ISO/TR 13973:2014
(Main)Artificial recharge to groundwater
Artificial recharge to groundwater
ISO/TR 13973:2014 provides details of methods aimed at augmentation of ground water resources by modifying the natural movement of surface water as a general guide. This Technical Report does not cover the process of deciding and planning artificial recharge
Recharge artificielle des eaux souterraines
General Information
Standards Content (Sample)
TECHNICAL ISO/TR
REPORT 13973
First edition
2014-11-15
Artificial recharge to groundwater
Recharge artificielle des eaux souterraines
Reference number
ISO/TR 13973:2014(E)
©
ISO 2014
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ISO/TR 13973:2014(E)
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ISO/TR 13973:2014(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope .1
2 Normative references .1
3 Terms and definitions .1
4 Artificial recharge techniques .1
4.1 Surface spreading techniques . 2
4.2 Subsurface techniques .18
4.3 Combination of surface and sub-surface techniques .27
5 Environmental impact assessment .28
5.1 Monitoring of recharge structures .28
5.2 Water level monitoring .28
5.3 Water quality monitoring .29
Bibliography .32
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ISO/TR 13973:2014(E)
Foreword
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The committee responsible for this document is ISO/TC 113, Ground water.
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ISO/TR 13973:2014(E)
Introduction
Excessive extraction/use of ground water for various applications has resulted in marked lowering of
ground water levels. Ground water levels are depleting very fast in various areas threatening ground
water sustainability and causing adverse environmental impacts. Artificial recharge to ground water
provides augmentation of ground water resources using surplus surface water available. Artificial
recharge techniques can be applied to address the following issues:
a) enhance the sustainability of ground water resources in an area where over-development has
depleted the aquifer;
b) conservation and storage of surplus water for future requirements;
c) improve the quality of existing ground water through dilution.
The following are basic requirements for recharging the ground water reservoir:
a) availability of surplus water of suitable quality in space and time;
b) suitable hydrogeological environment;
c) identification of sites for augmenting groundwater;
d) cost effective and appropriate artificial recharge techniques and structures.
Availability of source water of suitable quality is one of the prime requisites for ground water recharge.
This can be assessed by analysing the water resources available as runoff and rainfall. The physical,
chemical, and biological quality of the recharge water is important in planning and selection of recharge
method. Age of water used for recharge is also considered important in certain cases.
The hydrogeological situation in each area needs to be appraised with a view to assess the recharge
capabilities of the underlying geological formations. Detailed knowledge of geological and hydrological
features of the area is necessary for proper selection of site and type of recharge structure. In particular,
the input on geological boundaries, hydraulic boundaries, inflow and outflow of waters, storage capacity,
porosity, hydraulic conductivity, transmissivity, natural discharge of springs, water resources available
for recharge, natural recharge, water balance, lithology, depth of the aquifer, and tectonic boundaries
features such as lineaments, shear zones, etc. are required for effective and efficient artificial recharge
to ground water.
The aquifers best suited for artificial recharge are those that can hold large quantities of water and do
not release them too quickly. The evaluation of the storage potential of sub-surface reservoirs (aquifers)
is invariably based on the knowledge of dimensional data of permeable material in floodplain (alluvial),
reservoir rock which includes their thickness and lateral extent. The availability of sub-surface storage
space and its replenishment capacity further govern the extent of ground water recharge.
Artificial recharge techniques envisage integrating the surface water resources to ground water
repositories resulting in changes in the ground water regime, like
a) rise in water level,
b) increment in the total volume of the ground water reservoir,
c) availability for extended period, and
d) quality of ground water.
The upper part of the unsaturated zone is not considered for recharging since it can cause adverse
environmental impacts like water logging, soil salinity, dampness, etc.
Artificial recharge projects are site-specific and replication of the techniques even in similar areas is
to be based on the local hydrogeological and hydrological environments. Artificial recharge to ground
water is generally supported by the remote sensing studies, hydro-meteorological studies, hydro-
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ISO/TR 13973:2014(E)
geological studies, hydrological studies, soil infiltration testing, geophysical studies, hydro-chemical
studies, etc. The studies bring out the potential of unsaturated zone in terms of total volume, which can
be recharged.
Artificial recharge of ground water is normally undertaken in the following:
a) areas where ground water levels are continuously declining;
b) areas where substantial volume of aquifer has already been de-saturated;
c) areas where availability of ground water is inadequate in lean months;
d) areas where studies indicate scope for improvement of quality of ground water or areas where salinity
ingress into fresh water aquifers has already taken place or is likely to happen in the near future.
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TECHNICAL REPORT ISO/TR 13973:2014(E)
Artificial recharge to groundwater
1 Scope
This Technical Report provides details of methods aimed at augmentation of ground water resources
by modifying the natural movement of surface water as a general guide. This Technical Report does
not cover the process of deciding and planning artificial recharge within an overall water resource
management scheme.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated
references, only the edition cited applies. For undated references, the latest edition of the referenced
document (including any amendments) applies.
ISO 772, Hydrometry — Vocabulary and symbols
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 772 apply.
4 Artificial recharge techniques
A wide spectrum of techniques are used to recharge ground water reservoirs. Artificial recharge
techniques are broadly categorized as
a) surface spreading techniques,
b) sub-surface techniques, and
c) combination of surface and sub-surface techniques.
Aquifer disposition plays a decisive role in choosing the appropriate technique of artificial recharge of
ground water as illustrated in Figure 1.
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Key
1 and 2 surface spreading techniques
3, 4, and 5 sub-surface techniques
6 indication of water table/piezometeric head
NOTE Local regulations might exclude certain artificial recharge options, such as aquifer to aquifer
interconnection, as shown in item 4.
Figure 1 — Recharge techniques for increasingly deep permeable materials.
4.1 Surface spreading techniques
These are aimed at increasing the contact area and residence time of surface water over the soil to
enhance the infiltration and to augment the ground water storage in phreatic aquifers. The important
considerations in the selection of sites for artificial recharge through surface spreading techniques
include the following:
a) the aquifer being recharged should be unconfined, permeable, and sufficiently thick to provide
storage space;
b) the surface soil should be permeable and have high infiltration rate;
c) vadose zone should be permeable and free from clay lenses;
d) ground water levels in the phreatic zone should be deep so as to accommodate the recharged water
without water logging;
e) the aquifer material should have moderate hydraulic conductivity so that the recharged water
is retained for sufficiently long periods in the aquifer and can be used when needed as natural
repositories.
The most common surface spreading techniques used for artificial recharge to ground water are
flooding, ditch and furrow, recharge basins, runoff conservation structures, and stream modifications.
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4.1.1 Flooding
This technique is ideal for lands adjoining rivers or irrigation canals in which water levels remain deep
even after monsoons and where sufficient non-committed surface water supplies are available. The
schematics of a typical flooding system are shown in Figure 2. To ensure proper contact time and water
spread, embankments are provided on two sides to guide the unutilized surface water to a return canal
to carry the excess water to the stream or canal.
Flooding method helps reduce the evaporation losses from the surface water system, is the least
expensive of all artificial recharge methods available, and has very low maintenance costs.
4.1.2 Ditch and furrows method
This method involves construction of shallow, flat-bottomed, and closely spaced ditches or furrows to
provide maximum water contact area for recharge from source stream or canal. The ditches should
have adequate slope to maintain flow velocity and minimum deposition of sediments. The widths of
the ditches are typically in the range of 0,30 m to 1,80 m. A collecting channel to convey the excess
water back to the source stream or canal should also be provided. Figure 3 shows a typical plan of
a series of furrows originating from a supply ditch and trending down the topographic slope toward
the stream. Though this technique involves less soil preparation when compared to recharge basins
and is less sensitive to silting, the water contact area seldom exceeds 10 % of the total recharge area.
Three common patterns viz. lateral ditch pattern, dendritic pattern, and contour pattern are detailed as
follows and shown in Figure 4:
a) Lateral ditch pattern: the water from the stream is diverted to the feeder canal/ditch from which
smaller ditches are taken out at right angles. The rate of flow of water from the feeder canal to
these ditches is controlled by gate valves. The furrow depth is determined in accordance with the
topography and to ensure that maximum wetted surface is available along with maintenance of
uniform velocity. The excess water is routed to the main stream through a return canal along with
the residual silt.
b) Dendritic pattern: water from the stream can be diverted from the main canal into a series of smaller
ditches spread in a dendritic pattern. The bifurcation of ditches continues until practically all the
water is infiltrated into the ground.
c) Contour pattern: ditches are excavated following the ground surface contour of the area. When a
ditch comes close to the stream, a switch back is made to meander back and forth to traverse the
spread repeatedly. At the lowest point downstream, the ditch joins the main stream, returning the
excess water to it.
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Key
1 stream
2 direction of flow
3 return flow
4 delivery canal
5 sheet flow
6 embankment
Figure 2 — Schematics of a typical flood recharge system
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Key
1 stream
2 diversion structure
3 gate and measuring device
4 various recharge ditches
5 supply ditch
6 alternate diversion
7 supply ditch
8 wire bound check dam
9 collecting ditch
10 measuring device
11 prevailing ground slope
12 ditch
Figure 3 — Schematics of a typical ditch and furrows recharge system
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ISO/TR 13973:2014(E)
Key
1 stream
2 diversion structure
3 control ditch
A lateral ditch pattern
B dendritic ditch pattern
C contour ditch pattern
Figure 4 — Common patterns of ditch and furrow recharge systems
4.1.3 Recharge basins
Artificially recharged basins are commonly constructed parallel to ephemeral or intermittent stream
channels and are either excavated or are enclosed by dykes and levees. They can also be constructed
parallel to canals or surface water sources. In alluvial areas, multiple recharge basins can be constructed
parallel to the streams (see Figure 5), with a view to increase the water contact time, reduce suspended
material as water flows from one basin to another, and to facilitate periodic maintenance such as
scraping of silt, etc. to restore the infiltration rates by bypassing the basin under restoration.
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Key
1 stream
2 diversion structure
3 cut fall
4 fence as required
5 intake structure
6 sediment retention basin
7 main entrance road on levees as required
8 recharge basin
9 interbasin control structure
Figure 5 — Schematics of a typical recharge basin
In addition to the general design guidelines mentioned, other factors to be considered while constructing
recharge basins include the following:
a) area selected for recharge should have gentle ground slope;
b) the entry and exit points for water should be diagonally opposite to facilitate adequate water
circulation in individual basins;
c) water released into the basins should be as sediment-free as possible;
d) rate of inflow into the basin should be slightly more than the infiltration capacity of all the basins.
The water contact area in recharge basin is normally high and may range from 75 % to 90 % of the total
recharge area. It is also possible to make efficient use of space by making basins of different shapes to
suit the terrain conditions and available space.
4.1.4 Runoff conservation structures
These are normally multi-purpose measures, mutually complementary, and conducive to soil and
water conservation, afforestation, and increased agricultural productivity. They are suitable in areas
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receiving low to moderate rainfall mostly during a single monsoon season and having little or no scope
for transfer of water from other areas. Different measures applicable to runoff zone, recharge zone,
and discharge zone are available. The structures commonly used are bench terracing, contour bunds,
contour trenches, gully plugs, check dams, and percolation tank.
4.1.4.1 Bench terracing
Bench terracing involves levelling of sloping lands with surface gradients up to 8 %and having adequate
soil cover for bringing them under irrigation. It helps in soil conservation and holding runoff water on
the terraced area for longer durations, leading to increased infiltration and ground water recharge.
For implementing terracing, a map of the watershed should be prepared by level surveying and suitable
benchmarks fixed. A contour map of 0,3 m contour interval is then prepared. Depending on the land
slope, the width of individual terrace should be determined, which, in no case, should be less than 12 m.
The upland slope between two terraces should not be more than 1:10 and the terraces should be levelled.
The vertical elevation difference and width of terraces are controlled by the land slope. The soil and
weathered rock thickness, elevation difference, and the distance between the bunds of two terraces for
different slope categories are furnished in Table 1.
In cases where there is a possibility of diverting surface runoff from local drainage for irrigation, as
in case of paddy cultivation in high rainfall areas, outlet channels of adequate dimensions are to be
provided. The dimensions of the outlet channels depend on the watershed area as shown in Table 2. The
terraces should also be provided with bunds of adequate dimensions depending on the type of soils as
shown in Table3.
Table 1 — Soil thickness, vertical difference and distance between bunds of two terraces for
different slopes
Land slope Thickness of soil and Vertical separation Distance between
% weathered rock m bunds of two terraces
m m
1 0,30 0,30 30
2 0,375 0,45 22
3 0,450 0,60 20
4 0,525 0,75 18,75
5 0,600 0,90 18
6 0,750 1,05 17,5
7 0,750 1,20 17
8 0,750 1,20 15
[1]
Source: Manual on Artificial Recharge of Ground Water, Central Ground Water Board, India, 2007.
Table 2 — Dimensions of output channels for different watershed areas
Area of watershed Channel dimensions (m)
ha
Base width Top width Depth
<4 0,30 0,90 0,60
4 to 6 0,60 1,20 0,60
6 to 8 0,90 1,50 0,60
8 to 10 1,20 1,80 0,60
10 to 12 1,50 2,10 0,60
[1]
Source: Manual on Artificial Recharge of Ground Water, Central Ground Water Board, India, 2007.
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Table 3 — Dimensions of terraces in different soil types
Soil thickness Base width Top width Height Side slope
cm m m
m
7,50 to 22,50 1,50 0,30 0,60 1:1
22,50 to 45,00 1,80 0,45 0,65 1:1
45,00 to 90,00 2,25 0,45 0,75 1:1
>90,00 2,50 0,50 0,80 1:1
[1]
Source: Manual on Artificial Recharge of Ground Water, Central Ground Water Board, India, 2007.
In areas where paddy is cultivated, water outlets of adequate dimensions are to be provided to drain out
excess accumulated water and to maintain water circulation. The width of the outlets may vary from
0,60 m for watersheds up to 2 ha to 3,0 m for watersheds of up to 8 ha generally for rainfall intensity
between 7,5 cm and 10 cm. All the outlets should be connected to natural drainage channels.
4.1.4.2 Contour Bunds
Contour bunding is a watershed management practice which is aimed at building up soil moisture
storage involving construction of small embankments or bunds across the slope of the land. They derive
their names from the construction of bunds along contours of equal land elevation. This technique is
generally adopted in low rainfall areas (normally less than 800 mm per annum) where gently sloping
agricultural lands with very long slope lengths are available and the soils are permeable. They are not
recommended for soils with poor internal drainage e.g. clayey soils. Schematic of a typical system of
contour bunds is shown in Figure 6.
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Key
1 bund
2 trench
A plan view
B section view
Figure 6 — Schematics of a contour bund
Contour bund is a construction of narrow-based trapezoidal embankments (bunds) along contours to
impound water behind them, which infiltrates into the soil and ultimately augment ground water recharge.
Field activities required prior to contour bund include levelling of land by removing local ridges and
depressions, preparation of map of the area through level surveying and fixing of bench marks. Elevation
contours, preferably of 0,3 m interval are then drawn, leaving out areas not requiring bunding such as
habitations, drainage, etc. The alignment of bunds should then be marked on the map.
The important design aspects of contour bunds are
a) spacing,
b) cross section, and
c) deviation freedom to go higher or lower than the contour bund elevation for better alignment on
undulating land.
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4.1.4.2.1 Spacing of bunds
Spacing of contour bund is commonly expressed in terms of vertical interval (V.I), which is defined as
the difference in elevation between two similar points on two consecutive bunds. The main criterion for
spacing of bunds is to intercept the water before it attains the erosive velocity. Spacing depends on slope,
[1]
soil, rainfall, cropping pattern and conservation practices.
Spacing of contour bunds is normally calculated using Formula (1):
Vertical IntervalV.I =+0,305 XS Y (1)
() ()
where
X is the rainfall factor;
S is the land slope (%);
Y is the factor based on soil infiltration and crop cover during the erosive period of rains.
The rainfall factor “X” is taken as 0,80 for scanty rainfall regions with annual rainfall below 625 mm, as
0,60 for moderate rainfall regions with annual rainfall in the range of 625 mm to 875 mm and as 0,40 for
areas receiving annual rainfall in excess of 875 mm. The factor “Y” is taken as 1,0 for soils having poor
infiltration with low crop cover during erosive rains and as 2,0 for soils of medium to good infiltration
and good crop cover during erosive rains. When only one of these factors is favourable, the value of
Y is taken as 1,50. Vertical spacing can be increased by 10 % or 15 cm to provide better location and
alignment or to avoid obstacles.
The horizontal interval between two bunds is calculated using Formula (2):
Horizontal IntervalH.I =×V.IS100 lope (2)
()
4.1.4.2.2 Cross section of contour bund
A trapezoidal cross section is usually adopted for the bund. The design of the cross section involves
determination of height, top width, side slopes, and bottom width of the bund.
The height of the bund depends on the slope of the land, spacing of the bunds, and the rainfall excess
expected in 24 h period for 10 year frequency in the area. Once the height is determined, other dimensions
can be worked out depending on the nature of the soil.
Height of the bund can be determined by the following methods:
a) Arbitrary Design: The depth of impounding is designed as 30 cm. 30 cm is provided as depth flow
over the crest of the outlet weir and 20 cm is provided as free board. The overall height of the bund
in this case will be 80 cm. With top width of 0,50 m and base width of 2 m, the side slope will be 1:1
2
and the cross section, 1 m .
b) The height of bund to impound runoff from 24 h rain storm for a given frequency can be calculated
[1]
by Formula (3):
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Re×V.I
H= (3)
50
where
H is the depth of impounding behind the bund (m);
Re is the 24 h rainfall excess (m);
VI is the vertical interval (m).
To the height so computed, 20 % extra height or a minimum of 0,15 m is added for free board and another
15 % to 20 % extra height is added to compensate for the settlement due to consolidation.
Top width of the bund is normally kept as 0,3 m to 0,6 m to facilitate planting of grasses. Side slopes of
the bund are dependent on the angle of repose of the soil in the area and commonly range from 1:1 for
clayey soils to 2:1 for sandy soils. Base width of the bund depends on the hydraulic gradient of the water
in the bund material due to the impounding water. A general value of hydraulic gradient adopted is 4:1.
The base should be sufficiently wide so that the seepage line should not appear above the toe on the
downstream side of the bund.
Size of the bund is expressed in terms of its cross-sectional area. The cross sectional area of bunds depends
2 2
on the soil type and rainfall and may vary from 0,50 m to 1,0 m in different regions. Recommended
contour bund specifications for different soil depths are shown in Table 4.
Table 4 — Recommended contour bund specifications for different soil depths
Soil type Soil depth Top Bottom Height Side Area of
m width width m slope Cross section
2
m m m
Very shallow soils <7,5 0,45 1,95 0,75 1:1 0,09
Shallow soils 7,50 to 23,0 0,45 2,55 0,83 1,25:1 1,21
Medium soils 23,0 to 45,0 0,53 3,00 0,83 1,50:1 1,48
Deep soils 45,0 to 80,0 0,60 4,20 0,90 2:1 2,22
[1]
Source: Manual on Artificial Recharge of Ground Water, Central Ground Water Board, India, 2007.
The length of bunds per hectare of land is denoted by the bunding intensity, which can be computed
using Formula (4):
100 S
Bunding Intensity= (4)
V.I
where
−1
Bunding is the length of bunds per hectare of land (m );
Intensity
S is the land slope (%);
V.I is the vertical interval (m).
The earthwork for contour bund includes the main contour bund and side and lateral bunds. The area
of cross-section of side and lateral bunds is taken equal to the main contour bund. The product of
cross sectional area of the bund and the bund intensity gives the quantity of earthwork required for
bunding/hectare of land.
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Deviation Freedom: Strict adherence to contours while constructing bunds is a necessary prerequisite
for ensuring maximum conservation of moisture and soil. However, to avoid excessive curvature of
bunds, which makes agricultural operations difficult, the following deviations are permitted:
a) maximum of 15 cm while cutting across a narrow ridge;
b) maximum of 30 cm while crossing a gully or depression;
c) maximum of 1,5 m while crossing a sharp, na
...
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