various needs and luxuries of human being have started consuming voluminous quantity of Water .Groundwater is therefore a precious national asset and planning, development and Management of water resources need to be governed by national perspectives.
In the beginning, water from rainfall and snow and rivers were only source of water to mankind. As these surface water sources were dependent on rainfall, localized shortage was often witnessed. With primitive technologies men was not able to build sustainable water reservoir to see them through the drought period .But once man came to know of groundwater, his dependence on it increased with the advent of civilization. At present about two billion people in the world is dependent on groundwater. Fortunately, groundwater is a renewable resource that is recharged every year through rainfall. However, this recharging process is not entirely dependent on rainfall but on various other natural factors that differ from region to region and within space and time. Therefore, recharge of groundwater is never a constant factor .When the average quantity of draft exceeds recharge for repeated years we face the situation of over exploitation.
The manner and the scale in which the use of groundwater has accelerated, human being has become so much dependent on the assured source that no sign of the over increasing demand for groundwater stabilizing.
Beginning of 20th century witnessed demand for groundwater in industrial sector rising phenomenally at a faster rate than that in agriculture and domestic sector.
West Bengal is the only state in India that stretches from Mountain to the Sea and truly a “Asamudra himachalam” state as the meaning goes. West Bengal has a very good groundwater potential. The reason of such affluence is due to her geographical location, high rainfall and favorable geological setting .The state have land area of about 2.7% but have about 6% of total replenishible groundwater resources of India. Groundwater is the most exploited resource in west Bengal particularly in agriculture sector With the introduction of water intensive high yielding variety , the need for groundwater have skyrocketed. Quinquennial census of minor irrigation structures indicated a 64% growth in number of STWs over last 16 years,@4% annually.
Table Showing Number of Groundwater Structures from 1986 to 2001

Name of Structure 1986-87 1994-95 2000-2001
Dug Well 63387 55983 39377
Shallow Tubewell 368316 504638 603667
Deep Tubewell 3122 4039 5139

Hydrogeological Condition
Geologically West Bengal can be divided into two broad units (A) Consolidated or semi consolidated formation occurring in the northern most and western part of West Bengal and (B) Unconsolidated formation in the rest of West Bengal.
(A) Consolidated/ semi consolidated formations:
These formations cover the western and the northern part of the state. These are comprised of Archaean crystalline rocks and Gondwana group of rocks including Rajmahal traps covering part of Purulia, Bankura Paschim Medinipur, Birbhum and Burdwan.. Archaean metamorphics, Siwalik and Gondwana covers part of Darjeeling and Jalpaiguri District. In the western part and in some part of Darjeeling district , these hard and semi consolidated rocks are overlain by weathered residuum and laterite capping.
(B) Unconsolidated formations:
These formations belonging to the Tertiary and Quaternary age and covering rest of West Bengal. These formations may be subdivided into (a) Secondary laterite (b) Older alluvium and (c) Recent alluvium.

Secondary laterite occurs at the marginal area between the Consolidated/ semi-consolidated rock and older alluvium mainly in the districts of Bankura, Paschim Medinipur, Burdwan and Birbhum. Older alluvium occurs mainly in the elevated terraces fringing the lateritic margin of the Chhotonagpur plateau in Bankura, Pascim Medinipur, Burdwan, Birbhum, Hoogli and Murshidabad district and in the Barind region of North Bengal. Recent sediments occupy the river courses and flood plains.


Depletion of groundwater
In spite of having high groundwater reserve, exploitation of the resources in West Bengal shot up to such level that 80’s decade first witnessed the sign of depletion of groundwater level in some blocks of Murshidabad, Burdwan, Medinipur, Hoogly where pre-monsoon water level dropped below the centrifugal pumping limit and hand tubewells went dry. Introduction of Submersible motor driven pump though came as a blessing to the cultivators, for it can draw water from far deeper depth – caused further lowering of groundwater level.
Depth to water level data analyzed by the State Water Investigation Directorate, Govt. of W. Bengal, indicated significant average annual fall in pre monsoon depth to water level during the period 1995 to 2004 to the tune of 16 to 70 centimeters in some blocks of Murshidabad, Burdwan, Purba Medinipur and Hoogly districts. In some parts of Hooghly, Burdwan and Murshidabad districts, significant fall was noticed in both pre and post monsoon period.

Case 1 No change


Case 2- Post monsoon no change but pre monsoon falling trend


Case 3 both pre & post monsoon show falling trend


Case 4: Pre monsoon rising trend, post monsoon falling.


Groundwater Quality
In addition to the phenomenon of lowering of water level, deterioration in Chemical quality of groundwater was noticed in some parts of the state that took place in the form of Arsenic and Fluoride contamination. On the basis of preliminary survey 81 blocks in the state have been identified where Arsenic was found in groundwater above permissible limit. Similarly, presence of Fluoride beyond permissible limit in groundwater was detected in 49 blocks of the State.
It was observed that the entire younger and recent alluvium formation east of Bhagirathi River is arsenic bearing and reason for such occurrence is solely Geogenic. Arsenic held by the solid phases within the sediments, especially iron oxides, organic matter and sulphides might constitute the primary arsenic sources in groundwater under condition condusive to arsenic release from solid phases.
Occurrence of Fluoride, in groundwater is generally recorded from hard rock areas. The subsurface water may be contaminated with dissolved substance due to disintegration and dissolution of bed rock that rendered water unfit for drinking due to presence of certain toxic constituents. Fluoride is one such chronic toxic substance, that have affected large number of people causing Skeletal or Dental fluorosis. Fluorite (CaF2), Cryolite (Na Al F6) is the rock forming minerals which contribute Fluoride to the groundwater. Wastewater containing Fluoride originating from various industries viz phosphate fertilizer, ceramic industry brick kiln and pharmaceutical industries may find its way to the groundwater and elevate the Fluoride level.

Assessment of Groundwater Resources
Apprehending phenomenal increase in extraction of Groundwater, Government of India considered that quantitative assessment of these resources is necessary for planning and sustainable development. Accordingly , Ministry of water Resources formed Groundwater Estimation Committee , which came out with a methodology based on reasonably valid scientific principles and reliable data .The first assessment of the resources was carried out in 1984. Meanwhile, Central Groundwater Board and different State Water investigation Organizations carried out further detailed studies and generated additional database which along with the ever-rising Groundwater utilization through the country, indicated need for modifying the methodology for more precise assessment. Another Estimation Committee was set up in 1995 came out with modified methodology in 1997 known as GEC ’97 methodology. Assessment of Groundwater resources of all the States were carried out jointly by the Central Groundwater Board and the respective State groundwater Organizations with block as unit and 2004 as base year.
The assessment revealed that the national average for stage of groundwater development is 58% whereas the same for the State of West Bengal is 42%.The assessed blocks were categorized, on the basis of stage of development and long term significant decline of groundwater level, as ‘Safe’, ‘Semi-Critical’, ‘Critical’ and ‘Over exploited’ .In the national scenario, 4078 blocks are Safe out of total 5723 blocks.
In West Bengal assessment was carried out in 269 blocks out of total 341 blocks leaving aside 13 hilly blocks in the north and 59 Saline blocks of coastal region. As per the assessment carried out by application of GEC’97 methodology, 231 blocks have been found to be Safe .28 blocks were assessed to be Semi-Critical and 10 blocks as Critical. However State committee on groundwater assessment is reviewing assessment and categorization of this 10block.
Based on the assessment carried out the net groundwater availability in West Bengal was calculated to be 27.46 BCM, whereas existing groundwater draft in all sectors –irrigation , domestic and industrial , is 11.65 BCM, leaving 15.81 BCM of dynamic resources reserve for further use.
Planned approach for Groundwater development
The groundwater scenario at national level and that of West Bengal reveal that exploitation of groundwater in the state has not yet reached alarming critical stage .The national water policy 2002 states that exploitation of groundwater should be limited to the extent of annual recharge. Although the average stage of groundwater development is 42% in the state , adverse effects like water level depletion and chemical degradation have been noticed in some areas in scattered manner. Government is concerned about incidents of suffering of the local population in such areas due to shortage of water in peak summer and from diseases due to consumption of arsenic and fluoride contaminated water.
It was apprehended that if indiscriminate use of water go on unabated, adverse effects of degrading hydrogeological regime of the state, will amplify and will engulf the whole state in such a manner that the whole agriculture and industrial development process will suffer a set back. The Government had determined view not to allow such situation and decided to promulgate suitable Act to control and regulate the use of groundwater in the State.

Groundwater Act
West Bengal Groundwater Resources (Management , Control & Regulation ) Act 2005 was promulgated with effect from 15th September ‘2005.This act stipulates obtaining mandatory permit for installation of groundwater extraction structures operated by engine or motor driven pump .This act also , stipulate registration of all such structures existed before the act came into force.
Apart from West Bengal, other states viz. Himachal Pradesh, Kerala, Goa and Tamil Nadu have already passed suitable acts for control and regulation of groundwater .Andra Pradesh had enacted Water , land and tree act in 2002. Maharashtra enacted groundwater (regulation for drinking water sources) Act in 1993 for limited purpose of regulating public drinking water. For the remaining states either the groundwater bill is under drafting or draft bill is under consideration of the respective government.

Conclusion
Crisis of Water is probably the worst curse any civilization would like to face. It will be tragic for the next generation facing this crisis due to lack of foresight in part of the present generation. The groundwater resources, although renewable, are limited and vulnerable. Crisis of water may not be only quantitative; quality degradation may also add a different dimension to the problem.

West Bengal, which is considered to have tremendous groundwater potentialities, is no exception. Crunch is already felt in drinking water sector in rural west Bengal during Boro cultivation season precipitating a situation of artificial draught in almost every year. Unpredictable monsoons, destruction of green coverage, siltation of rivers, uncontrolled urbanization have compounded this problem. Area under arsenic and fluoride are increasing day by day. Failures in part of the authority to implement the Groundwater Act and lack of awareness in part of the users have failed to check unrestricted growth of tubewells in the state. Stages of groundwater development with 2004 as base year that show a meager 42% stages of groundwater development in the state as against a national average of 58% , needs to be upgraded .The 4th Minor Irrigation Census is presently underway and results might reflect a higher Stages of groundwater development for this state. The act for controlling extraction of groundwater is probably not adequate in itself for total management of groundwater resources unless people is made to aware about the adverse situation which may arise from unplanned and indiscriminate use of groundwater. The other strategies involve co-ordinate approach to conservation, augmentation and conjunctive use of groundwater, wherever possible. This can be successfully achieved through rain water harvesting and artificial recharge that make it possible to:
1. Restore supply in aquifer, depleted due to overexploitation.
2. Improve chemical quality
3. Prevent salinity ingress.
4. Increase hydrostatic pressure against land subsidence

To implement rain water harvesting and artificial recharge to be implemented , it is necessary to adopt policy decisions like mandatory installation of roof top rain water harvesting and artificial recharge structures in urban areas and restoration of all derelict tanks in the villages , building check dams etc in high slope areas.
Groundwater is not an isolated resource. It is a phenomenon within the hydrological cycle. So depending on the hydrogeological condition, water level condition and stage of development proper measure for augmentation of groundwater should be taken.

HYDROGEOLOGICAL INVESTIGATION IN A WATER SHED- A REPORT

Introduction:

A systematic hydrogeological study was carried out in the project area covering about…6500…ha. The survey includes geological and geomorphological mapping, periodic monitoring of water levels in a network of observation wells. 100% dugwells in the area have been selected as monitoring stations. Lithological log upto a depth of 10m (bgl) were obtained in certain areas to determine the geometry of the aquifers. Geomorphological and structural mapping was carried out in a larger area to determine the regional geology and trends of lineaments.

Complete geological mapping has been done on this area. The geology of the area is it is a granitic region with minor variation in the grain size. There is a pegmatite outcrop in the Sarenga Fulberia. There are basic intrusions in granite, which has a foliation dip and strike.

Geomorphologically the area can be subdivided as:

1. Denudation terraces

2. Shallow buried pediments

3. Moderately buried pediments

4. Valley fill deposits

The above four categories of geomorphological surfaces have been separately dealt with in the hydrogeological investigations as follows.

1. Pumping tests : Pumping tests to determine the aquifer parameters were carried out in a number of dugwells in the area. The wells were essentially situated in the Baid and Kanali area. The recuperation test data were analysed in G.W.W. programme and Kd (Transmissivity) value was determined.

2. Infiltration experiment: Infiltration experiments were carried out in the project area for determination of infiltration capacity. The infiltration capacity values are determined to classify the watershed in terms of infiltration capacity.

3. Monitoring of water level: From 160 nos. observation wells of water table below ground surface has been monitored every month. From these data pre-monsoon and post- monsoon depth to water level maps and water level fluctuation maps have been prepared.

4. Reduced level connection of wells: All wells have been connected by land level survey and reduced level (RL) of each well was determined. Thus RL of water table at each well point in each season was computed. Seasonal water table contour maps have been prepa- red to determine the groundwater flow direction and the geometry of the saturated surface.

5. Stream discharge measurements : At the mouth of the Chaggalkuta stream gauging station has been set up to measure the stream discharge continuously.

6. Meteorological Observations: Primary meteorological data have been generated at the weather station set up at Teghori village. Daily precipitation, sunshine, wind speed, rate of evaporation, maximum and minimum temperature, humidity etc. are continuously recorded at this station. With the help of necessary meteorological data daily PET (Pennman) has been computed with the help of a programme prepared for this purpose.

7. Soil Moisture: Monthly soil moisture percentage has been gauged at every land situation at 15 cm and 30 cm depth. With this data monthly change in soil moisture has been determined.

Aquifer Condition: The basement rock of Chagalkutta watershed is mainly granite along with some pegmatite and basic intrusive. Fractures in this rock system generated the secondary porosity. The weathered residuum and the thin alluvium cover that lie over the basement rock contain water and these along with the fractured part of the basement rock developed the treatic aquifer system. This area has a single unconfined aquifer and thickness is between 15 to 30m as revealed from local information of dug wells and hand tube wells. But these tube wells and dug wells are mostly confined to the ridge, back slope and rarely to the toe slope and valley region. There is hardly any well in the valley fills.

212 (100%) dug wells are monitored every month. It is very difficult to take water level from the drinking water tube wells because the local people do not allow opening of those hand pumps. So the present observations are totally based on the data available from those 212 wells.

It is observed that the wells are in most cases occur as clusters in settlement areas in some cases spacing between two wells is very small to generate contour lines between them. So 50 wells have randomly been selected for water level map generation water table contour maps have also been generated by RL connection data of those wells.

All contour maps and depth to water level zonation maps have been prepared with the help of SURFER-6 software and for better interpolation and extrapolation kriging method has been adopted for grid generation. Each depth to water level grid file and each contour grid file have been blanked with watershed.bln.

Depth to water level condition: Pre-monsoon and post-monsoon depth to water level maps have been prepared using the table (well.xls). The map shows that in the chhagalkuta watershed there is wide variation in the pre-monsoon water level (April 1999). The maximum depth to water level condition has been observed at Lakhanpur (well no. Lak 1) where the water level is 14.30 mbgl. At Golghori wide variation in water level is observed (5.05m to 11.05m) bgl. At Siromanipur, Danga, Kurchibedia, Kasibedia, etc. area water level is between 8 to 9m bgl. But it is observed that in most of the wells other than those described above major area of the watershed has depth to water level between 6 to 7m bgl. At Gopaldihi, Panjangora, one well at Kendsar (ken 1) shows water level below 5m and 2 wells at Gopaldih (Gop 1 and Gop 5) show water level within 4m bgl. The depth to water level map divided the watershed in depth to water level zones.

1) Between 3-6m bgl i.e. within centrifugal pumping limit

2) From 6-7m bgl i.e. sump well is possible

3) From 7-10m bgl i.e. beyond centrifugal pumping limit but within low HP submersible

Pumping limit.

4) Above 10m bgl i.e. special pumping device or high HP submersible pump is required.

Post monsoon depth to water level map (November) shows a remarkable rise in water level. It is to be mentioned that at Lakhanpur the rise is maximum (11 to 12m approximately). During the post monsoon period major part of the watershed show depth to water level between 2 to 3m bgl. Only at Kasibedia, Poirasol, Kanudih and Ghutia. Post-monsoon water level is between 3 and 5.5m. In the western ridge area i.e. at Dangra Lari and Kendsar and Panjangora in the south, the fluctuation is minimum (75m). There are some isolated patches showing fluctuation between 7 and 9m (at Danga).

Groundwater flow direction

Water table contour maps generated during pre and post monsoon period show the major trend in groundwater flow. Pre-monsoon water table rises upto 160m amsl at the southwestern corner of the watershed and comes to 99m amsl at the month of the Chhagalkota stream. The overall groundwater flow direction is from southwest to northeast in conformity with the surface.

During the post-monsoon period overall flow direction does not change much excepting with a rise in level. In the southwestern corner the R.L. of water table is about 165m amsl. In the northernmost corner of the watershed i.e. near the mouth of Chhagalkuta this value is about 103m amsl.

. HYDROLOGICAL ANALYSIS:

1. Purpose and scope:

Hydrological analysis carried out in Chagalkuta watershed started from February 1999. All investigations were conducted from the field station situated at Teghari in Chhatna block of Bankura district. The field station is equipped with all types of meteorological and hydrological gauging provisions

2. Parameters:

For detailed hydrological analysis the following parameters had been analysed in details.

i) Precipitation

ii) Potential evapotranspiration

iii) Soil moisture

iv) Pond water volume

v) Groundwater dynamic storage

vi) Runoff

vii) Groundwater draft

viii) Actual evapotranspiration

3. Basic data Generation:

For calculation of each of the above-mentioned parameters primary data have been generated from field and then computed. The table below shows the list of field database and frequency of reading behind each of the parameters mentioned above.

Table showing List of field database behind each hydrological parameter

Sl No.	Parameter	Field Data base	Reading frequency	Remarks
1	Potential evapotranspiration	Sunshine hour	Daily
		Wind speed
		Mean air temperature
		Relative humidity
2	Precipitation	Rain gauge reading	Daily
3	Soil moisture	Soil moisture %	Monthly
4	Pond water volume	Field measurement from pond	Monthly
5	Evaporation from pond	Pond surface area	Monthly
6	Groundwater dynamic storage	Depth to water level	Monthly
7	Runoff	Measurement from stream	Daily
8	Groundwater draft	Human use / irrigation draft/	Monthly
9	Actual evapotranspiration	Crop area for each crop	Monthly

4. Method of data collection.

The methods of collection of different types of field data are described below.

I. Daily sunshine hour is recorded from sunshine recorder installed at Teghai field station.

II. Daily maximum and minimum temperature is recorded using maximum-minimum thermometer and Stevenson’s screen. Mean daily air temperature is calculated from the readings.

III. Daily relative humidity is collected using hygrometer.

IV. Anemometer is used to collect the wind velocity. Daily two readings are collected and daily average wind speed is calculated.

V. Daily reading from rain gauge is collected at the hydro-meteorological station at Teghari..

VI. Daily evaporation rate is measured using pan evaporimeter.

VII. There are dug wells within the watershed area. Depth of water level from ground level is measured from each well every month.

VIII. The wet area and depth of each pond is measured every month to calculate the monthly pond volume.

IX. There is a gauging station at the confluence of Chagalkutta with Arkosa. At that point the daily stream flow is measured using flow meter.

X. The population of each mouza is an indicator of groundwater draft. In this area people depend mostly on ground water for their domestic use. Multiplying the population with the daily water use and the number of days in a month the groundwater draft is calculated.

XI. Soil moisture data are collected from the field using soil moisture meter, which gives the percentage of available water.

XII. Area of each crop is recorded in every month.

5. Computation

a) Computation of Potential evapotranspiration: this is calculated using Penman’s equation:-

PET= (AH_n + Eag)/(A+g)

Where PET = daily potential evapotranspiration in mm per day

A= slope of the saturated vapour pressure vs. temperature curve at the mean air temperature, in mm of mercury per ^oC. This value is achieved from the Table M1

Hn = net radiation in mm of evaporable water per day

Ea = parameter including wind velocity and saturtion deficit

g = psychrometric constant = 0.49 mm of mercury / ^oC

The net radiation is expressed as Hn= Ha (1-r) [a+bn/N] -st⁴a ( 0.56-0.092√e_a )[0.10+0.90n/N]

Where Ha= incident solar radiation outside the atmosphere on a horizontal surface, expressed in mm of evaporable water per day ( it is a function of latitude and the period of the year as computed in table M2)

a = a constant depending upon the latitude Φ and is given by a= 0.29 cos Φ

b = a constant with an average value of 0.52

n = actual duration of bright sunlight in hour

N = maximum possible hour of bright sunshine (it is a function of latitude as indicated in table M3)

r = soil albedo

s = Stefan- Boltzman constant= 2.01 X 10^-9 mm/day

Ta = mean air temperature in degrees Kelvin = 273 + ^oC

e_a = actual mean vapour pressure in the air in mm of mercury

The parameter Ea is estimated as Ea = 0.35 [1+ u₂/160] (e_w-e_a] in which

u_{2 =} mean wind speed at 2m above ground in km/day

e_w = saturation vapour pressure at mean air temperature in mm of mercury this is defined as a function of temperature and the equation is = 4.584 exp [17.27t/ ( 273.3+t)]

e_{a =} actual vapour pressure

For computation of PET the following basic data are necessary:- Latitude, Elevation, Mean temperature, Mean relative humidity, Observed sunshine hour, Wind velocity at 2m height, Nature of surface cover, Date of observation.

b) Computation of Soil Moisture volume: Soil moisture was monitored periodically. Soil moisture percentage data have been gauged from every mouza and every land situation in every month. For computation of monthly water balance, monthly average soil moisture percentage for every land situation was calculated first. From monthly soil moisture percentage soil depth of each land situation and soil character, soil moisture depth and volume have been computed. The following conditions hereby apply. For determining field capacity and wilting point a graph (fig 3.8) of page 65 from the book Hydrology and Management of Watershed by Keneth. N. Brookes, Peter F. Ffolliott , Haus. M Gregersen and Leonardo F Dabauo have been consulted. The table shows the average root depth, field capacity, wilting point and soil water holding capacity.

Soil water holding capacity (mm)=Root zone soil depth (m) x {Field capacity (mm) –Wilting point (mm)}

Land situation	Average Root Zone Soil Depth (m)	Field capacity (mm)	Wilting point (mm)	Soil moisture holding capacity (mm)
Ridge	0.15	120	30	13.5
Back Slope	0.45	240	60	80
Toe Slope	0.80	200	40	128
Valley Fill	0.90	370	150	198

From soil moisture % soil moisture depth of each land situation for each month has been calculated.

Soil moisture volume (in ham) was calculated as = Soil moisture percentage x Soil moisture holding capacity (in mm) x area (in ha) x .001

c) Computation of Groundwater recharge/ discharge: Ground water level (depth to water level) has been measured in every well in every month. Water level fluctuation of each well for each month with respect to previous month was calculated.

From mouzawise average fluctuation groundwater recharge and discharge have been calculated using the equation; Recharge / Discharge = Fluctuation x Area x Specific Yield

Since the total area falls within a granitic country and the aquifer mainly comprises of weathered and fractured granite the specific yield has been assumed as 0.05.

d) Computation of Pond volume:

Actual pond water volume of every month was measured (average depth x area) for every pond. Monthly total pond water storage was calculated from that value.

e) Computation of Actual Evapotranspiration:

Actual evapotranspiration (AET) has been calculated from the potential evapotranspiration (PET) using the following equation :

ET (vol ) in ham = PET (mm) x S Crop & other vegetation Area (ha ) x Crop Coefficient (k_c) for each crop x (0. 001)

f) Computation of evaporation from surface water bodies: Evaporation from surface water bodies is calculated using the following equation.

Evaporation in a month = pond surface area (Ha)* evaporation from pan evaporimeter (mm)* pan factor

In this case the pan factor is 0.70

WATER BALANCE:

The fundamental water balance equation used in this project is a modification of the Thornthwith Mather model in which groundwater recharge/ discharge and groundwater draft have been included. Thus the principal water balance equation is

P + surplus water of previous month + I = AET+ D Sm. + DGW + D Pond + evaporation + GW Draft + Runoff + Surplus water retained in the system at the end of the month.

Here P= precipitation volume

I = Irrigation input

AET = actual evapotranspiration

D Sm = change in soil moisture volume

DGW = Change in groundwater storage (recharge/ discharge)

D Pond = Change in pond storage

Table Showing the parameters and their mathematical relations involved in calculating the water balance

Item No	Parameter	Algorithm
A	WATER RETAINED IN THE SYSTEM	Water retained in the system at the end of previous month (+ve value=surplus, -ve value = deficit)
B	PRECIPITATION VOLUME (P)	Precipitation measured for the month * area of the watershed
C	IRRIGATION INPUT(I)	Actual irrigation input in the field, calculated on the basis of irrigated crop pattern and area
D	TOTAL WATER INPUT	Total of Water retained in the system at the end of previous month+ precipitation volume+ Irrigation input
E	SOIL MOISTURE CHANGE	Soil moisture volume of previous month - soil moisture volume of current month
F	POND VOLUME CHANGE	Pond volume in the previous month – pond volume in the current month
G	GROUNDWATER RECHARGE/ DISCHARGE	Average change in groundwater level * area of watershed* specific yield [+ve value means recharge into, -ve value means discharge from the reserve]
H	WATER GAIN IN THE RESERVES	Total of Abstraction of water in reserves= soil moisture change+ pond volume change+ groundwater recharge/ discharge
I	AET	Actual evapotranspiration based on Crop area* crop coefficient*PET
J	EVAP	Evaporation from wetlands
K	RUNOFF	Defined
L	TOTAL WATER LOSS	Total of AET+EVAP+RUNOFF
M	WATER RETAINED IN THE SYSTEM AT THE END OF THE MONTH	Total water input-Total abstraction of water in reserves-Total water loss[+ve value means water surplus and -ve value means water deficit ]

6. Water Estimation:

Water estimation is done to achieve at a conclusion that for a particular time and space there must be a tool for assessing the available water at any part of the whole system.

Thus the whole system is divided into three parts, i) water gaining system, ii) Water storage system and the iii) discharging system (water loss)

Water gain of the system is Precipitation, Irrigation (in case of the Chagalkutta watershed it is nil as no irrigation is being received from outside), and cumulative change of soil moisture storage, change in pond water volume, change in ground water volume. Total water loss from the system occurs as Evaporation loss, Actual ET, ground water seepage loss, and run off. The difference in water gain and water loss is the quantum of water that remains impounded within the system through various water harvesting structures excluding the traditional pond/tank system. It was found that some surplus water is generated within the system. It is explained that a huge amount of water is kept stored in the field (impounded) by the local people from the very first month of the monsoon to minimize runoff. But, how much water is stored cannot be quantified. Soil moisture is also measured from comparatively dry areas; therefore the surplus water is actually the artificial and temporary impoundment, which subsequently drains into streams or groundwater. So, for rational calculation the surplus water found in a month is added to the total water input of the next month.